What a Flame Sensor Is and Why It Matters

Receiving your routine furnace maintenance helps keep your heating system working up to thirty percent more efficient and helps extend the life of your furnace. But things may still stop working, and when they do, you may feel like there is always something else.

This time it’s your heat exchanger, next time it’s your control board. Now you need to replace your flame sensor.

What is a flame sensor, anyway?

A flame sensor is a crucial safety element on your gas heating equipment. During the ignition cycle, your gas furnace goes through a process where a spark or a hot surface ignitor will ignite the gas. When the gas is ignited, the flame sensor generates a current of electricity. The electricity 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 stop an explosion.

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

The way to diagnose if a dirty flame sensor is the reason 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 culprit, the furnace expert will clean the sensor with steel wool. If dirt was the single factor, we will see a much higher amp reading. If the reading doesn’t change, the technician will proceed with the heating system repair diagnostic process.

If you aren’t certain your furnace is going to outlast these last few weeks of winter, give Comfort Masters Service Experts a call and we’ll come out and provide you with a full furnace maintenance or a no-charge in-home estimate on a new heating system.

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