A furnace has electrical components and combusts fuel in order produce heat. Never should the twain meet. Thus, a furnace will have failsafes that help to prevent problems. If you have an older furnace that uses a pilot light, one of these failsafes is a thermocouple. The purpose of the thermocouple is to detect whether the pilot light is lit. If the pilot light goes out, the thermocouple closes the gas inlet valve which will prevent gas from flowing into the burner and leaking into your house. If you have problems with your thermocouple, you are at risk for gas leaks. Luckily, repairing a thermocouple is not a difficult task.
How a Thermocouple Works
A thermocouple will have a bulb at one end and will be attached to the gas inlet valve at the other end. The bulb end will hang down over the pilot light. The thermocouple converts the heat from the pilot light to electricity and then uses that electricity to open the inlet valve. As the thermocouple ages, it will wear down, and this wear can cause it to fail.
Repairing a Thermocouple
When a thermocouple wears out, the only thing to do is to install a new one. The following steps will guide you through the process of replacing your thermocouple:
1. Turn off the electricity and gas to your furnace. You can turn off the electricity at the breaker box. As for the gas, you will find a shut-off valve in your furnace room.
2. Once you have taken the necessary safety precautions described in step one, you can open the access panel and locate the thermocouple.
3. The thermocouple will be attached to the same bracket that holds your pilot light in place. Remove the bolts that hold the thermocouple in place.
4. Remove the thermocouple.
5. Put the new thermocouple in place and replace the screws that secure it and the pilot light.
6. Make sure that the bulb of the thermocouple hangs over the pilot light without completely obstructing the flame that comes from the pilot light.
7. Turn back on the electricity and gas to your furnace.
With your new thermocouple in place, your furnace will have new life. However, if you are heating your home with an old furnace, you might want to consider the possibility of installing a new, more efficient furnace. The new furnace will give you improved efficiency that you cannot get simply be making a repair. On the other hand, if you don't have the money to buy a new furnace, making heating repairs will keep your furnace working like it should.