What a Flame Sensor Is and Why It Matters

Receiving your routine furnace maintenance helps keep your furnace running up to 30% more efficient and helps extend the life of the equipment. But things may still go wrong, and when they do, you may feel like it’s always something else.

This time it’s your blower, next time it’s your control valve. Now you have to have your flame sensor replaced.

What is a flame sensor, anyway?

A flame sensor is a crucial safety element on your gas heating equipment. During the ignition cycle, your gas furnace undergoes a process where a spark or a hot surface ignitor will actually ignite the gas. Once the gas is ignited, the flame sensor generates a current of electricity. This is measured in micro amps. If the furnace’s control board does not 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 restrict the flame sensor’s ability to work properly, which can cause the furnace to malfunction.

The way to determine if a soiled flame sensor is causing a furnace malfunction is to take a micro amp draw reading, which an expert furnace technician can provide you. If a dirty flame sensor is the culprit, the furnace expert will clean the sensor with steel wool. If dirt was the single factor, we will see a much higher amp reading. If the reading does not change, the technician will carry on with the furnace repair diagnostic process.

If you aren’t certain your furnace is going to outlast these last few weeks of winter, give Boehmers/Cronin Emery 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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