Did My Flame Sensor Go Bad?

furnace in Puyallup, WA

Your heating system is fairly complex and has a lot of internal components. When just one of these components stops functioning correctly, it can hinder the overall operation of your system. Today, we’re going to take a look at what your flame sensor is and what you’ll experience when it goes bad.

What Is a Flame Sensor?

A flame sensor is basically a safety feature that most modern gas-powered furnaces have. This sensor controls the gas valve. When it senses that there is a flame present, it will leave the valve open. However, if it senses that there is no flame, it will turn off the valve for your gas.

Your sensor is programmed to do this as excess gas inside of your furnace can end up resulting in a leak or a fire. While your flame sensor is a very imperative part of your heating system, it can be utterly annoying when it fails.

Signs of a Bad Flame Sensor

Over time, it’s not uncommon for a flame sensor to malfunction. There are a few common indicators that will let you know that there is an issue with your flame sensor. These include:

  • Burners turn off a few seconds after turning on
  • Soot is covering your sensor
  • Flame sensor tip is black
  • Cracked sensor casing

If you notice any of these specific problems with your heating system, then it’s necessary to call in a professional to assess your flame sensor. It’s not highly recommended to try and replace your flame sensor on your own, as you could unintentionally damage other components inside of your heating system.

Cleaning vs. Replacement

Due to the nature of where your furnace’s flame sensor is located, the sensor can become covered with soot and excess debris. When this happens, it will block the sensor’s eye and prevent it from seeing the flame that is present. Instead of having to pay to replace the entire flame sensor, it can easily be cleaned.

Your licensed HVAC professional will likely try cleaning your sensor before replacing it. They will do this by first turning off your furnace at its circuit breaker and your gas at the valve handle. After about 30 minutes of waiting for your system to cool, they’ll proceed to remove the furnace’s cover to gain access to the flame sensor.

The easiest way to clean the sensor is to simply remove it from its housing. This is done via unscrewing the sensor from the assembly and disconnecting any wiring attached to it. Your technician will use an emery cloth to gently take off the soot and excess burnt debris from the surface of the sensor.

Once cleaned, they’ll reconnect the wiring and screw the flame sensor back into position. Once reattaching your furnace’s access panel, they’ll proceed to turn the electricity back on and open the gas valve. If your furnace turns on and runs without a problem, it confirms that your flame sensor was just dirty and needed a little cleaning. If this doesn’t work, then it’s likely that your flame sensor has gone bad.

Replacing the Flame Sensor

If your heating professional has determined that your flame sensor is bad, they will replace it with a new one. In some cases, the technician may be able to locate a cracked housing that will immediately let them know that a replacement is necessary over just cleaning the sensor.

Replacing the sensor is very similar to the cleaning process. They’ll remove the flame sensor from its housing behind your furnace’s access panel. Your technician will be sure to replace the sensor with one that is compatible with your specific heating system. Not all flame sensors have a universal fit.

Flame Sensor Lifespan

It’s important to have a good idea of how long certain components of your heating system will last so that you can properly plan for their replacement. While your furnace may last about 15 to 30 years, a flame sensor won’t last nearly as long. Flame sensors have an average lifespan of about five years. Therefore, you can expect to need to replace it at least twice before replacing your entire heating system.

Professional Heating Services

Puyallup Heating & Air Conditioning provides professional heating services for the entire Puyallup, WA, community. We take pride in offering full-service repairs, installations, and maintenance for heating and cooling systems. We can also assist with all your air purification needs. Call us today to get started.