My wife and I returned last night from vacation and found when we turned the hot water on in the kitchen that it was boiling hot. I checked the control on the heater and it is set for the correct temperature. Is this a thermostat problem?
No it sounds like an “AQUA” STAT problem as an aqua stat is immersed into the H/W directly with a probe and a thermostat is not.
Depending how long your vacation was could be a clue also. Why not run the water from every fixture until you get all the air out of this system then check the water temperature the next day to see if it back to normal settings. If not contact the manufacturer to replace the gas controller.
ALSO make sure your T&P is in proper working order and FULL SIZED outlet