The high limit switch has popped twice on my electric water heater, both times at night. I reset the switch and the water heats and it's ok throughout the day. Wake up in the morning and it's popped. I tested the switch, thermostats, and heating elements with a multimeter and everything seems ok. I'm getting 243v through everything and continuity through both upper and lower elements from what I can tell.
Any other ideas or should I just replace parts until it stops?