How to Install a Gas Shut off Valve in a Gas Furnace

When you have had your gas furnace for a while, you may decide to replace the gas shut-off valve, or thermocouple. The gas shut-off valve can be found in most modern gas appliances, and is designed to turn off the gas supply if the pilot light flame does not come on, or if it is extinguished for some reason. If you cannot light your furnace, or if your pilot light flame is a bright blue, then your gas shut-off valve has failed. In order to replace the thermocouple, you will need to extract the old one, and purchase a new device which can be used to turn the gas off in an emergency.

Step 1 - Find a Replacement Thermocouple

Finding a replacement thermocouple is not always easy. Some types of gas furnace require that all of the parts of the ignition are connected together, and the components cannot work if any of the parts don't match up. Buying an unsuitable replacement part would mean that the thermocouple may not be able to detect changes in the pilot light flame, rendering it useless. You could find out the right number for your thermocouple from the owner's manual, or by talking to the manufacturer of your furnace.

Step 2 - Prepare the Furnace

Turn off the electricity and gas supplies to your furnace, and allow it to cool down. This could take a while, so you might prefer to do another task while you are waiting for the furnace to become cold enough to touch. Using your wrench, remove the bolt on the access panel at the front, and place this to one side. You should then be able to see into the furnace, and locate the pilot light and the switch, which is usually found on one of the furnace burners.

Step 3 - Remove the Old Thermocouple

Find the gas valve, and then the copper tubing which connects it to your gas shut off valve. This should be removed from the gas valve, and also taken off of the thermocouple. You should then also take off the tubing which connects the gas valve to the pilot light. Use your screwdriver to remove the brackets holding the shut off valve in place, and then lift up the thermocouple. Discard this into the trash.

Step 4 - Add the new Thermocouple

Take your replacement gas shut-off valve, and fit it back into the bracket. You should then screw the bracket back onto the wall of the furnace. The thermocouple should be securely connected to the pilot assembly. You should replace the tubing between the thermocouple and the gas valve, and between the pilot light and the gas valve. Make sure that all of these connections are tight, and that the gas valve's connections are air-tight. You can then replace the access hatch of your furnace, and light the pilot light. Turn on the power supply.