Furnaces have built-in safety measures to ensure that noxious gases and fumes don’t leak into your house. A key component of the furnace’s safety circuit is the flame sensor, a small metal rod with a porcelain base that monitors the flame in the furnace through an electrical current. When the flame goes out, the furnace sensor immediately shuts off the gas supply to prevent it from leaking into your home and causing carbon monoxide poisoning. As such, it’s important to make sure the furnace sensor is working properly.
How can you tell if the furnace sensor is malfunctioning? By keeping an eye out for certain warning signs. Stone Heating and Air, a trusted heating and air conditioning company, lists them below:
Furnace shutting down a few seconds after starting
Cracks in the sensor’s porcelain base
Soot or rust on the tip of furnace sensor
The Usual Culprit Behind a Malfunctioning Furnace Sensor
While corrosion or wear and tear are possible causes, the usual culprit behind a sensor malfunction is carbon buildup. That’s why it’s important to routinely clean your furnace’s sensor.
How to Clean the Furnace Sensor
Shut off the furnace’s electrical supply – Simply turning it off isn’t enough—you need to shut off the electricity supply. Remember: safety should always come first.
Remove the heat sensor – The sensor is a rod-shaped device in the path of the burner. Loosen the screws and remove it from its bracket.
Carefully remove residue on the sensor using emery paper or light-grit sandpaper – After cleaning the sensor, wipe off the remaining dust using a lint-free cloth.
Reattach the furnace sensor – Make sure to tighten all screws fully after putting them back in.
If you’re still encountering furnace issues after cleaning the sensor or aren’t comfortable with handling sensitive furnace components, you should schedule an appointment with one of your local home heating companies. As a rule, your furnace should be inspected by a technician at least once a year.