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?

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I liked that drawing so much that, "just for fun," I tried to sketch out how my existing well pump might be used for both domestic water and a heat pump (standing column well) without having to add the domestic GPM (6 GPM) and heat pump GPM (6 GPM) requirements.  6 GPM total from the Well pump should satisfy everything.

Maybe someone who's done something like this can comment...  Think the check valve seperating the hi and low pressure zones will work?

Propanebegone, why is there the diverter valve V1 in your diagram? Why couldn't the water pass through the heat pump's exchanger all the time, with no temperature drop when the heat pump isn't running?

Second comment, why not locate the bleed valve (V3) it downstream of V2? That way, when the pump is running flow into the domestic tank and EWT is below the bleed cut-in temperature, the flow into the domestic tank constitutes the bleed. Valve V3 doesn't need to know if V2 is open or closed; it can be open whenever bleed is called for, even though there is no flow through it, simplifying interlocks. I am  assuming the bleed valve (V3) is sized to limit the flow relative to that returning to the well, and that pressure drops and static head changes of lines to bleed location and return to the well are such that the bleed flow is correct.

As to whether the check valve will hold pressure in the domestic system, my understanding of check valves is that after some time they may leak a bit. If this is a slow leak, it shouldn't matter, since an eventual drop of pressure in the domestic pressure tank will just turn on the pump and close V2 to bring pressure back up.

Repeating the remark in my opening post, it would be nice if someone out there who has actually plumbed things up somewhat like this would comment. Otherwise you'll be doing yours before mine, most likely, and I'll benefit from whatever you learn. We can call the arrangement the "PBG configuration," in your honor, unless it fails.