What a Flame Sensor Is and Why It Matters

Scheduling your annual furnace maintenance helps keep your heating system running up to thirty percent more efficient and helps extend the life of your system. But things could still go wrong, and when they do, you might feel like it’s always something else.

This time it’s your heat exchanger, next time it’s your control valve. Now you have to have your flame sensor replaced.

What is a flame sensor, anyway?

A flame sensor is a crucial safety component on your gas heating system. During the ignition sequence, your gas furnace enters a process where a spark or a hot surface ignitor will ignite the gas. As the gas is ignited, the flame sensor creates a current of electricity. The current is quantified in micro amps. If the furnace’s control board fails to read the right 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 properly, oxidation or carbon buildup can impede the flame sensor’s ability to work properly, which can end up causing the heating system to malfunction.

The way to diagnose if a soiled 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 guilty party, the heating expert will clean the sensor with steel wool. If dirt was the single factor, we will see a notably higher amp reading. If the reading doesn’t change, the technician will carry on with the furnace repair diagnostic process.

If you aren’t confident your heating system is going to outlast these last few weeks of winter, give Finch Air Conditioning & Heating a call and we’ll come out and perform a full furnace maintenance or a no-charge in-home estimate on a new HVAC system.

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