What a Flame Sensor Is and Why It Matters

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

This time it’s your heat exchanger, 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 furnace. During the ignition pattern, your gas furnace goes through a process where either a spark or a hot surface igniter actually ignites the gas. As the gas is ignited, the flame sensor creates 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 cleaned appropriately, oxidation or carbon buildup can interfere with the flame sensor’s ability to operate properly, which can cause the furnace to malfunction. 

The way to diagnose if an unclean flame sensor is to blame for a furnace malfunction is to take a micro amp draw reading, which a professional furnace 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 single factor, we will see a much higher amp reading. If the reading shows no change, the technician will proceed with the furnace repair diagnostic process. 

If you aren’t sure your furnace is going to survivie these last few weeks of winter, give Strogen's 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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