For a NH location, where groundwater is plentiful and a well must be drilled for domestic water anyway, a GSHP (standing column well, SCW) makes a lot of sense for a very well insulated house. That's the plan. The well will be drilled to the depth that provides sufficient water supply for the house or sufficient water column for heat transfer from rock to water for the heat pump, whichever is deepest.

Obviously, minimum pump circulation power will be for just enough head to move the water through the heat exchanger and back to the well. However, domestic water supply normally calls for pump on at 25-30 psig, off at 45-50. I have seen very limited info on how the plumbing is set up to minimize the pump power most of the time and boost the pressure when house use of water calls for it. It would seem a waste of power to have the pump always deliver water at a pressure just above maximum needed in the house plumbing.

So, what is typically done in this situation? One approach, from a GSHP design company, is to have a jet pump take water from downstream of the heat exchanger and boost the pressure into the pressure tank of the domestic supply. That's a second pump, however, and it would be inside the house, creating a noise problem if not isolated.

If I were designing this, I would be inclined to use a variable speed pump in the well, with a three-way valve downstream of the heat exchanger. When domestic water supply pressure dropped to cut-in, the valve would close the return to the well and open the flow to the pressure tank. The pump speed would be increased to deliver the pressure needed to deliver water into the pressure tank. At cut-out pressure, the valve would switch back, and a check valve in the line to the pressure tank would close, preventing backflow from the tank.

I want to know what other solutions are used. I would imagine all of this has been worked out by now, but I have to wonder. Where can I find descriptions of the various schemes used?