How to Replace a Gas Control Valve on a Water Heater

A pipe and crescent wrench adjusting a valve on a water heater.
  • 5-10 hours
  • Advanced
  • 300-600
What You'll Need
Protective overalls
Working gloves
Pipe wrench
New gas control valve
Pipe tape

If the water heater in your home is not working effectively, there might be a problem with the gas control valve. This can be the case when the water is not heating properly or to the desired temperature (including instances where it's too hot). While there can be other causes for this problem, if you confirm that a faulty gas control valve is the source, you can replace it. All you need are basic tools and instructions to help you along.

Step 1 - Inspect the Water Heater for Other Problems

Take a look at the appliance to see whether there could be other issues causing your water heater to malfunction. For example, there might be a problem with the volume of water getting into the heater. If it is too little, the water may overheat. Dirt or buildup of debris in the heating chamber can also cause bad temperature regulation, as well as other faulty parts such as the thermocouple or the thermostat. It is less common for the gas control valve to go bad than some other parts of your water heater, and it's also less expensive to fix one of these other causes.

Step 2 - Assemble the Materials

Gather the tools you will need and put on your protective gear. When you buy a new gas control valve from hardware or home supplies store, it's a good idea to carry the old one with you when you purchase. This helps you get appropriate equipment that matches the design of your specific water heater.

Step 3 - Shut Off Gas

Turn the gas control knob off to discontinue the supply of gas to the water heater. Make sure the gas control valve is off as well so that no gas is getting to the heating equipment. Even still, be on the look out for gas leakage. If there is a strong smell of gas in the room, then call the gas company to rectify the problem immediately.

Step 4 - Shut Down Water Supply and Empty the Tank

Locate the cold water supply knob and turn it off to discontinue the flow of cold water to the heating system. It makes it easier to drain the tank before you carry out the repair job. Use appropriate-sized buckets to remove water from the heating tank. Make sure the water heater is empty before you check the discharge pipe and disconnect it.

Step 5 - Remove the Old Valve

Use a pipe wrench to remove the old valve from the heating system. Depending on the design of the tank, pliers or a screwdriver can also be used for this purpose.

Step 6 - Fix New Gas Control Valve

Attach the new valve by reversing the previous process. Wrap some pipe tape around the threads, and fix the valve in place by hand first. Then, fasten it the rest of the way with the pipe wrench, pliers, or a screwdriver. Make sure it is tight and secure to avoid any leakages. Then, reattach the discharge pipe that was disconnected before and fasten it into the valve outlet. Note that not all water heating systems have this piece.

Finally, turn on the water supply to fill the tank, and open the gas valve and the gas knob for the heating system to start working. Check the gas pressure and watch out for leakages. If you don't detect any problems, then you can rest easy knowing your replacement was successful.