What a Flame Sensor Is and Why It Matters

Scheduling your annual furnace maintenance helps keep your heating system operating up to 30% more efficient and helps extend the life of your furnace. But things may still go wrong, 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 board. Now you need to replace your flame sensor. 

What is a flame sensor, anyway? 

A flame sensor is an important safety element on your gas heating equipment. During the ignition cycle, your gas furnace goes through 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 stop giving the system fuel to prevent an explosion. 

Over time, if the flame sensor is not cleaned properly, oxidation or carbon buildup can interfere with the flame sensor’s ability to function properly, which can end up causing the heating system to malfunction. 

The way to determine if an unclean flame sensor is to blame for a furnace malfunction is to take a micro amp draw reading, which an expert heating technician can provide you. If a dirty flame sensor is the culprit, the technician 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 continue 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 Neal Harris Service Experts 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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