I have 3 new heat pump systems in my new well insulated home. Two of the systems were working fine. The other system was had been set to 68 for several days. This morning it was 36 outside, the actual temperature registered on the theromastat was 68 and the aux heat was on.
My HVAC company is telling me it is normal for the aux heat to be on when it is below 40 outside. I am questioning if that is correct or not. I thought heat pumps worked well until the outside temperature was about 20 degrees.
Is my HVAC company correct? If not, at what outside temp should the aux heat be necessary in a well designed properly working system? Can you provide any reasonably authoritive info on the web that I can show to them?
Many thanks for any help.