Hi Dave,
I do reset the memory... but I only changed the dip switches after this issue started, and then only to put it in test mode to see if there was anything additional I could see or info to get... there was nothing.
Disconnecting the heater... ok I could do that, but I've sat there for hours waiting and watching to see what was going on. I did think of the overheated or clogged circulation pump but it ran fine the whole time... water coming out was a good steady stream warm but not hot (same flow with or without the filter). There was no warning from the pump... no humming or whining... just the click from the circuit board and then no flow, then the heater boiling the water.
I did check the sensors, first thing, all good resistance readings and flipped them A to B, B to A, with no change in behavior. If it was a sensor I would expect an error prior to the pump shutdown... and there isn't one.
I did hook up the circulation pump to an external power source and it ran for hours... that's what lead me to believe it was the circuit board shutting it down not the other way around.
I'll try the heater disconnect and let you know.
Kevin