How can I use an indirect hot water heater with my geothermal heat pump? Regulations and health rules say the water in a hot water tank needs to be at least 120F but heat pump is only set to produce 110F for radiant system. The water in the indirect hot water heater would only be at 100+. I planned on running the water from the indirect hot water heater through my on-demand heater to get it up to DHW levels, like 130F or so, and figured the preheating from the indirect would be very efficient. But, if I can't hold hot water in the tank at 100F or so for fear of bacteria (Legionaire's seems to be a big issue) then it appears I can't use the indirect hot water heater I have. It has no separate heating coil to boost the water temperature like some do, where the geo fluid goes through the coils in the tank to preheat and then an electric coil finishes raising the water temp.

There is a new product on the market called Therma-Hexx (www.therma-hex.com. They don’t use pex tubing they use these panels that you install in your ceiling just behind your drywall they are so efficient at transferring energy that you can use them for both heating AND cooling they they can accomplish that at lower temps (heating) and higher temps (cooling) you install a CERV and a air to water heat pump. Alternative energy systems like geothermal. Wood burning stoves, PVT solar can also be integrated with the system. No ductwork is required in the house. The system is much more efficient being installed in the ceiling as you generally have an unobstructed view of a room from the ceiling where if you install in the floor you have furniture blocking the panels. The system can be installed in the ceiling, floor or walls. In a large room with cathedral ceilings, you install both in the ceiling and the floor.it is the very best radiant system on the market no one else comes close!

Joe, you make good points, is your water well or city? I wonder how chlorinated water would make the difference for you to just use your original design. I thought they stopped doing desuperheater's because you lost more energy on the off cycle then gained on the on cycle plus the added complexity and cost added to the Geo unit cost?

My water to water geo heats my hot water tank....