How to test a water heater relief valve
Updated . By the OakTend team.
The temperature and pressure relief valve (the T&P valve) is the safety valve near the top of the tank. It opens if the water gets too hot or the pressure too high. Testing it means lifting its lever and checking it closes again.
Why it matters
It is the last line of defense if a thermostat fails. A valve that never gets exercised can stick, and you only find out by testing it. Each valve has a discharge pipe that should run down toward the floor or a drain with nothing blocking the end.
Steps
- Find the valve and follow its discharge pipe to where it ends. Make sure nothing blocks the opening.
- Put a bucket under the end of the pipe and make sure nobody is standing near it.
- Lift the valve's lever and let it snap back. Do this a few times.
- Check that water stops flowing once the lever is down.
- Watch the end of the pipe for a few minutes to be sure it is not still dripping.
When to call a pro
If the valve keeps letting water out after you release the lever, A.O. Smith says to close the cold water supply to the heater and replace the valve. A plumber can do that the same day.
Safety
The water that comes out can be scalding. Keep your hands and face away from the pipe, and never cap or plug the discharge pipe.
Go deeper
General information, not professional advice. Your equipment's manual comes first when it says something different.
Sources
- A.O. Smith: water heater instruction manual, temperature-pressure relief valve
Operate the valve by hand at least once a year; the water may be extremely hot; if it keeps releasing water, close the cold water inlet and replace it; the discharge line ends near the floor or a drain. - A.O. Smith: GDHE 50 manual (hosted by ManualsLib)
Lift the lever several times until the valve seats properly and operates freely.