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5 Signs the Flame Sensor In Your Furnace Is Bad

5 Signs the Flame Sensor In Your Furnace Is Bad

Although small in size, the flame sensor in your furnace plays a big role in household comfort and safety. Besides preventing your heater from short cycling, this safety component also reduces the risk of house fires by shutting down the system if it detects any sudden changes in the flame. A bad flame sensor results in wasted energy and an increased risk of house fires. How do you know if the flame sensor has gone bad? We have created an outline of tips to help you detect a malfunctioning flame sensor in your heating system.

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What Is the Purpose Of a Flame Sensor?

A flame sensor is a safety device that detects the presence of an open flame. If the component doesn’t detect a flame, the pilot light is not lit. An unlit pilot light causes the gas valve to close to shut off the gas supply, preventing potential gas leaks and fires. The flame sensor also saves energy by shutting down the furnace when no flame is present. This prevents your heater from repeatedly running partial cycles without heating your home.

Signs Of a Malfunctioning Flame Sensor

Here are the main signs that the flame sensor in your furnace has gone bad and needs maintenance:

  1. The heater doesn’t turn on
  2. Short cycling. When the heater turns on but doesn’t stay lit for full heating cycles.
  3. Your furnace makes an intermittent clicking sound
  4. The flame sensor is noticeably dirty
  5. A crack forms on the porcelain exterior of the flame sensor


Where Is the Flame Sensor Located?

Although every furnace is different, most flame sensors are located in the same place. Unscrew and pull back the cover on your heating system to get a better view of its internal components. Locate the burner assembly at the bottom of the furnace on its front side. Once you see a small metal box, open it up. The flame sensor is a metal rod with a porcelain exterior that is usually white in color. The flame sensor is located near the pilot light.

What Causes the Flame Sensor to Go Bad?

The most common cause of a bad flame sensor is dust buildup. Other causes include:

  • Sediment buildup
  • Damaged electrical wiring
  • Rust and corrosion
  • Cracks or breaks

How to Clean a Flame Sensor

The easiest way to prevent a bad flame sensor in your furnace is to continuously hire a professional to clean the component. Follow these main cleaning steps to get the device up and running again in no time:

  1. Turn off the heater
  2. Take out the flame sensor
  3. Remove any dust or sediment buildup
  4. Apply cleaning solvent to the rod
  5. Re-insert the flame sensor
  6. Restart the heater

If cleaning the flame sensor doesn’t fix the problem, you probably need to replace it with a brand new one. Schedule an appointment with Fenwick Home Services, and one of our licensed technicians will come to your home at a time that’s convenient for you to replace the flame sensor.

Furnace Repair Services

Furnace Repair & Replacement Services in Jacksonville, FL

Whether you have a bad flame sensor or want to schedule routine maintenance, the team of technicians at Fenwick Home Services are available to help you resolve your issue. We offer exceptional furnace repair and replacement services to homeowners in Jacksonville and other areas of Florida. In addition, our contractors offer other types of HVAC services such as air conditioning installation, heat pump maintenance, air conditioning repair, and mini-split system installation. Don’t get caught on a cold day with a malfunctioning heating system. Give our team a call by phone at (904) 217-5694 to schedule an appointment and maintain the safety and comfort of your home all year long.