What a Flame Sensor Is and Why It Matters

Setting up your routine furnace maintenance helps keep your heating system working up to thirty percent more efficient and helps extend the life of your system. But things may still malfunction, 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 pressure switch. Now your find out the flame sensor has to be replaced.

By the way – what is a flame sensor?

A flame sensor is a crucial safety component on your gas furnace. During the ignition sequence, your gas furnace goes through a process where either a spark or a hot surface igniter actually ignites the gas. Once the gas is ignited, the flame sensor generates a current of electricity. The electricity is measured 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 prevent an explosion.

Over time, if the flame sensor is not cleaned appropriately, 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 establish if a dirty flame sensor is the reason for a furnace malfunction is to take a micro amp draw reading, which an expert heating technician can supply you. If a dirty flame sensor is the guilty party, the technician will clean the sensor with steel wool. If dirt was the sole factor, we will see a much higher amp reading. If the reading shows no change, the technician will carry on with the heating system repair diagnostic process.

If you aren’t certain your furnace is going to make it through these last few weeks of winter, give All American Air Service Experts a call and we’ll come out and perform a full furnace maintenance or a complimentary in-home estimate on a new furnace.

Contact Us