Heat Recovery Unit suitablility for modern AC

[wulianlian]

I am a college student doing a report on AC hot water heat recovery systems. Several AC professionals and alternative energy specialist tell me that in the 80's they recommended and installed many of these heat recovery units, but they no longer recommend them or install very many. They said that modern AC units make heat recovery less beneficial and can, in some cases, create problems with the AC systems. After looking into the question, I am having difficulty understanding what are the problems with the heat recovery systems as an add-on to modern AC units. Can some of you AC professionals out there please point out some of the specific problems as you understand them?

[takepride]

You might post this to the general forum instead of the Alpine Coach-specific forum. You'll find a bigger audience and likely more AC professionals. Good luck!