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justgreenhomes 11-27-2009 09:59 AM

Solar Air Heater
Just finished this a week ago. It kicks out 95 deg air when the sun is shining! A 34"x48" solar air heater made from a salvaged window sash.

Scuba_Dave 11-27-2009 10:12 AM

Nice, is it Alum siding painted black?

I'm working on a couple larger ones
To the left of the ladder will be a ~6x6 unit w/Alum cans inside

wwpro 11-27-2009 04:49 PM

Good timing :)

I've been reading about this all week, I'll keep an eye on this thread .

Looking great by the way :thumbup:

Yoyizit 11-27-2009 05:00 PM

~3000 BTU/hr when the sun shines. . .?

justgreenhomes 11-27-2009 06:40 PM

Scuba_Dave: Most of the black surface is 3/4" polyiso insulation that separates the cool side from the hot side. The fins are just drywall corner bead. I've seen the ones with aluminum cans and I wondered if all of the work was worth it. Maybe I'll try it on my next one. My heater sits in the window so it can be removed in the spring.

I've got plans for a larger one, but I needed to warm my wife up to the idea. I'm llokin gforward to updates on yours.

I just posted an article on my blog about how I made mine.

Yoyizit: I'll have to do a test on the CFM to verify, but I think 3,000 BTU/hr is close.

Yoyizit 11-27-2009 09:32 PM


Originally Posted by justgreenhomes (Post 358376)
Yoyizit: I'll have to do a test on the CFM to verify, but I think 3,000 BTU/hr is close.

The Solar Constant is 1 kw per sq. meter and 34"x48" is about one sq. meter.

Red Squirrel 11-27-2009 09:46 PM

That's pretty cool. Just read up on the concept, think I'll look into trying this. Not sure where I'd set it up though but I'm sure I can find a place.

Scuba_Dave 11-27-2009 09:52 PM

So my system should put out about 9,000 BTU...nice
Once I get one going I'm going to build a few more
Yeah.....Wife's OK with one....more if she can see some heat from the 1st one :laughing:

justgreenhomes 11-27-2009 10:22 PM

Yoyizit: I was using the equation:
Q=4.5 x CFM x (delta h) so
CFM = Q/(4.5 (delta h))
CFM = 3000/4.5*30
CFM = 22.2

Here's a section drawing:

Yoyizit 11-28-2009 10:54 AM


Originally Posted by justgreenhomes (Post 358448)
Yoyizit: I was using the equation:
Q=4.5 x CFM x (delta h) so
CFM = Q/(4.5 (delta h))
CFM = 3000/4.5*30
CFM = 22.2

Here's a section drawing:

It must be a stack effect formula.

You could save some bucks with these things.
The cost of maintenance is ~$0 and the MTBF is probably very high.

But, treated wood is poisonous; I hope the moving air doesn't drag toxins out of the wood.

tpolk 11-28-2009 11:18 AM

I have six windows facing winter sun all day. I have ribbed commercial grade metal roofing I can use to build several. Is there a clearer design I can use or is this just a common sense build. Looks like air is circulating from house over face and back in. carpenter by trade so have some working knowledge. I'm guessing you need to be able to shut the window sash at nite or you have a reverse value thanks timothy

justgreenhomes 11-28-2009 10:30 PM

Yoyizit: I thought the toxins from treated wood were only a problem if they leach into the ground or if you have prolonged contact with your skin. I've never heard of a concern that they coudl become airborn. Just to be safe, I'll prime the rest of the exposed wood.
tpolk: how's this? There are more photos in my photo gallery. The ribbed metal roofing should work just fine. No the window closes on the top of the air heater. You should put foam insulation (air conditioner weatherstripping) between the glass of the bottom sash and the bottom rail for the top sach. I took the extra measure of installing insulating window film to help stop any air infiltration.

Red Squirrel 11-28-2009 10:38 PM

I'm really interested in trying this for my house, I'll have to pay more attention where the sun shines the most and see if that location is viable. Do you think this would work in -30 weather? Ironicly when it's that cold out it tends to be very sunny out.

Scuba_Dave 11-28-2009 10:41 PM

Here are some pics of one someone built
They just used Alum screening
Anything to soak up the heat from the sun will work
Alum works best I think....and cans are inexpensive

85+ degree air coming out

justgreenhomes 11-28-2009 10:50 PM

I'm betting that it will. Maybe not quite the 30 deg delta but I'll let you know when it gets that cold here.

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