What a Flame Sensor Is and Why It Matters

February 26, 2017

Receiving your routine furnace maintenance helps keep your furnace operating up to thirty percent more efficient and helps extend the life of your furnace. But things may still malfunction, and when they do, you might feel like it’s always something else.

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

By the way – what is a flame sensor?

A flame sensor is an important safety feature on your gas heating equipment. During the ignition sequence, your gas furnace undergoes a process where a spark or a hot surface ignitor will actually ignite the gas. When the gas is ignited, the flame sensor generates a current of electricity. This is calculated in micro amps. If the furnace’s control board does not read the correct level of micro amps, the furnace will quit giving the system fuel to prevent an explosion.

Over time, if the flame sensor is not cleaned properly, oxidation or carbon buildup can restrict the flame sensor’s ability to work properly, which can cause the furnace to malfunction.

The way to diagnose if a soiled flame sensor is causing a furnace malfunction is to take a micro amp draw reading, which an expert furnace technician can give 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 does not change, the technician will carry on with the furnace repair diagnostic process.

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

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