What a Flame Sensor Is and Why It Matters

February 26, 2017

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

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

Also, what is a flame sensor?

A flame sensor is a critical safety feature on your gas furnace. During the ignition pattern, your gas furnace undergoes a process where either a hot surface ignitor or a spark actually ignites the gas. As the gas is ignited, the flame sensor generates a current of electricity. The current is measured 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 avoid an explosion.

Over time, if the flame sensor is not adequately cleaned, oxidation or carbon buildup can restrict the flame sensor’s ability to operate properly, which can cause the furnace 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 heating technician can provide 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 does not change, the technician will proceed with the heating equipment repair diagnostic process.

If you aren’t certain your furnace is going to outlast these last few weeks of winter, give Levy & Son Service Experts a call and we’ll come out and perform a full furnace maintenance or a free in-home estimate on a new HVAC system.

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