What a Flame Sensor Is and Why It Matters

February 26, 2017

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

This time it’s your blower, 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 a crucial 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 ignite the gas. As the gas is ignited, the flame sensor generates 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 avoid an explosion.

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

The way to establish if a soiled 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 offender, the furnace expert will clean the sensor with steel wool. If dirt was the sole factor, we will see a significantly higher amp reading. If the reading shows no change, the technician will continue with the heating system repair diagnostic process.

If you aren’t certain your furnace is going to make it through these last few weeks of winter, give Service Experts Heating & Air Conditioning a call and we’ll come out and give you a full furnace maintenance or a free in-home estimate on a new HVAC system.

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