You're not thinking big enough. Use 4x8 insulation boards backing (see my video). Then add 5 length-wise baffles so a channel snakes back and forth 5 times. Cover with black trash bag plastic (it's so thin it will transfer heat well) then use painters sheet plastic or greenhouse plastic on top as the window. 4" deep, and use a 6" or 8" duct fan capable of at least 100 CFM to keep the temps low (lower box temp means HIGHER efficiency and more heat transfer) Watts = CFM*(F in - F out) / 3
@marauderhd You could use the heat from a compost pile or passive geothermal loop to keep a constant temp. See growingpower (dot) org and look up "compost heat" and "geothermal loop systems" for more. Also see "Earth Sheltered Solar Greenhouse" on YT, Mike Oehler uses a trench to move cold air out of the GH.
The curved surface of the cans provide much more surface area than a flat surface. The more surface area, the more air you can move through the box without it cooling down. In a cold climate winter you only get maybe 6 hours of good sun a day, so to have a solar furnace make a worth while heating contribution I would maximize all the important elements I could. Surface area, air flow, cabinet insulation, and insulating glazing.
Anything painted black, and put under sealed glass in the sun will get hot. Just gettting a high temperature from a box when it is exposed to the sun really means nothing. What is important is the amount of air you can move through the box , and the temperature and volume of air you can get into your home. My first fan was a 225 cfm duct booster fan. It really does not move much air, hardly enough to make any impact in heating a home.
I would think there has to be some limit to the depth of the box. Take a 1 by 10 by 1 foot deep box, it has ten cubic feet of air. Same box 10 feet deep, 100 cubic feet of air. Now do you think both heat up at the same rate ?No , the deeper box has more air molecules in it, therefore more mass to heat up, which takes more time. i am making a panel that is only 4 inches deep. Yes very little "mass of air, But it should get warmer faster, so just make "air turnover" through it faster.
Thank you for all the great ideas. I have my glass and insulation and I was saving cans up but now I think I'll use a sheet of aluminum painted black. Maybe I'll crush the cans flat and lay them in the box between two pieces of chicken wire after I paint them.
Anybody have any thoughts on increasing the depth of the box? ie Use 2x6's or 2x8's around it and just increase the cubic space of the hot air? On greenpowerscience they used a temp gauge on a dark colored car in the sun the inside temp was around 155 F. That is a ton of cubic heat add a fan and move it around.
@richallenmusic Hey Rich, thanks for the videos! I'm all about freaky cheap technology, so I have some ideas for you. Check out solarcooking (dot) org and the Capturing Heat pdf from weblife (dot) org. for more ideas, b/c a couple cardboard & foil reflector panels would triple your efficiency. Also check out richsoil (dot) com, aprovecho (dot) net technology section and any Permaculture websites, they usually have lots of cool appropriate technology links. Cheers!
@lad18913290 -If you live in Canada, unless you never have sun, this would be perfect for you!
Thanks, Rich for showing us how affordable passive solar heaters can really be! A lot of the other instructions online use power tools I don't have, and require supplies that would really increase the cost of the heater, making me really doubt the cost savings. Your experiments really show that I could harness free heat for nearly free supplies!
hmmm, i doubt a piece of poly over my collector would suffice in my climate - the tighter the seal, the better - that's my point, i meant no offense. Great insight Rich! :)
if you want simple - glass clutters, snips, hammer and a handsaw, it doesn't take a genius to build a box and cover it with glass. if you want cheap, RECYCLE. visit a few construction sites -contractors have lots of junk lying around that they're willing to part with, usually for FREE. all it takes is effort.
Exellent idea to compare various models. The real test would be to stick the same small fan (say from an old computer) on each in turn and compare temps after they stabilize. I also doubt the necessity of cans. Wonder if inside the box you strung used Aluminum Xmas garland and sprayed it black. Lots thinner and might conduct more heat to the air flowing past it. Double up layers of 4 mill clear plastic? Space them apart with small pieces of quarter inch weather strip door foam. Thoughts
Hi Rich. My concern is melting the glazing. I live in Flrorida. We do need heat for about 2 months in Tampa, but we only need to heat from about freezing to 70 (40 degree differential). A couple thermal solar furnaces can do the trick but mine has reached 200F easily in the October Florida sun, which makes me uneasy to have anything but glass as the glazing. Even in Maryland I have gotten the temp up to 175F on one I built at my brother's house. Are acrylic or plastic ok?
@landslave Most use polycarbonate for glaze. I have used old sliding glass doors. They are heavier, but most are free and are double glass sealed together. They usually will not break from hits from lawnmower or windstorms. You can grove (dado) the sides and set the glass panels in with foam insulation as a seal, then seal and cap the glass.
@solarguyable Lowes and Home Depot sell the new doors and have installers to put them in. Talk the the guys that sell the doors and tell them you would like a couple of old doors. The installers have to throw them in the dump. You can leave the trim on the old doors or remove it and just use the glass. I rather just use the glass. They usually are two pieces of glass sealed together. Most of the old ones will shatter into a millions pieces if dropped or hit with a sharp object like a hammer.
@solarguyable Continued: The installers usually don't want any money for the old doors unless they have to deliver them to you. Most old doors have a rubber seal around the glass which I would leave in place to help seal the glass in the box. I am going to make two more collectors this summer. Richallenmusic has some of the best ideas. Old highway signs make a good aluminum bases under the cans. Along with gutters with beer cans I think would be the best collectors. The more metal the better.
@solarguyable Continued: You have to use 2x4's or 2x6's for the box so that you can dado the wood for the glass to set in the top of the box so that it is setting on 3/4 of an inch of wood. I think 2x6's are better. You can also cut the grooves with a table saw. I would rather build a box with the proper angle to the sun on the house so all of the ductwork is enclosed in the insulated box. Then place the collector on the box. Paint or put siding on box to match the house.
@solarguyable Continued: I think that the opening in the bottom of the cans should be an X cut in the cans. The four triangles should the pushed into the can to about 45 degrees. I believe this would slow the air down and let the air collect more heat while passing through the cans. Find someone who collects cans and buy them. For five dollars you can get more cans than you need. They don't get more than 1 or 2 cents for the cans when they sell them at the recycle place.
@solarguyable Continued: We have been Mother Earth News people since the early 80"s. You can build a collector for almost nothing. To get maximum heat and a 20 year life from a collector that does not detrack from the appearance of your home you have to spend just a little bit more money. The payback is such a short time the extra money is worth it. Neighbors will want you to build them one. I will show them how but I cannot work on their homes. Too many problems to discuss. Maintence free heat.
Rich, thanks for the video, I am interested to see what happens to all your heaters once a fan is put on them. I may be wrong, but I think the ones with the cans and glass would hold the heat better, and once the fans come on, the plastic ones couldn't keep up with the metal/glass one. (they would heat up quicker, and radiate the heat better)
A solar can heater if built correctly will give you way over 200 degrees continuous. You should have built a larger unit unless your situation didn't accomodate for it. Nice work and thanks for posting all of your videos.
Very good info thank you. I remember reading years ago of person that placed reflective aluminum material on his veranda that reflected sunlight through house windows to warm his house. Keeping things simple and cheap is the way to go.
@FixedByDoc thanks no need to do all that other stuff if it dont give you more heat if you got good sun you wont be disapointed my downspout heater been cutting on today at about 110 degrees good luck
@1kings1918 cool im sure it will work fine i think i would have got higher temps if i got sun for a couple hours or more my sun goes behind trees never get full sun here good luck
Cool. I thnk someone else indicated that all you really need to do is paint the box black and it should generate heat as long as the sun is out. ?? So is it really necessary to even put the metal in the box? Could you just paint it black and put the plastic over it?
@sc00b3rt I think you need the metal to help grab the heat it does add more heat the one i made with metal roof plus cans works very well i may gut my big downspout heater i have hook up to my bedroom and covert to metal plus the can type
@richallenmusic The downspout heaters I made work well. I cut an extra hole at the bottom for more air volumn. That helps a lot . You need a good high volumn blower on them also. I know the blower takes electricity but remember when that one is running your furnace blower probably isn't so it's a wash :)
you should build these and sell them, id buy one.
Imachowderhead 3 months ago
Here's my thoughts on why pop cans are a god idea.
1. they are free and plentiful
2. they are made from aluminum which conducts heat FAST!
3. they add a little thermal mass which means they stay hotter longer
4. they slow down the air flow just enough to pick up the most heat
5. they are light weight which makes it easier to mount the box on a wall or roof
6. their shape makes for a larger area to catch solar heat on.
well that is all I could think of, hope it helps
Redshift21 4 months ago
@Redshift21 Oh and one last one
7. plastic is prone to UV damage while glass and pop cans aren't.
if you've ever seen what happens to plastic bags left out in the sunlight then you will know what I mean
Redshift21 4 months ago
You're not thinking big enough. Use 4x8 insulation boards backing (see my video). Then add 5 length-wise baffles so a channel snakes back and forth 5 times. Cover with black trash bag plastic (it's so thin it will transfer heat well) then use painters sheet plastic or greenhouse plastic on top as the window. 4" deep, and use a 6" or 8" duct fan capable of at least 100 CFM to keep the temps low (lower box temp means HIGHER efficiency and more heat transfer) Watts = CFM*(F in - F out) / 3
HudsonKnowsEconomics 4 months ago
We are needing to find a way to heat our Greenhouse. This would be great for during the day. But what about at night. How can you retain the heat?
marauderhd 5 months ago
@marauderhd You could use the heat from a compost pile or passive geothermal loop to keep a constant temp. See growingpower (dot) org and look up "compost heat" and "geothermal loop systems" for more. Also see "Earth Sheltered Solar Greenhouse" on YT, Mike Oehler uses a trench to move cold air out of the GH.
kingofthebrittains 3 months ago
how do the these heaters compare to the downspout heater, thanks mike
Dot0011 11 months ago
The curved surface of the cans provide much more surface area than a flat surface. The more surface area, the more air you can move through the box without it cooling down. In a cold climate winter you only get maybe 6 hours of good sun a day, so to have a solar furnace make a worth while heating contribution I would maximize all the important elements I could. Surface area, air flow, cabinet insulation, and insulating glazing.
GrumpyMadman 11 months ago
Anything painted black, and put under sealed glass in the sun will get hot. Just gettting a high temperature from a box when it is exposed to the sun really means nothing. What is important is the amount of air you can move through the box , and the temperature and volume of air you can get into your home. My first fan was a 225 cfm duct booster fan. It really does not move much air, hardly enough to make any impact in heating a home.
GrumpyMadman 11 months ago
can you use steel cans
MrJosiah2004 1 year ago
What fans if any do you use to run air through your panels?
solarguyable 1 year ago
Hi Rich, I like your heaters. I was wondering... have you ever tried a box with nothing in it besides just black paint? Thanks!
solarguyable 1 year ago
I would think there has to be some limit to the depth of the box. Take a 1 by 10 by 1 foot deep box, it has ten cubic feet of air. Same box 10 feet deep, 100 cubic feet of air. Now do you think both heat up at the same rate ?No , the deeper box has more air molecules in it, therefore more mass to heat up, which takes more time. i am making a panel that is only 4 inches deep. Yes very little "mass of air, But it should get warmer faster, so just make "air turnover" through it faster.
wildwindsca 1 year ago
It is ALL about MASS. The mass absorbs the sun's energy and the circulation extracts it.
IdahoViewing 1 year ago
Thank you for all the great ideas. I have my glass and insulation and I was saving cans up but now I think I'll use a sheet of aluminum painted black. Maybe I'll crush the cans flat and lay them in the box between two pieces of chicken wire after I paint them.
Cannibalriot 1 year ago
Anybody have any thoughts on increasing the depth of the box? ie Use 2x6's or 2x8's around it and just increase the cubic space of the hot air? On greenpowerscience they used a temp gauge on a dark colored car in the sun the inside temp was around 155 F. That is a ton of cubic heat add a fan and move it around.
ammob1 1 year ago
@ammob1 ive used 2x6 on my big downspout heater people are making all sizes of boxs the bigger the box the more air you heat and move
richallenmusic 1 year ago
@richallenmusic Hey Rich, thanks for the videos! I'm all about freaky cheap technology, so I have some ideas for you. Check out solarcooking (dot) org and the Capturing Heat pdf from weblife (dot) org. for more ideas, b/c a couple cardboard & foil reflector panels would triple your efficiency. Also check out richsoil (dot) com, aprovecho (dot) net technology section and any Permaculture websites, they usually have lots of cool appropriate technology links. Cheers!
kingofthebrittains 3 months ago
@ammob1 You could use interior door jam. It measures like 1/2 x 5.5 inches.
2JobsStillPoorUSA 4 months ago
I couldn't agree more Rich. Some metal in an insulated box covered in glass with an in and out is allya need. Pop cans are too much work.
N8Dogg1002 1 year ago
@N8Dogg1002 the pop cans work great if you just set them in the box i got 180 degrees like that watch my video the cheapest easy heater
richallenmusic 1 year ago
what if you live in Canada? ;)
just sayin...
lad18913290 1 year ago
@lad18913290 -If you live in Canada, unless you never have sun, this would be perfect for you!
Thanks, Rich for showing us how affordable passive solar heaters can really be! A lot of the other instructions online use power tools I don't have, and require supplies that would really increase the cost of the heater, making me really doubt the cost savings. Your experiments really show that I could harness free heat for nearly free supplies!
Dudeyowuzup 1 year ago
@Dudeyowuzup
hmmm, i doubt a piece of poly over my collector would suffice in my climate - the tighter the seal, the better - that's my point, i meant no offense. Great insight Rich! :)
if you want simple - glass clutters, snips, hammer and a handsaw, it doesn't take a genius to build a box and cover it with glass. if you want cheap, RECYCLE. visit a few construction sites -contractors have lots of junk lying around that they're willing to part with, usually for FREE. all it takes is effort.
lad18913290 1 year ago
Exellent idea to compare various models. The real test would be to stick the same small fan (say from an old computer) on each in turn and compare temps after they stabilize. I also doubt the necessity of cans. Wonder if inside the box you strung used Aluminum Xmas garland and sprayed it black. Lots thinner and might conduct more heat to the air flowing past it. Double up layers of 4 mill clear plastic? Space them apart with small pieces of quarter inch weather strip door foam. Thoughts
bfenti 1 year ago
Hi Rich. My concern is melting the glazing. I live in Flrorida. We do need heat for about 2 months in Tampa, but we only need to heat from about freezing to 70 (40 degree differential). A couple thermal solar furnaces can do the trick but mine has reached 200F easily in the October Florida sun, which makes me uneasy to have anything but glass as the glazing. Even in Maryland I have gotten the temp up to 175F on one I built at my brother's house. Are acrylic or plastic ok?
landslave 1 year ago
@landslave Most use polycarbonate for glaze. I have used old sliding glass doors. They are heavier, but most are free and are double glass sealed together. They usually will not break from hits from lawnmower or windstorms. You can grove (dado) the sides and set the glass panels in with foam insulation as a seal, then seal and cap the glass.
navajopa31 1 year ago
@navajopa31 Hi where do you find free old sliding glass doors? I want to use them too, but I have no idea where to look to find free doors. Thanks!
solarguyable 1 year ago
@solarguyable Lowes and Home Depot sell the new doors and have installers to put them in. Talk the the guys that sell the doors and tell them you would like a couple of old doors. The installers have to throw them in the dump. You can leave the trim on the old doors or remove it and just use the glass. I rather just use the glass. They usually are two pieces of glass sealed together. Most of the old ones will shatter into a millions pieces if dropped or hit with a sharp object like a hammer.
navajopa31 1 year ago
@solarguyable Continued: The installers usually don't want any money for the old doors unless they have to deliver them to you. Most old doors have a rubber seal around the glass which I would leave in place to help seal the glass in the box. I am going to make two more collectors this summer. Richallenmusic has some of the best ideas. Old highway signs make a good aluminum bases under the cans. Along with gutters with beer cans I think would be the best collectors. The more metal the better.
navajopa31 1 year ago
@solarguyable Continued: You have to use 2x4's or 2x6's for the box so that you can dado the wood for the glass to set in the top of the box so that it is setting on 3/4 of an inch of wood. I think 2x6's are better. You can also cut the grooves with a table saw. I would rather build a box with the proper angle to the sun on the house so all of the ductwork is enclosed in the insulated box. Then place the collector on the box. Paint or put siding on box to match the house.
navajopa31 1 year ago
@solarguyable Continued: I think that the opening in the bottom of the cans should be an X cut in the cans. The four triangles should the pushed into the can to about 45 degrees. I believe this would slow the air down and let the air collect more heat while passing through the cans. Find someone who collects cans and buy them. For five dollars you can get more cans than you need. They don't get more than 1 or 2 cents for the cans when they sell them at the recycle place.
navajopa31 1 year ago
@solarguyable Continued: We have been Mother Earth News people since the early 80"s. You can build a collector for almost nothing. To get maximum heat and a 20 year life from a collector that does not detrack from the appearance of your home you have to spend just a little bit more money. The payback is such a short time the extra money is worth it. Neighbors will want you to build them one. I will show them how but I cannot work on their homes. Too many problems to discuss. Maintence free heat.
navajopa31 1 year ago
@solarguyable craigs list free section
Dot0011 11 months ago
Rich, thanks for the video, I am interested to see what happens to all your heaters once a fan is put on them. I may be wrong, but I think the ones with the cans and glass would hold the heat better, and once the fans come on, the plastic ones couldn't keep up with the metal/glass one. (they would heat up quicker, and radiate the heat better)
hitmanhite 1 year ago
A solar can heater if built correctly will give you way over 200 degrees continuous. You should have built a larger unit unless your situation didn't accomodate for it. Nice work and thanks for posting all of your videos.
MandalayWind 1 year ago
i was thinking it was going to be empty. almost was. thanks heater man
qsk2pc602 1 year ago
Damn, that a chep heater!
***** :-)
pgm98387 1 year ago
... next thing I expect to see is you walking around naked in the sun after spraying yourself with flat black paint. LOL.
Fearlessthinker 1 year ago 5
@Fearlessthinker O NO YOU MUST HAVE A HIDDEN CAMERA IN MY YARD!!!!!!!!!!!
richallenmusic 1 year ago 10
@richallenmusic ha ha ha... that made me spew coffee.
2JobsStillPoorUSA 4 months ago
Very good info thank you. I remember reading years ago of person that placed reflective aluminum material on his veranda that reflected sunlight through house windows to warm his house. Keeping things simple and cheap is the way to go.
0urGaia 1 year ago
Well done Rich, Thank you.
richardliz23 1 year ago
great news. thanks for all the testing and introduction to this stuff. it will hopefully save me some money here this winter.
FixedByDoc 1 year ago
@FixedByDoc thanks no need to do all that other stuff if it dont give you more heat if you got good sun you wont be disapointed my downspout heater been cutting on today at about 110 degrees good luck
richallenmusic 1 year ago
The glass front has always been my hang up. I think I have some thick plastic drop cloth that I will use. Thanks.
1kings1918 1 year ago
@1kings1918 cool im sure it will work fine i think i would have got higher temps if i got sun for a couple hours or more my sun goes behind trees never get full sun here good luck
richallenmusic 1 year ago
thanks!!
MrJerryanderson 1 year ago
Cool. I thnk someone else indicated that all you really need to do is paint the box black and it should generate heat as long as the sun is out. ?? So is it really necessary to even put the metal in the box? Could you just paint it black and put the plastic over it?
sc00b3rt 1 year ago
@sc00b3rt I think you need the metal to help grab the heat it does add more heat the one i made with metal roof plus cans works very well i may gut my big downspout heater i have hook up to my bedroom and covert to metal plus the can type
richallenmusic 1 year ago
@richallenmusic The downspout heaters I made work well. I cut an extra hole at the bottom for more air volumn. That helps a lot . You need a good high volumn blower on them also. I know the blower takes electricity but remember when that one is running your furnace blower probably isn't so it's a wash :)
wiboater4 1 year ago
I think you nailed is Rich, very cool I must say. I look at these panels as green houses, catch the sun and pull it into your home, it is a win win.
Thank you for all of your videos, you are an inspiration to many
CTOL1 1 year ago
YOU ARE THE BONG!!! At last an honest man!!!!! Simple, cheap, real by a real guy. What a concept, thank you!
yonny1954 1 year ago