What a Flame Sensor Is and Why It Matters

Receiving your routine furnace maintenance helps keep your furnace working up to thirty percent more efficient and helps extend the life of the equipment. But things could still stop working, and when they do, you could feel like it’s always something else.

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

By the way – what is a flame sensor?

A flame sensor is a crucial safety element on your gas furnace. During the ignition cycle, your gas furnace goes through a process where either a hot surface ignitor or a spark will actually ignite the gas. When the gas is ignited, the flame sensor creates a current of electricity. This is quantified in micro amps. If the furnace’s control board doesn’t read the proper level of micro amps, the furnace will quit giving the system fuel to avoid an explosion.

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

The way to diagnose if a dirty flame sensor is causing a furnace malfunction is to take a micro amp draw reading, which a professional furnace technician can give you. If a dirty flame sensor is the guilty party, the heating expert will clean the sensor with steel wool. If dirt was the only factor, we will see a much higher amp reading. If the reading shows no change, the technician will carry on with the heating system repair diagnostic process.

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

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