We have a new Geothermal system in a new construction single family home here in Eastern NC. Our unit is a Heat Controller model HEV048A1D0ART. The unit has been operational since February of this year and has done well in both heating and now in an intense cooling season. We had the technician here this week to work on a few issues one of which was that the hot water generation system did not seem to be performing up to expectations even with the extreme heat we were experiencing. He bleed air from the system several times and we now seem to be producing hot water based on the temperature of the lines going into and out of the hot water tank. We are using a non-energized electric tank that then feeds a tankless gas water heater that feeds the hot water distribution system. Our issue is that since we now have the Geo system producing hot water somehow that water is making its way to the cold water side of the house's plumbing system, it's not just one faucet but in multiple locations. Looking for a steer on what I should suggest to our plumber the solution might be. I'm thinking we must be missing a check valve on the water supply line to the hot water tank that is allowing the heated water to flow back into the cold water side of the system but maybe it is something else. Appreciate any suggestions on what I should have the plumber look at. Ed K.