What a Flame Sensor Is and Why It Matters

Scheduling your annual furnace maintenance helps keep your furnace operating up to thirty percent more efficient and helps extend the life of the equipment. But things may still stop working, and when they do, you may feel like it’s always something else.

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

By the way – what is a flame sensor?

A flame sensor is a critical safety feature on your gas heating system. During the ignition pattern, your gas furnace goes through a process where either a spark or a hot surface igniter actually ignites the gas. When the gas is ignited, the flame sensor generates a current of electricity. The current is calculated in micro amps. If the furnace’s control board doesn’t 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 restrict the flame sensor’s ability to work properly, which can end up causing the heating system to malfunction.

The way to diagnose if a soiled 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 offender, 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 does not change, the technician will continue with the heating equipment repair diagnostic process.

If you aren’t confident your heating system is going to outlast these last few weeks of winter, give Norrell Service Experts a call and we’ll come out and perform a full furnace maintenance or a no-charge in-home estimate on a new furnace.