There's a fair amount of discussion on this - also called Hollowell (sp?) Heat Pump - on HVAC Talk.

Best regards,

Bill

I thought someone here might care so the " hoax " has ben explained
COP claims by all independent studies where greatly inflated advertised average cop 2.9 , feild tests reveal 1.9-2.1
advertising discharge air temp 90-120 , actual feild test 90-95
the lower temps are acheived by what would normally be considered to be an oversized system
To close this misplaced thread out I would like to say while the eff. preformance and seer (14) are not in the least impressive the idea is, but even with a variable speed compressor these things cant hold a candle to geo. and with how complicated the controlls are the faliure rate would be pretty high

there is a debate about this heat pump here.
http://ths.gardenweb.com/forums/load/hvac/msg1115313614618.html?115

I think calling the Acadia a "hoax" is a bit over the top. Some of their advertising is a bit misleading but certainly no worse than that of most major Geo manufacturers. If you look at the technical documentation for their heat pumps their #s are believable. Before oil prices came back to earth a seasonal average COP of 2 or greater in a heating dominated climate would make these a very attractive product for a lot of people. Obviously a well designed GSHP will outperform it, but in some cases the payback will be much faster for the ASHP.

I do agree that they aren’t some miracle technology, just a well-engineered multi-stage heat pump with good controls and some clever things in the refrigerant circuit to aid in staging and defrost, etc. Some of the mini-split units from Japan (Mitsubishi is one I think) have similarly good low-temperature performance.

I think a lot of the pushback on these is simply due to the fact until recently heating has always been a secondary function for ASHPs. They were simply not optimized for cold climate operation because fossil fuels were just so much cheaper. Heck, until about 8 years ago it would have been cheaper for me to heat with oil than with my GSHP with a COP of 4! No one in their right mind would even consider a heat pump in a cold climate, so designs were optimized for mild climates where performance below 20F was immaterial. Much more cost effective to just shut down the heat pump below that temp and kick on the resistance heating. As a result, it is firmly ingrained in most people’s minds that ASHPS don’t work below a certain temperature. Which was certainly true, but not because of any physical limitation. Manufacturers just hadn’t tried because it didn’t make economic sense.

Reliability is a another issue – I don’t see anything that makes me think these would be any worse than other ASHPs, but they are new to the market so we’ll have to wait and see. Assuming the company doesn’t go bust it might actually work in customer’s favor because if they are smart they will be hypersensitive and respond quickly to any failures in order to avoid any whiff of bad publicity. From the posts in that huge thread on Gardenweb it sounds like this might be the case.