Aluminum pop/beer can solar heater

Just got my pop/beer can solar heater going today. I built this heater this past summer but just now got it installed and going on my container cabin now called the Taj MaLodge  .
It outside temp was 40 degrees
It was 56 degrees at the cold air intake
Exhaust temp was 104 degrees
Airflow is powered by a 12 volt 110cfm cage motor.
I think if my panel faced the sun at a more direct angle the exhaust would be a little better, keep in mind that our sun here in ok is at it's lowest point of the year, so as we advance towards spring and the sun starts its climb back up, the exhaust heat will keep climbing with the sun. Yehaaaaaaaaaa!!!
Here are a few pics of it.

I forgot to mention that all the cans were collected along the roadsides by my boy and I.

nice work.  any trouble with fumes from the paint blowing into your living space?  there was some concern about that on a previous thread here.  and is it enough to heat your space?

tel jetson wrote:
nice work.  any trouble with fumes from the paint blowing into your living space?  there was some concern about that on a previous thread here.  and is it enough to heat your space?

Thank you.
I am not sure why the the paint would be an issue. On mine the cans have been painted since the first part of may and only in the last couple weeks has the lexan been put on, so the paint has had 7 months to cure. Also the actual airflow is totally separate and sealed off from the paint. Each can is sealed into the other, then the columns are sealed to the headers which in turn is sealed from all outside air source.
I smelled a slight odor  when it first came on, but it was a slight smell of Styrofoam, and the interior of each header is lined with that, so I really don't think I have any worries from the paint. 
Oh and as far as it being enough to heat the space, the jury is still out on that one. I would just say that it works with the wood stove, I could not get by solely on it I am sure of that. It will produce heat from about 9:00am to 3:00 pm. I can use less wood during that period, so it helps cut down on wood consumption from say October-April. I just got this going so there is no way to give you any real numbers, just the fact that it puts out heat for free.      

How did you seal the cans together?

ronie wrote:
How did you seal the cans together?

High heat mortar. I made mine similar to the one in this video, just mine is a lot bigger with 240 cans

If you hinged it at the bottom and added an adjustable stand at the top you could benefit better from the angle of the sun.

Tinknal wrote:
If you hinged it at the bottom and added an adjustable stand at the top you could benefit better from the angle of the sun.

That  is a great idea, think I will run with it. I should have it done in the next few days and will post back the difference it makes. I would expect a difference of at least 10-15 degrees.

Maybe I am not awake enough as my supply of Vitmain D hasn't risen in the NE yet...  how is this working to heat your home?  I live w/ out highspeed internet so following those video links is asking me to run a computer for 8 hours. 

WOW!
I had no idea this was possible. Why isn't this more widely known? Could you convert the energy to something other than heat? and how would you do that? This looks like something my dad would be really into!

Larry wrote:
High heat mortar. I made mine similar to the one in this video, just mine is a lot bigger with 240 cans
http://www.youtube.com/watch?v=QLNViUsRCVU

He has a couple of other videos.  His fifth version of the pop can heater (http://www.youtube.com/watch?v=2Cm-cbOWvSs) he doesn't bother sealing the cans together.  Instead, he uses downspouts to hold the cans in a line, and also as the headers/footers in the assembly.  Using that, running a test in full sun without sealing the glass , he got 220* after one hour fifteen minutes.

Pakanohida wrote:
Maybe I am not awake enough as my supply of Vitmain D hasn't risen in the NE yet...  how is this working to heat your home?  I live w/ out highspeed internet so following those video links is asking me to run a computer for 8 hours. 

The way it works is, cold air from the bottom (near base board) is drawn up into the solar collector via a 12 volt 110cfm fan and through the aluminum cans that have been heated by the sun and on out the exhaust towards the ceiling. The colder air at the floor is constantly being moved through the system lets say 55 degrees at the base and heated to over 100 degrees as it goes through the cans. So with each passing hour the temp should keep rising as the air keeps being replaced by warmer air. Well so long as the sun is shinning

Larry wrote:
The way it works is, cold air from the bottom (near base board) is drawn up into the solar collector via a 12 volt 110cfm fan and through the aluminum cans that have been heated by the sun and on out the exhaust towards the ceiling. The colder air at the floor is constantly being moved through the system lets say 55 degrees at the base and heated to over 100 degrees as it goes through the cans. So with each passing hour the temp should keep rising as the air keeps being replaced by warmer air. Well so long as the sun is shinning

Thank you, I think I will try to set up an overnight download for this and Paul's one above. 

Larry wrote:

It was 56 degrees at the cold air intake
Exhaust temp was 104 degrees
Airflow is powered by a 12 volt 110cfm cage motor.

Q = CFM * 1.08 * TD

So we have 110*1.08*48 = 5702.4 BTU's of heat per hour while performing at that level, not a lot in the grand scheme of most heating loads for a space, but darn near 2kw of output which is not to be sneezed at at all.

One thing that concerns me on accuracy here and I have no time to effectively evaluate it 110 cfm may well be the rating, but that rating does not account for pressure drop and there is significant amounts in that can set up in contrast to smooth duct. Again this is not to detract from an impressive performance, one I would not have off the cuff expected.

Air has about 1/4 the heat carrying capacity of water, obviously the design is similar to a solar water heater, I have to wonder if a small recirculation pump and water flowing through it could not be effective as well for something like a giant hot water bag to line Paul's chair with bike pedals to drive the pump and desk pad to really make the temp in his electrical experiment very comfy!

Oh yeah, the 1.08 is a constant to convert cfm's to pounds per hour and water cooled units pretty much ise the same formula but insert 500 at the 1.08 to convert GPM to pounds per hour for water.

The U factor on the cans is going to be fantastic with the only non-productive part being the plastic coatings on the inside and out. The jagged design of the cans compared to smooth duct really actually improve the thermal capacity even though they create some pressure drop fan performance issues.

Cool project, very nice craftsmanship, 2kw off your heating load without regard for the "minor" part, if you have a 100k load (typical guestimate for 1,000 sq ft in the st louis area) you have indeed saved close to 2% of your heating bill. I would call that a win!

Professor Rich wrote:
Q = CFM * 1.08 * TD

So we have 110*1.08*48 = 5702.4 BTU's of heat per hour while performing at that level, not a lot in the grand scheme of most heating loads for a space, but darn near 2kw of output which is not to be sneezed at at all.

One thing that concerns me on accuracy here and I have no time to effectively evaluate it 110 cfm may well be the rating, but that rating does not account for pressure drop and there is significant amounts in that can set up in contrast to smooth duct. Again this is not to detract from an impressive performance, one I would not have off the cuff expected.

Air has about 1/4 the heat carrying capacity of water, obviously the design is similar to a solar water heater, I have to wonder if a small recirculation pump and water flowing through it could not be effective as well for something like a giant hot water bag to line Paul's chair with bike pedals to drive the pump and desk pad to really make the temp in his electrical experiment very comfy!

Oh yeah, the 1.08 is a constant to convert cfm's to pounds per hour and water cooled units pretty much ise the same formula but insert 500 at the 1.08 to convert GPM to pounds per hour for water.

The U factor on the cans is going to be fantastic with the only non-productive part being the plastic coatings on the inside and out. The jagged design of the cans compared to smooth duct really actually improve the thermal capacity even though they create some pressure drop fan performance issues.

Cool project, very nice craftsmanship, 2kw off your heating load without regard for the "minor" part, if you have a 100k load (typical guestimate for 1,000 sq ft in the st louis area) you have indeed saved close to 2% of your heating bill. I would call that a win!

HUH
There are two video's that I based my heater on. The can design was fashioned from the Rich Allen video, and the cabinet and #of cans were designed from this video http://www.youtube.com/watch?v=bRZvAAqzXIw I think he sells these heaters for about $800.00ea. He uses a 100cfm fan and I knew there would be a good drop in cfm's going through the system which is why I bumped mine up to a 110. I am only heating a 640 sq.ft space and once I angle my panel more directly into the sun, I expect the exhaust temps to rise quite a bit. I am sure there are ways to improve this type of heater, but as is, it is simple and maintenance free. I do not have electric heat, just a wood stove, and the fan  only uses 7 watts to run, and that is from a 12 volt battery which is also part of the solar electric I am working on, so it is just free heat for me, well now that it is paid for    

I found it interesting that Rich Allen's last video about his heating system found virtually no difference in efficiency between his aluminum can design, his aluminum downspout design, and having a box that's just filled with pieces of junk metal.

There's a very active conversation about solar thermal heating on simply solar (a yahoo group) - about 600 people, including many who have done extensive work on these sorts of things (mostly the conversation is about solar thermal heating- air and water). It's a yahoo group, which i'm not too fond of, but a great group of people doing great work along these lines.

As far as professor Rich's note about 2% of the need- regardless of the calculations, i suspect the heat generated is a far greater proportion than 2%. The cansolair guy in canada says one unit he sells is good for about 1000sq feet.

icky

My pop can solar heater was not working real good today Feb 5 2011.



After removing the snow, it was 39 degrees out and room temp was 54, it was producing 112 degrees 11:00 am.
A few day ago when the temps were in the upper sixty's, it was producing over 120 degrees with a intake temp of 45 degrees, (45 degrees was room temp after a cold night with no fire burning in two days) also my cheapo thermometer only went to 120 and I think the exhaust was much hotter because it was pretty uncomfortable to hold my hand by it very long. I think I am going to keep the panel in it's fixed position because I believe it is probably angled the best for the 6 or 7 months of the year that it will get used.   

A friend sent me the youtube link and this site link.  Have been saving cans and gathering materials with the intention for raising the temp in the crawl space under the house.  also intend to incorporate into winter greenhouse

R U kidding? You can make a functional solar panel out of old cans? My goodness, I had no idea... that is amazing. Wow.

G'day

seeing hot air rises, and provided you had the space, would it be possible to position one of these units underneath a window and run it without an electric fan?

cheers, Jan

j_cornelissen wrote:
G'day

seeing hot air rises, and provided you had the space, would it be possible to position one of these units underneath a window and run it without an electric fan?

cheers, Jan

Yes, that is how a lot of them are set up, using natural convection to move the air.

Cool project! Nice material use as well.

Plus, if you miss the aromas of college, you can leave the cans unwashed! Odour of stale beer anyone?

But seriously, nice work.

Professor Rich brought up it's similarity to a solar water heating system, and I agree. I saw systems like the one below on every single house on the outskirts of Shanghai. I guess they must work.



picture from: http://blog.sustainablog.org/solar-hot-water-revolution/

taking the fan out of the equation means you don't hve to worry about cold air being pumped in on a cloudless day!

j_cornelissen wrote:
taking the fan out of the equation means you don't hve to worry about cold air being pumped in on a cloudless day!

the convection loop can and will reverse itself if the cans are colder than your inside air like say at night, so you either need to be mindfull of the system or install some type of automation to shut off the airflow

Another note on that pop can solar heater.
I have not worked on my cabin for a couple days now and we just got about 8" of snow here, so I have not built a fire in the cabin for two days. Today it was one degree in the morning, (day before was similar), and the cabin temp was 38 degrees (earth berm is doing its job). I did not start a fire but I brushed the snow off the solar panel and turned it on at 10:30am (sunny out today). I went back at 2:30pm, and it was 48 degrees in the cabin, outside temp was 25 degrees. Exhaust temp was 102 degrees. So in 4 hours the solar panel raised the room temp 10 degrees on its own. 10 degrees warmer then it started and 23 degrees warmer then the outside. I say it is worth it.

Just skimmed through this thread and appreciate all the photos, links and details on how this works. I ran across a 2008 video of a Newfounlander who was being touted as the inventor of the aluminum can solar heater.



He's selling panels - an interesting business model.

Wow, wonderful set up dear. I was wondering how you manage to put all cans in one box, you know painting from outside will help to keep it cold..

Larry, nice craftsmanship on the solar air heater. There is something you can do to improve performance. Find a blower fan with a higher capacity, then put it on a thermostat on a fairly low temp setting. It's undesirable to have very high air temperatures leaving the heater as this contributes to thermal losses from the heater. Basically, you're putting energy into the air through radiant heating (sunlight), and losing this energy through convection (i.e. hot air tranfers heat to the cooler outside air). If you minimize the temperature of the air leaving the heater, then convective losses will also be minimized. This will optimize the performance of your air heater.

I was looking at this again, and I do think it's a rather brilliant idea. I'm gonna have to retract my previous statement. Sure, a higher capacity blower would increase heating output, but then there are other losses that should be minimized. Besides, who cares about a moderate gain in heating output when the heat is free and the panel is inexpensive... just build another panel if you need it! I don't need much space heating where I'm located, but I would build a whole gang of these if I lived in a cold climate.

Larry, thanks for sharing your project.

Hey all, I think im going to try and tackle one of these babies as my next project, but i was wondering if anyone had any concerns or insight on the use of aluminum cans in the design. Specifically, any potential toxins or chemical leaches due to the high heat exposure.

I was thinking of maybe using rocks, bricks or glass bottles in the design as a possibility. Any thoughts?

Hi everybody.

Well, where i live in the mountains of france, we use steel rooves.



I'm doing roofing as my day job. And i'm pretty sure i could do an air tight box with the steel on top. Do you think i could make a heating system with this? I'm sure it would work. I could even use aluminium because we have the same profiles in AL. And use à darker collor, it's alowed where i live. May be it has been done before?

Thanks.

Max.

Everyone interedted in this topic would benefit from reading this research on solar collector design: http://www.builditsolar.com/Experimental/AirColTesting/Index.htm

Hi,
Very informative stuff!
I’ve been contemplating building one of these for some time, but as neither I nor anyone in my family consumes drinks out of pop cans I baulked at the idea of collecting so many cans. I live in the UK in central London and the local council and the residents in my area are almost fanatical on re-cycling so most of the used cans get put in the re-cycling bins and I wouldn’t feel happy taking them from there. So my project stalled at the basic requirements.
I have however seen some rather nice aluminium ducting on eBay that retails at £6.50 (approx $10.00) for 10 meters with a diameter of 4 inches. The ducting is corrugated and flexible. My idea is to use this rather than tin cans, as it's essentially the same material but in a different form factor.
I can foresee some benefits of this approach:
1) I can wrap string around the tubing at various locations to create air turbulence.
2) The tubing can run directly into my inlet thus minimising heat loss.
3) No need to use caulk to stick the cans together.
4) No need to collect, clean & soak any cans.

Also as I have quite a large back garden I'm thinking of strategically placing some mirrors to direct sunlight onto the panel.

I'd like to know if anyone has tried this approach; and if so has any observations or tips that might prove beneficial for me?
I'd also like to hear from anyone who might know of any potential pitfalls of this approach.

Thanks chaps!

Mike

Mike Griffiths wrote:Hi,
Very informative stuff!
I’ve been contemplating building one of these for some time, but as neither I nor anyone in my family consumes drinks out of pop cans I baulked at the idea of collecting so many cans. I live in the UK in central London and the local council and the residents in my area are almost fanatical on re-cycling so most of the used cans get put in the re-cycling bins and I wouldn’t feel happy taking them from there. So my project stalled at the basic requirements.
I have however seen some rather nice aluminium ducting on eBay that retails at £6.50 (approx $10.00) for 10 meters with a diameter of 4 inches. The ducting is corrugated and flexible. My idea is to use this rather than tin cans, as it's essentially the same material but in a different form factor.
I can foresee some benefits of this approach:
1) I can wrap string around the tubing at various locations to create air turbulence.
2) The tubing can run directly into my inlet thus minimising heat loss.
3) No need to use caulk to stick the cans together.
4) No need to collect, clean & soak any cans.

Also as I have quite a large back garden I'm thinking of strategically placing some mirrors to direct sunlight onto the panel.

I'd like to know if anyone has tried this approach; and if so has any observations or tips that might prove beneficial for me?
I'd also like to hear from anyone who might know of any potential pitfalls of this approach.

Thanks chaps!

Mike

I created a login just to get in on this conversation. I think the overall idea is wonderful.

Mike: I think ducting is a great idea, but you may want to look for a smaller diameter. The more surface area you can get, the more heat you're going to collect. Also, the ducting provides an option I've been looking into, which would be to arrange the ducting back and forth in a repeating "S" pattern to create one long tube. This may require a more powerful fan, but I think that one computer fan on each end should do quite fine. This long duct should raise the overall temperature. If we were dealing with water, I would definitely say the flow rate would be much lower, but given that air is compressible I don't think there will be much of an issue.

For your turbulence idea, I wouldn't worry too much. As long as your duct has that "bendy straw" look to it, there will be plenty of turbulence to stir the air up from the inner wall alone. My only real suggestion would be to make sure the ducting doesn't have any kind of coating on it. I don't know if it would or wouldn't, just something to always look for.

I hope your project goes well!

~Adam

If you guys get time, appreciate any help on my solar heater project https://permies.com/t/18856/passive-solar/UK-heater-project-HELP-required

I'm sold! Will definitely build one of these when I get my farm (soon) or if it's not soon, on my present house. A question about location: people put solar heaters in greenhouses, where they get a little less sun but are protected from those below-zero days we still have in MN. Do folks recommend inside the greenhouse or not?

Be careful with the styrofoam if it gets to hot inside of a box it will start to melt and put fumes into your home. My younger brother built one and it worked great the first winter. That summer it got to hot and melted the insulation !