Sorry I took so long to remember to check MY ATS and look back in here. We live in the Cayman Islands. MBF, I'd guess that you can get about 75%
of the solar efficiency that we get..
Each 4X8 frame uses about 100 feet of 3/8" tubing.... I bent the tubing gently into about 2" curves. Afterward, I thought that it might've been
a little more slick to drill 7/16" holes an equal distance apart on both long sides of the frame, such that the tubing went in and out of it -- it
would sure look a lot more tidy, as I had to use little cable clamps to hold the tubing flat in the frame. Around the interior of the frame, I used
1" styrofoam insulation, and shot the whole works with flat black paint.
I"m not certain of the volume of water heated; I could figure it out if this weren't a lazy Sunday afternoon
I use a 12V pump to circulate the
water, so it'll heat for a bit, circulate, etc.
With the hot tub, I just let the water flow during it's cleaning cycle, at it heats 400 gallons about 10 degrees....... lately with it being so hot,
we have to give the tub an hour or so to cool down to 104.
With the house system, I circulate the VERY hot water twice a day into an insulated 55-gallon drum (also black), and the output from that goes into
the cold side of our water heater. The hot side of our water heater has a tempering valve on it to mix cold with hot, to deliver 120 degrees F. to
our faucets and shower. I take one line directly untempered to our dishwasher, which normally heats the water up to 140 degrees.
The 12V circulating pump is powered by a deep cycle battery, charged by a 5W (I think I said 10, but it's a 5W) PV cell. It will also pressurize
our house to 40 psi, which is plenty.
I'm really interested in your heat exchange idea. Only thing I did with our A/c, was run a coil of copper into a 10-gallon bucket (the hot side).
The bucket is filled with water and that knocks a few degrees off the hot side of the ductless split system. A counterflow would certainly be more
efficient, I'm just not certain I have the knowledge to create a counterflow chiller (sort of like a wort chiller for beermaking).
This morning I was shopping online for a solar-powered attic fan. I think that'd take care of 75% of our a/c needs. As it is, we just run the
thing at night while sleeping. Wouldn't you know it.......... I ended up ordering another 1st Gen. NV monocular to replace our ol' one that
finally gave up the ghost. Won't my Bride be surprised. haha