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50+ Years of Serving
The Shreveport Area

50+ Years of Serving The Shreveport Area


Moon's Air Blog

What Your Flame Sensor Does and Why It Might Be Your Furnace’s Problem Right Now


Oh, no! It sounds like something serious is wrong with your furnace! It keeps trying to start up, but then it immediately shuts down again! What could be going on? Is it going to be tremendously expensive to fix?

Don’t panic just yet. It’s true that this is a serious issue, especially if it happens on a very cold night and you’re not getting any heat. But there’s a common problem that can cause it, and the repair is actually simple. Why does your furnace keep shutting down just as it tries to start? It could very well be the flame sensor’s fault. Here’s what might be going on.

The Job of the Flame Sensor

While most of the components of your furnace are there to help with the main purpose of the system—creating heat—the flame sensor is different. It is one of the components that is strictly there for safety. It prevents gas from flowing if there is no flame, making sure dangerous gas leaks don’t occur.

This is how it works: When the thermostat sends the signal that heat is needed, the furnace starts up. In older furnaces, there’s a standing pilot light, which means there’s already a flame. In newer furnaces, there’s an ignition system, so it starts the flame only when it’s needed. The flame sensor detects that the flame is there, and only then does it allow gas to flow to the burners so the furnace can actually run.

If the Flame Sensor Is Working

Provided the flame sensor is working properly, your furnace is probably shutting down because of a problem with the pilot light or the ignition system. If you have a pilot, you can take a peek. If it’s out, get your owner’s manual and carefully follow the instructions for relighting it. If you have an ignition system problem, you’ll need professional furnace repair in Benton, LA.

If the Flame Sensor Isn’t Working

Sometimes, the pilot or ignition system is operating exactly as it should. The problem is the flame sensor itself. Even though there’s a flame right there, the sensor is failing to detect it, so it’s shutting the whole system down. Why would the flame sensor be unable to detect a flame?

Usually, it’s just because it’s dirty! Imagine it like reflective paint on a street sign being unable to reflect light when it’s covered in mud, or like a security camera not recording what the criminals are doing because they’ve spray-painted over the lens. That flame sensor has a pretty rough job in there, and it frequently ends up caked in carbon from the combustion that’s happening.

Don’t try to clean the flame sensor yourself. It will need to be completely disassembled for a thorough cleaning. A professional technician can do it in the most streamlined, safe, and effective way. And then your furnace will be up and running again, keeping you cozy for the rest of the winter.

Contact us today to schedule your furnace repair.

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