We had our 181 winterized at the dealership as part of the final warranty check, so whether they did anything to the furnace or not I don't know. I suspect that they made sure that the propane was turned off, though. I just went out to check, though, since the temperature here is cold enough that the furnace should come on. The furnace wasn't running, but I did hear a chirp from inside. Since I had already pulled the batteries from the rear smoke detector, I was a bit surprised. Turns out that the front smoke detector is also battery-operated. Somehow I always thought it was hard-wired in. I've now removed the (original) battery from it, and the next time we take the mpg out I'll put new batteries in both units.