What a Flame Sensor Is and Why It Matters

February 26, 2017

Scheduling your routine furnace maintenance helps keep your heating equipment working up to thirty percent more efficient and helps extend the life of the equipment. But things can still stop working, and when they do, you could feel like there is always something else.

This time it’s your motor, next time it’s your control valve. Now your find out the flame sensor has to be replaced.

What is a flame sensor, anyway?

A flame sensor is a critical safety element on your gas heating system. During the ignition pattern, your gas furnace undergoes a process where either a spark or a hot surface igniter actually ignites the gas. Once the gas is ignited, the flame sensor produces a current of electricity. The current is quantified in micro amps. If the furnace’s control board does not 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 interfere with the flame sensor’s ability to work properly, which can cause the furnace to malfunction.

The way to establish if a soiled flame sensor is to blame for a furnace malfunction is to take a micro amp draw reading, which a professional furnace technician can provide you. If a dirty flame sensor is the reason, the furnace expert will clean the sensor with steel wool. If dirt was the single factor, we will see a significantly higher amp reading. If the reading shows no change, the technician will continue with the furnace repair diagnostic process.

If you aren’t sure your heating system is going to outlast these last few weeks of winter, give 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 furnace.

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