What a Flame Sensor Is and Why It Matters

February 26, 2017

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

This time it’s your heat exchanger, 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 a crucial safety component on your gas furnace. During the ignition cycle, your gas furnace undergoes a process where either a spark or a hot surface igniter actually ignites the gas. Once the gas is ignited, the flame sensor creates a current of electricity. The electricity 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 restrict the flame sensor’s ability to function properly, which can end up causing the heating system 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 an expert heating technician can supply you. If a dirty flame sensor is the reason, the technician will clean the sensor with steel wool. If dirt was the sole factor, we will see a much higher amp reading. If the reading shows no change, the technician will carry on with the furnace repair diagnostic process.

If you aren’t certain your heating system is going to survivie these last few weeks of winter, give All American Air Service Experts Heating & Air Conditioning a call and we’ll come out and perform a full furnace maintenance or a complimentary in-home estimate on a new furnace.

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