Need advise on pressure valve leak in hot water heater

Several things would cause your T&P valve to open up. Does it run all the time or just in spurts?
1. Excessive house pressure. Do you have a PRV (pressure reducing valve installed?
2. Temperature set too high
3, If it leaks every time a faucet is opened and closed you need to install a expansion tank on the cold water line.
Out of the three which one fits the best? Back to you, Tom

I agree with Tom but there is a 4th situation when the PRV leaks, when it is broken. Star by putting a pressure gauge on the water heater drain spigot, what psi do you read?