What a Flame Sensor Is and Why It Matters

February 26, 2017

Scheduling your seasonal furnace maintenance helps keep your heating equipment working up to thirty percent more efficient and helps extend the life of the equipment. But things may still malfunction, 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 control valve. Now your find out the flame sensor has to be replaced.

What is a flame sensor, anyway?

A flame sensor is an important safety component on your gas heating system. During the ignition pattern, your gas furnace undergoes a process where either a hot surface ignitor or a spark will actually ignite the gas. As the gas is ignited, the flame sensor produces a current of electricity. The electricity is measured in micro amps. If the furnace’s control board does not read the proper level of micro amps, the furnace will quit giving the system fuel to prevent an explosion.

Over time, if the flame sensor is not adequately cleaned, oxidation or carbon buildup can impede the flame sensor’s ability to function properly, which can cause the furnace 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 sole factor, we will see a much higher amp reading. If the reading doesn’t change, the technician will carry on with the furnace repair diagnostic process.

If you aren’t sure your furnace is going to outlast these last few weeks of winter, give Atmostemp 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 HVAC system.

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