[Fulltiming]

Your under bed engine coolant controlled heater does allow you to keep the bedroom warm while traveling without having to run the generator. I have used mine a few times but not often. My 1992, like several of the others have stated, does have four valves by the engine. I believe one pair of valves controls the coolant flow to the marine water heater and the other set controls the flow of coolant to the dash heater as that line has an in-line booster pump on my coach. I have not checked to see which set of valves control the under the bed heater. I do have a switch on the dash that controls the fan for the under the bed coolant controlled heater.