Furnace heat plus heat pump

[Fred]

We have a heat pump unit for the living room and just an ac unit for the bedroom. The Dometic thermostat in the bedroom has an ac and furnace setting but bet I can tell it in no way controls the furnace. The living room unit has ac, heat pump and furnace settings.

Is there a way to get the furnace and heat pump to run at the same time? Should I replace the thermostat in the living room or run the furnace off of the bedroom thermostat, or have two thermostats in the living room? One for the furnace and one for the heatpump.

[DQDick]

As far as I know, the only way to get what you want is to replace the bedroom AC unit with a heat pump. The bedroom thermostat in most Monty's shows furnace, but really doesn't control anything. The furnace is only controled by the main thermostat that also controls the heat pump. The problem with adding a thermostat is that the board that controls sending the message to the furnace is also in that AC unit. I found that out the hard way when I knocked the control cable loose on my 2010 and then had no heat that night.

[rohrmann]

You’ll probably get as much heat from the fireplace, or more, than from the heat pump, so I’d just turn on the fireplace if it’s that cold. We survived cold into the teens some years ago doing the fireplace and furnace and we were very comfortable and nothing froze inside.