tpr valve releases on occasion

[bentool]

Hello, I have an A.O. Smith electric 40 gallon water heater. Recently the water main ruptured and was replaced on my street. Since that time my water heater has been releasing approximately 1 gallon of water every 8 hours through the pressure relief valve(all at once - not a slow leak). This heater appears to be rather old, but it works well except for the leak which has been ruining my home. Upon inspection I found that the heater was set to 160 degrees. I turned it down to 120(the recommended setting as far as I can tell), but it still leaks. I am not opposed to replacing the whole thing, but if anyone could make a suggestion that would be much appreciated. Thank you for any replies!
Ben

[Ejbogusch]

All at once usually indicates a release on temperature. Check your water temperature with a thermometer to get a correct reading. Also you could have an element going to ground where this would cause slow continued heating until an over heat condition occurs.

A very simple way for you to check this is to turn the power off at the breaker for a short period of time and see if your valve still leaks.