It’s been a great 31 years, but the single-zone HVAC system has finally reached the end of the road, and gtmsmith has narrowed the search for a replacement to two possibilities. Neither involves fossil fuels.
Gtmsmith describes his options in this Q&A post:
Gtmsmith says the 2700-square-foot house is well insulated for a building of its age. It has new doors and will be getting new windows and is located in southeast Pennsylvania on the border between Climate Zones 4A and 5A.
“We are easy going and happy with 66-68ºF in the winter and 74-76°F in the summer on the T-stat,” gtmsmith writes. “We have been happy with single stage heat pump heat in previous winter winters in a much tighter and smaller home prior to this.”
He plans to add a small wood stove for supplemental heat, although not for the entire house.
Gtmsmith is leaning toward the air-source heat pump option for a number of reasons, including lower cost and better financial terms, a longer warranty and less disruptive installation.
“Did I just make up my mind?” he asks. “Help!”
That’s where we start this Q&A Spotlight.
Josh Durston thinks the air-source option is, on balance, the better route for gtmsmith. First, the air-source system uses “inverter technology,” a means of varying DC power to ramp output up and down so it matches heating and cooling loads more precisely than a one- or two-stage system powered by AC would.
“The GSHP [ground-source heat pump] is on off with maybe an unloaded first stage on some models, the ASHP [air-source heat pumps] will run longer and modulate to the load for better comfort,” Durston says.
Durston’s parents have had a ground-source heat pump for nearly 25 years with “essentially no issues or…