We are planning to stay in MH this winter. Do I need to leave the water heater on all the time to keep water from freezin or can I just do like I do now and just turn it on when needed ?
My water heater did not freeze when the ambient was -37 c (-34 f). It was not turned on. I maintain 20 c (68 f) inside the RV.
Pipes on the other hand must be kept warm. I've replaced the cold air return for the furnace with dual window fans to push warm cabin air through the duct work and under the cabinets.
Please see the winter camping thread under the full time forum for many other cold weather solutions.