I have a 2002 Four Winds Windsport which I purchased in April of this year. I have been having problems with the hot and cold water getting mixed up in the system. Sometimes hot water flows from the cold faucets and cold water from the hot. I first noticed this when I was getting hot water in the toilet. The kicker is..it can happen when I'm on city water or using the water pump. I've noticed that the cold water inlet hose to the water heater will get hot when this happens making me think that there is a pressure problem and hot water is backing up through the cold water line. I've tried putting a check valve at the inlet to the water heater but then no water would flow from the cold water faucets. This doesn't make sense to me. Any help as to what might be causing this problem would be appreciated.