What a Flame Sensor Is and Why It Matters

Receiving your seasonal furnace maintenance helps keep your heating system operating up to 30 percent more efficient and helps extend the life of your furnace. But things can still stop working, and when they do, you might feel like there is always something else.

This time it’s your heat exchanger, next time it’s your control valve. Now you need to replace your flame sensor.

What is a flame sensor, anyway?

A flame sensor is a crucial safety feature on your gas heating equipment. During the ignition sequence, your gas furnace goes through a process where a spark or a hot surface ignitor actually ignites the gas. As the gas is ignited, the flame sensor produces a current of electricity. This is measured in micro amps. If the furnace’s control board does not read the correct level of micro amps, the furnace will stop giving the system fuel to prevent an explosion.

Over time, if the flame sensor is not cleaned appropriately, oxidation or carbon buildup can interfere with the flame sensor’s ability to work properly, which can end up causing the heating system to malfunction.

The way to determine if a dirty flame sensor is to blame for a furnace malfunction is to take a micro amp draw reading, which an expert heating technician can supply you. If a dirty flame sensor is the guilty party, the heating expert will clean the sensor with steel wool. If dirt was the single factor, we will see a much higher amp reading. If the reading does not change, the technician will continue with the heating system repair diagnostic process.

If you aren’t certain your heating equipment is going to outlast these last few weeks of winter, give Service Experts Heating & Air Conditioning a call and we’ll come out and provide you with a full furnace maintenance or a free in-home estimate on a new heating system.

Contact Us