This past summer, I was looking forward to getting the free domestic hot water from my GSHP that I’d read so much about. I was gone on a long trip, so I had turned off my hot water heater. When I returned, it was a hot day, so I turned on the A/C and left the water heater off. After several hours, I found that the water was still cold, so I started to investigate. I found that the incoming vs outgoing temperature through the DSH was only 3 deg F. I called my HVAC contractor who spent several hours taking the DSH apart and making sure that there was no sediment or air in it. At most, he got a 7 degree difference, but the following day, it was back to a 3-4 deg difference and it stayed that way pretty consistently. I kept asking what I should be getting. A vague reference in the manufacturer’s literature said 120 deg. The proposal for the system said 130 deg. Eventually, I was told that there wasn’t an absolute temperature, but that I should expect an 8-10 deg difference between incoming and outgoing. I never did achieve that in cooling mode. Now that we’re in heating season, I checked again. Surprisingly, I’m now getting an 8-14 degree difference and it’s actually heating up the water to above 120 deg. I would barely reach 100 deg in cooling mode under the best circumstances. So…, where is this free hot water I thought I’d be getting when using the A/C? Does it make sense that the DSH would work better in heating than cooling mode? I would think that the unit would be trying to dump as much heat as it could through the DSH in cooling mode.