Replacing a Water Heater Gas Valve – Tips and How To

Removing and replacing a gas valve on a hot water tank isn’t as hard as it may seem. Here’s how to do it quickly and safely. 

Replacing a Water Heater Gas Valve

As part of the manifold/burner assembly, the gas valve is an important component of a hot water tank.  It’s usually located toward the bottom of the tank, and has several other components attached to it, including the manifold tube, pilot tube, and temperature probe. High limit probe, thermal fuse, igniter, and thermocouple. 

Most valves include two or three knobs or buttons. These will be used to change the temperature  and ignite the pilot. The valve is where you can control and set the temperature and turn off the heater. It’s a vital component of your hot water tank. 

Some of the more common gas valves include White Rodgers, Robert Shaw, and Honeywell. These three models can be found on most heating units from AO Smith, Rheem, State, American, Bradford White, GE, Kenmore, and other popular manufacturers.

How Does a Hot Water Tank Work?

Essentially, a water heater heats cold water until it reaches the temperature you’ve set, ensuring that hot water is available when it’s needed. This works through a thermostat probe, which signals the heater to kick on when the water isn’t at the temperature the thermostat is set for. Once the temperature is gained, the gas flow stops, and heating stops. 

Removing a Gas Control Valve

The first thing to do is to turn the gas valve to the “off” position. Depending on the model, it may need to be depressed before turning it. From there, turn the gas valve off for the line leading to the hot water tank. Turn the water line off at the shut off, and drain the water tank. Disconnect and take off the piezo igniter, manifold tube, pilot tube, thermal switches, and thermocouple, being careful not to damage the thread. 

Using the correctly-sized threaded pipe, place it into the inlet and unscrew, thereby removing the valve. Be careful to not use a pipe wrench or place any items into the inlet, as they may cause damage. 

Replacing a Gas Control Valve

Using either teflon tape or a pipe compound, reconnect the gas valve to the gas tube. Use the previously mentioned threaded pipe to put the valve back on, but avoid over-tightening. This could damage the valve and cause gas to leak. Put the piezo igniter, manifold tube, pilot tube, thermal switches, and thermocouple back on, making sure to pay attention to the threading. Make sure the combustion chamber is clean, and free of debris. 

From there, refill the tank, and open the water tap to let any air out. Test the valve for gas leaks by using foamy, soapy water, and using a sponge to apply to the gas connections. If it bubbles, that may indicate a leak, and will need to be fixed. Re-light the pilot using the instructions for your tank.

Temperature Adjustment

Once everything is all set with your hot water tank and the gas valve, you can adjust the temperature. For most valves, the safest and most economical setting is for 120 degrees. There are also settings for vacation mode, when you won’t be using hot water, and the ability to set it higher than 120 degrees. For children, the optimum setting is between 120 and 125 degrees. 


If you’ve replaced the gas valve, but are still having issues, it could be something else. For instance, if you can’t get the pilot to stay lit, it could be an issue with the thermocouple. You can check the pilot tube to make sure it’s not clogged. 

When to call a plumber to fix your hot water heater

If you’re unable or uncomfortable changing the gas valve on your hot water heater, it may require a professional. At Rick’s Plumbing, we’ve been helping homeowners in New Haven and Fairfield Counties since 1992. To schedule a look at your hot water heater, call us today at (203) 874-6629.