How to fix a water heater

Saving energy; draining off sediment; testing the relief valve

To save fuel, set heater thermostats at 120°F (140°F for a dishwasher). Cover the heater with an insulating jacket sold in a kit. To keep sediment from building up in a heater tank, open the drain valve; drain water into a bucket until it runs clear. Do this monthly if the water is hard; every 2 or 3 months if it’s soft. If the tap water is dirty or the heater noisy, flush out the tank. Turn off power to the heater at the distribution panel: on a gas heater, turn off the control unit’s gas cock. Shut the cold-water valve and open an upstairs hot-water faucet. Attach a hose to the drain valve to direct water outdoors or to a floor drain. Open the drain valve.

When the tank is empty, open and close the cold-water valve until the water runs dear. To refill the tank, close the drain valve; open the cold-water valve. When the tank is full (water flows out the open hot-water faucet), turn on the heater.

If a faulty thermostat lets tank water overheat, a relief valve will prevent an explosion by venting hot water. You should have the valve tested annually by a plumber. If the valve doesn’t release hot water when tested, have the plumber replace it at once. If an electric water heater doesn’t heat-and there’s no tripped circuit breaker or blown fuse-turn off power to the heater. Unscrew the access panel: set aside the insulation. Push the reset button on the high temperature cutoff; restore power. If the water still fails to heat, have the thermostats and heating elements tested and, if necessary, replaced.