In this video, This Old House plumbing and heating expert Richard Trethewey explains the extreme importance of maintaining your water heater's temperature-and-pressure relief valve.
1. Regardless of the type of water heater, whenever water is heated, it expands. And the water-heating system must accommodate the expansion. Otherwise an explosion could occur.
2. Expanding water can move out the cold-water line. However, if there's a pressure-reducing valve mounted near the water main, the valve can block expansion.
3. Adding an expansion tank to the heater can accommodate a certain amount of expansion.
4. All water heaters are equipped with a thermostat that controls the water temperature.
5. If the thermostat fails and pressure builds up in the tank, the temperature-and-pressure relief valve will open and discharge built-up steam and hot water.
6. Temperature-and-pressure relief valves should always be connected to a discharge pipe that extends down to the floor.
7. Once a year, open the valve to flush out minerals and sediment.
8. Never install a plug into a temperature-and-pressure relief valve. And if you see a plug in the valve, turn off the water heater and immediately call a plumber.
9. To prevent someone from plugging the valve, install a tamperproof adapter.
10. If you see water dripping from the discharge tube, turn off the water heater and call a plumber. The temperature-and-pressure relief valve should be replaced.