Our first night out in our NTU camper the furnace came on in the middle of the night. We had no idea what it was, at first. The problem was we had no propane and I couldn't figure out how to turn it off as it was just blowing cold air.. I had to go outside and unplug the electric cord from the post to get it to stop. I have since disconnected the wiring and we just use a small electric space heater if it gets too cold.