What a Flame Sensor Is and Why It Matters

Receiving your routine furnace maintenance helps keep your furnace operating up to 30 percent more efficient and helps extend the life of your system. But things can still stop working, 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 control valve. Now you need to replace your flame sensor. 

By the way – what is a flame sensor? 

A flame sensor is an important safety component on your gas furnace. During the ignition cycle, your gas furnace goes through a process where either a spark or a hot surface igniter will actually ignite the gas. When the gas is ignited, the flame sensor produces a current of electricity. The current is measured 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 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 function properly, which can result in a malfunction of the furnace. 

The way to determine if an unclean flame sensor is to blame 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 single factor, we will see a much higher amp reading. If the reading doesn’t change, the technician will proceed with the heating equipment repair diagnostic process. 

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