A temperature and pressure valve is basically a safety spigot at the top of your hot water tank. This valve releases pressure in the form of steam or hot water when a water heater malfunctions. T&P valves should be checked annually to assure the safe operation of any water heater. Lift the metal tab on the top of the valve to release a small amount of hot water, then close the valve. If the valve fails to release water, releases steam or leaks after you close it, it is time to replace the valve.
Step 1: Turn the thermostat completely down (not off) on gas water heaters or for electric heaters; turn the power off at the main electrical panel. If possible, allow the water in the tank to cool for several hours before proceeding.
Step 2: Shut off the heater’s cold water supply and open a hot water sink faucet nearby. Attach a garden hose rated for hot water to the heater’s drain valve. If the floor drain is near the hot water heater, a washing machine hose may suffice. Drain enough water from the tank to allow for the safe removal of the T&P valve. If the water is rusty or filled with sediment, drain the water until it runs clear. Once the tank has been partially drained, shut off the drain valve and turn off the nearby sink faucet that was open.
Step 3: Test the pressure and water level of the heater by lifting the metal tab on the T&P valve. Let any additional water or steam flow out of the overflow tube. Close the T&P valve before proceeding.
Step 4: Remove the overflow tube attached to the T&P valve and use a pipe wrench to unscrew the T&P valve by turning it counterclockwise.
Step 5: Wrap the threads of the new T&P valve with Teflon tape, or coat the threads with joint compound. Screw the new valve into place, being careful to align the valve opening in roughly the same position as the old valve.
Step 6: Reinstall the overflow tube.
Step 7: Turn the water heater’s cold water supply back on and allow hot water to run from the nearest faucet for several minutes to release any air that may be trapped in the heater.
Step 8: Turn the power back on, check for leaks and make note to test the valve next year.