What a Flame Sensor Is and Why It Matters

February 26, 2017

Setting up your annual furnace maintenance helps keep your furnace operating up to thirty percent more efficient and helps extend the life of the equipment. But things could still malfunction, and when they do, you could feel like it’s always 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 critical safety component on your gas heating equipment. During the ignition cycle, your gas furnace enters 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 calculated in micro amps. If the furnace’s control board does not read the right level of micro amps, the furnace will stop giving the system fuel to prevent an explosion.

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

The way to determine if a soiled flame sensor is the reason for 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 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 heating equipment repair diagnostic process.

If you aren’t confident your heating equipment is going to survivie these last few weeks of winter, give Epperson Service Experts Heating & Air Conditioning a call and we’ll come out and give you a full furnace maintenance or a complimentary in-home estimate on a new heating system.

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