Well, this is frustrating. Saturday morning, Out in the rain I go to sample the RV's hot water temperature. It's piping hot!
I'm going to assume you folks don't think I'm nuts. Now it is working but last camping season it was consistent, initial heating cycle only on electric.
Looking over all the information I've been provided there are two areas of possibilities, the thermostat which I assume turns on the heating element when the water temperature drops below a preset threshold value or the possibility of the on/off switch (I did cycle the switch). The relay shown in the schematic that feeds the on/off switch I can not locate.