Related question for heat pump owners: At what outside temperature does your heat pump struggle to keep up, and start switching over to back-up (emergency) heat?
I notice mine doing so when the temp. gets below 30. My December electric bill sucked - we used as many kilowatts in Dec. as we did for A/C in July, and that's unacceptable given that the heat pump only does the upstairs in my house - we have propane for the basement & ground floor.
I had an HVAC tech come out to check the system, he said that it's functioning as designed. That the heat pump simply isn't going to keep up when the temp. falls below freezing outside. I just want to know, is he blowing smoke up my ass because it's still under warranty and they just don't feel like fixing/adjusting it?