What a Flame Sensor Is and Why It Matters

February 26, 2017

Setting up your annual furnace maintenance helps keep your furnace running up to 30 percent more efficient and helps extend the life of your system. But things can still stop working, and when they do, you could 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.

By the way – what is a flame sensor?

A flame sensor is a crucial safety feature on your gas heating equipment. During the ignition pattern, your gas furnace goes through a process where either a hot surface ignitor or a spark will actually ignite the gas. As the gas is ignited, the flame sensor produces a current of electricity. The current is measured in micro amps. If the furnace’s control board fails to read the proper level of micro amps, the furnace will quit giving the system fuel to prevent an explosion.

Over time, if the flame sensor is not cleaned properly, oxidation or carbon buildup can interfere with 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 causing a furnace malfunction is to take a micro amp draw reading, which an expert furnace technician can supply you. If a dirty flame sensor is the offender, the furnace expert will clean the sensor with steel wool. If dirt was the single factor, we will see a notably higher amp reading. If the reading shows no change, the technician will carry on with the heating system repair diagnostic process.

If you aren’t confident your heating equipment is going to make it through these last few weeks of winter, give Chief / Bauer Service Experts Heating & Air Conditioning 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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