Originally Posted by mpsgolf
My Dometic thermostat does NOT automatically switch to furnace. HP and Furn are separate modes.
You might be pleasantly surprised if you test your thermostat. I See that you have a 2015 International. I have a 2012 with the wimpy 13.5 heat pump. When MODE is set to HP it will automatically go to FURN at 30° F. When the propane runs out or is very low it will flicker between HP and FURN as you slowly turn blue. The Dometic thermostat is a PIA.. Wretchedly complex and easy to mess up.
Even resetting it means pulling out the manual and 2 to 5 tries to get it right.
I always leave the fan on AUTO which may or may not have anything to do with the FURN kicking in. (Maybe airflow from fan hits the thermostat faster? With everything OFF the trailer gets cold from the bottom up.)
In my previous 2006 Safari the heat pump couldn't function much below 37°F, and automatically switching over sometimes failed, especially when propane pressure was not optimal... one tank empty and the second one half gone.
The air conditioners with heat strips were very common in small Airstreams before 2006 and they worked, but used almost all of the 30 amp service to do so. There were no 50 amp units then, and you didnt want to try to make a slice of toast or use a hair dryer without turning the strips off for the duration... brrr!
Carrying spare propane tanks is not uncommon, but can be risky. It is safer in the back of a truck than than inside a van or SUV. I instantly threw out a cheap "Safty RIng" when I saw a neighboring camper who carried his spare with a heavy duty plastic milk carton carrier - much more stable.