We'll be leaving upstate NY and heading for warmer weather in 2 or 3 weeks. The day before we leave, I'll fill the fresh water tank, the water heater, and the water lines. The furnace and water heater will be on and we'll likely sleep in the coach that night. We've done this each year since we started getting out of the cold weather mid-winter, with no problems before reaching warmer weather so far. The water lines were blown out with no antifreeze added except to the drain traps, so flushing the lines is not an issue. Our furnace is ducted into the wet bays and keeps the tanks and pump from freezing.