I had my heat pump replaced recently and had it hooked it up to the hot water tank so that as the pump was on, whether cooling or heating the home would also partially heat the water in the tank. My question is about how it heats this water - I've followed the piping and noticed its split before going to the softener and uv filter coming from the well to get to the heat exchanger - is it dumping the heated water into the tank or heating the existing water in the tank? I hope the latter, otherwise my hot water will be harder than it needs to be, and if the water is contaminated, not UV filtered.

Pardon the crude diagram

  • Some photos would be very helpful. Also, a simple sketch of the plumbing would help.
    – Tester101
    May 9, 2014 at 12:01
  • @Tester101, there you go, hope this is clear - the well return goes OUT of the house (I just noticed that there is no arrow indicating the direction of water for that line)
    – paquetp
    May 9, 2014 at 15:55

1 Answer 1


It's heating the existing water in the tank. And the tubes between the pump and the tank don't carry water; they carry refrigerant. The pump heats the refrigerant using the latent heat of the well water. The refrigerant goes through a large coil in the tank, heating the coil. The coil is immersed in your soft/clean water.

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