It is a 2002 hr 5er that the po's spent summers in, it has no road miles. They told me that the water heater was doing that lately and they controlled it the way I described. The 1st thing I could think of was replace the therm and eco, cheap enough, right? I've owned many rv's in my life, and this one is either gonna be a flipper, or gonna be parked somewhere, and the water is hotter than any rv Ive ever owned. The wiring is all correct, I've checked it against a diagram, I think I will run it and see if I can get a temp on the water running out of the faucet. At least that will tell me if the tpv has failed.