What a Flame Sensor Is and Why It Matters

February 26, 2017

Setting up your routine furnace maintenance helps keep your furnace operating up to 30% more efficient and helps extend the life of your system. But things may still malfunction, and when they do, you could feel like there is always something else.

This time it’s your blower, next time it’s your pressure switch. Now you need to replace your flame sensor.

What is a flame sensor, anyway?

A flame sensor is a critical safety element on your gas heating system. During the ignition pattern, your gas furnace enters a process where either a hot surface ignitor or a spark will ignite the gas. When the gas is ignited, the flame sensor creates a current of electricity. This is calculated 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 prevent an explosion.

Over time, if the flame sensor is not cleaned appropriately, oxidation or carbon buildup can hinder the flame sensor’s ability to work properly, which can cause the furnace to malfunction.

The way to establish if an unclean flame sensor is the reason for a furnace malfunction is to take a micro amp draw reading, which a professional furnace technician can give you. If a dirty flame sensor is the reason, 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 does not change, the technician will continue with the heating system repair diagnostic process.

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

Contact Us