My water heater is doing the same thing. I suspect a faulty thermostat, but my laziness has kept me from verifying that. I'm guessing that like mine, the issue with yours happened suddenly. That would rule out a sediment build up issue, that and the age of your heater.


I don't suspect a heating element as an issue, because mine does reach the target temperature. The thermostat has to have a cut on temp in addition to the cut off temp you can adjust. What seems to be happening with mine is the thermostat is not recognizing when the water has cooled below that point. It doesn't start heating until the water has become too cold. That's why sometimes you have lukewarm water, I suspect.


At any rate, please post what the resolution is, as I'm obviously curious. You're likely to beat me to the repair.

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