What a Flame Sensor Is and Why It Matters

Receiving your seasonal furnace maintenance helps keep your heating equipment running up to 30% more efficient and helps extend the life of your furnace. But things may still malfunction, and when they do, you might feel like you’re always hearing about something else. 

This time it’s your blower, next time it’s your control board. Now you need to replace your flame sensor. 

By the way – what is a flame sensor? 

A flame sensor is a crucial safety element on your gas heating equipment. During the ignition sequence, your gas furnace enters a process where either a hot surface ignitor or a spark will ignite the gas. Once the gas is ignited, the flame sensor produces a current of electricity. The current is calculated in micro amps. If the furnace’s control board fails to read the correct level of micro amps, the furnace will quit giving 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 operate properly, which can result in a malfunction of the furnace. 

The way to diagnose if a soiled flame sensor is causing 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 guilty party, the furnace expert will clean the sensor with steel wool. If dirt was the only factor, we will see a much higher amp reading. If the reading does not change, the technician will continue with the furnace repair diagnostic process. 

If you aren’t sure your furnace is going to survivie these last few weeks of winter, give Stevenson 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 heating system.