What a Flame Sensor Is and Why It Matters

Receiving your seasonal furnace maintenance helps keep your heating equipment operating up to thirty percent more efficient and helps extend the life of the equipment. But things may 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 pressure switch. Now you need to replace your flame sensor.

By the way – what is a flame sensor?

A flame sensor is an important safety element on your gas heating system. During the ignition sequence, your gas furnace enters a process where either a spark or a hot surface igniter will actually ignite the gas. As the gas is ignited, the flame sensor generates a current of electricity. The electricity is quantified in micro amps. If the furnace’s control board does not read the proper level of micro amps, the furnace will stop giving the system fuel to stop an explosion.

Over time, if the flame sensor is not cleaned appropriately, oxidation or carbon buildup can hinder the flame sensor’s ability to work properly, which can end up causing the heating system to malfunction.

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 a professional furnace technician can give you. If a dirty flame sensor is the guilty party, the technician will clean the sensor with steel wool. If dirt was the single 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 certain your furnace is going to make it through these last few weeks of winter, give Service Experts Heating & Air Conditioning a call and we’ll come out and perform a full furnace maintenance or a complimentary in-home estimate on a new HVAC system.

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