Not trying to hijack the thread, but the question was asked about 110-volt and the RV furnace. While no OEM regular furnaces (I am aware of) are LP and
electric, there is a company that offers a kit to add on an electric element to your furnace that does work on 120-volts. The company's website is CheapHeat
I don't have one and have not spoken to anyone first-hand who does. But as someone who camps through all 4 seasons the idea is interesting since propane is a limited commodity. And as an RV owner whose unit needs furnace heat to keep the utility bays from freezing, it is required that I run the furnace during freezing weather to keep the plumbing working. If this add-on would keep things defrosted while at camp, it would certainly stretch one's propane supply. Above 38 degrees I can use the A/Cs heat pump function to take the chill off the unit since at that temperature I don't need to push heat "down below".