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Old 11-11-13, 11:16 AM   #13
AC_Hacker
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Default Stealth Solar Heating...

Quote:
Originally Posted by skyking View Post
you're from Portland, so you know what happens around here. We get serious bad spells with no sun.
You're talking about sun exposure from time to time. Your air will be about as mold-laden as the air you breathe when you walk around outdoors.

Quote:
Originally Posted by skyking View Post
I think the thing to do is build wall air collectors where I can, and put HDPE tubing under the standing seam metal for a liquid based collector. I was going with a dark green roof so that will deliver some heat OK.
That is a very viable plan. I even have a lab report laying around here someplace about doing that very thing.

It's been a while since I read the report, but as I recall, the big advantagea are that your solar collector is totally hidden and protected from the elements and from complaining neighbors, if that is relevant. Also, your incremental cost is very small if you are already doing a roof.

The biggest disadvantage is that the amount heat that will be collected is much lower than from a full on flat plate collector or evacuated tubes... something in the neighborhood of 8% to 10% as opposed to 40% or slightly higher for evac tubes. But if your whole roof is your collector, it all adds up. I have no data for heated air to use as a comparison.

If you're gonna do it, put some rigid foam under the roof/tubing setup.

And don't use HDPE, it's too likely to melt. PEX would be a better bet.

And if you're gonna do it, you only need to do it to the faces of the roof that receive significant sun.

I wish I had done this when I did my roof.

BTW, my roof is dark green and yest, it gets very hot... even on a sunny winter day.

Take lots of pix.

-AC
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Last edited by AC_Hacker; 11-11-13 at 11:24 AM..
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