What a Flame Sensor Is and Why It Matters

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

This time it’s your motor, next time it’s your control board. 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 furnace. During the ignition sequence, your gas furnace enters a process where either a spark or a hot surface igniter will actually 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 fails to read the proper level of micro amps, the furnace will no longer give the system fuel to stop 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 cause the furnace to malfunction.

The way to establish if a soiled flame sensor is to blame 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 offender, 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 does not change, the technician will carry on with the heating system repair diagnostic process.

If you aren’t confident your furnace is going to outlast these last few weeks of winter, give Midland Air Service Experts a call and we’ll come out and perform a full furnace maintenance or a free in-home estimate on a new HVAC system.

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