Shutting down your hot water heater is an emergency procedure that every homeowner needs to know -- it could prevent a disaster in the event of pressure buildup inside the tank. Other reasons for turning off the water heater include the need to make small repairs -- such as replacing the temperature and pressure valve -- or leaving the house empty for an extended period. Turning off the heater when you're away for several days saves energy.
The method for turning off a water heater varies depending on the type of water heater -- gas or electric -- and how long you intend to turn the heater off. When completely shutting down your water heater to make repairs or before going on a trip, you should also drain it. When completely shutting down your water heater to make repairs or before going on a trip, you should also drain it.
Turning Off a Gas Water Heater
The control valve on the front of a gas water heater provides the means to turn it off both temporarily and permanently.
Turn the dial from the "On" position to "Pilot" to prevent the gas burner from cycling on. The pilot light remains lit, and as soon as you turn the dial back to on, the burner will light.
Turn the dial to the "Off" position to turn off the pilot; when you do this, you'll have to relight the pilot to start the heater up again. To prevent gas leaks and ensure the heater remains off, turn off the gas valve by rotating the handle until it is perpendicular to the gas line.
Turning Off an Electric Water Heater
The easiest and safest way to turn off an electric water heater is to turn off the breaker in the panel that controls it. It should be labeled, but if not, look for a double breaker -- water heaters run on 240-V power. If there is more than one double breaker, find the one that has the same amperage rating as the water heater; you'll find that displayed on a label near the main temperature control. Turning off the breakers avoids the need to touch the heater -- which may be wet -- and to alter the temperature control. Use a noncontact voltage tester to confirm that no electricity is flowing through the unit's wiring.
Shutting Down the Water Heater
If you're turning off the water heater to make a major repair or because you're leaving town for the winter, you should also drain it. It's best to wait for 12 hours or more before doing this, but if you don't have time, beware; the water is hot.
Shut off the cold water inlet, but leave the hot water outlet open.
Open one or two hot water faucets in the house, let water drain and then leave them open to admit air.
Connect a garden hose to the drain outlet on the bottom of the tank and run the hose to a place where you can drain the water.
Open the drain valve and let the water drain out. Be sure to close the drainage valve and the hot water faucets when water stops draining.