What a Flame Sensor Is and Why It Matters

February 26, 2017

Receiving your annual furnace maintenance helps keep your heating equipment operating up to thirty percent more efficient and helps extend the life of the equipment. But things can still stop working, and when they do, you may feel like you’re always hearing about something else.

This time it’s your motor, 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 sequence, your gas furnace goes through a process where a spark or a hot surface ignitor will ignite the gas. When the gas is ignited, the flame sensor creates a current of electricity. The current is measured in micro amps. If the furnace’s control board does not read the right 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 impede the flame sensor’s ability to operate properly, which can end up causing the heating system to malfunction.

The way to diagnose if a dirty flame sensor is causing a furnace malfunction is to take a micro amp draw reading, which an expert furnace technician can supply you. If a dirty flame sensor is the culprit, 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 carry on with the heating equipment repair diagnostic process.

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

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