I have am looking for space in my circuit breaker panel to do an upgrade. There is a 30 amp dual pole breaker labeled "water heater". Our water heater was upgraded to a tankless about 6 years ago and has a standard 3 prong power cord that plugs into the wall. Does that mean that the 30amp breakers are free now, or does my water heater use both the plug (maybe for the controls; that would seem odd but my old water heater didn't have digital controls). On the other hand, I don't remember the old water heater having any electrical components. The old water heater had a tank, and was installed some time before we moved in 15 years ago, though I don't recall the age.
Is there a way to figure out if that 30 amp circuit is being used? We turned it off and nothing seemed affected; the water heater still seemed to work. But maybe there is some internal component that is directly wired?