What a Flame Sensor Is and Why It Matters

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

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

What is a flame sensor, anyway?

A flame sensor is a crucial safety element on your gas furnace. During the ignition cycle, your gas furnace goes through a process where a spark or a hot surface ignitor will ignite the gas. As the gas is ignited, the flame sensor generates a current of electricity. The electricity is quantified in micro amps. If the furnace’s control board fails to read the correct level of micro amps, the furnace will stop giving the system fuel to avoid an explosion.

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

The way to establish if an unclean flame sensor is causing a furnace malfunction is to take a micro amp draw reading, which an expert heating technician can give you. If a dirty flame sensor is the reason, the furnace expert 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 continue with the furnace repair diagnostic process.

If you aren’t confident your furnace is going to survivie these last few weeks of winter, give Service Experts Heating & Air Conditioning a call and we’ll come out and give you a full furnace maintenance or a free in-home estimate on a new furnace.

Contact Us