What a Flame Sensor Is and Why It Matters

February 26, 2017

Receiving your routine furnace maintenance helps keep your furnace running up to thirty percent more efficient and helps extend the life of your system. But things may still malfunction, and when they do, you might feel like you’re always hearing about something else.

This time it’s your motor, 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 crucial safety component on your gas furnace. During the ignition cycle, your gas furnace undergoes a process where either a hot surface ignitor or a spark actually ignites the gas. When the gas is ignited, the flame sensor generates a current of electricity. This is measured in micro amps. If the furnace’s control board does not read the proper level of micro amps, the furnace will quit giving the system fuel to stop an explosion.

Over time, if the flame sensor is not cleaned properly, oxidation or carbon buildup can hinder the flame sensor’s ability to function properly, which can cause the furnace to malfunction.

The way to diagnose if a dirty flame sensor is to blame for a furnace malfunction is to take a micro amp draw reading, which an expert furnace technician can provide 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 notably 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 certain your furnace is going to outlast these last few weeks of winter, give Service Experts Heating & Air Conditioning a call and we’ll come out and provide you with a full furnace maintenance or a free in-home estimate on a new heating system.

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