How to Replace a Gas Water Heater Thermocouple

If you're having trouble with the pilot light on your gas water heater, you need to check the thermocouple. It is one of the first things to check when troubleshooting a pilot light problem with a gas water heater. A thermocouple determines if the pilot light is lit. If it's not lit, the gas valve fails. If that's the problem, replace the thermocouple.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• Wrench
• Screwdriver

1. Shut off the gas valve on the water heater and the gas valve on the line near the heater. Remove outer and inner doors, and loosen the pilot and supply tubes and the thermocouple connections to remove the burner assembly.

2. Loosen the screw holding the thermocouple to the bracket. Remove old thermocouple. Bring it with you to the store to ensure you are buying the proper replacement.

3. Install the new thermocouple. Position the thermocouple so that the pilot flame heats 1/2 inch of the tip.

4. Reinstall burner assembly in the water heater. Tighten burner supply tube, pilot tube and thermocouple connections. Tighten thermocouple no more than a quarter turn more than hand-tight.

5. Turn on both gas valves. Check supply tube and pilot tube for leaks with soapy water. If soap bubbles, tighten connections to fix leak. Ignite the pilot light, and make sure the thermocouple tip is heating up. Replace inner and outer doors.

Tips & Warnings

• While both doors are off, vacuum the burner compartment and check the water heater for water leaks.
• Follow instructions on water heater to reignite the pilot light.