What a Flame Sensor Is and Why It Matters

Scheduling your seasonal furnace maintenance helps keep your furnace operating up to 30% more efficient and helps extend the life of your furnace. But things could still stop working, and when they do, you might feel like there is always something else. 

This time it’s your heat exchanger, next time it’s your control board. Now you have to have your flame sensor replaced. 

Also, what is a flame sensor? 

A flame sensor is an important safety element on your gas heating system. During the ignition cycle, your gas furnace enters a process where either a spark or a hot surface igniter will actually ignite the gas. When the gas is ignited, the flame sensor produces 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 no longer give the system fuel to stop 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 work properly, which can cause the furnace to malfunction. 

The way to determine if a dirty flame sensor is causing a furnace malfunction is to take a micro amp draw reading, which an expert furnace technician can give 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 doesn’t change, the technician will carry on with the furnace repair diagnostic process. 

If you aren’t sure your furnace is going to make it through these last few weeks of winter, give Stevenson Service Experts a call and we’ll come out and provide you with a full furnace maintenance or a complimentary in-home estimate on a new HVAC system.