T&P Valve Replacement

Most homeowners are capable of doing a lot of their water heater maintenance. If you want to learn how to replace the water heater pressure relief valve, then you're in the right place. First of all, let's get our terms right. It's technically not a pressure relief valve (or reducing). Those are installed on the mainline of the house. On a water heater, it's called a T&P valve (temperature and pressure) or a pop-off valve.

T&P Valve Leaking

The T&P valve serves an essential function as a safety feature. It offers your water heater built-in protection against high pressure and hot temperatures. It's pretty standard for the pop-off valve to need replacement during the life of your water heater. The telltale sign that it needs replacement is when you see it dripping or leaking water. When you need a new valve, try one of the following options:

Watts 100XL-4 3/4" standard T&P valve
Watts L100XL 3/4" long-shank T&P valve (for water heaters with insulation)
Jones J34980 3/4" top-mount T&P valve

T&P Valve Replacement in 7 Steps

Cut off the water supply to the water heater.
Turn the gas/electricity off to the water heater.
Drain a little water from the tank. It only needs to fall below the pop-off valve, wherever that resides. If you have a top mount configuration, you only need to drain a little bit. For side mounts, you probably need to drain about 10 gallons. You might take this opportunity to flush the water heater entirely, removing minerals and sediment in the tank. For a complete tutorial, read how to drain a water heater.

Remove the T&P valve. There may still be pressure in the line, so raise the lever on the valve before using a wrench to unscrew it. If water comes pouring out, it means you didn't drain enough water.
Install the new T&P valve. Wrapping pipe thread tape around the threads of the valve, screw it into place. You should use a wrench, but you do not want to overtighten it.
Check for leaking. Fill the tank back up by opening the water supply valve back up. When the water level rises to the level of the new T&P valve, you can look for leaks.
Turn the water heater back on. If it's electric, juice it up. If it's gas, open the supply valve and get this baby going.

Testing a T&P Valve

Our best advice is don't test the T&P valve. The reason is that the test requires you to flick the release lever. This action can cause an old valve to start leaking. Why rock the boat if it's still working? Just give the T&P valve a thorough visual exam, looking for leaks, and call it good.

Replacement Projects with PlumbersStock

The beautiful thing about our tutorial guides here at PlumbersStock is that you can use our site to buy everything you need at discount prices. Check out all of our water heater accessories and replacement parts. We carry the most trusted brands in the plumbing industry, including Bradford White. If you have any questions remaining about water heater pressure relief valve replacement, please contact us.