We have a propane furnace...but it requires electric for the blower. Everything else is electric. I’ll probably wire it so that I can easily switch it over to run off the generator for next time.
I put a main breaker outside so I could disconnect from the grid when the generator is running. My furnace and stove are propane. I have an old 2 cylinder diesel generator from a police station near St Louis, it is 3 phase but I just tap a single 240 volt phase for everything and have it going to the garage panel which is in turn connected to the house main breaker box.
JT