4 years ago I somehow stumbled onto HT's website, their combination systems do everything I wanted, Air and water at the same time.

After 3 1/2 yrs of working very well it's now using a lot more KWH's. I noticed it during the shoulder season, when the unit is operating only to heat up DHW.

Why doesn't HT give more info on their plumbing diagrams? GT1980 mentioned in another forum that I should have been flushing my DHW heat exchanger with vinagar every year, now I will have to reconfigure plumbing so I could do flushing.

GT1980,

When the loop pump is off and the DHW is circulating in it's place, isn't that like having a ground loop running at 125*F EWT? How long will compressors last (dual compressor system) running that way?

ChrisJ