What a Flame Sensor Is and Why It Matters

Scheduling your annual furnace maintenance helps keep your heating equipment working up to 30 percent more efficient and helps extend the life of your furnace. But things could still stop working, and when they do, you might feel like there is 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 crucial safety feature on your gas furnace. During the ignition sequence, your gas furnace undergoes 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 electricity is calculated in micro amps. If the furnace’s control board doesn’t 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 function properly, which can result in a malfunction of the furnace.

The way to determine if a soiled 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 reason, 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 does not change, the technician will proceed with the heating system repair diagnostic process.

If you aren’t certain your heating equipment is going to survivie these last few weeks of winter, give Aramendia Plumbing, Heating and Air a call and we’ll come out and provide you with a full furnace maintenance or a complimentary in-home estimate on a new HVAC system.

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