Thanks Eric, that is a helpful diagram. I guess the next test would be to see if the internal relay has indeed failed. If so, I imagine that it simply wouldn't heat at all. I guess the next step after that would be a new control board, and deciding if that's worthwhile as it seems to work for me given my current real word usage.

The way I read the electrical diagram is that the default position of the internal relay is to provide continuous power to the heating element (other than pstat operation). So, a failure of the relay would not typically cut out power to the heater. But, an original relay failure would disable the autofill function and that is why you have the new, external relay.

With the machine unplugged, I would take a real close look at the replacement relay to try and detect some OBVIOUS problem. If you want a blank diagram of the circuit, email me: erics at erols dot com.

i dont understand why you're not using a multimeter to diagnose the problem.

I'm surprised that a relay for the heater would be added that, if I read EricS's schematic correctly, doesn't not remove the high current from the factory electronics, which if done could avoid things like this:

-Ed