What a Flame Sensor Is and Why It Matters

Receiving your annual furnace maintenance helps keep your heating system operating up to 30 percent more efficient and helps extend the life of the equipment. But things could still go wrong, and when they do, you might feel like it’s always something else.

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

By the way – what is a flame sensor?

A flame sensor is a critical safety feature on your gas heating equipment. During the ignition sequence, your gas furnace goes through a process where either a spark or a hot surface igniter will actually ignite the gas. Once the gas is ignited, the flame sensor generates a current of electricity. This is quantified in micro amps. If the furnace’s control board does not read the right level of micro amps, the furnace will stop giving the system fuel to prevent an explosion.

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

The way to determine if an unclean flame sensor is the reason for a furnace malfunction is to take a micro amp draw reading, which an expert heating technician can provide you. If a dirty flame sensor is the culprit, the heating 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 doesn’t change, the technician will proceed with the heating system repair diagnostic process.

If you aren’t certain your furnace is going to make it through these last few weeks of winter, give Fras-Air/General Service Experts a call and we’ll come out and perform a full furnace maintenance or a no-charge in-home estimate on a new furnace.

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