What a Flame Sensor Is and Why It Matters

Receiving your annual furnace maintenance helps keep your furnace running up to 30 percent more efficient and helps extend the life of your system. But things can still stop working, and when they do, you might feel like it’s always something else. 

This time it’s your heat exchanger, next time it’s your control board. Now you have to have your flame sensor replaced. 

What is a flame sensor, anyway? 

A flame sensor is an important safety feature on your gas heating system. During the ignition cycle, your gas furnace undergoes a process where either a hot surface ignitor or a spark will actually ignite the gas. As the gas is ignited, the flame sensor creates a current of electricity. The current is measured in micro amps. If the furnace’s control board doesn’t read the proper level of micro amps, the furnace will stop giving the system fuel to stop an explosion. 

Over time, if the flame sensor is not adequately cleaned, oxidation or carbon buildup can restrict the flame sensor’s ability to operate properly, which can result in a malfunction of the furnace. 

The way to establish if an unclean flame sensor is the reason for a furnace malfunction is to take a micro amp draw reading, which an expert furnace technician can supply you. If a dirty flame sensor is the reason, 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 doesn’t change, the technician will carry on with the heating equipment repair diagnostic process. 

If you aren’t sure your heating system is going to make it through 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 no-charge in-home estimate on a new heating system. 

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