What a Flame Sensor Is and Why It Matters Published on February 26, 2017 Receiving your annual furnace maintenance helps keep your heating equipment operating up to 30% more efficient and helps extend the life of your furnace. But things may still malfunction, and when they do, you could feel like there is always something else. This time it’s your motor, next time it’s your pressure switch. Now you need to replace your flame sensor. What is a flame sensor, anyway? A flame sensor is an important safety feature on your gas heating equipment. During the ignition pattern, your gas furnace enters a process where either a spark or a hot surface igniter will actually ignite the gas. When the gas is ignited, the flame sensor creates a current of electricity. This is calculated in micro amps. If the furnace’s control board does not read the correct level of micro amps, the furnace will quit giving the system fuel to prevent an explosion. Over time, if the flame sensor is not cleaned appropriately, oxidation or carbon buildup can hinder the flame sensor’s ability to operate properly, which can cause the furnace to malfunction. The way to establish if an unclean flame sensor is the reason for a furnace malfunction is to take a micro amp draw reading, which a professional furnace technician can supply you. If a dirty flame sensor is the offender, the furnace expert will clean the sensor with steel wool. If dirt was the sole factor, we will see a much higher amp reading. If the reading does not change, the technician will proceed with the heating equipment repair diagnostic process. If you aren’t sure your heating equipment is going to outlast these last few weeks of winter, give Barlow Service Experts Heating & Air Conditioning a call and we’ll come out and perform a full furnace maintenance or a no-charge in-home estimate on a new furnace.