What is a Pressure Relief Valve and Why is Mine Leaking?

That little puddle of water around the water heater has you worried.   It doesn’t seem to get bigger and sometimes it looks like it’s altogether disappeared.  But then there’s that tell-tale stain on the floor that reminds you of the history of water puddles.

Problem with the Pressure Relief Valve

When you have the symptoms described above, it may not be a problem with your water heater.  It may be the relief valve on your heater.  Commonly referred to in the trades as a T&P valve (temperature and pressure relief valve), this little fella has a very important job to do.  Have you ever seen that insurance TV commercial where the water heater explodes through the roof of the house and winds up in the street out front?  If not-Google it. It’s a good illustration of what can happen if the T&P valve is not working properly. That little brass valve on the side or top of your water heater is designed to let water or steam out of your water heater when the temperature or pressure inside exceeds the safe operating limits.

Why the Relief Valve May Leak

There are a couple of main reasons why your relief valve may leak.  If you have a backflow preventer on the water service coming into your house, and you have no, an improperly installed, or a defective expansion tank on your water heater, the pressure in the tank will exceed the operating limits of the heater every time it heats up and the relief valve will do its job—it will release the extra pressure in the form of hot water through the valve and onto the floor.

The next reason might be a faulty relief valve.  As the water heater gets older, the rubber washer in the bottom of the relief valve gets harder and harder.  Then when you test the relief valve during periodic maintenance, the washer may crack or crumble just enough to create a leak.  If you don’t test the relief valve periodically (you do test it, right?) then the washer may even stick to the bottom of the bottom of the valve (called the seat) and crack or crumble the next time you do test it.  The solution is to replace the relief valve.

At Yes! Plumbing we find several faulty relief valves a year when we are doing our yearly free maintenance services for our Club Members.  For this reason we carry them on the trucks and are prepared to replace them if they turn out to be faulty when tested.

Give Yes! Plumbing a call if you have any concerns or would like to have your heater checked out.