What a Flame Sensor Is and Why It Matters

Receiving your routine furnace maintenance helps keep your heating system working up to 30 percent more efficient and helps extend the life of the equipment. But things can still go wrong, and when they do, you may feel like there is always something else.

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

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 undergoes a process where either a hot surface ignitor or a spark actually ignites the gas. As the gas is ignited, the flame sensor generates a current of electricity. This is measured in micro amps. If the furnace’s control board does not 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 impede the flame sensor’s ability to operate properly, which can result in a malfunction of the furnace.

The way to diagnose if an unclean flame sensor is causing 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 culprit, 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 shows no change, the technician will continue with the heating equipment repair diagnostic process.

If you aren’t sure 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 provide you with a full furnace maintenance or a complimentary in-home estimate on a new HVAC system.

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