As the heat continues here in Cent FL, I continue to wonder why heat recovery units on A/Cs and heat pumps continue to be ignored. Most A/C pros dismiss them offhand saying 'they don't work with high efficiency units' but they most certainly work with 13 SEER systems and lower compressor draw about 20%. Easy to measure with an amprobe and a switch to turn the HRU circulator pump on and off. Another complaint I've heard is that local water quality affects the circulator pumps but that would also be a problem with solar hot water heaters...people just need to know that an HRU may need some maintenance just like a solar system does. At least you don't have the big panels cluttering up your roof and becoming an issue when the roof is replaced. I feel that solar hot water in Florida is a huge, costly mistake as opposed to a HRU. Any solar fans want to scrap on that comment? I've had experience with 3 HRU's (one on a 7 SEER York that was recently replaced with a 13 SEER Ducane, another 13 and a 10) and all have cut electric bills at least $30 a month..usually more. Easy to tell if the unit needs work...your power bill goes up. I know I'd never have a house in Florida without one. Can anyone give me reasons not to use them other than anecdotal evidence? The money you save 'downgrading' from a 15 to a 13 SEER system more than pays for the HRU and the HRU will add the efficiency points back into the system....plus give free hot water. Interestingly enough, once you have one, you begin to see using hot water is cheaper than using cold...the more heat you shed, the more efficient the A/C becomes. I made sure to install a recirculating loop for my hot water...the HRU pump provides instant hot water throughout the house (saving me more money as it dissapates more heat) . Also clothes always clean better in hot water...My next idea is installing a mixing valve to dump a little hot water into my sprinkler system. I don't see where watering with slightly warm water will be a problem and should cut the power bill some more...