->  The main city public service (CPS) office in San Antonio, TX
-> is doing just that. Solar collectors on the roof provide the heat
-> source and the hotter the temps the more efficient the a/c in the
-> building.

->  There may be something abt it on the internet but dunno.

->  Fwiw this is also how the old propane gas powered refrigerators
-> worked. A pilot flame provided the heat source.

 Actualy if by Old you mean No Longer avaialble that is NOT true. They
are still alive and well not only in Motorhome refigerators but also for
Remote locations. Powered either by Propane or in some cases by a Solar
Electrical System. The electrial Heated units are a littlew less
efficent. As WILL be the Solar Heated Hor water system you were talking
about. I used to work at the Local VA Medical Center here in San Diego
Califronia. 
In the 80's we invested I don't know how many hundreds of Millions of
Dollars of the Tax Payers "Pie i nthe Sky" Solar Powered Systems. The
one supposedly able to ren a Still for our Distilled Water needs, The
Labs gsue Galons and Galonns of it, Was a Dismal Failure gight form the
get GO.
The How Water Heating Booster system actualy cost us MORE in cost of
pumping the water arrouind through the Huge Solar Solar Heat collection
system then it cost us to Heat he water with Steam from the Power Plant.
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