What a Flame Sensor Is and Why It Matters

Setting up your seasonal furnace maintenance helps keep your heating equipment working up to 30% more efficient and helps extend the life of your furnace. But things can still stop working, and when they do, you could feel like there is always something else.

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

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 undergoes a process where either a spark or a hot surface igniter actually ignites the gas. When the gas is ignited, the flame sensor creates a current of electricity. The electricity is measured 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 adequately cleaned, oxidation or carbon buildup can impede the flame sensor’s ability to operate properly, which can result in a malfunction of the furnace.

The way to diagnose if an unclean flame sensor is causing a furnace malfunction is to take a micro amp draw reading, which an expert heating technician can supply you. If a dirty flame sensor is the culprit, the furnace 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 sure your heating equipment is going to outlast these last few weeks of winter, give Freschi Service Experts a call and we’ll come out and give you a full furnace maintenance or a free in-home estimate on a new HVAC system.

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