Dometic Comfort Air Thermostat Operation

[hohenwald48]

I have a 2019 Newmar Canyon Star class A. It is equipped with (2) 15K Dometic heat pump air conditioners and a Suburban 30K propane furnace all controlled via a Dometic Comfort Air thermostat.

A few weeks ago I had a problem with the furnace not operating and found a wire off the furnace control board. I plugged it back up and all is fine. While troubleshooting that problem I read the thermostat manual and found an entry that seemed to indicate there are circumstances where the furnace could operate even if the "Furnace" option was not selected for the front system (system #1). The propane furnace is controlled by the thermostat in conjunction with the front a/c/HP.

As it turns out, if the motorhome is being heated using the heat pump(s) and the outside temperature drops below 30*F and the thermostat calls for heat, the LP furnace will be cycled to provide the heating regardless of the system selected on the thermostat control panel.

I was not aware of that feature but noticed my propane supply was decreasing over time. In Nashville our weather is such that the outdoor temperature is usually above 40 for most of the day and night with the temps dipping below 30F for a few hours at night on a couple of days per week. When that happens the furnace fires up to maintain coach temperature.

Maybe I'm the only person who didn't know about that feature. Just thought I would pass it along.

[Jim_HiTek]

My '02 with a Coleman basement heat pump and a TrueAir thermostat works the same way. I was pretty confused the first few times it decided to turn on the propane furnace when I'd switched it to 'Elec Heat'.

I think the propane furnace does a much better job of quickly warming up the RV compared to the heat pump, but I know that if I need to, I can remove the fuse for the propane furnace to keep it off.

[MSHappyCampers]

Yup, it seems that many MH's are set up that way, including our 2002 Windsor!