What a Flame Sensor Is and Why It Matters

February 26, 2017

Setting up your routine furnace maintenance helps keep your heating system working 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 may feel like there is always something else.

This time it’s your blower, 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 feature on your gas heating equipment. During the ignition sequence, your gas furnace undergoes a process where either a spark or a hot surface igniter will actually ignite the gas. As the gas is ignited, the flame sensor creates a current of electricity. The electricity is quantified in micro amps. If the furnace’s control board doesn’t read the proper 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 appropriately, oxidation or carbon buildup can restrict the flame sensor’s ability to work properly, which can cause the furnace 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 provide you. If a dirty flame sensor is the guilty party, the furnace expert will clean the sensor with steel wool. If dirt was the only factor, we will see a significantly higher amp reading. If the reading does not change, the technician will proceed with the furnace repair diagnostic process.

If you aren’t confident your heating equipment 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 free in-home estimate on a new heating system.

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