water just got much hotter. What happened?

First off, thanks for providing this wonderful forum. I'm bookmarking, and will contribute as much as I can, as well as enjoy the site. That said, I don't claim to have any knowledge of any value to anyone else. I'm pretty much a novice with most things around the house, and I am completely ignorant about plumbing. So, please, take it easy on me with this question.

I have a gas water heater in the basement. This morning, I turned on a bathroom faucet to shave, and the water was scalding hot. We usually keep it set to 120 degrees, and suddenly, it burns to the touch. I have no clue what happened. We've lived here for 5 years this month without an issue or one single event with our water heater. Only variables I can think of are the weather, and basement temperature. Down in the teens at night for the last couple of nights, and basement is probably around 35 - 37 degrees.

I'm going to call for a plumber monday morning, but till then, my main concerns are, am I doing any more damage by waiting, and am I endangering my family? I don't see anything unusual upon visual inspection. I can't if the tank is full of water or not. The out pipes are warm to the touch, but not burning hot. Should I worry tonight, or can I sleep?

Thanks, again. So much.
C

Sounds like your temp sensor/control unit is on its way out. The T&P relief valve on the water heater is intended to protect you in a "runaway" firing scenario. You may want to check it by "popping" it open to make sre it's not rusted closed. This manual popping is recommended as routine maintenance.

For absolute safety, you can turn to WH control to the "pilot" position, in which case it will not fire to heat water. Wake up an hour early tomorrow, turn it back to the "on" position, take showers while monitoring HW temp, then return to "pilot".

Thanks for the advice, TedL. I'll be sure to follow it tonight.