Actually for the tubes on the roof surface, there is usually not much of a temperature difference to drive heat transfer. The roof surface is about 120 F and the dark gray surfaces of the painted PVC tubes are about this temperature too. However, I imagine I am losing some significant heat from the tube for the length that it runs underground since the soil stays around 65 F. When I get in on a new pool installation (as opposed to a retrofit) I will specify that the heat supply tube be insulated before it is buried.

In regard to preheating domestic hot water, a WS heater would, at best, be only effective only during March to November; the period which an attic space gets above room temperature. Objectively speaking, I think that a better approach to generating domestic hot water would be to use a glazed 2-D nonimaginging solar concentrator. Such a collector could produce high temperatures practically anytime the sun is up. There is an article about these nonimagining concentrators in the March 1991 Scientific American, in addition to the book by Joseph O'Gallagher I mentioned in one of my other posts.

If the water in the pool is to be kept above the temperature of the soil (65 F; EXTREMELY LIKELY) you could also specify that the exterior of the concrete be insulated. This is probably the biggest heat loss area even though the temperature difference is smallest. You could also insulate the underground portion of the pipe going to the Warm Spring, all the way up to the attic.

My **Official** guesses as to improvements:
Insulating the return portion of the pipe from the roof, Exit Temperature +5F
Insulating the send portion of the pipe to the attic, Exit Temperature +3F
Insulating the pool, Pool Temp +5F
--Doing more than one of these will add to the effects of the others

These **Official** guesses are PDOMA (Pulled Driectly Out of My...), but are based on reason. I could run some numbers and see where things fall out with slightly more confidence, but these

Hi! Very nice what you do! Do you built your airtowater exchanger or you buy it?:thumbup:

Regards
Gaetan

I get the heat exchangers custom-made for WarmSpring.

I have a business partner now: Truly Noble Services, Inc. We have five units operating in the Dallas area. I expect to ship a rooftop unit to Georgia this week.

Thats great to hear you're making it work out. I like the idea.