What is the furnace flame sensor and what purpose does it serve?

Your furnace has a variety of parts. They all work together to create heat and distribute it throughout your home or building. The furnace flame sensor is one of those parts. When one part doesn’t work properly, it can affect the integrity of the entire system and leave you in the cold this winter.

A flame sensor can be found at the burner assembly and is a very simple device. It is positioned in front of the flame stream. When you locate it, you will see it’s simply a thin metallic rod that is usually bent. Despite its minimalistic appearance, it’s one of the most important parts of your furnace.

How does the furnace flame sensor work?

The flame sensor detects the presence of a flame. If the flame in the furnace goes out, the sensor can detect the change and send electrical signals to the furnace’s central controller. If you have any questions about whether your sensor is in good working order, AxsomAir can check things out.

What safety function does the furnace flame sensor serve?

Although the furnace flame sensor looks and seems very simple, it performs an extremely important safety function. To understand this function, you first need to understand how the furnace ignition process works.

When a furnace initiates an ignition sequence, a spark (or hot igniter) ignites gas within the furnace. When the gas is ignited, it helps to create a current of electricity within the flame sensor. If the sensor detects that the furnace has not ignited properly, it signals the central controller to stop putting out fuel.

Without a flame sensor, your furnace could put out too much fuel and cause your home to explode. Unfortunately, these sensors don’t last forever and are susceptible to corrosion and wear over time. Frequently receiving flame sensor cleaning services can help extend the life of this important part.

If the flame sensor in your furnace is not working properly, it may not sense the heat from the flame in the furnace and may shut down the furnace. This is the last thing you want to experience during the coldest time of the year.

What are some things that can go wrong?

Over time, carbon buildup or oxidation can prevent the flame sensor in your furnace from working properly. When this happens, the furnace can malfunction and your family and home can be put at risk. That’s why it’s important to schedule flame sensor cleaning on a regular basis.

Here are a few common symptoms of flame sensor issues:

  • The sensor appears to be corroded and/or blackened with soot.
  • The furnace lights properly but shuts down after just a few seconds.
  • The porcelain portion of the flame sensor is chipped, cracked or otherwise damaged.

If you notice any of these problems, you can visually analyze the flame sensor to see if there are any obvious problems. Before you do this, make sure you turn off the electrical power to the furnace and close the gas valve. Safety is very important when you’re inspecting any part of your furnace.

Have AxsomAir check your furnace flame sensor

If your furnace isn’t working properly because of a faulty flame sensor, call AxsomAir. We will be happy to come out and inspect your furnace and replace any damaged or faulty parts. Contact us to schedule your appointment today.