What a Flame Sensor Is and Why It Matters

Scheduling your seasonal furnace maintenance helps keep your heating equipment running up to thirty percent more efficient and helps extend the life of the equipment. 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 valve. Now you have to have your flame sensor replaced.

What is a flame sensor, anyway?

A flame sensor is a crucial safety feature on your gas heating equipment. During the ignition cycle, your gas furnace undergoes a process where a spark or a hot surface ignitor will ignite the gas. When the gas is ignited, the flame sensor creates a current of electricity. This is measured in micro amps. If the furnace’s control board does not read the right 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 operate properly, which can end up causing the heating system to malfunction.

The way to diagnose 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 culprit, the furnace expert will clean the sensor with steel wool. If dirt was the single factor, we will see a significantly 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 confident your furnace is going to outlast these last few weeks of winter, give Knochelmann Service Experts a call and we’ll come out and perform a full furnace maintenance or a complimentary in-home estimate on a new furnace.

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