First trip of the season completed and water heater issue. Heater works on gas and electric. In fact when I pull the lever on the pop off valve it is very hot - just like it is supposed to be. When I turn on the hot water in either the bathroom or the kitchen, I get a slug of hot water and then it cools back off. It is not as cool as the water coming into the coach from the outside source or the holding tank, but not warm either. I have checked and double/triple checked and the valves for input, output and bypass are set correctly.
I can set the water running and close the input valve at the WH and the flow stops - just as it should. Same with the output from the WH. I figured the handle on the by-pass valve might be put on wrong. I opened that with the input valve closed and had water again flowing. So, all the valves work.
It appears from the water temp there is some mixing of the hot, but the full flow is not coming through the heater.
I have checked the outside shower, thinking there might be mixture there. Both hot and cold are turned off. I know water is gong to and coming from the heater, and the water is hot in the heater. I hate to drive nearly 200 miles to the dealer and find out I am missing something simple.
Is there anykind of valve in the heater that might be stuck? I know a TT we had had a back-flow preventer internal valve, but I cannot figure how that would affect this probem. Ideas, fixes or intelligent discussion greatly appreciated. Oh yes, Atwood 10 gallon heater.