What a Flame Sensor Is and Why It Matters

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

This time it’s your motor, next time it’s your control board. Now you have to have your flame sensor replaced. 

By the way – what is a flame sensor? 

A flame sensor is a crucial safety feature on your gas heating system. During the ignition cycle, your gas furnace enters a process where a spark or a hot surface ignitor actually ignites the gas. When the gas is ignited, the flame sensor creates a current of electricity. The electricity is calculated in micro amps. If the furnace’s control board doesn’t read the correct level of micro amps, the furnace will quit giving the system fuel to prevent an explosion. 

Over time, if the flame sensor is not cleaned properly, 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 determine if a dirty flame sensor is the reason for a furnace malfunction is to take a micro amp draw reading, which an expert furnace technician can provide you. If a dirty flame sensor is the culprit, the furnace expert will clean the sensor with steel wool. If dirt was the single factor, we will see a significantly higher amp reading. If the reading doesn’t change, the technician will continue with the heating equipment repair diagnostic process. 

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