[DebNJim B]

My heat pump is in the bedroom in the rear. It is also the A/C unit and has a separate setting on the thermostat. These unit as has been stated work good down to about 40deg. If you get into the 30's and continue to run it, it can ice up on you and the fan starts rattling. I speak from experience. On cool nights 40-60 outside temps, I will run the heat pump and fireplace. The H/P pushes heat into the main ducts in the ceiling and will heat throughout the trailer. Below 40 I turn on the furnace. Definitely below 30 you want to run the furnace even if you're running aux heaters so your pipes don't freeze. I have put a thermometer in the basement and it keeps it at about 60 even when it's in the teens outside.