Step-by-step advice for replacing a water heater’s temperature and pressure relief valve.
A conventional storage water heater has a small valve screwed into its tank that is designed to relieve built-up steam pressure if the water heater overheats—otherwise, the pressure could cause the water heater to explode.
This valve has several names, including temperature and pressure relief valve, pressure relief valve, T&P valve, or—in its shortest form—TP valve. As T&P valves get old, they can begin to drip or leak and may need to be replaced. You can order a water heater T&P valve online or buy one at a hardware store or home improvement center.
Though it is recommended that you periodically test this device by lifting its lever to make sure it is working, doing this with an old valve can cause it to leak. With this in mind, be ready to shut off the water supply to the water heater and replace the TP valve if this happens when you test it.
Note: Be aware that a pressure relief valve is designed so that water will pour out of it if pressure builds up too high in the water heater. With this in mind, the valve should be piped outdoors or to a drain.
Here’s how to replace a water heater temperature-pressure relief valve:
1Shut off the cold water and gas or electricity coming to the water heater.
2Drain the water from the tank until the water level is below the valve. To do this, run hot water at any faucet, shower, or bathtub. Or, instead of wasting water at your fixtures, take this opportunity to flush accumulated minerals and sediment from the water heater tank by following the directions in the article How to Flush a Water Heater.
Caution: The water may be hot unless you’ve allowed time for it to cool!
3Raise the lever on the valve to release any excess pressure. If the valve has a copper pipe attached to it, unscrew the pipe. Loosen the valve by turning it counter-clockwise with a wrench, and then remove it slowly. If water begins to pour out, screw it back in and drain more water from the tank.
4Put pipe-thread tape on the threads of the T&P valve and then screw it in, turning clockwise. Tighten it with a wrench.
5Turn the cold water supply and gas or electricity back on and, for a gas water heater, relight the pilot light or restart it with the electronic igniter if necessary.