Installing a water heater shut off valve is a fairly simple task, and usually does not require a professional. Before beginning, however, it is best that to have an understanding of the project and safety concerns, and to make sure the necessary tools are available. It also never hurts to have the phone number of a plumber handy, just in case of emergency.
Step 1: Turn Off Hot Water Heater
If the water heater is gas and uses a pilot light, be sure to turn the gas off. Contacting the gas company to make them aware of repairs is also a good idea. Many localities have ordinances in place that if gas appliances are replaced or repaired, they must be inspected by a professional before the gas can be reconnected. If it uses an electric igniter system, turn off the power at the breaker box. Once the electric and/or gas supply is disabled, give the water heater a chance to cool down before handling the parts, to avoid burns.
Step 2: Turn Off the Water
Once the tools are gathered and the tank has cooled, turn off all water going to the unit by using the water shut-off valve. If you have a problem with this valve, you will need to turn the water off at the main outside the house. The main is generally under a plate in a box underground. Sometimes this can be in your yard, and sometimes it can be on the street.
Step 3: Drain Water
Drain the water from the tank using a garden hose or electric pump. Be careful—the water may still be hot and it could be rusty. Run the water into a sink or tub, or outside.
Step 3: Install the Valve
Once the tank is empty, carefully remove the old valve, which should unscrew with a wrench. The valve can be found on the top of the water heater in most cases, and is almost always color coded. Look for the black valve. Clean any gunk off the exposed pipe threads and then apply appropriate pipe joint adhesive compound. If there is no old valve, you can just prepare the new threads and proceed. Now you can screw on the new valve and tighten it with a wrench.
Step 4: Test for Leaks
Next, test for leaks. Turn the new valve to “OFF” and turn off any drains you might have opened. Turn the water supply to the tank back on, and turn the valve back on. Check to see if the valve is leaking. Soapy water can be applied around the valve and pipe joints to check for leaks. If air is leaking, it will create visible bubbles in the soap. Air leaks can lead to water leaks down the road, and a more costly repair. Making sure everything is tight now will help you prevent a mess, as well as help save money on your water bills.
Step 5: Finishing
If there appear to be no leaks as the tank is filling with water, it should be safe to re-light pilot light and/or reconnect the electricity. Now simply clean up any mess and put the tools away so they are ready for the next project.