To install a gas furnace thermocouple, turn off the gas and power, access the thermocouple through the access panel, remove the old unit, install the new unit and relight the pilot light. Consult a professional with any questions, and immediately turn off the gas and power if the new thermocouple does not operate properly.
The thermocouple on a gas furnace acts as a shut off valve for the gas flow, and if it fails, the furnace is unable to light. To replace a thermocouple:
- Turn off the gas and power
- Access the thermocouple
- Disconnect the thermocouple
- Replace the thermocouple
- Turn on the gas and power
Before attempting to perform any work on the furnace, turn off both the gas and the power to the furnace.
Remove the front panel on the furnace to access the upper and lower access panels. Remove the upper panel to access the thermocouple, which is located next to the pilot light.
Unscrew the copper lead and remove the connection nuts on the gas line and the thermocouple tube. Clean and dry the connection parts surrounding the area before installing the replacement part.
Purchase a compatible replacement thermocouple and set in place with the copper tube pointing down and the steel tub pointing up. Connect all of the nuts to their proper positions.
Ensure that the new thermocouple is working properly by turning on the power and gas and relighting the pilot light. Ensure the pilot light remains lit, and then re-install the panel door.