What a Flame Sensor Is and Why It Matters

February 26, 2017

Receiving your seasonal furnace maintenance helps keep your heating equipment operating up to 30 percent more efficient and helps extend the life of the equipment. But things could still malfunction, and when they do, you might feel like you’re always hearing about something else.

This time it’s your motor, next time it’s your pressure switch. Now your find out the flame sensor has to be replaced.

By the way – what is a flame sensor?

A flame sensor is a crucial safety element on your gas heating equipment. During the ignition sequence, your gas furnace undergoes a process where either a hot surface ignitor or a spark will ignite the gas. When 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 no longer give 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 operate properly, which can cause the furnace to malfunction.

The way to determine if a soiled flame sensor is causing 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 reason, the technician will clean the sensor with steel wool. If dirt was the single factor, we will see a significantly higher amp reading. If the reading does not change, the technician will continue with the furnace repair diagnostic process.

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

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