What a Flame Sensor Is and Why It Matters

Receiving your annual furnace maintenance helps keep your heating equipment working up to 30% more efficient and helps extend the life of your furnace. But things could still malfunction, 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 pressure switch. Now your find out the flame sensor has to be replaced.

What is a flame sensor, anyway?

A flame sensor is a critical safety element on your gas heating system. During the ignition sequence, your gas furnace undergoes 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 fails to read the proper level of micro amps, the furnace will no longer give the system fuel to avoid an explosion.

Over time, if the flame sensor is not cleaned properly, oxidation or carbon buildup can impede the flame sensor’s ability to work properly, which can cause the furnace 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 furnace 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 sole factor, we will see a much higher amp reading. If the reading doesn’t change, the technician will carry on with the furnace repair diagnostic process.

If you aren’t certain your heating system is going to survivie these last few weeks of winter, give Bryant Heating & Cooling Service Experts a call and we’ll come out and perform a full furnace maintenance or a no-charge in-home estimate on a new heating system.

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