I have the opportunity to bid a decent project here utilizing water-air heat pumps, Mcquay is specified and there are 3 4ton units. The whole thing is pretty straight forward except the loop side: There are two taps onto a main city water line (3") , one is brought in and is pumped up to overtake the pressure and go through a double wall plate heat exchanger and back out into the main line. The other side of the heat exchanger is where the source loop for the heat pumps connects. This seems pretty counter productive to me, but to what extent? Any ideas? I was thinking atleast 30% less efficient than a normal closed earth loop due to the energy lost on the extra pumps as well as the heat exchanger. The material costs for the heat exchanger alone are more than the cost of the three HP's. I also think the idea is a little shady because of the heat loss/gain of the city water, the next guy down the line will have to heat his water that much more. I realize the other end of the stick is he will have to heat it less in the summer, but this climate is a heating dominant one. Just odd to me to be allowed this sort of thing, if you get a whole block of people doing this, the city water mains will be a mess.

Thanks for any thoughts on this one!