Repairing a hot water heater pressure relief valve is not that difficult. Usually 'repair' means 'replacement'. The parts are inexpensive and it takes less than an hour.
See 'Troubleshooting Hot Water Heaters', if this is not your problem.
There are two things that can be done with the valve. First review the article 'Checking a Pressure Relief Valve' to see if the valve is bad or just has sediment in it. This information will help you check to make sure it is seating correctly. Second, if the valve is bad, the only option is to replace it, see 'Replacing a Pressure Relief Valve', is the more common scenario.
A pressure relief valve, well, as the name implies relieves the pressure in your tank. Heated water generates pressure. Should that pressure go beyond what it considered safe or into the danger zone. The lowly valve acts as a safety feature. It relieves the pressure before your hot water tank blows up.
So what happens when the valve fails. Does the tank blow up? You would see a lot of 'film at eleven' spots if it did. Instead, when it fails it goes the other way. It starts releasing pressure before the danger level. What does that mean exactly? It means hot water spraying all over the place around your hot water tank. Basically a mess.
Not a lot of options when this happens. Installing a new valve is usually the fix. Read on and see if you are up for the challenge.
Hot Water Heater Pressure Relief Valve - Information
What Can You Save?
A new valve is less than $20. I don't want to upset you, but, when they start acting up they are usually terminal. Call in the family and get the arrangements worked out. $100 to $150 to have someone come out and change it. It takes a half an hour, you be the judge.
How Hard Could It Be?
Replacing a hot water heater pressure relief valve is not that hard, it will take less than an hour, including the trip to the supply store. Do you live in Montana? Maybe a little longer.
Check the Simple Things!
There is a chance that something got caught in it. How did that happen? It hasn't moved in years. I said a chance, take a look at Step One.
What Can Go Wrong?
You don't have a lot of choices here. You cannot use the hot water tank without the hot water heater pressure relief valve installed. No hot water is no fun, no other way to put it.
Troubleshooting Water Heater Pressure Relief Valves
How can I check and test my pressure relief valve?
It is possible that the valve was not seated properly. There is a simple way to check this and see if the valve is still functioning correctly.
See the article 'Checking a Water Heater Pressure Relief Valve', for information on what to do.
My pressure relief valve is bad, what do I need to do to replace it?
Changing the pressure relief valve is not a big job and they are fairly inexpensive. It will involve finding a replacement valve, removing the old one and installing the new one.
The article 'Replacing a Water Heater Pressure Relief Valve' covers these topics and the steps needed to complete the task..
Summary
There are not many options for a troublesome water heater pressure relief valve. Once in awhile the valve gets something it and it won't seat properly. As a rule the valve works without complaint for years and then one day it starts venting. All of us do that from time to time, can we blame the valve?
The usual solution is to replace the valve. It is not that big of a job and the part is not that expensive. You should have paid about $15 dollars for a new valve. Hopefully you were able to deal with your valve.