Answers to a few of John’s questions:
The pump is a Lippert Flow Max 689051.
The water heater is a Suburban SW6DE. I did not notice any weeping around the pressure relief valve. The thermostat seems to be around 129, which is a little hotter than I would like.
I really did mean leave the water heater on. As long as the water stays hot, it doesn’t leak. It is only when is is heating and expanding that it leaks. That is why this was such a pain to track down.
The water heater is so close to the floor that I can’t slip any kind of bowl under it, but I built a little frame to hold a plastic sheet to confine the water. When it leaks, it is about 1/2 cup, then it stops.
My last trailer had significant water damage to the floor, and I’m not sure I ever knew where the leak was, so I’m paying a lot of attention to this one. I can see what a big job your hobby could be.
Wayne