What a Flame Sensor Is and Why It Matters

Setting up your annual furnace maintenance helps keep your heating system operating up to thirty percent more efficient and helps extend the life of your system. But things may still stop working, and when they do, you could feel like there is always 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 hot surface ignitor or a spark will ignite the gas. As the gas is ignited, the flame sensor generates a current of electricity. This is quantified in micro amps. If the furnace’s control board does not read the right level of micro amps, the furnace will stop giving the system fuel to avoid an explosion.

Over time, if the flame sensor is not adequately cleaned, oxidation or carbon buildup can impede the flame sensor’s ability to operate properly, which can end up causing the heating system to malfunction.

The way to diagnose if a dirty flame sensor is causing 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 guilty party, the furnace expert will clean the sensor with steel wool. If dirt was the only factor, we will see a notably higher amp reading. If the reading doesn’t change, the technician will continue with the heating equipment repair diagnostic process.

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

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