We keep inside of bus in the 55-60 range even in cold weather with inside heat from the toe heaters....also I keep a small elec space heater in bath on the floor area that is still marble and it seems to keep the floor "warm" which should backfeed into my watercompartement below. The Webasto Central heating is set for about 35 so if all fails, the Webasto will cut in. I have heard it a couple of times but not on regular basis. Main concern here was engine and your replies helped me a lot. Leave er on till after bus starts up. Engine actually is warm to touch with it on which is good. Thanks again, even if Northern Arkansas is not as cold as previous home of Omaha, NE or Toledo . OH.