What a Flame Sensor Is and Why It Matters

Receiving your annual furnace maintenance helps keep your heating system running up to 30% more efficient and helps extend the life of your system. But things could still go wrong, and when they do, you may feel like you’re always hearing about something else. 

This time it’s your heat exchanger, next time it’s your control valve. Now you need to replace your flame sensor. 

What is a flame sensor, anyway? 

A flame sensor is an important safety component on your gas furnace. During the ignition cycle, your gas furnace undergoes a process where a spark or a hot surface ignitor 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 doesn’t read the correct level of micro amps, the furnace will stop giving the system fuel to prevent an explosion. 

Over time, if the flame sensor is not adequately cleaned, 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 carry on with the furnace repair diagnostic process. 

If you aren’t confident your furnace is going to make it through these last few weeks of winter, give Comfort Masters Service Experts 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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