What a Flame Sensor Is and Why It Matters

February 26, 2017

Receiving your seasonal furnace maintenance helps keep your heating system operating up to 30% more efficient and helps extend the life of the equipment. But things may still stop working, and when they do, you may feel like it’s always something else.

This time it’s your heat exchanger, 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 critical safety feature on your gas heating system. During the ignition pattern, your gas furnace undergoes a process where either a spark or a hot surface igniter will actually ignite the gas. Once the gas is ignited, the flame sensor generates a current of electricity. The current is calculated in micro amps. If the furnace’s control board doesn’t read the proper level of micro amps, the furnace will no longer give the system fuel to prevent an explosion.

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

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

If you aren’t sure your furnace is going to outlast these last few weeks of winter, give Norrell Service Experts a call and we’ll come out and perform a full furnace maintenance or a no-charge in-home estimate on a new heating system.

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