What a Flame Sensor Is and Why It Matters

February 26, 2017

Setting up your annual furnace maintenance helps keep your heating equipment working up to 30% more efficient and helps extend the life of your system. But things can still stop working, and when they do, you could feel like you’re always hearing about something else.

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

By the way – what is a flame sensor?

A flame sensor is a critical safety element on your gas heating system. During the ignition sequence, your gas furnace undergoes a process where a spark or a hot surface ignitor actually ignites the gas. As the gas is ignited, the flame sensor generates a current of electricity. This is calculated in micro amps. If the furnace’s control board doesn’t read the correct level of micro amps, the furnace will stop giving the system fuel to avoid an explosion.

Over time, if the flame sensor is not adequately cleaned, oxidation or carbon buildup can restrict the flame sensor’s ability to function properly, which can cause the furnace to malfunction.

The way to diagnose if an unclean flame sensor is causing 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 offender, the furnace expert will clean the sensor with steel wool. If dirt was the only factor, we will see a much higher amp reading. If the reading doesn’t change, the technician will continue with the heating equipment repair diagnostic process.

If you aren’t confident your heating system 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 heating system.

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