What a Flame Sensor Is and Why It Matters

February 26, 2017

Receiving your routine furnace maintenance helps keep your furnace running up to 30 percent more efficient and helps extend the life of the equipment. But things could still stop working, and when they do, you might feel like there is 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 an important safety feature on your gas heating system. During the ignition pattern, your gas furnace undergoes a process where either a hot surface ignitor or a spark will ignite the gas. Once the gas is ignited, the flame sensor creates a current of electricity. The electricity is quantified in micro amps. If the furnace’s control board fails to read the right level of micro amps, the furnace will quit giving the system fuel to avoid an explosion.

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

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 a professional furnace technician can provide you. If a dirty flame sensor is the guilty party, the furnace 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 shows no change, the technician will carry on with the furnace repair diagnostic process.

If you aren’t sure your furnace is going to make it through these last few weeks of winter, give Donelson Air Service Experts a call and we’ll come out and give you a full furnace maintenance or a complimentary in-home estimate on a new furnace.

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