I’ll start out with an acknowledgement that what makes this comparison so shocking is the 30% federal tax credit. A straight comparison of a super high-end HVAC system with a geothermal system will be a completely different scenario if the tax credit expires.
Last year, we got the top of the line air-exchange heat pump. And we’ve had a lot of problems. Installation problems, air leakage problems, thermostat problems … all compounded by terrible difficulties getting service people out to sort the issues. And at the end of the day, the house isn’t comfortable. The “this is the only thermostat you can use” thermostat … well, first off all freezes up every now and again and the system is either ON or OFF at the time and stays there. But from a firmware / logic standpoint – there is nothing that looks at the relative humidity in our house and says “hey, we should drop the temperature set-point a degree or two to avoid living in a swamp”. Which wouldn’t be a problem if we could tie the thing into OpenHAB. But we cannot.
The system came with a 365 day 100% satisfaction guarantee … which, really, was the reason I was OK with installing it last year. Worst case, we ask for it to be removed & the entire contract price gets refunded. Well, we are not satisfied … but that means we’re back to shopping for an HVAC system.
I researched geothermal system manufacturers. Evidently there are only a few actual manufacturers whose product is sold under a lot of different labels. I contacted local installers to get a quote for each of the major systems I found. My expectation was that a geothermal system would be a couple thousand more than we paid for the air exchange heat pump once you take off the 30% tax credit money.
We got our first quote today — for 600$ less than the air exchange heat pump. It’ll be more to do vertical bores instead of horizontal bores, but that’s a decision to spend money for efficiency. I expect vertical bores will take us into the “couple grand more than we paid” territory. But I don’t see the point of high-end air exchange heat pump systems up North here — a two-stage geothermal system is going to be quite a bit more efficient, not engage the backup heating as often, and cost less than the top of the line variable speed air exchange systems.
The HVAC company that installed our current unit had horror stories of people having to rip out entire yards because of leaking tubes … but, thinking about it without needing to make a decision now … I suspect those are older installations. So, yeah, we have the possibility of leaking lines twenty years from now (lines are warrantied for 50 years, but you are still paying labor). And that would totally suck, but do I really expect the air-exchange heat pump sitting outside is going to be in service twenty years from now?