What a Flame Sensor Is and Why It Matters

February 26, 2017

Setting up your routine furnace maintenance helps keep your heating equipment running up to 30 percent more efficient and helps extend the life of your furnace. But things may still malfunction, and when they do, you might feel like you’re always hearing about something else.

This time it’s your blower, next time it’s your pressure switch. Now your find out the flame sensor has to be replaced.

What is a flame sensor, anyway?

A flame sensor is a crucial safety component on your gas heating system. During the ignition sequence, your gas furnace goes through a process where either a hot surface ignitor or a spark will ignite the gas. As the gas is ignited, the flame sensor produces a current of electricity. This is quantified 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 stop an explosion.

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

The way to determine if a dirty flame sensor is to blame for a furnace malfunction is to take a micro amp draw reading, which an expert furnace technician can give you. If a dirty flame sensor is the offender, 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 doesn’t change, the technician will continue with the furnace repair diagnostic process.

If you aren’t sure your heating system is going to make it through these last few weeks of winter, give Strogen's Service Experts Heating & Air Conditioning a call and we’ll come out and give you a full furnace maintenance or a no-charge in-home estimate on a new HVAC system.

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