What a Flame Sensor Is and Why It Matters

Receiving your routine furnace maintenance helps keep your furnace operating up to 30 percent more efficient and helps extend the life of the equipment. But things may still go wrong, and when they do, you could feel like there is always something else.

This time it’s your heat exchanger, next time it’s your control valve. Now your find out the flame sensor has to be replaced.

Also, what is a flame sensor?

A flame sensor is an important safety element on your gas furnace. During the ignition sequence, your gas furnace goes through a process where a spark or a hot surface ignitor will actually ignite the gas. As the gas is ignited, the flame sensor generates a current of electricity. This is quantified in micro amps. If the furnace’s control board does not read the correct level of micro amps, the furnace will no longer give the system fuel to avoid an explosion.

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

The way to establish if a dirty flame sensor is the reason for 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 reason, the heating expert will clean the sensor with steel wool. If dirt was the single factor, we will see a much 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 outlast these last few weeks of winter, give BW/Cook Service Experts Heating & Air Conditioning a call and we’ll come out and perform a full furnace maintenance or a complimentary in-home estimate on a new heating system.