I have a Suburban hot water heater in my 2010 3055 Bighorn. Recently when I turn it on the electric side, the water gets hot and stays that way. In the morning the water is barely warm. If I turn it on propane it is always hot. If I turn the propane off, let it cool, and try the electric side it gets hot for about 4 or 5 hours then cools off. Any ideas? Thanks