Things You'll Need
Phillips or slotted screwdriver
The thermocouple allows the gas control valve/temperature control to remain open, feeding gas to the burner assembly inside the combustion chamber. A damaged or broken thermocouple turns off the gas control valve/temperature control, not allowing gas to leak into your residence. The pilot light heats the tip of the thermocouple, producing a small electric charge that signals the gas control valve/temperature control that it is safe to continue to feed gas to the burner. Consistent inspection of your water heater thermocouple for signs of wear and damage helps it last longer.
Turn off the gas supply valve that feeds the gas control valve/temperature control. This valve is located on the supply line, and turning it counterclockwise shuts down the gas flow.
Video of the Day
Turn the temperature control knob to the lowest temperature setting. Turn the pilot control knob on top of the temperature control to the "Off" position.
Remove the outer door that covers the pilot tube, thermocouple and gas supply tube at the bottom of the water heater. Use an adjustable wrench to loosen the two tubes and the thermocouple from the bottom of the gas control valve/temperature control. Grasp the tubes and the thermocouple and pull down, releasing them from the gas control valve/temperature control.
Remove the door that covers the burner assembly and combustion chamber by removing the screws that hold it to the water heater. This door is located behind the outer door you removed in Step 3. Remove the burner assembly from the combustion chamber by pulling it out of the chamber.
Inspect the end of the thermocouple for signs of carbon buildup. Carbon buildup appears as a white powdery residue on the tip of the thermocouple. Pull the thermocouple from the bracket and use emery cloth to sand the end of the thermocouple, removing the carbon and adding life to your thermocouple.
Push the thermocouple into the burner assembly bracket that holds the pilot tube and the thermocouple. Verify the tip of the thermocouple sets 1/8- to 1/4-inch past the pilot head. Proper positioning helps the thermocouple last longer.
Inspect the thermocouple for kinks, as these shorten the life of the thermocouple. Reinstall the burner assembly into the combustion chamber and attach the outer door.
Thread the pilot tube, thermocouple and gas supply tube back into the gas control valve/temperature control and tighten. Turn the gas supply valve on and turn the temperature control to your desired temperature. Light the pilot and replace the outer door.