What a Flame Sensor Is and Why It Matters

Receiving your seasonal furnace maintenance helps keep your heating equipment working up to 30% more efficient and helps extend the life of your furnace. But things could 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 valve. Now you need to replace your flame sensor.

By the way – what is a flame sensor?

A flame sensor is a critical safety feature on your gas furnace. During the ignition pattern, your gas furnace goes through a process where either a spark or a hot surface igniter will actually ignite the gas. As the gas is ignited, the flame sensor generates a current of electricity. The current is quantified in micro amps. If the furnace’s control board fails to read the correct level of micro amps, the furnace will quit 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 result in a malfunction of the furnace.

The way to diagnose if a dirty flame sensor is to blame for 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 technician 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 carry on with the heating system repair diagnostic process.

If you aren’t certain your heating system is going to make it through these last few weeks of winter, give Eveready Service Experts a call and we’ll come out and provide you with a full furnace maintenance or a free in-home estimate on a new heating system.

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