What Is a Thermocouple?
Homeowners who use any sort of natural gas in their homes, whether it fuels their heating devices or lets flames leap out of a barbecue grill or fireplace, know that this reliable natural fuel has a dark side. If you aren’t careful, propane and natural gas can be quite dangerous or even deadly.
This is where the thermocouple comes in. This humble metallic coil is like a lifeguard standing sentinel within your furnace. The thermocouple’s temperature sensors determine the potential for a leak of uncombusted gas, and if the pilot light goes out or produces a weak flame, the thermocouple springs into action, sending signals through the system that shut off the gas supply.
Locating the Thermocouple
It shouldn’t be too hard to find the thermocouple in your furnace’s pilot light assembly. If you know where the pilot light is, look around that area for a coil or length of copper wire with a silvery metal probe tip. That probe tip should stand within an inch of the pilot light flame.
Can You Fix Your Own Thermocouple?
It’s best to shut off your furnace and close the gas supply right away if you suspect an issue with the thermocouple, but if you haven’t yet shut off the power, you absolutely must do so before you attempt a thermocouple repair. If you don’t know how to shut your furnace down, that’s a good sign that this repair is beyond your capability.
If your pilot light burns bright blue in a strong, tall cone but your heat system still shuts off, that could mean that the thermocouple isn’t working properly. Do not wait to replace your thermocouple. As mentioned above, this is an important piece of safety equipment, and it needs immediate attention.
If you see soot or other debris on the sensor unit, that’s a potentially easy DIY fix. You can use a soft cloth to remove the debris or, if it’s really stuck on there, a bristle brush. Just make sure you don’t knock the thermocouple out of place, scratch it, or spread the debris around the pilot light assembly.
If there isn’t any visible issue or if cleaning the thermocouple doesn’t fix the problem, it’s up to you to decide whether you feel comfortable going further. If there’s any step in the process you’re not sure of, don’t hesitate to call a professional.
If you do go the DIY route, it won’t cost much to fix. Most replacement thermocouples are about $15-$20, but your exact furnace model may require a more expensive temperature sensor replacement. You must get the proper brand and type of thermocouple replacement for your specific furnace. Don’t substitute a cheaper option.
Finally, you’ll need to hook up your new thermocouple so it functions properly, and the exact procedure for this can vary based on what kind of furnace you have. Remember that a broken or improperly installed thermocouple can spell disaster, so if you’re not 100 percent confident that you know how to do the job correctly, ask a professional to come in and show you how it’s done. Once you learn firsthand from someone in the know, you’ll be in a better position to fix it on your own if you experience more thermocouple problems in the future.