We recently traveled in 19 degree weather and were boondocking 3 nights. The propane furnace functioned flawlessly and provided plenty of heat. I would guess we would be comfortable down to zero. Our's is a 25' Classic without the wrap around windows in the bedroom. I have heard that the wrap around windows allow more heat to come in in summer and cold in winter. I added some weather stripping to the outside trunk doors to make them seal up tighter than with only the factory gasket. We will find out next winter how it is when we go to Santa Fe, NM in January.
