It's amazing how the mass of water can keep things warm. I have the 20 gallon hot water heater on to protect the plumbing bay. Even though the water heater is on the starboard side, the inside temp of the bay on the port side is above 50 degree's. Bus barn has been down to 25 degree's on a couple mornings. The floor heat on a low setting of 70 is keeping the inside temp at 50.