Bob, Thanks for the reply. I’ll look into doing an actual power use measurement – my voltmeter experience has been confined diagnosing car problems.

Our motivation for making our house more energy efficient was entirely to use less fossil fuels and electric grid power, so return on investment was never brought into the equation, except with the PV array – we wanted to not produce more electricity than we used, so sizing of the PV system was important and, unlike the heat pump, of the three companies that gave us PV bids, all of their sales pitches were concerned with how soon the system could pay for itself. And to your point of concentrating on insulation first – our skinny two-story 1909 house had no subsheathing (it would shake dramatically in high winds) and in our extreme seismic zone, we wanted to know it would survive a major earthquake, so we removed all the old ratty siding and doubled up the outside wall studs to make 8” to 12” deep walls, put sheathing on… basically, we improved it to a relatively tight envelope (0.8 ACH – but we replaced most of the existing double hung windows in kind to keep the historic character, so that, as the guy who did the testing showed us repeatedly with cold smoke, was our weakest link), which was a difficult task with an irregularly shaped old house.

We put in the ground loop pipes in 2009 when we replaced our house’s foundation, and at that time there were no small residential air-to-water heat pumps available in the U.S., and we did not install the heat pump until 2017. If we had to do it again, we would install an air-to-water heat pump and forgo the ground source expense and contractor hassles. We got 3 bids for the water heat pump and the sizing, system design, and costs varied enormously, so it made it impossible to decide what the best route was. And no HVAC contractor ever mentioned alternative systems and ROI – their job was to sell us a ground source heat pump and nothing else.

I am in complete agreement with your arguments against ground source heating in a mild environment. I do primarily residential design, and I regularly advise people not to install GS in favor an air-source heat pump (or gas, when they have no interest in reducing their CO2 impact). And, I always start with better insulation/envelope design, but more often than not, any improved insulation or higher performing windows get nixed by the contractor during construction – anything more than code minimum makes zero sense to their profit margin, but occasionally they do return a percentage of the installation cost savings back to the client or you get a client who see its benefits (ROI) and insists they stick to their original contractual obligations.

I whole heatedly applaud what it appears you do and your business model. If there are any contractors who do the equivalent in the Portland area that you’d recommend, I’d love to know about them.

As to your not being able to comment on how heat pump units work and their efficiencies, I understand, especially if you sell Water Furnace products, and you would not want to risk denigrating their reputation and losing a positive relationship with the company. What I did not ask in my post was whether the Water Furnace control system could be controlled differently and whether it would be worth contacting a different HVAC contractor to see if the system could be modified – I guess I was really asking if my contractor was maybe misinformed about the possible ways our system could be controlled and if the pump can be set up to run only when the heat pump is operating. But, again, I realize that giving such advise might be construed as impugning the reputation of the contractor… If Water Furnace systems do require the continuously running pumps, then I would not want a contractor to jury-rig our system, just because I asked them to.