What a Flame Sensor Is and Why It Matters

Receiving your seasonal furnace maintenance helps keep your furnace working up to 30% more efficient and helps extend the life of your furnace. But things could still stop working, and when they do, you could feel like it’s always something else. 

This time it’s your heat exchanger, next time it’s your control board. Now your find out the flame sensor has to be replaced. 

Also, what is a flame sensor? 

A flame sensor is a critical safety element on your gas heating system. During the ignition sequence, your gas furnace goes through a process where either a hot surface ignitor or a spark will actually ignite the gas. When the gas is ignited, the flame sensor generates a current of electricity. The electricity is quantified in micro amps. If the furnace’s control board does not read the proper level of micro amps, the furnace will no longer give the system fuel to prevent an explosion. 

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

The way to diagnose if a soiled flame sensor is to blame for a furnace malfunction is to take a micro amp draw reading, which a professional furnace technician can supply you. If a dirty flame sensor is the guilty party, the technician will clean the sensor with steel wool. If dirt was the only factor, we will see a significantly higher amp reading. If the reading shows no change, the technician will continue with the heating equipment repair diagnostic process. 

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