I live in South Texas where both my AC units run non-stop from sun up to sun down, and then some more. The units still work fine but they are older (10 + years) and much less efficient than the newer models. I'd like recover the heat that's generated by the AC system to supplement my hot water heater. I initially read about HRU's in the Renewable Energy section of the forums but the last post was a while ago. Was wondering if anyone has any recent experience with HRU's? Looking for info regarding installation, usefulness, and recommended brands.