I have an electric heat pump w/ electric backup, and it works fine until the outside temps get down in the twenties and then it won't get above 65 in my house, no matter what I set the thermostat to. I usually leave the thermostat set at 69 at night, and in the morning, it will be 63 - 65 degrees in the house, with the aux heat running constantly. This doesn't seem normal to me, but the HVAC guy that checked it out said it might just be "all the heat pump can do" and he switched my thermostat out just in case that was causing it, to no effect. I've tried running all the ceiling fans on low, blowing upward to circulate the heat, since I have very high ceilings, but that doesn't seem to help much. I have a bonus room with its own thermostat, which I had been keeping on 55, and the tech suggested I raise it to closer to what the other zone is set at, but that didn't help, either. My house is less than 2 years old. Any help would be greatly appreciated! Thanks!