What a Flame Sensor Is and Why It Matters

Setting up your routine furnace maintenance helps keep your heating system running up to 30% 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 pressure switch. Now you need to replace your flame sensor.

What is a flame sensor, anyway?

A flame sensor is a critical safety feature on your gas furnace. During the ignition cycle, your gas furnace enters a process where either a spark or a hot surface igniter actually ignites the gas. Once 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 correct level of micro amps, the furnace will no longer give 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 operate properly, which can cause the furnace to malfunction.

The way to establish if a soiled flame sensor is causing a furnace malfunction is to take a micro amp draw reading, which an expert furnace technician can give you. If a dirty flame sensor is the reason, the heating expert will clean the sensor with steel wool. If dirt was the sole 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 sure your heating equipment is going to survivie these last few weeks of winter, give Service Experts Heating & Air Conditioning a call and we’ll come out and perform a full furnace maintenance or a no-charge in-home estimate on a new furnace.

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