What a Flame Sensor Is and Why It Matters

Setting up your routine furnace maintenance helps keep your heating equipment operating up to 30 percent more efficient and helps extend the life of your furnace. But things may still go wrong, and when they do, you may feel like you’re always hearing about something else.

This time it’s your blower, next time it’s your pressure switch. Now your find out the flame sensor has to be replaced.

What is a flame sensor, anyway?

A flame sensor is an important safety component on your gas heating system. During the ignition cycle, your gas furnace undergoes a process where either a spark or a hot surface igniter will ignite the gas. As the gas is ignited, the flame sensor produces a current of electricity. The current is quantified in micro amps. If the furnace’s control board fails to read the proper level of micro amps, the furnace will quit giving the system fuel to stop an explosion.

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

The way to determine if an unclean flame sensor is causing a furnace malfunction is to take a micro amp draw reading, which an expert furnace technician can provide you. If a dirty flame sensor is the offender, the furnace 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 system repair diagnostic process.

If you aren’t sure your heating system is going to make it through these last few weeks of winter, give Strogen's Service Experts a call and we’ll come out and give you a full furnace maintenance or a no-charge in-home estimate on a new HVAC system.