What a Flame Sensor Is and Why It Matters

February 26, 2017

Receiving your routine furnace maintenance helps keep your furnace operating up to 30% more efficient and helps extend the life of your system. But things could still stop working, and when they do, you may feel like there is always something else.

This time it’s your blower, next time it’s your control valve. Now you need to replace your flame sensor.

By the way – what is a flame sensor?

A flame sensor is an important safety feature 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 current is measured in micro amps. If the furnace’s control board doesn’t read the right level of micro amps, the furnace will quit giving the system fuel to prevent an explosion.

Over time, if the flame sensor is not adequately cleaned, 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 determine if an unclean flame sensor is to blame 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 technician will clean the sensor with steel wool. If dirt was the sole factor, we will see a significantly 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 heating system is going to survivie these last few weeks of winter, give Gordon's Service Experts Heating & Air Conditioning a call and we’ll come out and perform a full furnace maintenance or a no-charge in-home estimate on a new HVAC system.

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