How do you know it is on the same breaker as the hot water heater? Is the unit hard wired or plugged in via outlet? Mine is plugged in and on the same circuit as the ground fault plug in the bathroom, so when it is tripped it does not work. The units themselves are easy to remove, just remove the facia piece and it will be held in place by screws. Remove those and pull the unit out of the cabinet, then you have access to the switches and wiring. I've replaced one switch and the heating/fan element. Contacted the manufacturer and they sent the parts needed for a very reasonable price.