Did you notice if the water was hotter than normal when it pops? Replace the lower thermostat.

Bob

No, I didn't notice, but I can keep an eye on it. Is there a way to determine if there's anything wrong with the lower thermostat before I replace it? How much are they?

Thanks,

Mark

Mark - hi, it does sound like the thermostat's gone bad. I'm not aware of an easy way to test it, but I recently replaced the upper and lower thermostats on my mother-in-law's water heater. I paid about $26 for both at a plumbing supply store in Waldorf, MD. She was having the same problem, although not as frequently (it only tripped once a week unless she had extra house guests and put a big load on the water heater). The thermostats haven't tripped for over 4 months now. Good luck! Jim D/Heathsville, VA

This is a good time to verify that the pressure relief valve is working. I'd put a bucket under it and then open and close the valve handle several times quickly to make sure it's free.

there is no way to tell if it is the upper or lowwer stat, one of them is sticking on and causing it to trip, (im asuming that you are reseting at the thermostat and not the breaker) you need to replace both, they should run around $15.00 ec