I have a Geothermally heated house, with 4 zones. I have a ground loop using a nearby year round stream. So far I've heated the house using the domestic water heater, with great success. Time for a heat pump though, so after searching what is available, I decided to try a new aproach. I purchased a 2 ton mini split system, with a DC inverter technology Panasonic compressor. This is an air to air system, I needed a water to water system. It turned out this was the cheapest way to get all the parts I needed. I swapped out the two air exchange units for 50 plate heat exchangers. The box got very small. I'm just in the process of checking it all out at this time. Here was my thinking. With a normal 2 ton unit: With 4 zones in the house, when all 4 zone call for heat, the 2 tons would be a good match, providing the right temps into the floor. When only one zone calls for heat, 2 tons is too much, and provides too high a temp into the floor. With the variable output unit: When 4 zones call for heat, the unit can run at full output, and supply all zones with the proper temp water. When only one zone calls for heat, the unit can operate at a lower speed, and again, provide the proper temp water into the floor. Shoot me down... As I said, this is almost completed at this time, so before long I will know how it all works out. However, I'd like your thoughts on the concept, and execution.