Question:
I’m looking for a schematic for a 1970 Sunn Sceptre. I’ve checked all the obvious sources and although there are plenty of Sceptre schematics out there, they are all the same…. and all of the late ’60s model, which is slightly different. The most notable visual difference in the 1970 model is the addition of a mid boost switch on the front panel. Schematic-wise, the power supply, power amp, and 1st input stage are identical, but the tone stack is different and the solidstate reverb/tremolo board is different. The differences are not so drastic as to make restoration impossible, but is does add a layer of frustration. The physical layout, point to point terminal strip to tube socket and neatly laced wiring harness will make drawing this circuit difficult. Any info on this amp would be much appreciated. BTW, the amp works but I just want a valid schematic to check everything in detail. ….Thanks, Steve
Response:
- Hide quoted text — Show quoted text – > I’m looking for a schematic for a 1970 Sunn Sceptre. I’ve checked all the > obvious sources and although there are plenty of Sceptre schematics out > there, they are all the same…. and all of the late ’60s model, which is > slightly different. > The most notable visual difference in the 1970 model is the addition of a > mid boost switch on the front panel. Schematic-wise, the power supply, power > amp, and 1st input stage are identical, but the tone stack is different and > the solidstate reverb/tremolo board is different. > The differences are not so drastic as to make restoration impossible, but is > does add a layer of frustration. The physical layout, point to point > terminal strip to tube socket and neatly laced wiring harness will make > drawing this circuit difficult. > Any info on this amp would be much appreciated. BTW, the amp works but I > just want a valid schematic to check everything in detail. > ….Thanks, Steve
Have you tried checking for Solaris schematics? They had a similar or same separate reverb/trem board. Tone stack might be the same too, I don’t remember for sure. Here’s an obscure tip for you, if you check the layout of those amps, *all* of the preamp signal is forced through that SS verb/trem board, and it sucks gain and tone. I once bought a Solaris that was modified with a mini switch in one input jack hole; to bypass that whole board. The result was an amazing boost in gain and tone. Of course, while in that mode the "effects" didn’t work. I may still have drawings and pictures of the circuit around here if you’re interested. Regards, John King
Response:
– Hide quoted text — Show quoted text -> I’m looking for a schematic for a 1970 Sunn Sceptre. I’ve checked all the > obvious sources and although there are plenty of Sceptre schematics out > there, they are all the same…. and all of the late ’60s model, which is > slightly different. > The most notable visual difference in the 1970 model is the addition of a > mid boost switch on the front panel. Schematic-wise, the power supply, > power amp, and 1st input stage are identical, but the tone stack is > different and the solidstate reverb/tremolo board is different. > The differences are not so drastic as to make restoration impossible, but > is does add a layer of frustration. The physical layout, point to point > terminal strip to tube socket and neatly laced wiring harness will make > drawing this circuit difficult. > Any info on this amp would be much appreciated. BTW, the amp works but I > just want a valid schematic to check everything in detail. > ….Thanks, Steve > Have you tried checking for Solaris schematics? They had a similar > or same separate reverb/trem board. Tone stack might be the same too, > I don’t remember for sure.
Hi John. Yes, I’ve checked all the different models. No help. I finally gave up looking and just drew it out. Here’s a copy. And I’ve also sent a copy to Larry’s schematic heaven. Take a look…. http://home.comcast.net/~seluckey/sceptre.pdf > Here’s an obscure tip for you, if you check the layout of those amps, > *all* of the preamp signal is forced through that SS verb/trem board, > and it sucks gain and tone.
Yes, the signal does pass thru the R/T board…., but only thru the LDR in the tremolo ‘roach’. Sure, that knocks the signal down, but it’s simply a series variable resistor that cannot suck tone. Unlike the Fender shunt type roach, Sunn choose to use a series application, hence the ‘pass thru’. However, the signal loss is very well compensated in other ares of the amp. I’ve never heard anyone say my ‘old’ Sunn is not loud enough! Unless it was broken. > I once bought a Solaris that was modified with a mini switch in one > input jack hole; to bypass that whole board. The result was an amazing > boost in gain and tone. Of course, while in that mode the "effects" > didn’t work. I may still have drawings and pictures of the circuit > around here if you’re interested.
Yes, it would be very easy to bypass the tremolo circuit. A 1/2′ jumper on a terminal strip in the preamp is all it would take. Or you could run shielded cables to a switch to do this. I don’t doubt that the tone changed when you bypassed your trem, but I suspect it was due to the huge signal level (gain) increase that in turn just over drove the already high gain 6AN8 amp following the tone stack. The Sunn amps were built to be clean, warm, but powerful sounding amps. Anyone who wanted distortion just put a pedal in front of it. One more obscure point… The reverb recovery amp is a single transistor. I’m not too keen on the Sunn reverb anyway. That single transistor is the only silicon in the reverb path and the main signal path is pure tube. Thanks for your interest….Steve – Hide quoted text — Show quoted text -> Regards, > John King
Response:
- Hide quoted text — Show quoted text ->> I’m looking for a schematic for a 1970 Sunn Sceptre. I’ve checked all the >> obvious sources and although there are plenty of Sceptre schematics out >> there, they are all the same…. and all of the late ’60s model, which is >> slightly different. >> The most notable visual difference in the 1970 model is the addition of a >> mid boost switch on the front panel. Schematic-wise, the power supply, >> power amp, and 1st input stage are identical, but the tone stack is >> different and the solidstate reverb/tremolo board is different. >> The differences are not so drastic as to make restoration impossible, but >> is does add a layer of frustration. The physical layout, point to point >> terminal strip to tube socket and neatly laced wiring harness will make >> drawing this circuit difficult. >> Any info on this amp would be much appreciated. BTW, the amp works but I >> just want a valid schematic to check everything in detail. >> ….Thanks, Steve > Have you tried checking for Solaris schematics? They had a similar > or same separate reverb/trem board. Tone stack might be the same too, > I don’t remember for sure. > Hi John. Yes, I’ve checked all the different models. No help. I finally gave > up looking and just drew it out. Here’s a copy. And I’ve also sent a copy to > Larry’s schematic heaven. Take a look…. > http://home.comcast.net/~seluckey/sceptre.pdf > Here’s an obscure tip for you, if you check the layout of those amps, > *all* of the preamp signal is forced through that SS verb/trem board, > and it sucks gain and tone. > Yes, the signal does pass thru the R/T board…., but only thru the LDR in > the tremolo ‘roach’. Sure, that knocks the signal down, but it’s simply a > series variable resistor that cannot suck tone. Unlike the Fender shunt type > roach, Sunn choose to use a series application, hence the ‘pass thru’. > However, the signal loss is very well compensated in other ares of the amp. > I’ve never heard anyone say my ‘old’ Sunn is not loud enough! Unless it was > broken. > I once bought a Solaris that was modified with a mini switch in one > input jack hole; to bypass that whole board. The result was an amazing > boost in gain and tone. Of course, while in that mode the "effects" > didn’t work. I may still have drawings and pictures of the circuit > around here if you’re interested. > Yes, it would be very easy to bypass the tremolo circuit. A 1/2′ jumper on a > terminal strip in the preamp is all it would take. Or you could run shielded > cables to a switch to do this. I don’t doubt that the tone changed when you > bypassed your trem, but I suspect it was due to the huge signal level > (gain) increase that in turn just over drove the already high gain 6AN8 amp > following the tone stack. The Sunn amps were built to be clean, warm, but > powerful sounding amps. Anyone who wanted distortion just put a pedal in > front of it. > One more obscure point… The reverb recovery amp is a single transistor. > I’m not too keen on the Sunn reverb anyway. That single transistor is the > only silicon in the reverb path and the main signal path is pure tube. > Thanks for your interest….Steve > Regards, > John King
Steve, Sorry it has taken so long to respond. I forgot to mark this thread. Thanks for the nice drawing. The few of Sunn Heads I’ve had were Sonoro, Sorado and a Solaris. I got the 6550 powered Sonoro first, and though it was killer, but it didn’t have reverb… So I sold it to Walter Campbell. Bought the Solaris with the bypass switch for reverb & tremolo. It had EL-34s and only sounded ok to me at best; but the bypass mod really was a significant boost in tone and gain, almost into the range of a "high gain" amp. Simple, and certainly worthwhile for anyone into such tone, but as you said, the warm clean was what I appreciated about them. The last one I had was a Sorado that had KT-88s in it, though probably came from the factory with 6550s. At any rate, it sounded great. I’ll have another one of these days if the right deal comes along on a keeper. I should have kept the KT-88 equipped one. Oh, and the guy that did the "mod" on the Solaris… didn’t use properly terminated (grounded) shielded wire in the circuit, so it was a little more noisy that it might otherwise have been. Like I said though, worth the trouble for anyone that wants to be able to get a "high gain" sound our of one of the effects equipped Sunns without having to resort to a pedal. Regards, John King
Response:
> Steve, > Sorry it has taken so long to respond. I forgot to mark > this thread. Thanks for the nice drawing.
You’re welcome John. BTW, I made some minor labeling corrections to the drawing. If yours shaws a 12AU7 for the preamp and 330VAC on the PT, you may want to d/l the updated schematic. The wiring remains the same. > The few of Sunn Heads I’ve had were Sonoro, Sorado and > a Solaris. I got the 6550 powered Sonoro first, and though
My first amp project (still in trade school!) back in ‘68 was a Sunn Sonora Bass amp. That thing served me for 4 years doubling as a guitar and bass rig. It later became the PA and phono amp at the local skating rink. I even have an old polaroid of that amp…. http://home.comcast.net/~seluckey/tdr/1st_build.jpg And if you’re interested, here’s the link to my Tweed Deluxe Reverb page again. I’ve done the final upgrades to that project, but also spun off another project, L’il Sister. Check the link near the bottom of the page. You’ll also see all the stuff I have to walk around in my bedroom. ;>) http://home.comcast.net/~seluckey/tdr/tdr.htm This stuff really is addictive! ….Steve
Response:
Question:
>Little Ice Age
<snip> >Burroughs (Weather, 1981) analyses the depiction of winter in paintings. >He notes that this occurred almost entirely from 1565 to 1665, and was >associated with the climatic decline from 1550 onwards. He notes that >before this there were almost no depictions of winter in art, and >hypothesises that the unusually harsh winter of 1565 inspired great >artists to depict highly original images, and the decline in such >paintings was a combination of the "theme" having been fully explored, >and mild winters interrupting the flow of painting. >The famous winter paintings by Pieter Brueghel the Elder (e.g. Hunters >in the Snow)
I have art-book copies of three Brueghels on my computer-room walls, and that’s one of them. The others are the equally famous peasant wedding and peasant dance. <snip> – Hide quoted text — Show quoted text ->Indoarsman >www.Frys.com
Response:
>From the Wikipedia article "Scientists have identified two causes of
the Little Ice Age from outside the ocean/atmosphere/land systems: decreased solar activity and increased volcanic activity" This is a most interesting article. It would indicate that increased solar activity and decreased volcanic activity could be the cause of our current warming, if it is indeed occuring.
Response:
>>From the Wikipedia article "Scientists have identified two >causes of > the Little Ice Age from outside > the ocean/atmosphere/land systems: decreased solar activity > and increased volcanic activity" > This is a most interesting article. It would indicate that > increased solar activity and decreased volcanic activity > could be the cause of our current warming, if it is indeed > occuring.
It even allows for GW to be caused by EVIL HUMANS. Of course these evil humans are the environmentalists who forced the power companies to stop emitting carbon soot. The particulates caused a cooling behavior in the major cities, With the air clean, the temperature of the cities increased. Up until the enviros got acive, the concensus in the scientific community was that we were entering a new Ice Age, with predictions of Canada and England under a mile of ice. There really is an unbelievable shortage of good data to make a determination. Not that activists need data to put forth a scare story. Remember that warming trends have been observed on most of the planets and moons with atmospheres. And only one has a human population.
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> Remember that warming trends have been observed on most of the > planets and moons with atmospheres. And only one has a human > population.
I did not realize that this warming was also observed on other planets and moons. Seems like it must be sun activity, then.
Response:
Little Ice Age From Wikipedia, the free encyclopedia The Little Ice Age (LIA) was a period of cooling lasting approximately from the 14th to the mid-19th centuries, although there is no generally cooler period occurs after a warmer era known as the Medieval climate optimum. There were three minima, beginning about 1650, about 1770, and 1850, each separated by slight warming intervals [1]. It was initially believed that the LIA was a global phenomenon; it is now less clear that this is true. See Medieval climate optimum for more on this. The IPCC, based on Bradley and Jones, 1993; Hughes and Diaz, 1994; Crowley and Lowery, 2000 describes the LIA as a modest cooling of the Northern Hemisphere during this period of less than 1
Question:
Those words were spoken by Jimmy Carter in 1977: "President Jimmy Carter made energy policy the centerpiece of his administration. He notoriously declared on April 18, 1977, that achieving energy independence was the "moral equivalent of war." In August of that year, Carter signed the law creating the United States Department of Energy, intended to manage America’s energy crisis. In late 1978, the beginning of the Iranian revolution caused a shortfall in oil exports, and prices doubled over the next couple of years. Carter, wearing a sweater on national television, urged Americans to turn down their thermostats. "Beginning this moment, this nation will never use more foreign oil than we did in 1977-never," Carter declared in his nationally televised speech on July 15, 1979. He proposed a sweeping $142 billion energy plan which would achieve energy independence by 1990. Part of his plan included the "creation of this nation’s first solar bank, which will help us achieve the crucial goal of 20 percent of our energy coming from solar power by the year 2000." Carter imposed an import quota of 8.5 million barrels of oil per day and created the $20 billion Synfuels program, which was supposed to produce 2.5 million barrels of synthetic fuels per day by 1990. To his credit, Carter did begin to dismantle Nixon’s crude oil price controls. (Auto aside: In his 1979 speech Carter warned: Citizens who insist on driving large, unnecessarily powerful cars must expect to pay more for that luxury.)" G.W. Bush in 2006: "America is addicted to oil, which is often imported from unstable parts of the world," Bush said as he sought to drive the election-year agenda in his annual State of the Union address. Carter & Ford (1975 Energy Policy and Conservation Act) were right back then. But the American people elected a cowboy in 1980 and all was undone. I used to buy Ethanol gas in the late 70’s but it soon became unavailable after Reagan took over. I believe Reagan also wanted to dismantle the DOE. Carter was right back then but Americans were too young & immature to listen. We still are that way today IMO & we’ll pay the price for it very soon. We would have been free of Mideast Oil Carter’s plan was implemented. Think about it. Mr Soul Proud Democrat
Response:
Once again you prove you are an IGNORANT FUCK! We were burning off gas during that so called energy crisis. Jimmy Carter promised us $1.00 a gal gas & delivered it. There never was a shortfall. The oil companies <<< all of them, made their 1st move. You need to learn to read.
– Hide quoted text — Show quoted text -> Those words were spoken by Jimmy Carter in 1977: > "President Jimmy Carter made energy policy the centerpiece of his > administration. He notoriously declared on April 18, 1977, that > achieving energy independence was the "moral equivalent of war." In > August of that year, Carter signed the law creating the United States > Department of Energy, intended to manage America’s energy crisis. > In late 1978, the beginning of the Iranian revolution caused a > shortfall in oil exports, and prices doubled over the next couple of > years. Carter, wearing a sweater on national television, urged > Americans to turn down their thermostats. "Beginning this moment, this > nation will never use more foreign oil than we did in 1977-never," > Carter declared in his nationally televised speech on July 15, 1979. > He proposed a sweeping $142 billion energy plan which would achieve > energy independence by 1990. Part of his plan included the "creation of > this nation’s first solar bank, which will help us achieve the crucial > goal of 20 percent of our energy coming from solar power by the year > 2000." Carter imposed an import quota of 8.5 million barrels of oil per > day and created the $20 billion Synfuels program, which was supposed to > produce 2.5 million barrels of synthetic fuels per day by 1990. To his > credit, Carter did begin to dismantle Nixon’s crude oil price controls. > (Auto aside: In his 1979 speech Carter warned: Citizens who insist on > driving large, unnecessarily powerful cars must expect to pay more for > that luxury.)" > G.W. Bush in 2006: > "America is addicted to oil, which is often imported from unstable > parts of the world," Bush said as he sought to drive the election-year > agenda in his annual State of the Union address. > Carter & Ford (1975 Energy Policy and Conservation Act) were right back > then. But the American people elected a cowboy in 1980 and all was > undone. I used to buy Ethanol gas in the late 70’s but it soon became > unavailable after Reagan took over. I believe Reagan also wanted to > dismantle the DOE. > Carter was right back then but Americans were too young & immature to > listen. We still are that way today IMO & we’ll pay the price for it > very soon. We would have been free of Mideast Oil Carter’s plan was > implemented. Think about it. > Mr Soul > Proud Democrat
Response:
– Hide quoted text — Show quoted text -> Those words were spoken by Jimmy Carter in 1977: > "President Jimmy Carter made energy policy the centerpiece of his > administration. He notoriously declared on April 18, 1977, that > achieving energy independence was the "moral equivalent of war." In > August of that year, Carter signed the law creating the United States > Department of Energy, intended to manage America’s energy crisis. > In late 1978, the beginning of the Iranian revolution caused a > shortfall in oil exports, and prices doubled over the next couple of > years. Carter, wearing a sweater on national television, urged > Americans to turn down their thermostats. "Beginning this moment, this > nation will never use more foreign oil than we did in 1977-never," > Carter declared in his nationally televised speech on July 15, 1979. > He proposed a sweeping $142 billion energy plan which would achieve > energy independence by 1990. Part of his plan included the "creation of > this nation’s first solar bank, which will help us achieve the crucial > goal of 20 percent of our energy coming from solar power by the year
hydrogen is the answer to oil… NOT solar energy. solar should not be discarded, but it is clearly just a blip on the screen unless you live here in Arizona, and even then the base investment would be huge with miniscule results. hydrogen is an unlimited energy source. hydrogen is the answer. – Hide quoted text — Show quoted text -> 2000." Carter imposed an import quota of 8.5 million barrels of oil per > day and created the $20 billion Synfuels program, which was supposed to > produce 2.5 million barrels of synthetic fuels per day by 1990. To his > credit, Carter did begin to dismantle Nixon’s crude oil price controls. > (Auto aside: In his 1979 speech Carter warned: Citizens who insist on > driving large, unnecessarily powerful cars must expect to pay more for > that luxury.)" > G.W. Bush in 2006: > "America is addicted to oil, which is often imported from unstable > parts of the world," Bush said as he sought to drive the election-year > agenda in his annual State of the Union address. > Carter & Ford (1975 Energy Policy and Conservation Act) were right back > then. But the American people elected a cowboy in 1980 and all was > undone. I used to buy Ethanol gas in the late 70’s but it soon became > unavailable after Reagan took over. I believe Reagan also wanted to > dismantle the DOE. > Carter was right back then but Americans were too young & immature to > listen. We still are that way today IMO & we’ll pay the price for it > very soon. We would have been free of Mideast Oil Carter’s plan was > implemented. Think about it.
you failed to mention that Bush is the first leader to propose hydrogen as an alternative to oil. paul proud american – Hide quoted text — Show quoted text -> Mr Soul > Proud Democrat
Response:
Isn’t hydrogen a little dangerous to use in cars? By you’re missing the point – if we’d followed Carter 30 years ago we would be there now. And we’d probably being using hydrogen, assuming that it will work. So yes – I’ll acknowledge Bush for saving he wants to develop hydrogen energy. But saying & doing are 2 different things. Make no mistake – Bush’s main policy is to find more oil. Mr Soul
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Hey Green Peace – I hope you have Exxon stock. Mr Soul
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- Hide quoted text — Show quoted text -> Those words were spoken by Jimmy Carter in 1977: > "President Jimmy Carter made energy policy the centerpiece of his > administration. He notoriously declared on April 18, 1977, that > achieving energy independence was the "moral equivalent of war." In > August of that year, Carter signed the law creating the United States > Department of Energy, intended to manage America’s energy crisis. > In late 1978, the beginning of the Iranian revolution caused a > shortfall in oil exports, and prices doubled over the next couple of > years. Carter, wearing a sweater on national television, urged > Americans to turn down their thermostats. "Beginning this moment, this > nation will never use more foreign oil than we did in 1977-never," > Carter declared in his nationally televised speech on July 15, 1979. > He proposed a sweeping $142 billion energy plan which would achieve > energy independence by 1990. Part of his plan included the "creation of > this nation’s first solar bank, which will help us achieve the crucial > goal of 20 percent of our energy coming from solar power by the year >hydrogen is the answer to oil… NOT solar energy. solar should not be >discarded, but it is clearly just a blip on the screen unless you live here >in Arizona, and even then the base investment would be huge with miniscule >results. >hydrogen is an unlimited energy source. hydrogen is the answer. > 2000." Carter imposed an import quota of 8.5 million barrels of oil per > day and created the $20 billion Synfuels program, which was supposed to > produce 2.5 million barrels of synthetic fuels per day by 1990. To his > credit, Carter did begin to dismantle Nixon’s crude oil price controls. > (Auto aside: In his 1979 speech Carter warned: Citizens who insist on > driving large, unnecessarily powerful cars must expect to pay more for > that luxury.)" > G.W. Bush in 2006: > "America is addicted to oil, which is often imported from unstable > parts of the world," Bush said as he sought to drive the election-year > agenda in his annual State of the Union address. > Carter & Ford (1975 Energy Policy and Conservation Act) were right back > then. But the American people elected a cowboy in 1980 and all was > undone. I used to buy Ethanol gas in the late 70’s but it soon became > unavailable after Reagan took over. I believe Reagan also wanted to > dismantle the DOE. > Carter was right back then but Americans were too young & immature to > listen. We still are that way today IMO & we’ll pay the price for it > very soon. We would have been free of Mideast Oil Carter’s plan was > implemented. Think about it. >you failed to mention that Bush is the first leader to propose hydrogen as >an alternative to oil.
…after five years of living in the pants of the energy industry and doing everything imaginable to facilitate record profits for them at the expense of the American people and the national economy. He has all the credibility of Gene Simmons giving a lecture on musical integrity or Esteban touting the importance of choosing only top-quality music gear. Posted via TITANnews – Uncensored Newsgroups Access >>>> at http://www.TitanNews.com <<<< -=Every Newsgroup – Anonymous, UNCENSORED, BROADBAND Downloads=-
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Why don’t they just pass a law, saying, I dunno — we havta find more oil in Texas or something like that? Or maybe a law that solar has to
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– Hide quoted text — Show quoted text ->> Those words were spoken by Jimmy Carter in 1977: >> "President Jimmy Carter made energy policy the centerpiece of his >> administration. He notoriously declared on April 18, 1977, that >> achieving energy independence was the "moral equivalent of war." In >> August of that year, Carter signed the law creating the United States >> Department of Energy, intended to manage America’s energy crisis. >> In late 1978, the beginning of the Iranian revolution caused a >> shortfall in oil exports, and prices doubled over the next couple of >> years. Carter, wearing a sweater on national television, urged >> Americans to turn down their thermostats. "Beginning this moment, this >> nation will never use more foreign oil than we did in 1977-never," >> Carter declared in his nationally televised speech on July 15, 1979. >> He proposed a sweeping $142 billion energy plan which would achieve >> energy independence by 1990. Part of his plan included the "creation of >> this nation’s first solar bank, which will help us achieve the crucial >> goal of 20 percent of our energy coming from solar power by the year >hydrogen is the answer to oil… NOT solar energy. solar should not be >discarded, but it is clearly just a blip on the screen unless you live >here >in Arizona, and even then the base investment would be huge with miniscule >results. >hydrogen is an unlimited energy source. hydrogen is the answer. >> 2000." Carter imposed an import quota of 8.5 million barrels of oil per >> day and created the $20 billion Synfuels program, which was supposed to >> produce 2.5 million barrels of synthetic fuels per day by 1990. To his >> credit, Carter did begin to dismantle Nixon’s crude oil price controls. >> (Auto aside: In his 1979 speech Carter warned: Citizens who insist on >> driving large, unnecessarily powerful cars must expect to pay more for >> that luxury.)" >> G.W. Bush in 2006: >> "America is addicted to oil, which is often imported from unstable >> parts of the world," Bush said as he sought to drive the election-year >> agenda in his annual State of the Union address. >> Carter & Ford (1975 Energy Policy and Conservation Act) were right back >> then. But the American people elected a cowboy in 1980 and all was >> undone. I used to buy Ethanol gas in the late 70’s but it soon became >> unavailable after Reagan took over. I believe Reagan also wanted to >> dismantle the DOE. >> Carter was right back then but Americans were too young & immature to >> listen. We still are that way today IMO & we’ll pay the price for it >> very soon. We would have been free of Mideast Oil Carter’s plan was >> implemented. Think about it. >you failed to mention that Bush is the first leader to propose hydrogen as >an alternative to oil. > …after five years of living > in the pants of the energy > industry and doing everything > imaginable to facilitate > record profits for them at > the expense of the American > people and the national > economy. He has all the > credibility of Gene Simmons > giving a lecture on musical > integrity or Esteban touting > the importance of choosing > only top-quality music gear.
soooooooooo, you are now AGAINST energy independance? or do you support the president and hope that this time the country listens and follows his lead to freedom from oil? do YOU own oil stocks?!?!? paul az – Hide quoted text — Show quoted text – > Posted via TITANnews – Uncensored Newsgroups Access > >>>> at http://www.TitanNews.com <<<< > -=Every Newsgroup – Anonymous, UNCENSORED, BROADBAND Downloads=-
Response:
> Isn’t hydrogen a little dangerous to use in cars? > By you’re missing the point – if we’d followed Carter 30 years ago we > would be there now. And we’d probably being using hydrogen, assuming
and maybe we should have. we didn’t. President Bush asks "are we ready to commit to this yet?" > that it will work. So yes – I’ll acknowledge Bush for saving he wants > to develop hydrogen energy. But saying & doing are 2 different things. > Make no mistake – Bush’s main policy is to find more oil.
and yet he is working at direct odds with that idea. Soul, there ISN’T enough oil to sustain the oil industry much longer… certainly not enuff of it where responsible managers can have any say. Oil men are NOT working to protect their industry against alternatives. they will make money off oil until the wells run dry (which is sooner than most of the world thinks). even oil men are looking for alternative energy sources to invest in. take care, paul az – Hide quoted text — Show quoted text -> Mr Soul
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courageously avow: – Hide quoted text — Show quoted text -> Those words were spoken by Jimmy Carter in 1977: > "President Jimmy Carter made energy policy the centerpiece of his > administration. He notoriously declared on April 18, 1977, that > achieving energy independence was the "moral equivalent of war." In > August of that year, Carter signed the law creating the United States > Department of Energy, intended to manage America’s energy crisis. > In late 1978, the beginning of the Iranian revolution caused a > shortfall in oil exports, and prices doubled over the next couple of > years. Carter, wearing a sweater on national television, urged > Americans to turn down their thermostats. "Beginning this moment, this > nation will never use more foreign oil than we did in 1977-never," > Carter declared in his nationally televised speech on July 15, 1979. > He proposed a sweeping $142 billion energy plan which would achieve > energy independence by 1990. Part of his plan included the "creation of > this nation’s first solar bank, which will help us achieve the crucial > goal of 20 percent of our energy coming from solar power by the year
Unfortunately one of the current problems to be overcome is it can take more energy to produce and package hydrogen in a viable form for domestic usage than is realized from the expenditure of the hydrogen’s energy once obtained. I believe the solar equation runs into the same fate, if not more so, at this time. Ken Wilson Supporting the Troops at http://www.resisters.ca http://www.criticalhistory.com/ For the Other Side of Things http://www.whitehouse.org/
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courageously avow: >Isn’t hydrogen a little dangerous to use in cars? >By you’re missing the point – if we’d followed Carter 30 years ago we >would be there now. And we’d probably being using hydrogen, assuming >that it will work. So yes – I’ll acknowledge Bush for saving he wants >to develop hydrogen energy. But saying & doing are 2 different things. > Make no mistake – Bush’s main policy is to find more oil. >Mr Soul
Bush’s main policy is to last 3 more years and start working with daddy to see if Jeb gets to be Presentdink too. Ken Wilson Supporting the Troops at http://www.resisters.ca http://www.criticalhistory.com/ For the Other Side of Things http://www.whitehouse.org/
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And I hope that you have invested in Exxon stock! Mr Soul
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- Hide quoted text — Show quoted text -> …after five years of living > in the pants of the energy > industry and doing everything > imaginable to facilitate > record profits for them at > the expense of the American > people and the national > economy. He has all the > credibility of Gene Simmons > giving a lecture on musical > integrity or Esteban touting > the importance of choosing > only top-quality music gear.
Yeah…and you have to suppose that *he* has been profiting quite well from oil, too. However….I kinda figure that he’s starting to accept the fact that the Iraq gamble is going bust, and the USA is not going to have the strong foothold in the region, and thus, easy access to mid-east oil….as he’d hoped. So now, ol’ Sparky figures it would be a good time to start pushing alternative fuels! "I figger I can get a piece o’ that action, too!" he says. Don’t get me wrong…I agree 100% with the idea…it’s the first intelligent suggestion he’s had in years. But, it’s certainly not *his* idea! Energy analysts have been saying that for a LONG TIME. It’s about time he listened to something someone said. Mike
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Yeah, the govt spent 10 billion or so trying to make shale oil economically feasible. Didn’t work. Same with solar to a lesser degree (less spent, works better, but still not great).
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There’s nothing wrong with "freedom from oil" but saying this is actually aiming pretty low: "Breakthroughs on this and other new technologies will help us reach another great goal: to replace more than 75 percent of our oil imports from the Middle East by 2025. " Most US oil doesn’t come from the Middle East, at most 25% of it (including Saudi Arabia) is Middle Eastern. So he’s saying that US imports on oil from the middle east will go from a current 25% down to around 6%, so reducing by 75% is technically accurate but not as big a deal as it sounds, especially over nearly 20 years. http://www.eia.doe.gov/pub/oil_gas/petroleum/data_publications/compan… — Phil Wilson —-
– Hide quoted text — Show quoted text – <snipped>>> > soooooooooo, you are now AGAINST energy independance? or do you support > the president and hope that this time the country listens and follows his > lead to freedom from oil? > do YOU own oil stocks?!?!? > paul > az
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> Those words were spoken by Jimmy Carter in 1977:
If it were truly important to Democrats why didn’t they pass something like that in Carter’s term, or Clinton’s first term. They had the White House, the House, and the Senate at that time.
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- Hide quoted text — Show quoted text ->>> Those words were spoken by Jimmy Carter in 1977: >>> "President Jimmy Carter made energy policy the centerpiece of his >>> administration. He notoriously declared on April 18, 1977, that >>> achieving energy independence was the "moral equivalent of war." In >>> August of that year, Carter signed the law creating the United States >>> Department of Energy, intended to manage America’s energy crisis. >>> In late 1978, the beginning of the Iranian revolution caused a >>> shortfall in oil exports, and prices doubled over the next couple of >>> years. Carter, wearing a sweater on national television, urged >>> Americans to turn down their thermostats. "Beginning this moment, this >>> nation will never use more foreign oil than we did in 1977-never," >>> Carter declared in his nationally televised speech on July 15, 1979. >>> He proposed a sweeping $142 billion energy plan which would achieve >>> energy independence by 1990. Part of his plan included the "creation of >>> this nation’s first solar bank, which will help us achieve the crucial >>> goal of 20 percent of our energy coming from solar power by the year >>hydrogen is the answer to oil… NOT solar energy. solar should not be >>discarded, but it is clearly just a blip on the screen unless you live >>here >>in Arizona, and even then the base investment would be huge with miniscule >>results. >>hydrogen is an unlimited energy source. hydrogen is the answer. >>> 2000." Carter imposed an import quota of 8.5 million barrels of oil per >>> day and created the $20 billion Synfuels program, which was supposed to >>> produce 2.5 million barrels of synthetic fuels per day by 1990. To his >>> credit, Carter did begin to dismantle Nixon’s crude oil price controls. >>> (Auto aside: In his 1979 speech Carter warned: Citizens who insist on >>> driving large, unnecessarily powerful cars must expect to pay more for >>> that luxury.)" >>> G.W. Bush in 2006: >>> "America is addicted to oil, which is often imported from unstable >>> parts of the world," Bush said as he sought to drive the election-year >>> agenda in his annual State of the Union address. >>> Carter & Ford (1975 Energy Policy and Conservation Act) were right back >>> then. But the American people elected a cowboy in 1980 and all was >>> undone. I used to buy Ethanol gas in the late 70’s but it soon became >>> unavailable after Reagan took over. I believe Reagan also wanted to >>> dismantle the DOE. >>> Carter was right back then but Americans were too young & immature to >>> listen. We still are that way today IMO & we’ll pay the price for it >>> very soon. We would have been free of Mideast Oil Carter’s plan was >>> implemented. Think about it. >>you failed to mention that Bush is the first leader to propose hydrogen as >>an alternative to oil. > …after five years of living > in the pants of the energy > industry and doing everything > imaginable to facilitate > record profits for them at > the expense of the American > people and the national > economy. He has all the > credibility of Gene Simmons > giving a lecture on musical > integrity or Esteban touting > the importance of choosing > only top-quality music gear. >soooooooooo, you are now AGAINST energy independance? or do you support the >president and hope that this time the country listens and follows his lead >to freedom from oil?
I think the President is trying steal long-standing lefty ideas in a vain attempt to improve his limp poll standings and doesn’t have any intention of doing anything that might piss off the big corporations that have always owned him lock, stock, and barrel. Iow, imo it’s just political posturing and he won’t do squat about following through with any practical proposals. If I’m wrong and he proposes something workable, I’ll let you know what I think of it. >do YOU own oil stocks?!?!?
Nope, and no drug company or defense contractor shares either. I am an ethical investor, not an exploiter of my fellow Americans. Posted via TITANnews – Uncensored Newsgroups Access >>>> at http://www.TitanNews.com <<<< -=Every Newsgroup – Anonymous, UNCENSORED, BROADBAND Downloads=-
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Question:
I am sure there are 100 of these a week, but I’ll toss mine in anyhow. I am working on a new web site that is all about energey conservation methods, renewable enegry, etc. Currenlty we don’t have much content, but we’re working on a release date of January ish for some great content, a nice look and feel, etc. I’d love it if you took a moment to check out our forums, http://www.time2conserve.com/forums. BV. www.time2conserve.com
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go for it. took a look at the site and look forward to a long relationship. good to see uk groups n forums. like the vacuum tubes travelogue. am trying work up plans on a new build industrial estate and will post updates. break a leg – Hide quoted text — Show quoted text – > I am sure there are 100 of these a week, but I’ll toss mine in anyhow. I am > working on a new web site that is all about energey conservation methods, > renewable enegry, etc. Currenlty we don’t have much content, but we’re > working on a release date of January ish for some great content, a nice look > and feel, etc. > I’d love it if you took a moment to check out our forums, > http://www.time2conserve.com/forums. > BV. > www.time2conserve.com
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> go for it. took a look at the site and look forward to a long > relationship. good to see uk groups n forums. like the vacuum tubes > travelogue. am trying work up plans on a new build industrial estate > and will post updates. break a leg > I’d love it if you took a moment to check out our forums, > http://www.time2conserve.com/forums.
Thanks for the kind feedback. The look and feel and the content are a bit lame now, but we are working on it. The forums are growing every day, so we’re hoping we can y’all comin back for the conversation at least. BV. www.time2conserve.com
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> go for it. took a look at the site and look forward to a long > relationship. good to see uk groups n forums. like the vacuum tubes > travelogue. am trying work up plans on a new build industrial estate > and will post updates. break a leg
<snip> Also…I wanted to mention one of our pioneer (LOL) forum members is a manufacturer of evacuated tubes. I am sure he’d love to see some conversation about them. We also have a member that is putting huge tube array now. He recently posted the photos of the tubes unloaded from the truck into is garage. We hope to see them on his roof in a few weeks. BV.
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>I am sure there are 100 of these a week, but I’ll toss mine in anyhow. I am >working on a new web site that is all about energey conservation methods, >renewable enegry, etc. Currenlty we don’t have much content, but we’re >working on a release date of January ish for some great content, a nice look >and feel, etc. >I’d love it if you took a moment to check out our forums, >http://www.time2conserve.com/forums. >BV. >www.time2conserve.com
OK, but who are you, who funds it, why the adverts, how impartial is it ? Lastly, what does putting it in yet another ‘100 a week’ web forum offer that expressing yourself in this very news group doesn’t ? Cheers, J/. — John Beardmore
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>I’d love it if you took a moment to check out our forums, >http://www.time2conserve.com/forums. >BV. >www.time2conserve.com > OK, but who are you, who funds it, why the adverts, how impartial is > it ?
Fair questions, all of them. I am just a guy, that over the past year has been geeking out about energy conservation for a number of reasons. I fund the site in full from my wallet, because I am very interested in this topic. The site has not purposeful bias. I am working to collect information about conservation. I try to avoid overtly biased articles, but I do include politics when it seems to fit. The forums of course, are just forums, nothing special there. The original site was inspired by this email, > Lastly, what does putting it in yet another ‘100 a week’ web forum offer > that expressing yourself in this very news group doesn’t ?
I am hoping to make the site a sort of knowledge base on energy topics, from politics to conservation to new ideas. The forums, I hope will add to that base of information. Thanks for asking, and I hope that answers your questions. BV www.time2conserve.com
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Good idea that this site about renewable energy I suggest in the "Solar" chapter, that you speak some words about promoting PV solar via solar powered vehicles and races (for kids or students or hobbyists or organizations ) Solar planes Full : Pathfinder, Challenger, Helios, Bertrand Picard’s plane … RC models Solar Cars Full : WSC in Australia, Sunrayce RC models : SolaRCup in France & Germany, "Defi solaire" (Solar Challenge) Free models : Junior Solar Sprint For Solar powered RC models there is a Yahoo Group named Solar-RC-cars with a lot of links in the group files space + photos Regards Louis
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Thanks, that’s a great idea.
– Hide quoted text — Show quoted text -> Good idea that this site about renewable energy > I suggest in the "Solar" chapter, that you speak some words about > promoting PV solar via solar powered vehicles and races (for kids or > students or hobbyists or organizations ) > Solar planes > Full : Pathfinder, Challenger, Helios, Bertrand Picard’s plane … > RC models > Solar Cars > Full : WSC in Australia, Sunrayce > RC models : SolaRCup in France & Germany, "Defi solaire" (Solar > Challenge) > Free models : Junior Solar Sprint > For Solar powered RC models there is a Yahoo Group named Solar-RC-cars > with a lot of links in the group files space + photos > Regards > Louis
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Question:
I’m interested in installing a solar hotwater system (I’m in Brisbane, Australia). I’m just wondering how well they work, how much do they cut down your power usage for hotwater generation? Also, are you better of with gas or electricity back up, and what are the things to consider in such a case. I would like to install this in a two bedroom unit. Thanks, Lionel.
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Lionel, Have a look at : http://www.retscreen.net/ang/menu.php and download their free Excel program to calculate solar domestic hot water systems. This is from the Canadian Government and it is NOT a commercial web site. They claim to have solar data for the world (but I haven’t checked for Australia). You must know the properties of your solar panels to run this program – it’s really well done. It has the economic calculations too. For me in New England, the saving in energy is typically 60-70% for a 4-person house. Try it out and let us know. Regards. Gilles – Hide quoted text — Show quoted text – > I’m interested in installing a solar hotwater system (I’m in Brisbane, > Australia). I’m just wondering how well they work, how much do they cut > down your power usage for hotwater generation? Also, are you better of > with gas or electricity back up, and what are the things to consider in > such a case. I would like to install this in a two bedroom unit. > Thanks, > Lionel.
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> I’m interested in installing a solar hotwater system (I’m in Brisbane, > Australia). I’m just wondering how well they work, how much do they cut > down your power usage for hotwater generation? Also, are you better of > with gas or electricity back up, and what are the things to consider in > such a case. I would like to install this in a two bedroom unit. > Thanks, > Lionel.
Hi, SolaHart has a software package called SCF that does very detailed solar hot water systems analysis. You can set your city (Brisbane included), and what type of system you are interested in, and it estimates month by month hot water output, energy saving, and greenhouse gas reduction. They used to offer this as a download from their site, but now it is apparently only available through their dealers. You might ask a local SolarHart dealer for a copy. Or, I could email you a copy. — Gary www.BuildItSolar.com "Build It Yourself" Solar Projects —-== Posted via Newsfeeds.Com – Unlimited-Unrestricted-Secure Usenet News==—- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups —-= East and West-Coast Server Farms – Total Privacy via Encryption =—-
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Question:
Does anyone have a good reference for proper spacing of the plate and baffles for a 4X8 air collector? Planning to take air in at one bottom corner and out at the other bottom corner. Plate spaced 2" from back of unit for airflow, 1" spacing between plate and glazing. One main baffle up middle splitting the 4′ width and then a cross baffle every 2′ up the sides, with an 8" opening into next chamber.
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Here are two baffle design ideas. One is just using foam baffles in the air flow. The other uses aluminum angle iron attached to the collector plate. Was thinking this would both act as a baffle and also provide for better heat transfer to the air. Any thought? http://www.corl.ca/drawing1.jpg http://www.corl.ca/drawing2.jpg
– Hide quoted text — Show quoted text -> Does anyone have a good reference for proper spacing of the plate and > baffles for a 4X8 air collector? > Planning to take air in at one bottom corner and out at the other bottom > corner. Plate spaced 2" from back of unit for airflow, 1" spacing between > plate and glazing. One main baffle up middle splitting the 4′ width and > then a cross baffle every 2′ up the sides, with an 8" opening into next > chamber.
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| Here are two baffle design ideas. One is just using foam baffles | in the air flow. The other uses aluminum angle iron attached to | the collector plate. Was thinking this would both act as a baffle | and also provide for better heat transfer to the air. | | Any thought? A bit… It’s probably worth pointing out that the objective is to get heat out of the panel rather than achieve the highest possible temperature inside the panel. Since warm air wants to rise, you’re planning to use electrical power to overcome what mother nature would’ve given you as a gift. High temperatures inside the panel promote losses. Lower temperatures yield higher efficiencies. Baffles aren’t the friends you seem to think they are – seek to maximize the cross-sectional areas of your plenum(s). Angle iron/aluminum is (thermally) massy. If you want to use aluminum as an absorber/heat exchanger, look for minimal thermal mass and high surface area – and try to impede airflow as little as possible. Warning: this is a non-trivial balancing act; but worth the effort to achieve the balance. A lot of experimentation went into the designs at the link below – perhaps you’ll find an idea or two you can use. — Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/collectors.html
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Ideally yes I would take heat put at the top, but where this needs to be mounted that is not an option. I want to have the heat returned into the ground floor and thus need to have the out at bottom. Thanks for the info. The baffles were meant to help disrupt airflow over the flat panel, otherwise I assume it would be too smooth a flow and not extract enough heat. Using the angle iron or flanges was to help again in heat transfer from the plate, not to hold the heat.
– Hide quoted text — Show quoted text – > | Here are two baffle design ideas. One is just using foam baffles > | in the air flow. The other uses aluminum angle iron attached to > | the collector plate. Was thinking this would both act as a baffle > | and also provide for better heat transfer to the air. > | > | Any thought? > A bit… > It’s probably worth pointing out that the objective is to get heat out > of the panel rather than achieve the highest possible temperature > inside the panel. Since warm air wants to rise, you’re planning to use > electrical power to overcome what mother nature would’ve given you as > a gift. > High temperatures inside the panel promote losses. Lower temperatures > yield higher efficiencies. Baffles aren’t the friends you seem to > think they are – seek to maximize the cross-sectional areas of your > plenum(s). > Angle iron/aluminum is (thermally) massy. If you want to use aluminum > as an absorber/heat exchanger, look for minimal thermal mass and high > surface area – and try to impede airflow as little as possible. > Warning: this is a non-trivial balancing act; but worth the effort to > achieve the balance. > A lot of experimentation went into the designs at the link below – > perhaps you’ll find an idea or two you can use. > — > Morris Dovey > DeSoto Solar > DeSoto, Iowa USA > http://www.iedu.com/DeSoto/collectors.html
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> Does anyone have a good reference for proper spacing of the plate and > baffles for a 4X8 air collector? > Planning to take air in at one bottom corner and out at the other bottom > corner. Plate spaced 2" from back of unit for airflow, 1" spacing between > plate and glazing. One main baffle up middle splitting the 4′ width and > then a cross baffle every 2′ up the sides, with an 8" opening into next > chamber.
Hi, You might take a look here: http://www.builditsolar.com/Projects/SpaceHeating/SolAirHtSysBook/Sol… While this dates back a ways, these guys built many, many air collectors, and learned and refined a lot as they went along. Gary www.BuildItSolar.com "Build It Yourself" Solar Projects —-== Posted via Newsfeeds.Com – Unlimited-Unrestricted-Secure Usenet News==—- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups —-= East and West-Coast Server Farms – Total Privacy via Encryption =—-
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> Ideally yes I would take heat put at the top, but where this needs to be > mounted that is not an option. I want to have the heat returned into the > ground floor and thus need to have the out at bottom.
I don’t have any experience with this, so this is just a "thought experiment" observation. If you have to have the intake and outlet at the bottom, I think you’d do better to have a straight shot from the top down to the outlet. In drawing 1, move your vertical divider to the left, so that 85% (wild ass guess) of the collector’s area is to the right. All of your baffles should be in that right-side region. Does that make sense?
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Thanks Gary. I’ll check the link for some info on baffling. In general do you think the tabs/angle iron would be a better option over baffles to both improve heat exchange and provide the baffling?
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Question:
I’ve been looking for 1" foil faced polyiso at the usual suspects (Home Despot and Lowes) and do not seem to find it. I do find 1" foil faced styrofoam and thinner polyiso without the foil. Perhaps these are temporary shortages??? It seems that polyiso has about a 40% greater R value, but are there any other properties of styrofoam that would make it unsuitable for a solar collector? (probably air) Google is is unrevealing as to polyiso vs styrofoam comparisons. I’ve seen some annectdotal comments that make me think polysterene (styrofoam) is more flamable and more water resistant. Resources? Cheers, Jeff
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> I’ve been looking for 1" foil faced polyiso at the usual suspects > (Home Despot and Lowes) and do not seem to find it. I do find 1" foil > faced styrofoam and thinner polyiso without the foil. Perhaps these are > temporary shortages??? > It seems that polyiso has about a 40% greater R value, but are there > any other properties of styrofoam that would make it unsuitable for a > solar collector? (probably air) > Google is is unrevealing as to polyiso vs styrofoam comparisons. I’ve > seen some annectdotal comments that make me think polysterene > (styrofoam) is more flamable and more water resistant. Resources?
I just found this: <URL: http://www.pima.org/technical_bulletins/tb201.pdf > which indicates vastly inferior performance (of styrofoam) at temps over 165 degrees as well as some other nasties. Jeff – Hide quoted text — Show quoted text -> Cheers, > Jeff
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> I’ve been looking for 1" foil faced polyiso at the usual suspects > (Home Despot and Lowes) and do not seem to find it. I do find 1" foil
Perhaps you should try an actual lumberyard. Mine has Celotex in any thickness you’d like, and I’ve been noticing some interesting things as I watch prices there and at HD – for instance, HD has a roll of 9" wide flashing (Vycor) for about the same price that the lumberyard does. But HD’s is 33 feet long, and the lumberyard’s is 75 feet long… — Cats, coffee, chocolate…vices to live by
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> I’ve been looking for 1" foil faced polyiso at the usual suspects (Home > Despot and Lowes) and do not seem to find it. I do find 1" foil faced > styrofoam and thinner polyiso without the foil. Perhaps these are > temporary shortages??? > It seems that polyiso has about a 40% greater R value, but are there any > other properties of styrofoam that would make it unsuitable for a solar > collector? (probably air)
Be careful about the ‘40% greater R value’ claim. Polyiso, *with a foil face* can have a higher R value than polystyrene, but it’s the foil face that makes the difference. I bought some polyiso at Lowes, 1" thick with single foil face. Reading the printed information carefully, I found that it is R-value 5.0 if installed between two other layers, and R-7.6 if installed such that the foil faced a dead air gap. Unless you’re building with a dead air gap between it and another layer of material, you don’t really get the full R-value of 7.6. Unfaced polystyrene is a fire hazard and doesn’t meet building codes in many areas. It’s okay if you’re putting a layer of drywall or sheathing over it or something, but it can’t be left exposed (much like kraft-faced fibreglass batting). Of course, a collector may not be subject to building codes, but there you are. The polyiso I bought didn’t mention if it met fire codes on the un-foiled side, so I don’t know about it. Polystrene probably wouldn’t be the best choice for a collector if you expect to get high temperatures from it, it tends to degrade/soften if heated much past 150F. daestrom
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I use Johns Manville Ap foil faced poly foam,,good to temp 250 f . www.jm.com
– Hide quoted text — Show quoted text -> I’ve been looking for 1" foil faced polyiso at the usual suspects (Home > Despot and Lowes) and do not seem to find it. I do find 1" foil faced > styrofoam and thinner polyiso without the foil. Perhaps these are > temporary shortages??? > It seems that polyiso has about a 40% greater R value, but are there any > other properties of styrofoam that would make it unsuitable for a solar > collector? (probably air) > Be careful about the ‘40% greater R value’ claim. Polyiso, *with a foil > face* can have a higher R value than polystyrene, but it’s the foil face > that makes the difference. I bought some polyiso at Lowes, 1" thick with > single foil face. Reading the printed information carefully, I found that > it is R-value 5.0 if installed between two other layers, and R-7.6 if > installed such that the foil faced a dead air gap. Unless you’re building > with a dead air gap between it and another layer of material, you don’t > really get the full R-value of 7.6. > Unfaced polystyrene is a fire hazard and doesn’t meet building codes in > many areas. It’s okay if you’re putting a layer of drywall or sheathing > over it or something, but it can’t be left exposed (much like kraft-faced > fibreglass batting). Of course, a collector may not be subject to > building codes, but there you are. > The polyiso I bought didn’t mention if it met fire codes on the un-foiled > side, so I don’t know about it. > Polystrene probably wouldn’t be the best choice for a collector if you > expect to get high temperatures from it, it tends to degrade/soften if > heated much past 150F. > daestrom
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>Be careful about the ‘40% greater R value’ claim. Polyiso, *with a foil >face* can have a higher R value than polystyrene, but it’s the foil face >that makes the difference.
I’ve heard most people find the foil’s radiant R-value so confusing to estimate (depending on mean and temp diff, emissivity, orientation, direction of heat flow, and air space dimensions) that the FTC will not allow manufacturers to advertise or mention or count it, even tho it can be estimated with Table 2 on page 22.2 of the 1993 in the ASHRAE HOF (which contains over 800 numbers 
OTOH, the Atlas Energy Shield folk say the foils increase the aged R-value by keeping the gas in the board over time, compared to EPS or Styrofoam. >I bought some polyiso at Lowes, 1" thick with single foil face. Reading >the printed information carefully, I found that it is R-value 5.0 if >installed between two other layers, and R-7.6 if installed such that >the foil faced a dead air gap.
I’m surprised they were allowed to mention that. >Unless you’re building with a dead air gap between it and another layer of >material, you don’t really get the full R-value of 7.6.
With 2 foils and no air gaps, you might get R6.5 from the Atlas product. Nick Article 101464 of alt.energy.renewable: Organization: Villanova University >I "built" a house out of a sturdy cardboard box lying about >and glued 2" foamboard insulation to it. >Added an extra 2" on the bottom. >"Door" opening just big enough to allow cat to enter. >An old blanket on the floor inside for comfort.
This sounds good, especially if the top of the door opening is a few inches below the floor inside (like an igloo) so cat-warmed air won’t leak out. An ASHRAE-standard 6.61 pound cat with a basal heat generation of 27.21 Btu/h could keep a 1′x2′x1′ tall house with 6 ft^2 of exterior walls and ceiling 70 F on a 30 F day if 27.21 = (70-30)6/Rv, with Rv = 8.8 walls, eg 1" "R6.5" double-foil polyiso board with aluminum foil-taped seams. The ASHRAE HOF says a wall surface with a 50 F mean temp and 30 F temp diff and a 3.5" airspace and e = 0.05 has R2.55. A similar ceiling surface with upward heatflow has R2.01, for R2.55+6.5+2.55 = R11.6 walls and an R10.52 ceiling, so G = 4/11.6+2/10.52 = 0.535 Btu/h-F, and the house could be 70 F on a 70-27.21/G = 19 F day. A normally-active or shivering vs basal ASHRAE cat might keep it 70 F on a 70-68.02/G = -57 F day We might add an entrance tunnel and a few tiny clerestory windows, eg 2"x4" holes with 0.020" clear flat polycarbonate taped over each side. Nick
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– Hide quoted text — Show quoted text ->Be careful about the ‘40% greater R value’ claim. Polyiso, *with a foil >face* can have a higher R value than polystyrene, but it’s the foil face >that makes the difference. > I’ve heard most people find the foil’s radiant R-value so confusing > to estimate (depending on mean and temp diff, emissivity, orientation, > direction of heat flow, and air space dimensions) that the FTC will not > allow manufacturers to advertise or mention or count it, even tho it can > be > estimated with Table 2 on page 22.2 of the 1993 in the ASHRAE HOF (which > contains over 800 numbers OTOH, the Atlas Energy Shield folk say > the foils increase the aged R-value by keeping the gas in the board > over time, compared to EPS or Styrofoam. >I bought some polyiso at Lowes, 1" thick with single foil face. Reading >the printed information carefully, I found that it is R-value 5.0 if >installed between two other layers, and R-7.6 if installed such that >the foil faced a dead air gap. > I’m surprised they were allowed to mention that.
Written write on the unfoiled side of the board. Plain as day. >Unless you’re building with a dead air gap between it and another layer of >material, you don’t really get the full R-value of 7.6. > With 2 foils and no air gaps, you might get R6.5 from the Atlas product.
If there’s ‘no air gap’ then the emissivity of the foil becomes pretty much irrelevant. Direct conduction is much higher. In that case I suspect only the R 5.0 for the polyiso is the only relavance. daestrom
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I wonder what the net result is for "trapped air" insulation such a spun wool. Would the thermal conduction apply and the radiant reflection still be defeated, as per the manufacturer’s warnings? I would think they have done thorough testing of different structures.
– Hide quoted text — Show quoted text -> If there’s ‘no air gap’ then the emissivity of the foil becomes pretty much > irrelevant. Direct conduction is much higher. In that case I suspect only > the R 5.0 for the polyiso is the only relavance. > daestrom
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Hi Daestrom;
> If there’s ‘no air gap’ then the emissivity of the > foil becomes pretty much irrelevant. Would you mind giving a citation for this? I have seen this stated a number of times and no where can I find any studies that support this idea. I suspect this is a "wives tail". Nick, can you give us citations pro or con? > daestrom Duane — Home of the $35 Solar Tracker Receiver http://www.redrok.com/led3xassm.htm [*] Powered by //| Thermonuclear Solar Energy from the Sun / | Energy (the SUN) / / | Red Rock Energy / / | Duane C. Johnson Designer / / | 1825 Florence St Heliostat,Control,& Mounts | White Bear Lake, Minnesota === / | USA 55110-3364 === | (651)426-4766 use Courier New Font | http://www.redrok.com (Web site) ===
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> Hi Daestrom; > > If there’s ‘no air gap’ then the emissivity of the > > foil becomes pretty much irrelevant.
I was struck by this also. This seems to have gotten muddled. If we were talking about emissivity then I believe this "radiated loss" is proportional to the temperature difference. The temperature difference in sandwiched material with the foil in the middle, would be small. On the other hand, if this was the last "barrier" before ambient, the tempearture difference would be at it’s greatest and this would be the only place where a low e foil barrier would be usefull. My understanding of this is shaky… There may be more going on as reflection may not equal emissivity. Cheers, Jeff – Hide quoted text — Show quoted text -> Would you mind giving a citation for this? > I have seen this stated a number of times and no where > can I find any studies that support this idea. > I suspect this is a "wives tail". > Nick, can you give us citations pro or con? > > daestrom > Duane
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> > If there’s ‘no air gap’ then the emissivity of the > foil becomes pretty much irrelevant.
I agree. >Nick, can you give us citations pro or con?
Table 2 on page 22.2 of the 1993 ASHRAE HOF covers air gaps down to 0.5", with a footnote a: … Thermal resistance R = 1/C, where C = Hc + EeffHr, Hc is the conduction- convective coefficient, EeffHr is the radiation coefficient ~ 0.00686Eeff[(Tm+460)/100]^3, and Tm is the mean temp of the air space… For extrapolation from Table 2 to air spaces less than 0.5 inches (as in insulating window glass), assume Hc = 0.159(L+0.0016Tm)/L, where L is the air space thickness in inches and Hc is heat transfer through the air space only. So, the surface conductance is the sum of its radiation conductance EeffHr and Hc, which becomes a lot larger than EffHr as L decreases. For instance, with Eeff = 0.05 (1 foil) at 50 F, EffHr = 0.0455 (R22 , but Hc = 0.159(L+0.08)/L, ie 0.17 (R5.8) for L = 1", 0.29 (R3.5) for 0.1", 1.43 (R0.7) for 0.01", and 12.9 (R0.08) for L = 0.001". L Hc EffHr U = Hc+EffHr R = 1/U 1" 0.17 0.0455 0.2155 4.6 0.1" 0.29 0.0455 0.3317 3.0 (surprisingly large) 0.01" 1.43 0.0455 1.4755 0.7 0.001" 12.90 0.0455 12.9455 0.1 Each foil can count, on double-foil foamboard, but 2 facing foils with an air gap only reduce the combined emissivity from 0.05 to 0.03 (1/Eff = 1/E1+1/E2-1) OTOH, 2 foils may retain inert gas longer than 1 foil. Notes b and c say Values apply for ideal conditions, ie air spaces of uniform thickness bounded by plane, smooth, parallel surfaces with no air leakage from the space… Thermal resistance values of multiple air spaces must be based on careful estimates of mean temp differences for each space. A single resistance value cannot account for multiple air spaces; each space requires a separate resitance calculation that applies only for the established boundary conditions. Resistance of horizontal spaces with heat flow downward are sustantially independent of temp diff [and large, eg R8.17 for e = 0.05 with 3.5" and a 50 F mean and 30 F temp diff.] Nick
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> Hi Daestrom; > If there’s ‘no air gap’ then the emissivity of the > foil becomes pretty much irrelevant. > Would you mind giving a citation for this? > I have seen this stated a number of times and no where > can I find any studies that support this idea. > I suspect this is a "wives tail".
Well then, "I suspect" you haven’t studied heat transfer and fluid flow for 30 years like I have 
The heat transfer by radiation between two metal films is orders of magnitude lower than conduction through direction contact between the films. The only reason radiant heat transfer even becomes an issue is because it is on a comparable level with heat transfer through a stagnant air gap (in which internal convection currents are minimal). Two surfaces spaced a modest 1/2 inch apart with emissivity/abortivity of about 0.5, with temperatures of 460 R and 461 R will have a net radiant flux of q’ = emissivity*Stefan-Boltzmann * (461^4 – 460^4) = 0.34 BTU/hr-ft^2 (R-value of 3.0). Even without the metal foil, which would up the emissivity/absorbtance to almost 1.0 (ideal black-body), you only get a radiant heat flux of 0.67 BTU/hr-ft^2 (R-value of 1.5). Compare that with the conductive heat transfer for 2 layers of Al foil for a total of 0.039 inch (1 mm, or 0.0033 ft). Al has a conductance of 136 BTU/hr-ft-R, so the heat flux through the two films when in contact with 1 degree R difference would be q’ = (461-460)*136 / 0.0033 = 41200 BTU/hr-ft^2 (R-value of 2.4e-5) (even worse if you think the Al film might be thinner). So you see the foil layer in direct contact with another surface provides basically no ‘R-value’ at all. Interestingly, if the foil is facing into a room with no other material ’shielding’ it, you have performance in between. In this case, the metalized film does reduce radiant heat transfer slightly over other surface emissivities, but you now have convection heat transfer. And how much heat is transfered by convection can depend on a lot of factors. A second material properly spaced from the metal film, forming an enclosed ‘air-gap’ can minimize convection currents, leaving radiant heat transfer as the only significant factor. But if the metalized film is just exposed to an outside wind of 15 mph, the convection heat losses through the air layer will far exceed the radiant heat losses, regardless of using a low-e metal coating or not. This is the ’state of the art’ with regard to double-pane windows. Conduction and convection heat transfer between the panes has been reduced to the point where radiant heat transfer between the panes is a significant factor. Hence low-e (low emissivity) coatings are applied to the face *between* the panes to reduce the radiant heat-transfer component. "Principles of Heat Transfer 3rd Edition" Frank Kreith is a good source. Or search google for radiant heat transfer. One of the major window manufacturers has a good writeup about how low-e coatings work in their product, but I don’t remember which (Andersen maybe? or the national-fenestration web site (www.nfrc.org)??) daestrom
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I understand there is an associated R value associated with air gaps. However, I would have assumed that the R value of of conventional insulation, say fiber glass, would have been better than that of an air gap. At least for gaps that were greater than the separation of the fibers. What I understood was that the foil on foil backed insulation had a different function. It was to "Reflect" infra red radiation. This reflector can be behind sheet rock which is able to transmit the infra red back to the source. Duane — Home of the $35 Solar Tracker Receiver http://www.redrok.com/led3xassm.htm [*] Powered by //| Thermonuclear Solar Energy from the Sun / | Energy (the SUN) / / | Red Rock Energy / / | Duane C. Johnson Designer / / | 1825 Florence St Heliostat,Control,& Mounts | White Bear Lake, Minnesota === / | USA 55110-3364 === | (651)426-4766 use Courier New Font | http://www.redrok.com (Web site) ===
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Fibregalss is not a great insulation. However air is a good insulaltion when you stop it from transmitting heat by convection. Fibreglass woll makes "trapped air" a good insulation. The foil people state an air gap is needed to reflect the radiant heat. If in contact it is still a metal to conduct the heat very well. – Hide quoted text — Show quoted text -> I understand there is an associated R value associated with > air gaps. However, I would have assumed that the R value of > of conventional insulation, say fiber glass, would have been > better than that of an air gap. At least for gaps that were > greater than the separation of the fibers. > What I understood was that the foil on foil backed insulation > had a different function. It was to "Reflect" infra red > radiation. This reflector can be behind sheet rock which is > able to transmit the infra red back to the source. > Duane > — > Home of the $35 Solar Tracker Receiver > http://www.redrok.com/led3xassm.htm [*] > Powered by //| > Thermonuclear Solar Energy from the Sun / | > Energy (the SUN) / / | > Red Rock Energy / / | > Duane C. Johnson Designer / / | > 1825 Florence St Heliostat,Control,& Mounts | > White Bear Lake, Minnesota === / | > USA 55110-3364 === | > (651)426-4766 use Courier New Font | > http://www.redrok.com (Web site) ===
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>I understand there is an associated R value associated with air gaps.
Sure… >However, I would have assumed that the R value of conventional >insulation, say fiber glass, would have been better than that >of an air gap.
Add the air gap’s R-value to the insulation’s R-value. >What I understood was that the foil on foil backed insulation >had a different function. It was to "Reflect" infra red >radiation. This reflector can be behind sheet rock which is >able to transmit the infra red back to the source.
It could do that, with an air gap bgetween the foil and the sheet rock, but the foil won’t do much if it touches the sheet rock, except to act as a vapor barrier. Nick
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- Hide quoted text — Show quoted text ->I understand there is an associated R value associated with air gaps. > Sure… >However, I would have assumed that the R value of conventional >insulation, say fiber glass, would have been better than that >of an air gap. > Add the air gap’s R-value to the insulation’s R-value.
As long as we’re talking about insulation, I’ve been trying to figure out the radiation from the insulation and am not getting far. From a EffHr 0.0455 (for that .05 foil Eff) and: Thermal resistance R = 1/C, where C = Hc + EeffHr. It appears to me that the max effective R value would be 22, and that for an infinitely thick blanket with a foil outer barrier. It would seem that the radiation from the insulation would mean these high R blankets would have diminishing returns. It also seems that a foil barrier on the ambient side of the insulation would be very valuable. But things are not done this way, what have I misunderstood? Cheers, Jeff – Hide quoted text — Show quoted text ->What I understood was that the foil on foil backed insulation >had a different function. It was to "Reflect" infra red >radiation. This reflector can be behind sheet rock which is >able to transmit the infra red back to the source. > It could do that, with an air gap bgetween the foil and the sheet rock, > but the foil won’t do much if it touches the sheet rock, except to act > as a vapor barrier. > Nick
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Daestrom> Two surfaces spaced a modest 1/2 inch apart with Daestrom> emissivity/abortivity of about 0.5, with temperatures Daestrom> of 460 R and 461 R will have a net radiant flux of Daestrom> q’ = emissivity*Stefan-Boltzmann * (461^4 – 460^4) Daestrom> = 0.34 BTU/hr-ft^2 (R-value of 3.0). Seems like the air-gapped foil-backed insulation’s R-value is dependent on the foil temp. i^4 – (i-d)^4 = -4i^3d +6i^2d^2 -4id^3 +d^4 ~= -4i^3d So the air gap heat flow is just about linear with delta-T, but goes up as the cube of ambient temp. So while you got an R-value of 3.0 for the interior of a cold refrigerator, the same foil against the interior of a house would see an R-value of 2.0. Seems like the R-value would be a lot higher if the foil faces the cold side. If it’s -30 F outside, R-value of that gap is 3.75.
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>> Add the air gap’s R-value to the insulation’s R-value. >As long as we’re talking about insulation, I’ve been trying to figure >out the radiation from the insulation and am not getting far. >From a EffHr 0.0455 (for that .05 foil Eff)
That’s a radiation conductance. >Thermal resistance R = 1/C, where C = Hc + EeffHr.
Which you add to the convection conductance, which typically brings the combined R-value of the foil down to something between 1 and 10. > It appears to me that the max effective R value would be 22…
For the foil radiation alone. But you have to add the convective conductance Hc for the foil to its radiation conductance EeffHr. Then take the reciprocal, then add the insulation’s R-value. >It would seem that the radiation from the insulation would mean >these high R blankets would have diminishing returns.
No. Add the insulation’s R-value to the foil’s R-value… >It also seems that a foil barrier on the ambient side of the insulation >would be very valuable.
It’s valuable on either side, but people don’t like foil walls, and the foil would weather badly outdoors, and wind would raise its convection loss. Nick
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– Hide quoted text — Show quoted text ->>I understand there is an associated R value associated with air gaps. > Sure… >>However, I would have assumed that the R value of conventional >>insulation, say fiber glass, would have been better than that >>of an air gap. > Add the air gap’s R-value to the insulation’s R-value. > As long as we’re talking about insulation, I’ve been trying to figure out > the radiation from the insulation and am not getting far. > From a EffHr 0.0455 (for that .05 foil Eff) and: > Thermal resistance R = 1/C, where C = Hc + EeffHr. > It appears to me that the max effective R value would be 22, and that > for an infinitely thick blanket with a foil outer barrier. It would seem > that the radiation from the insulation would mean these high R blankets > would have diminishing returns.
Well, the law of diminishing returns certainly applies to any insulation project. But you can certainly insulate with higher effective R values than 22. Don’t see what you’re getting at there. One foot thick fibreglass can give you about R-38, irrespective of the coatings or any ‘facing’ such as drywall or OSB over it. Remember, a higher R-value *behind* the foil surface makes the foil surface temperature closer to the ambient temperature. And that reduces radiant losses as well. > It also seems that a foil barrier on the ambient side of the insulation > would be very valuable. > But things are not done this way, what have I misunderstood?
As far as a foil barrier on the ambient side, it isn’t really all that valuable in most circumstances. Yes, it would certainly reduce the heat gain from direct sunlight, and reduce radiant heat loss. But if you look at how much heat is lost to the environment due to simple convection, you will realize that even if radiant heat losses were cut to zero, it wouldn’t reduce the total heat losses by a significant percentage in most cases. You won’t get a lot of improvement for the ‘buck’. And a lot of folks don’t like the idea of living in an aluminum foil sided house. Radiant losses can be a big issue if the temperature difference is large and/or you’ve already taken steps to reduce the other forms of heat loss (conduction/convection). Or if your goal is to reduce absorption from the sun. daestrom
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>>I’m not on usenet and don’t know how to post there, but I read your = >posts frequently… >If you can read usenet posts, you can probably post yourself… >Might be worth learning how.
OK. Looks like I got it figured out. Now as far as window insulation goes, what about packing peanuts between the panes? Dennis
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>Daestrom> Two surfaces spaced a modest 1/2 inch apart with >Daestrom> emissivity/abortivity of about 0.5, with temperatures >Daestrom> of 460 R and 461 R will have a net radiant flux of >Daestrom> q’ = emissivity*Stefan-Boltzmann * (461^4 – 460^4) >Daestrom> = 0.34 BTU/hr-ft^2 (R-value of 3.0).
What 1/2"? Why 0.5? Most materials are closer to 1. >Seems like the air-gapped foil-backed insulation’s R-value is >dependent on the foil temp. > i^4 -(i-d)^4
= i^4 -(i^2-2d+d^2)(i^2-2d+d^2) = i^4 -(i^4-2i^2d+i^2d^2-2i^2d+4d^2-2d^3+i^2d^2-2d^3+d^4) = 2i^2d-i^2d^2+2i^2d-4d^2+2d^3-i^2d^2+2d^3-d^4 = 4i^2d-2i^2d^2 -4d^2+4d^3 -d^4 >~= -4i^3d
Yes, with a + vs -, if i>>d. >So the air gap heat flow is just about linear with delta-T, but goes up >as the cube of ambient temp.
You’ve just reinvented the "linearized radiation conductance" G = 4×0.1714×10^-8Tm^3 Btu/h-F-ft^2, where Tm is the mean Rankine temp. But air spaces also transfer heat by convection and conduction… >So while you got an R-value of 3.0 for the interior of a cold refrigerator, >the same foil against the interior of a house would see an R-value of 2.0.
That also depends on convection and conduction, which depend on the temp diff and the direction of heatflow. >Seems like the R-value would be a lot higher if the foil faces >the cold side. If it’s -30 F outside, R-value of that gap is 3.75.
Our local college keeps liquid helium for their electron microscope’s superconducting magnet in a Dewar vacuum flask surrounded by liquid nitrogen, with insulation around that. H2 boils at 4.2 K. N2 boils at 77.3 K. So 2 mirrors with e = 0.03 would lose 5.67×10^-8×0.03×40.75^3 = 0.000115 W/m^2C by radiation, ie 0.00002027 Btu/h-F-ft^2, ie US R49335, vs an R20 house wall. Nick
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>>If you can read usenet posts, you can probably post yourself… >Might be worth learning how. >OK. Looks like I got it figured out.
Congratulations! >Now as far as window insulation goes, what about packing peanuts >between the panes?
Sounds rather permanent. The Zomeworks Beadwall system moved small styrofoam beads into and out of a window cavity with a vacuum cleaner. It worked well, but the beads required lots of storage space and they wouldn’t flow well through fittings, so each window cavity required a separate store and vacuum cleaner. And the multiple vacs required an electrical sequencer to avoid blowing fuses. "Replacement foam insulation" (filling the space between two glazings with soap bubble foam at night) seems more practical. It’s being applied to greenhouses now. In one system, a shop vac pushes air through a 100′x2" pipe with some holes in a 10% detergent solution near the ground, making bubbles rise to the top of a 100′ long quonset-shaped greenhouse. When the bubbles reach the top, the vac automatically turns off until they recede, then starts again for a few seconds every hour or so to replenish them during the night. The bubble system turns off at dawn and a small blower inflates the space between the 2 plastic glazings with air. Nick
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>>Now as far as window insulation goes, what about packing peanuts >between the panes? > Sounds rather permanent. The Zomeworks Beadwall system moved small > styrofoam beads into and out of a window cavity with a vacuum cleaner.
… As I recall, I’ve heard reports that there were other issues with the beadwall system. For instance, the foam beads would break down over time. > "Replacement foam insulation" (filling the space between two glazings > with soap bubble foam at night) seems more practical.
This might be fine for a greenhouse but I question it’s usefullness in a house. For instance, how clear and streak free are the windows when the foam goes away? How do you insure that the window cavities are sealed well enough that they don’t ever leak in some hard to detect fashion and cause damage to the structure? With a bubble foam system, how do you design the windows so that they can open? How about this for a possible solution. There are double pane windows being sold now that have window shades or blinds inbetween the panes. Mostly, this means that they never get dusty and you won’t find the cat has hung himself from them. Air is a pretty good insulator except when there is some kind of circulation going on. A cellular shade could be produced using thin mylar or paper such that it folds up into a small space at the top or bottom of the window cavity and yet can unfold to fill the entire space with small air-filled pockets. One or more layers of aluminum coatings could be added as well to help cut down on radiant loss. Anthony
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>… I’ve heard reports that there were other issues with >the beadwall system. For instance, the foam beads would >break down over time.
Not exactly. They tended to clump if never cycled. IIRC, cycling once a month would fix that. > "Replacement foam insulation" (filling the space between two glazings > with soap bubble foam at night) seems more practical. >… I question it’s usefullness in a house. For instance, how clear and >streak free are the windows when the foam goes away?
Moreso than my $500 500 ft^2 cloudy plastic film sunspace >How do you insure that the window cavities are sealed well enough that >they don’t ever leak in some hard to detect fashion and cause damage to >the structure?
I’d probably make the "windows" with 2 layers of 0.020" clear polycarbonate from a 48" roll, over plastic 2×4s, with lots of silicone caulk. >… how do you design the windows so that they can open?
You don’t. A few plain windows might do that. >How about this for a possible solution. There are double pane windows >being sold now that have window shades or blinds inbetween the panes. >Mostly, this means that they never get dusty and you won’t find the >cat has hung himself from them. Air is a pretty good insulator except >when there is some kind of circulation going on.
Even tiny circulations. >A cellular shade could be produced using thin mylar or paper such that >it folds up into a small space at the top or bottom of the window cavity >and yet can unfold to fill the entire space with small air-filled pockets.
It could be… >One or more layers of aluminum coatings could be added as well to >help cut down on radiant loss.
Good idea. Scheme 18.7 on page 168 of Bill Shurcliff’s 1980 Brick House book "Thermal Shutters and Shades" describes 5 sheets of metallized Mylar with springy spacers that unfold when it’s rolled down. Scheme 18.8 on page 170 describes an interesting self-inflating Mylar shade. Alas, these are no longer being made. Perhaps they can be recreated with an iron or a $118 -RS1 hot roller for plastic film seam-sealing from Hillas at (800) 952 7274. Symphony "energy track" shades with tracks on each side to reduce air leaks are fairly expensive and low performing. They (877) 966-3689 say their room darkening shade has a R-value of 3.2, when used with an R1.8 window This increases to R4.8 with side tracks. A 3′x6′ shade costs $170 with the tracks. Tiny cold soap bubbles can have the same R-value as fiberglass. A 6" window might transmit 80% of the sun during the day and become an R20 wall at night. Nick
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– Hide quoted text — Show quoted text -> Daestrom> Two surfaces spaced a modest 1/2 inch apart with > Daestrom> emissivity/abortivity of about 0.5, with temperatures > Daestrom> of 460 R and 461 R will have a net radiant flux of > Daestrom> q’ = emissivity*Stefan-Boltzmann * (461^4 – 460^4) > Daestrom> = 0.34 BTU/hr-ft^2 (R-value of 3.0). > Seems like the air-gapped foil-backed insulation’s R-value is > dependent on the foil temp. > i^4 – (i-d)^4 > = -4i^3d +6i^2d^2 -4id^3 +d^4 > ~= -4i^3d > So the air gap heat flow is just about linear with delta-T, but > goes up as the cube of ambient temp. So while you got an > R-value of 3.0 for the interior of a cold refrigerator, the same > foil against the interior of a house would see an R-value of 2.0. > Seems like the R-value would be a lot higher if the foil faces > the cold side. If it’s -30 F outside, R-value of that gap is 3.75.
Yes, you have an interesting point. The absolute temperature involved does make a difference. But contriving a system where you can get the foil to be coldest isn’t easy. You can’t just put it on the outside surface, convection losses would over-shadow any radiant issues. If the air gap is embedded in the wall, then it will be at some temperature between inside and outside, depending on exactly where the air gap is in relation to other materials. I suppose ideally we would put the air gap as close to the lower temperature side of the construction as possible. That sounds like an outer surface with a low emissivity foil, then protected from excessive convection losses by some thin film to form the air gap. Not sure how practical such a construction would be in a high wind situation though. daestrom
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Question:
For a solar air collector is there an advantage to using selective paint for the collector over normal heat paint? Does selective paint offer that much improvement and hold up better over time?
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> For a solar air collector is there an advantage to using selective > paint for the collector over normal heat paint?
I’m no expert, but the higher the temperature the collector operates at the more heat that is reradiated and the more important a selective coating would be. So this would be less important for forced air solar than domestic hot water. Selective paints themselves reradiate more than a selective coating like black chrome. In other words, consider your application and look for a solution. I just wanted you to have something to mull over before a more experienced hand answers. This appears to be a low volume newsgroup. Cheers, Jeff Does selective paint – Hide quoted text — Show quoted text -> offer that much improvement and hold up better over time?
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> For a solar air collector is there an advantage to using selective > paint for the collector over normal heat paint? Does selective paint > offer that much improvement and hold up better over time?
When you look at the science of selective coatings, it would *seem* like an easy choice. They re-radiate a lot less than they absorb, so should get much hotter. A simply black body absorbing sunlight will re-radiate more and more as it heats up until it radiates as much as it absorbes. For simply coatings that have an emissivity equal to their absorption, this max temperature is <200 F though. A high tech coating could improve on this to get higher temperatures. But, with all that said, those numbers and such *assume* a couple things. First, that no convective/conduction losses occur. Second, that there is no medium between the surface and the sunlight. But that isn’t typical collector construction. So putting a *glass* plate over a collector will reduce the incoming sunlight slightly, but reduce the re-radiated losses dramatically. So a simple black surface *under glass* should get much hotter simply because it can’t re-radiate as much energy back out. Air collectors don’t really need to get that warm. They can be kept relatively cool and maximize the amount of heat gained by absorbing as much sunlight as possible (flat-black surface) and high air flow rates. If the collector surface is kept cool with a high air flow rate, the re-radiation is minimized. Of course, you don’t want the air to lose heat to the outside through contact with cold glass either. So I’ve wondered if a second cheap plastic film to make a ‘double-glazing’ with only one layer of glass could work well. Lower conduction/convection losses due to the insulating air gap, and higher transmittance of light through just a single pane of glass. Sorry, got to rambling a bit there, not sure I answered your question really. daestrom
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So selective paint really just allows you to up the max temperature of the collector correct? So if that is the case you would need to increase airflow to properly cool it.
– Hide quoted text — Show quoted text -> For a solar air collector is there an advantage to using selective > paint for the collector over normal heat paint? Does selective paint > offer that much improvement and hold up better over time? > When you look at the science of selective coatings, it would *seem* like > an easy choice. They re-radiate a lot less than they absorb, so should > get much hotter. A simply black body absorbing sunlight will re-radiate > more and more as it heats up until it radiates as much as it absorbes. > For simply coatings that have an emissivity equal to their absorption, > this max temperature is <200 F though. A high tech coating could improve > on this to get higher temperatures. > But, with all that said, those numbers and such *assume* a couple things. > First, that no convective/conduction losses occur. Second, that there is > no medium between the surface and the sunlight. But that isn’t typical > collector construction. So putting a *glass* plate over a collector will > reduce the incoming sunlight slightly, but reduce the re-radiated losses > dramatically. So a simple black surface *under glass* should get much > hotter simply because it can’t re-radiate as much energy back out. > Air collectors don’t really need to get that warm. They can be kept > relatively cool and maximize the amount of heat gained by absorbing as > much sunlight as possible (flat-black surface) and high air flow rates. > If the collector surface is kept cool with a high air flow rate, the > re-radiation is minimized. Of course, you don’t want the air to lose heat > to the outside through contact with cold glass either. > So I’ve wondered if a second cheap plastic film to make a ‘double-glazing’ > with only one layer of glass could work well. Lower conduction/convection > losses due to the insulating air gap, and higher transmittance of light > through just a single pane of glass. > Sorry, got to rambling a bit there, not sure I answered your question > really. > daestrom
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- Hide quoted text — Show quoted text – > So selective paint really just allows you to up the max temperature of the > collector correct? So if that is the case you would need to increase > airflow to properly cool it. >>For a solar air collector is there an advantage to using selective >>paint for the collector over normal heat paint? Does selective paint >>offer that much improvement and hold up better over time? >When you look at the science of selective coatings, it would *seem* like >an easy choice. They re-radiate a lot less than they absorb, so should >get much hotter. A simply black body absorbing sunlight will re-radiate >more and more as it heats up until it radiates as much as it absorbes. >For simply coatings that have an emissivity equal to their absorption, >this max temperature is <200 F though. A high tech coating could improve >on this to get higher temperatures. >But, with all that said, those numbers and such *assume* a couple things. >First, that no convective/conduction losses occur. Second, that there is >no medium between the surface and the sunlight. But that isn’t typical >collector construction. So putting a *glass* plate over a collector will >reduce the incoming sunlight slightly, but reduce the re-radiated losses >dramatically. So a simple black surface *under glass* should get much >hotter simply because it can’t re-radiate as much energy back out. >Air collectors don’t really need to get that warm. They can be kept >relatively cool and maximize the amount of heat gained by absorbing as >much sunlight as possible (flat-black surface) and high air flow rates. >If the collector surface is kept cool with a high air flow rate, the >re-radiation is minimized. Of course, you don’t want the air to lose heat >to the outside through contact with cold glass either. >So I’ve wondered if a second cheap plastic film to make a ‘double-glazing’ >with only one layer of glass could work well. Lower conduction/convection >losses due to the insulating air gap, and higher transmittance of light >through just a single pane of glass.
The emisive/reradiated loss rises as the collector temp rises. Normal glazing (and I don’t know how you would make a one way IR reflective glazing) will simply let this escape back, no matter how many layers. It only helps with the convective/conductive loss. I think the interesting question is at what temp does the emissive loss excede the convective loss for single pane. I would think this would be well above 100 degree F (closer to the max temp limit mentioned above). Also, it looks like the selective paints must be applied very carefully. No real knowledge here, so take it like a "W" stay the course speech. Cheers, Jeff – Hide quoted text — Show quoted text ->Sorry, got to rambling a bit there, not sure I answered your question >really. >daestrom
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> For a solar air collector is there an advantage to using selective > paint for the collector over normal heat paint? Does selective paint > offer that much improvement and hold up better over time?
Hi, The SRCC site ( http://www.solar-rating.org/ ) tests collectors and gives data on heat collected. You can compare collectors with selective coatings to ones without. For example, comparing 2 Radco brand collectors that appear to be identical except that one use a selective coating and the other uses black paint: Service ClearDay PrtlyCldy ClearDay PrtlyCldy C 38K 25K 45K 30K D 16K 6K 28K 15K Service "C" is for (Tinlet – Tambient) = 20C (36F) Service "D" is for (Tinlet – Tambient) = 50C (90F) The selective surface gain is moderate for service C — about 20%, but increases to around 100%(!) for service D. So, the difference between the collector fluid temperature (which is presumably related to the absorber temperature), and the ambient temperature seems to be a very big factor in how effective the selective coating is? These Radco collectors are flat plate water collectors, but I’m not clear on why they would be running at absorber temps that are that much different than air collectors (as has been suggested)? The air comes out of my air collector at around 120F under full sun conditions — the absorber is running a fair bit hotter than this — I’ll measure it next chance I get, but I’m guessing 160F ish. A water collector probably spends most of its time in the same general area — ie output temps around 120F depending on the storage tank temperature, and since there is excellent thermal contact between the absorber and the fluid, the absorber to fluid temperature difference is probably less than for an air collector. I’d be interested in hearing any further opinions on this, as I am shopping for absorber plates for my new project, and there is a whole lot of difference in price between some of the the selective coating absorbers and the black paint absorbers: For example: Sun-Ray: www.sunraysolar.com/absorber.html non-selective $4.50 sqft Solarenergy: http://www.solarenergy.com/ws400CS.cgi?category=sh_absorbers.html&car… selective $7.50 sqft I am leaning toward the selective coating even though its near twice the price. But, I’d be glad to be talked out of it Does anyone know a good (cheap) source of selective coating absorber plates? — Gary www.BuildItSolar.com "Build It Yourself" Solar Projects
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Thanks Gary. How would you go about using those collectors in an air collector? They seem to be made for water based systems.
– Hide quoted text — Show quoted text -> For a solar air collector is there an advantage to using selective > paint for the collector over normal heat paint? Does selective paint > offer that much improvement and hold up better over time? > Hi, > The SRCC site ( http://www.solar-rating.org/ ) tests collectors and > gives data on heat collected. You can compare collectors with > selective coatings to ones without. For example, comparing 2 Radco > brand collectors that appear to be identical except that one use a > selective coating and the other uses black paint: > Service ClearDay PrtlyCldy ClearDay PrtlyCldy > C 38K 25K 45K 30K > D 16K 6K 28K 15K > Service "C" is for (Tinlet – Tambient) = 20C (36F) > Service "D" is for (Tinlet – Tambient) = 50C (90F) > The selective surface gain is moderate for service C — about 20%, > but increases to around 100%(!) for service D. So, the difference > between the collector fluid temperature (which is presumably related > to the absorber temperature), and the ambient temperature seems to be > a very big factor in how effective the selective coating is? > These Radco collectors are flat plate water collectors, but I’m not > clear on why they would be running at absorber temps that are that > much different than air collectors (as has been suggested)? The air > comes out of my air collector at around 120F under full sun conditions > — the absorber is running a fair bit hotter than this — I’ll measure > it next chance I get, but I’m guessing 160F ish. A water collector > probably spends most of its time in the same general area — ie output > temps around 120F depending on the storage tank temperature, and since > there is excellent thermal contact between the absorber and the fluid, > the absorber to fluid temperature difference is probably less than for > an air collector. > I’d be interested in hearing any further opinions on this, as I am > shopping for absorber plates for my new project, and there is a whole > lot of difference in price between some of the the selective coating > absorbers and the black paint absorbers: > For example: > Sun-Ray: > www.sunraysolar.com/absorber.html non-selective $4.50 sqft > Solarenergy: > http://www.solarenergy.com/ws400CS.cgi?category=sh_absorbers.html&car… > selective $7.50 sqft > I am leaning toward the selective coating even though its near twice > the price. But, I’d be glad to be talked out of it > Does anyone know a good (cheap) source of selective coating absorber > plates? > — > Gary > www.BuildItSolar.com > "Build It Yourself" Solar Projects
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- Hide quoted text — Show quoted text -> For a solar air collector is there an advantage to using selective > paint for the collector over normal heat paint? Does selective paint > offer that much improvement and hold up better over time? > Hi, > The SRCC site ( http://www.solar-rating.org/ ) tests collectors and > gives data on heat collected. You can compare collectors with > selective coatings to ones without. For example, comparing 2 Radco > brand collectors that appear to be identical except that one use a > selective coating and the other uses black paint: > Service ClearDay PrtlyCldy ClearDay PrtlyCldy > C 38K 25K 45K 30K > D 16K 6K 28K 15K > Service "C" is for (Tinlet – Tambient) = 20C (36F) > Service "D" is for (Tinlet – Tambient) = 50C (90F) > The selective surface gain is moderate for service C — about 20%, > but increases to around 100%(!) for service D. So, the difference > between the collector fluid temperature (which is presumably related > to the absorber temperature), and the ambient temperature seems to be > a very big factor in how effective the selective coating is?
Look up Stefan-Boltzman law of radiation. The radiation is proportional to the 4th power of the absorber minus the 4th power of ambient. So, larger temperature differentials yield much higher losses. E=K(T 4th – To 4th). (Those are absolute temps, ie Kelvin) I’m sure that’s at least a large part of why solar air collectors are much more efficient at lower temperature differentials. Cheers, Jeff
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> Thanks Gary. How would you go about using those collectors in an air > collector? They seem to be made for water based systems.
Hi, Sorry, I guess I confused things by talking about two things — Subject 1 The original question was whether the selective coatings help on an air collector. The info on the SRCC site says the selective coating makes a lot of difference on water collectors when there is a large temp difference between ambient and the collector. And, it seems to me, that this would also hold true for air collectors because air and water collectors operate at fairly similar temperatures. Subject 2 I’m looking for some water collector absorber plates, and was wondering if anyone has a good source (meaning cheap) of water collector absorber plates with selective coating? Or, whether anyone would like to argue that the selective coating is not worth the extra money? Gary – Hide quoted text — Show quoted text ->>For a solar air collector is there an advantage to using selective >>paint for the collector over normal heat paint? Does selective paint >>offer that much improvement and hold up better over time? >Hi, >The SRCC site ( http://www.solar-rating.org/ ) tests collectors and >gives data on heat collected. You can compare collectors with >selective coatings to ones without. For example, comparing 2 Radco >brand collectors that appear to be identical except that one use a >selective coating and the other uses black paint: >Service ClearDay PrtlyCldy ClearDay PrtlyCldy >C 38K 25K 45K 30K >D 16K 6K 28K 15K >Service "C" is for (Tinlet – Tambient) = 20C (36F) >Service "D" is for (Tinlet – Tambient) = 50C (90F) >The selective surface gain is moderate for service C — about 20%, >but increases to around 100%(!) for service D. So, the difference >between the collector fluid temperature (which is presumably related >to the absorber temperature), and the ambient temperature seems to be >a very big factor in how effective the selective coating is? >These Radco collectors are flat plate water collectors, but I’m not >clear on why they would be running at absorber temps that are that >much different than air collectors (as has been suggested)? The air >comes out of my air collector at around 120F under full sun conditions >– the absorber is running a fair bit hotter than this — I’ll measure >it next chance I get, but I’m guessing 160F ish. A water collector >probably spends most of its time in the same general area — ie output >temps around 120F depending on the storage tank temperature, and since >there is excellent thermal contact between the absorber and the fluid, >the absorber to fluid temperature difference is probably less than for >an air collector. >I’d be interested in hearing any further opinions on this, as I am >shopping for absorber plates for my new project, and there is a whole >lot of difference in price between some of the the selective coating >absorbers and the black paint absorbers: >For example: >Sun-Ray: >www.sunraysolar.com/absorber.html non-selective $4.50 sqft >Solarenergy: >http://www.solarenergy.com/ws400CS.cgi?category=sh_absorbers.html&car… > selective $7.50 sqft >I am leaning toward the selective coating even though its near twice >the price. But, I’d be glad to be talked out of it >Does anyone know a good (cheap) source of selective coating absorber >plates? >– >Gary >www.BuildItSolar.com >"Build It Yourself" Solar Projects
– Gary www.BuildItSolar.com "Build It Yourself" Solar Projects —-== Posted via Newsfeeds.Com – Unlimited-Uncensored-Secure Usenet News==—- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups —-= East and West-Coast Server Farms – Total Privacy via Encryption =—-
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- Hide quoted text — Show quoted text ->Hi, >Subject 2 >I’m looking for some water collector absorber plates, and was >wondering if anyone has a good source (meaning cheap) of water >collector absorber plates with selective coating? Or, whether anyone >would like to argue that the selective coating is not worth the extra >money? >Gary > for a low-cost and highly-effective coating; that you may be able to > apply yourself (if suitably equipped with shop), look at: > http://lib.tkk.fi/Diss/2004/isbn951227003X/
Thanks — Looks promising — I’ll give it a good read — Gary > —-== Posted via Newsfeeds.Com – Unlimited-Unrestricted-Secure Usenet News==—- > http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups > —-= East and West-Coast Server Farms – Total Privacy via Encryption =—-
– Gary www.BuildItSolar.com "Build It Yourself" Solar Projects —-== Posted via Newsfeeds.Com – Unlimited-Unrestricted-Secure Usenet News==—- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups —-= East and West-Coast Server Farms – Total Privacy via Encryption =—-
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>> for a low-cost and highly-effective coating; that you may be able to > apply yourself (if suitably equipped with shop), look at:
http://lib.tkk.fi/Diss/2004/isbn951227003X/ >Thanks — Looks promising — I’ll give it a good read — Gary
You have a scanning electron microscope, and so on? Nick
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said: | You have a scanning electron microscope, and so on? Hmmm. You just stirred up an interesting question. If two smooth, flat metal absorber plates, one normal to the sun’s rays and one aslant, present the same (projected) area to the sun – will one absorb more energy than the other? — Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/solar.html
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The one normal one will collect more heat as it has less surface to reradiate heat away.
– Hide quoted text — Show quoted text -> said: > | You have a scanning electron microscope, and so on? > Hmmm. You just stirred up an interesting question. If two smooth, flat > metal absorber plates, one normal to the sun’s rays and one aslant, > present the same (projected) area to the sun – will one absorb more > energy than the other? > — > Morris Dovey > DeSoto Solar > DeSoto, Iowa USA > http://www.iedu.com/DeSoto/solar.html
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> The one normal one will collect more heat as it has > less surface to reradiate heat away.
An interesting point. Also, just about any surface reflects a different amount depending on the angle of incoming sunlight. More reflection, less absorption. daestrom
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Yeah, I thought of that point, later, but I was asleep…LOL message > The one normal one will collect more heat as it has > less surface to reradiate heat away. > An interesting point. > Also, just about any surface reflects a different
amount depending on the – Hide quoted text — Show quoted text -> angle of incoming sunlight. More reflection, less absorption. > daestrom
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|| The one normal one will collect more heat as it has || less surface to reradiate heat away. My server missed SolarFlaire’s post – I’m glad you quoted to I know to go to Google groups… Re-radiation wasn’t wasn’t my primary concern when I asked; but it certainly is part of the picture. This prompts me to inquire into the manner in which energy is re-radiated. Should it be considered as being emitted normal to the hot surface; or is it more correctly thought of as omnidirectional? | An interesting point. | | Also, just about any surface reflects a different amount depending | on the angle of incoming sunlight. More reflection, less | absorption. This comes closer to my original question. Remember that the surface is smooth and the metal opaque – are you saying that there is a surface effect analogous to critical angle behavior of glass? I’m having difficulty wrapping my head around this… — Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/solar.html
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May not get this post but, there may be totally different reflective amounts of energy at the different spectrums. In other words if you are collecting heat it may a totally different picture than collecting PV electricity. I have not obtained information on this as yet. It may be needed at specific times, for specific interests so I haven’t bothered.
> daestrom (in
– Hide quoted text — Show quoted text – message > || The one normal one will collect more heat as it has > || less surface to reradiate heat away. > My server missed SolarFlaire’s post – I’m glad you quoted to I know to > go to Google groups… > Re-radiation wasn’t wasn’t my primary concern when I asked; but it > certainly is part of the picture. This prompts me to inquire into the > manner in which energy is re-radiated. Should it be considered as > being emitted normal to the hot surface; or is it more correctly > thought of as omnidirectional? > | An interesting point. > | > | Also, just about any surface reflects a different amount depending > | on the angle of incoming sunlight. More reflection, less > | absorption. > This comes closer to my original question. Remember that the surface > is smooth and the metal opaque – are you saying that there is a > surface effect analogous to critical angle behavior of glass? > I’m having difficulty wrapping my head around this… > — > Morris Dovey > DeSoto Solar > DeSoto, Iowa USA > http://www.iedu.com/DeSoto/solar.html
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On Jan 14, 2:45 pm SolarFlaire wrote (captured from Google groups): << May not get this post but, there may be totally different reflective amounts of energy at the different spectrums. In other words if you are collecting heat it may a totally different picture than collecting PV electricity. I have not obtained information on this as yet. It may be needed at specific times, for specific interests so I haven’t bothered. >> Thanks for responding – even though news.qwest.net doesn’t seem to like you I’m collecting heat and my absorber consists of very thin black horizontal aluminum ribbons that have been curved so that any sunlight reflected from one ribbon is "focused" on the back of the ribbon directly above it. At present the ribbons are spaced such that (if all surfaces were mirrored) there would be no (reflective) return path to the glazing. [If you have difficulty visualizing from this description, one of the photos at the link below might clarify somewhat.] The heat is transfered to air circulating (bottom to top, as you’d expect) over both surfaces of these ribbons and this heated air is delivered into the space being heated. I’ve experimented with this approach until I’ve satisfied myself that it’s working well, now I’m trying to zero in on an optimal spacing for the ribbons… — Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/collectors.html
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- Hide quoted text — Show quoted text – > On Jan 14, 2:45 pm SolarFlaire wrote (captured from Google groups): > << May not get this post but, there may be totally > different reflective amounts of energy at the different > spectrums. In other words if you are collecting heat it > may a totally different picture than collecting PV > electricity. > I have not obtained information on this as yet. It may > be needed at specific times, for specific interests so > I haven’t bothered. >> > Thanks for responding – even though news.qwest.net doesn’t seem to > like you > I’m collecting heat and my absorber consists of very thin black > horizontal aluminum ribbons that have been curved so that any sunlight > reflected from one ribbon is "focused" on the back of the ribbon > directly above it. At present the ribbons are spaced such that (if all > surfaces were mirrored) there would be no (reflective) return path to > the glazing. [If you have difficulty visualizing from this > description, one of the photos at the link below might clarify > somewhat.] > The heat is transfered to air circulating (bottom to top, as you’d > expect) over both surfaces of these ribbons and this heated air is > delivered into the space being heated. > I’ve experimented with this approach until I’ve satisfied myself that > it’s working well, now I’m trying to zero in on an optimal spacing for > the ribbons… > — > Morris Dovey > DeSoto Solar > DeSoto, Iowa USA > http://www.iedu.com/DeSoto/collectors.html
It looks like you have a good idea to me. I have thought that the radiation is more omnidirectional and longer wave and is related to the temperature. In other words, the hotter it gets the more radiation given off. I think that is why selective coatings are used on trough concentrators that get well above 300f.
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<snip> | I have thought that | the radiation is more omnidirectional and longer wave and is | related to the temperature. Shucks – and thanks. That means that efficiency should go up if the ribbons are more closely spaced – which means it’ll take more aluminum. Not good since one of my objectives was to minimize the materials energy requirement. I think I try halving the spacing between ribbons and see how performance changes. I’m pretty sure there’s a point of diminishing returns here somewhere; but haven’t a clue where it might be. This business of building/measuring/discarding is beginning to seem frustratingly expensive. How come I can never find a physicist when I really need one? [I _still_ haven't figured out if photons are more like boogers or BBs.] :-/ — Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/
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Morris, Very dark surfaces, like charcoal, have convolutions so that for light to escape from the surface it must reflect off several surfaces. So if each individual surface has an absorptivity of, say, 90%, you get an overall absorptivity of 1 – (1-90%)^n, where n is 5-10. Accoustic absorbing surfaces work this way as well. Your curved vanes are accomplishing some of this convolution on a macroscopic scale, with better permeability to air, which is good. The overall effect is to increase the absorptivity coefficient. There is no change to the emissivity coefficient, nor any change to either the absorptivity or emissivity aperture. Why no change to emissivity aperture or coefficient? Emission is, so far as I understand, omnidirectional. You have more area, but much of your emissions will be absorbed by the other vanes, so there is no net gain of aperture. Now this could be a very interesting benefit. Look at the table (which I’m sure you know about) at http://www.redrok.com/concept.htm The best selective surface there, plated nickel oxide, has absorptivity = 0.92 emissivity = 0.08 ratio = 11.0 Now note that there are surfaces with better emissivity than that. Convolutions change one number but not the other, which gives the possibility of changing the ratio, and thus the stagnation temperature, and best of all… *doing it with a cheaper material than nickel oxide*. Specifically, polished aluminum is absorptivity = 0.09 emissivity = 0.03 native ratio = 3.0 absorptivity, 10 reflections = 0.61 convoluted ratio = 20.3 Aluminum foil is absorptivity = 0.15 emissivity = 0.05 absorptivity, 10 reflections = 0.80 convoluted ratio = 5.35 Aluminum sheet is absorptivity = 0.80 (seems really high, suppose 0.3 instead) emissivity = 0.12 absorptivity, 10 reflections = 0.97 convoluted ratio = 8.08 Chromium absorptivity = 0.30? emissivity = 0.10? absorptivity, 10 reflections = 0.97 convoluted ratio = 9.7 I’m sure you have the idea by now. You’re looking for something cheap, bright, tough, and moderately selective, say, emissivity < 0.12, and absorptivity > 0.2. One difficulty is that you must ensure actual reflection on the way in, not merely scattering (off dirt). That means your surfaces have to stay clean, which is difficult. Perhaps that means a cover glass. Another difficulty is that the convolutions require more material.
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Iain McClatchie (in Iain… Thank you! Your response was/is *most* helpful. | Very dark surfaces, like charcoal, have convolutions so that for | light to escape from the surface it must reflect off several | surfaces. So if each individual surface has an absorptivity of, | say, 90%, you get an overall absorptivity of 1 – (1-90%)^n, where n | is 5-10. Accoustic absorbing surfaces work this way as well. | | Your curved vanes are accomplishing some of this convolution on | a macroscopic scale, with better permeability to air, which is good. | The overall effect is to increase the absorptivity coefficient. | There is no change to the emissivity coefficient, nor any change to | either the absorptivity or emissivity aperture. Yuppers – this is the observed behavior. I had a choice of bright metal or powder-coated in my choice of colors. I opted for the thinnest (opaque) black the factory could produce with the intention of spraying the absorber vanes flat black (my first real goof in the design since all of the coatings I could add actually /degraded/ the absorber performance). | Why no change to emissivity aperture or coefficient? Emission | is, so far as I understand, omnidirectional. You have more area, | but much of your emissions will be absorbed by the other vanes, | so there is no net gain of aperture. Exactly so – this was my original "aha!". However, it would appear that the emissivity aperture can be improved (reduced) by spacing the vanes closer together. There’re a couple of downsides to this: it raises the panel costs and it’ll impede airflow within the panel. At the moment I’m inclined to say: "It’ll cost what it costs," but it’s still bothersome. The airflow trade-off is a PIA and will need to be determined experimentally: I’ll build a pair of collectors and do the analog of a binary search by altering the vane spacing of the least efficient panel each trial until I can’t observe improvement in performance… | Now this could be a very interesting benefit. It has been – and is. [useful info quoted from http://www.redrok.com/concept.htm snipped] | I’m sure you have the idea by now. You’re looking for something | cheap, bright, tough, and moderately selective, say, emissivity | < 0.12, and absorptivity > 0.2. I think I don’t want ‘bright’ and I’m not sure I want ’selective’; but I definitely want to minimize _losses_ resulting from emissivity and maximize the other characteristics. | One difficulty is that you must ensure actual reflection on the | way in, not merely scattering (off dirt). That means your surfaces | have to stay clean, which is difficult. Perhaps that means a | cover glass. To my amazement, dirt hasn’t been a significant degrading influence. The 6′x12′ panel in my shop has sucked up a _lot_ of powder-fine sawdust (although it isn’t very visible to anyone outside) without significant performance drop-off. I suspect that effective aperture plays a much bigger role in this design than I’d imagined… | Another difficulty is that the convolutions require more material. I’m not sure about that. I don’t think I want to attempt those convolutions in the extrusion process because of die wear considerations; but it may be possible to improve the surface with a rolling process that’d net out with the same amount of material. Iain, thank you again. You’ve been more help than you could even begin to guess. — Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Morris> However, it would appear that the emissivity aperture can Morris> be improved (reduced) by spacing the vanes closer Morris> together. Can you elaborate on this? Is the emission from a surface a bit anisotropic? I see a possible way to reduce emissivity slightly, detailed below, but it has nothing to do with aperture. Morris> I think I don’t want ‘bright’ and I’m not sure I want Morris> ’selective’ If you want to get high utilization of the solar energy crossing your aperture, you’ll need absorptivity > 0.2. If you want to get high stagnation temperatures, you’ll need a ratio better than 3-5. I haven’t done any math on this, but if you want to match the stagnation temperature of black chrome, you’ll need an emissivity < 0.10, since after reflections the best your absorptivity could be is 1.0. Since 0.2 > 0.1, you’re looking for a surface that is at least moderately selective. However, you don’t need super-high selectivity. It seems like the selectivity of aluminum or chrome will do fine, and both are known to weather well and are widely available. Anything that’s not a high cost highly selective surface, with an emissivity < 0.10, is going to have an absorptivity < 0.30. It’s also got to be highly reflective to make the multiple-bounce trick work. Any such surface will appear bright. So, I stand by my point: you’re looking for something bright, not black. Morris> I suspect that effective aperture plays a much bigger role Morris> in this design than I’d imagined… What’s "effective aperture"? I suspect your absorptivity/emissivity ratio is not dramatically better than 3 yet, and you are not yet relying on multiple reflections. My guess is that when you get multiple reflections actually working in your favor, you will see a noticeable boost in performance. Maybe you don’t need that boost if you’re happy with what you see now. Morris> it may be possible to improve the surface with a rolling Morris> process that’d net out with the same amount of material. You aren’t going to get more than 2-3 reflections (average) with an extruded surface, and there is no way you’ll get the material thickness down. Rolled aluminum sheet, or chrome-plated steel sheet, would appear to be your best bet. I know you don’t yet buy the idea of using a bright shiny surface to capture sunlight. Give it a try, please, and tell me if I’m wrong. Oh, one other thing: how to get 10 reflections. It’s a lot. – Imagine a "V" pointed at the sun. Imagine a ray of sunshine coming straight in. It’s first reflection (most obviously), and every reflection after (less obviously), will be turned by the interior angle of the V. If you want 10 reflections before that ray goes out, you’ll need an interior angle of 18 degrees. That’s a depth 3.2 times the aperture opening. – But you want to get 10 reflections even when the sun does not come straight in. Let’s say it comes in (and subsequently leaves) at a 45 degree angle. Then you need 10 reflections to turn it 90 degrees and an interior angle of 9 degrees. That’s a depth 6.4 times the aperture opening. – I guess, but haven’t worked through the geometry, that your curved vanes are nearly the same as the straight-sided V above. In particular, the vane length will have to be the same. So if you have a vane every inch, then you’ll need a six-inch wide sheet of metal, curved through nearly 90 degrees. The resulting structure is 3.8 inches deep. If the curved vanes are attached in any way where they lap over one another, they’ll be quite strong. If they are soldered onto a copper tube where they lap, you’ll have an interesting liquid- cooled absorber. Final note: I think you can get your emissivity down further. If you draw a V with a bunch of reflected light rays, you’ll notice that most of the reflections happen deep in the V. So that’s where most of the absorption happens. But most of the emission happens at the outer part of the V. If there is a temperature difference between these two surfaces of the V, you will alter the absorption/emission ratio. Since emission goes as the 4th power of temperature, a difference of even 30 F (say, 170 F vs 200 F) would change your relative point emission by 20%. You might see an overall 10% difference then, which would lower an emissivity coefficient of 0.1 to 0.09. This is a small effect compared to the V thing, but it’s still something. If you draw air from outside in, you’ll get some sort of temperature delta. It will be larger in a less conductive material like chromed steel, and less in aluminum. If you solder a copper tube to the back side of the vanes and absorb the heat with water, you’ll get a reverse temperature gradient, and see more emission than you’d like. I don’t see a way around this yet. Perhaps having the tubing run perpendicular to the vanes, as in a heat pipe CPU heatsink, and midway through the vanes might help. But this gets into fin-tube construction, which is already expensive without adding curves.
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known those depth numbers were way too good. Assume V width is 2 inches. Assume straight in, 10 reflections to turn 180 degrees, internal angle 18 degrees, then depth = 6.3 inches. Assume 45 degrees in and out, 10 reflections to turn 90 degrees, internal angle 9 degrees, then depth = 12.7 inches. That’s more like it. Now since the noon sun swings through 47 vertical degrees, (half of that in the colder six months of the year) and the United States is just 31 N – 47 N (another 16 degrees), and in the three hours on either side of noon the sun swings up/down perhaps another 20 degrees, you really only need to have a "sweet spot" for this collector that’s 50 degrees wide. Furthermore, if your material actually has an absorbtivity of 30%, 8 reflections will do. 8 reflections turning 130 degrees is an internal angle of 16 degrees, depth = 7.1 inches, which is not so costly. Finally, even if the panel is always mounted vertically, you can bias the entry angle of the vanes to point up from the horizon a bit. I think I’m done now.
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Iain McClatchie (in | Morris> However, it would appear that the emissivity aperture can | Morris> be improved (reduced) by spacing the vanes closer | Morris> together. | | Can you elaborate on this? Is the emission from a surface a bit | anisotropic? | | I see a possible way to reduce emissivity slightly, detailed below, | but it has nothing to do with aperture. I’ll try – keep in mind that I’m not a physics cat and that it’s been four decades since I took my last thermodynamics course. Consider me "vocabulary impaired". I’d like to inexpensively capture all energy that makes it past the glazing. My objective is not to make the box (or any part of it) hot – but rather to transfer as much of that energy to the air in the box as quickly and efficiently as I can; and to facilitate the natural convective flow of air through the box. The aluminum vanes that constitute the absorber are fairly thin (only a few thousandths of an inch thick) and seem to warm and cool quite quickly as the incident energy varies in intensity. My gross interpretation of this is that they’re functioning well as both absorbers and exchangers. That interpretation is reinforced by observing that even in the brightest sun, the individual vanes are nearly impossible to discern from the front of the panel. For the photo on my web page, it was necessary to set the absorber in an unpainted, unglazed panel and aim the camera up through the vanes to see anything other than just a black area in the photo. This has led me to consider the entire absorber area as an "input aperture"; which eventually led to consideration of an "output aperture" – and to consider the quality of both of these and how their qualities might be optimized. Obviously, I’d like to maximize the ability of the input aperture to accept energy – and minimize the ability of the output aperture to provide a return path. I think that spacing the vanes more closely will not have a significant effect on the quality of the input aperture. I could be wrong but don’t think so. I think that spacing the vanes more closely may "close the window" at least somewhat on the return path – not so much for the reflected energy which already seems adequately trapped – as for the re-radiated energy. I could be wrong here, too, but in this case I’m not quite so sure. Thus the urge to conduct the experiment. | | Morris> I think I don’t want ‘bright’ and I’m not sure I want | Morris> ’selective’ | | If you want to get high utilization of the solar energy crossing | your aperture, you’ll need absorptivity > 0.2. Ok. I’ll buy that. What I’m attempting to do is catch what’s pitched at me, and to catch what I miss on the first (second, third, …) bounce. My hope is to have an effective absorbtivity that is the sum of all of the "catches" and minimizes re-radiation back to the outside. | If you want to get high stagnation temperatures, you’ll need a ratio | better than 3-5. I haven’t done any math on this, but if you want | to match the stagnation temperature of black chrome, you’ll need an | emissivity < 0.10, since after reflections the best your | absorptivity could be is 1.0. | | Since 0.2 > 0.1, you’re looking for a surface that is at least | moderately selective. However, you don’t need super-high | selectivity. It seems like the selectivity of aluminum or chrome | will do fine, and both are known to weather well and are widely | available. I have a problem here. I don’t understand what you mean by "stagnation" and "selectivity" – and my dictionary doesn’t provide definitions that make sense to me in the current context. I know that I don’t want to block the removal of heat from the panel and I know that I don’t want to exclude any of the incident energy from the capture process. Would you please clarify? | Anything that’s not a high cost highly selective surface, with an | emissivity < 0.10, is going to have an absorptivity < 0.30. It’s | also got to be highly reflective to make the multiple-bounce | trick work. Any such surface will appear bright. So, I stand by | my point: you’re looking for something bright, not black. Aha! This I understand. But I don’t really /want/ this stuff to reflect. I want it to stick (be absorbed) without bouncing. Unfortunately, in the real world some of it is going to bounce, no matter what my preferences. What I decided was that I could live with the reflectivity so long as there was a really poor quality exit path (to the outside world). | Morris> I suspect that effective aperture plays a much bigger role | Morris> in this design than I’d imagined… | | What’s "effective aperture"? Good question. I wish I had a nice, crisp answer. In sloppy terms I think that if emissivity is omnidirectional, then it will be reduced with a closer vane spacing which may cause energy that might have been unproductively radiated to be absorbed by a neighboring vane. | I suspect your absorptivity/emissivity ratio is not dramatically | better than 3 yet, and you are not yet relying on multiple | reflections. My guess is that when you get multiple reflections | actually working | in your favor, you will see a noticeable boost in performance. | Maybe you don’t need that boost if you’re happy with what you see | now. Somehow I suspect that I’ll always be looking for "just a little more," no matter how well it performs. | Morris> it may be possible to improve the surface with a rolling | Morris> process that’d net out with the same amount of material. | | You aren’t going to get more than 2-3 reflections (average) with an | extruded surface, and there is no way you’ll get the material | thickness down. Rolled aluminum sheet, or chrome-plated steel | sheet, would appear to be your best bet. | | I know you don’t yet buy the idea of using a bright shiny surface to | capture sunlight. Give it a try, please, and tell me if I’m wrong. | | Oh, one other thing: how to get 10 reflections. It’s a lot. | – Imagine a "V" pointed at the sun. Imagine a ray of sunshine | coming straight in. It’s first reflection (most obviously), and | every reflection after (less obviously), will be turned by the | interior angle of the V. If you want 10 reflections before that | ray goes out, you’ll need an interior angle of 18 degrees. | That’s a depth 3.2 times the aperture opening. | – But you want to get 10 reflections even when the sun does not | come straight in. Let’s say it comes in (and subsequently | leaves) at a 45 degree angle. Then you need 10 reflections to | turn it 90 degrees and an interior angle of 9 degrees. That’s a | depth 6.4 times the aperture opening. | – I guess, but haven’t worked through the geometry, that your | curved vanes are nearly the same as the straight-sided V | above. In particular, the vane length will have to be the same. | So if you have a vane every inch, then you’ll need a six-inch | wide sheet of metal, curved through nearly 90 degrees. The | resulting structure is 3.8 inches deep. | | If the curved vanes are attached in any way where they lap over | one another, they’ll be quite strong. If they are soldered onto a | copper tube where they lap, you’ll have an interesting liquid- | cooled absorber. Indeed, but we’re talking about serious cost increase here. Ultimately the product must be inexpensive enough for ordinary people to purchase as a practical means of buying down current heating costs without having to mortgage the farm. | Final note: I think you can get your emissivity down further. | If you draw a V with a bunch of reflected light rays, you’ll | notice that most of the reflections happen deep in the V. So | that’s where most of the absorption happens. But most of the | emission happens at the outer part of the V. This is the effect I’m after, even though I’m not using the V geometry. | If there is a temperature difference between these two surfaces | of the V, you will alter the absorption/emission ratio. Since | emission goes as the 4th power of temperature, a difference of | even 30 F (say, 170 F vs 200 F) would change your relative point | emission by 20%. You might see an overall 10% difference then, | which would lower an emissivity coefficient of 0.1 to 0.09. This is | a small effect compared to the V thing, but it’s still something. From where I am now, I don’t think anything affordable is going to produce an overall 10% difference. FWIW, it took a year to get the maximum operating temperature down from 180F to 165F. | If you draw air from outside in, you’ll get some sort of | temperature delta. It will be larger in a less conductive material | like chromed steel, and less in aluminum. | | If you solder a copper tube to the back side of the vanes and | absorb the heat with water, you’ll get a reverse temperature | gradient, and see more emission than you’d like. I don’t see a | way around this yet. Perhaps having the tubing run | perpendicular to the vanes, as in a heat pipe CPU heatsink, | and midway through the vanes might help. But this gets into | fin-tube construction, which is already expensive without adding | curves. I did a bit of experimenting in this direction – and yes, the fin tube isn’t cheap. Iain, thank you agin. You’ve give me much to think about and provided some much-needed "handles" to hang onto. — Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/solar.html
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Question:
>… my 1.6m^2 collector can typically get 40degC outlet temperature >with close to 100m^3/hour airflow rate.
How do you measure the airflow? Nick
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> >… my 1.6m^2 collector can typically get 40degC outlet temperature >with close to 100m^3/hour airflow rate. > How do you measure the airflow?
An anemometer on the outlet. You have to be careful to take a number of readings over the entire outlet and average the result to get the most accurate reading. >From the m/s reading it’s possible to calculate the air volume rate in
CFM based on your duct size. Hot wire anemometers are the most accurate at low speeds (the air-con installers use these), but vane type ones are much cheaper. Overall it’s hard to get a very accurate measurement, as there is significant error involved. But at least it gives you a typical figure that you can then use to calcuate: – A power output graph for your collector (like this one http://www.solarsponge.com/temp/SolarSpongePowerOutputGraph1.gif) – how quickly you can heat a room of a given size by a given temperature. – The total efficiency of the collector. Dave
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> Just curious what the typical output temps people are getting from their > units on a bright sunny day. > What sort of range is common/expected for a decent designed and working > unit?
Outlet temperature means nothing in itself without knowing the airflow rate. No point pumping out 70degC air if your airflow rate is 1m^3/hour. Much better to have 30degC air and 100m^3/hour. It is all about how much total energy you are pumping into the room, not what temperature you are pumping in. If you must know some typical figures though, my 1.6m^2 collector can typically get 40degC outlet temperature with close to 100m^3/hour airflow rate. And the collector is by no means optimally angled, so the actual collector area is less than 1.6m^2. Without any airflow at all a collector plate can easily get >100degC Dave
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said: | A temp gain seems fairly meaningless by itself. Lower temps might | indicate better performance, with less heat loss to the outdoors. | How would you measure airflow? It pretty much is. Lower temps on the *same* passive collector probably would not indicate better performance. How? Using the handy-dandy flowmeter the guys here on a.s.t suggested. Did that (but not yesterday) and then hung some yarn at the top of the discharge opening to tell me what I want to know without needing to chase down fresh batteries and spending more time than I want massaging numbers. After keeping an eye on this thing for a couple of years, I can fairly accurately predict the yarn deviation from vertical by glancing at the thermometer – which takes only a second or two. How often do you actually measure flow through your shop panel? — Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/solar.html
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>Gack! OE converted degree signs into zeros – please note!
I saw them as blodges, squares full of dots. >| The south-facing 6′x12′ passive collector on my shop wall
http://www.iedu.com/DeSoto/On-Wall(S).jpg) was producing ~100 degrees F temperature gain for a good part of Friday (yesterday) – but I didn’t take time to measure airflow. A temp gain seems fairly meaningless by itself. Lower temps might indicate better performance, with less heat loss to the outdoors. How would you measure airflow? Nick
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I was more just looking to get a ballpark idea just to gauge whether out collector is working at a respectable level or not. We just did a first test run yesterday with the unit outside taking in approx 50F and output of 120-130F. This was just test to make sure the thing worked at all
– Hide quoted text — Show quoted text ->Gack! OE converted degree signs into zeros – please note! > I saw them as blodges, squares full of dots. >| The south-facing 6′x12′ passive collector on my shop wall > http://www.iedu.com/DeSoto/On-Wall(S).jpg) was producing ~100 degrees F > temperature gain for a good part of Friday (yesterday) – but I > didn’t take time to measure airflow. > A temp gain seems fairly meaningless by itself. Lower temps might indicate > better performance, with less heat loss to the outdoors. > How would you measure airflow? > Nick
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Gack! OE converted degree signs into zeros – please note! | || Just curious what the typical output temps people are getting from || their units on a bright sunny day. || What sort of range is common/expected for a decent designed and || working unit? | | The south-facing 6′x12′ passive collector on my shop wall | (http://www.iedu.com/DeSoto/On-Wall(S).jpg) was producing ~1000F 100 degrees F | temperature gain for a good part of Friday (yesterday) – but I | didn’t take time to measure airflow. | | Gain ranges from about 150F midsummer to about 1500F at midwinter; 15 degrees F 150 degrees F | and the airflow depends on the temperature. | | Subsequent redesigns have raised the operating temperature somewhat | while significantly increasing airflow – one of these days RSN (Real | Soon Now) I need to rebuild this panel using what I’ve learned | since I built it. | | Decency is a fairly subjective item in this arena – with a fair | number of variables involved (such as reliability, longevity, cost, | efficiency, control systems, power requirements, and even | aesthetics). — Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/solar.html
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Just curious what the typical output temps people are getting from their units on a bright sunny day. What sort of range is common/expected for a decent designed and working unit?
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Or I guess a better way to ask is what is the typical temp rise from input to output.
– Hide quoted text — Show quoted text -> Just curious what the typical output temps people are getting from their > units on a bright sunny day. > What sort of range is common/expected for a decent designed and working > unit?
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| Just curious what the typical output temps people are getting from | their units on a bright sunny day. | What sort of range is common/expected for a decent designed and | working unit? The south-facing 6′x12′ passive collector on my shop wall (http://www.iedu.com/DeSoto/On-Wall(S).jpg) was producing ~100
Question:
Hi folks. I have inherited some solar hw panels and am setting them up. Panels are mounted and tank in place, need to run pipe and make the connections next. I have been researching pumps for a while. In my installation I will have 22-23 feet (approx 7m) of static head. This will be a drainback system, circulating pure water. I was hoping to be able to configure a PV-driven pump, but I cannot find details of any proven, affordable installation that will deal with this much head and provide adequate flow. I am probably going to end up using a Taco model 009 pump driven off mains power. I have found details of several makes of low-voltage pumps, including March, Hartnell and the "El Sid", but none of them appear to be up to the task. Multiple pumps in series may be workable in theory, but probably not very affordable given the size of PV panel(s) required , plus current booster(s). Have I missed something? It would be really nice to use PV power for circulating the water, but it doesn’t look practical to do so. I am in NB eastern Canada.
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I hope you get a reasonable answer to this. I am designing the same dilemma and am considering the Taco 009 or 010 I can;t seem to find anybody knowledgable in these pump specs. The published specs say they won’t do it, save the two mentioned ones. Also, does anybody know if the power draw on these pumps goes down upon restrictions or lack of head or restrictions?
– Hide quoted text — Show quoted text -> Hi folks. I have inherited some solar hw panels and am setting them up. > Panels are mounted and tank in place, need to run pipe and make the > connections next. I have been researching pumps for a while. In my > installation I will have 22-23 feet (approx 7m) of static head. This > will be a drainback system, circulating pure water. I was hoping to be > able to configure a PV-driven pump, but I cannot find details of any > proven, affordable installation that will deal with this much head and > provide adequate flow. I am probably going to end up using a Taco > model 009 pump driven off mains power. I have found details of several > makes of low-voltage pumps, including March, Hartnell and the "El Sid", > but none of them appear to be up to the task. Multiple pumps in series > may be workable in theory, but probably not very affordable given the > size of PV panel(s) required , plus current booster(s). Have I missed > something? It would be really nice to use PV power for circulating the > water, but it doesn’t look practical to do so. I am in NB eastern > Canada.
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> something? It would be really nice to use PV power for circulating the > water, but it doesn’t look practical to do so. I am in NB eastern > Canada.
Handy company, also from eastern Canada… http://www.thermo-dynamics.com/solar_pumps.html — Cats, coffee, chocolate…vices to live by
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- Hide quoted text — Show quoted text – > Hi folks. I have inherited some solar hw panels and am setting them up. > Panels are mounted and tank in place, need to run pipe and make the > connections next. I have been researching pumps for a while. In my > installation I will have 22-23 feet (approx 7m) of static head. This > will be a drainback system, circulating pure water. I was hoping to be > able to configure a PV-driven pump, but I cannot find details of any > proven, affordable installation that will deal with this much head and > provide adequate flow. I am probably going to end up using a Taco > model 009 pump driven off mains power. I have found details of several > makes of low-voltage pumps, including March, Hartnell and the "El Sid", > but none of them appear to be up to the task. Multiple pumps in series > may be workable in theory, but probably not very affordable given the > size of PV panel(s) required , plus current booster(s). Have I missed > something? It would be really nice to use PV power for circulating the > water, but it doesn’t look practical to do so. I am in NB eastern > Canada.
Hi, These guys appear to offer a high head PV powered pump: http://www.thermo-dynamics.com/solar_pumps.html You might also look at the Dankoff site here: http://www.conergy.us/Desktopdefault.aspx/tabid-157/224_read-1768/ They appear to have some PV driven pumps with high head capability, although they don’t list DHW as an application they might work? Dankoff appears to have changed hands? I remember reading a HomePower article that stated that drainback systems (which have higher head requirements on startup than a closed loop system) normally cannot be driven by a PV powered pump. I also wonder if a differential control (Goldline style) does not do a better job of deciding when to turn the pump on (based on collector temperature AND storage tank temperature) than a PV driven pump, which just turns the pump on when there is enough sun to drive it? — Gary www.BuildItSolar.com "Build It Yourself" Solar Projects —-== Posted via Newsfeeds.Com – Unlimited-Uncensored-Secure Usenet News==—- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups —-= East and West-Coast Server Farms – Total Privacy via Encryption =—-
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I tend to agree with your doubt on a PV logic pump. When it is really cold out ans sunny your solar pump should be running top speed and you may be pumping warmer water to the collectors to radiate heat into the cold blue sky. It would seem to me on a very clear cold day we would need to only circulate slowly from the collectors in order to warm up the return water the most. There may be a phase lag where we would only be pumping below 0C solution back to the heat reserve when the sun first shines. Also there may be a nicely warmed roof/attic area capable of supplying more BTUs after the sun goes behind the clouds. Maybe some NiMh batts to may a delay from the bright sunshine. They need to charge before the pump starts and continue for 20-30 minutes after the sun goes away.
– Hide quoted text — Show quoted text -> I also wonder if a differential control (Goldline style) does not do a > better job of deciding when to turn the pump on (based on collector > temperature AND storage tank temperature) than a PV driven pump, which > just turns the pump on when there is enough sun to drive it? > — > Gary > www.BuildItSolar.com > "Build It Yourself" Solar Projects > —-== Posted via Newsfeeds.Com – Unlimited-Uncensored-Secure Usenet News==—- > http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups > —-= East and West-Coast Server Farms – Total Privacy via Encryption =—-
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Thanks for the various replies. I had previously checked out Thermo-dynamics, but I wrote off their solar pump. It looks and sounds nice, but the price tag isn’t. Hence the qualifier ‘affordable" in my original post….:) $700 for the pump, same for the pv panel, plus another $100 for a current booster, then add tax, shipping and whatnot. If I were not dead before being ahead in terms of power used, other parts of the hw system would probably be. Also, I emailed Thermo-dynamics a product enquiry and got no answer, so I was not impressed with them. I am not sure those pumps will deliver an adequate flow rate. Also, I did see the homepower mag article on drainback systems. It’s one of their technical downloads and very useful. One of the best info sources I found. On the w/e I spent a long time orienting and lining up my panels to ensure proper drainage. That took a lot longer than expected! I am planning to use gradual bends in 3/4" pipe in my system, no elbows, to reduce friction, plus ball shut-off valves that also provide an unrestricted bore when open. And probably the Taco pump. cheers, Rob
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> Thanks for the various replies. I had previously checked out > Thermo-dynamics, but I wrote off their solar pump. It looks and sounds > nice, but the price tag isn’t. Hence the qualifier ‘affordable" in my > original post….:) $700 for the pump, same for the pv panel, plus > another $100 for a current booster, then add tax, shipping and whatnot.
I would think with that much invested you would be better off with the other solar energy source, wind… And actually have some real power, Of course, commercial power is so cheap in most of the developed world… Cheers, Jeff – Hide quoted text — Show quoted text -> If I were not dead before being ahead in terms of power used, other > parts of the hw system would probably be. Also, I emailed > Thermo-dynamics a product enquiry and got no answer, so I was not > impressed with them. I am not sure those pumps will deliver an adequate > flow rate. > Also, I did see the homepower mag article on drainback systems. It’s > one of their technical downloads and very useful. One of the best info > sources I found. > On the w/e I spent a long time orienting and lining up my panels to > ensure proper drainage. That took a lot longer than expected! I am > planning to use gradual bends in 3/4" pipe in my system, no elbows, to > reduce friction, plus ball shut-off valves that also provide an > unrestricted bore when open. And probably the Taco pump. > cheers, > Rob
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Right..well, whether commercial power is really cheap is another vast debate. I guess by getting my panels going I will be will be doing something towards reducing power demand in the grand scheme of things. Anyhow….the latest is that I have found someone who has a decomissioned solar h/w system who has plumbing and pumps they are willing to give me for nothing, so that is what I will pursue. I filled and drain-tested my panels last night and all looked good. Even here in November at 46N the outlet pipes get too hot to touch when the sun is out. cheers Rob
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