Do you know how a flame sensor works on a furnace? Or why it is so important? We’ve got you covered! A flame sensor is a crucial part of your furnace’s safety system. Not only will we explain what it does, but we’ll also tell you how it works, signs of failure, and how to maintain it.
What is a Flame Sensor?
A flame sensor is a small but vital device that ensures your furnace operates safely. It detects whether the burner is producing a flame. If no flame is detected, the sensor stops the gas supply, preventing gas leaks and potential explosions.
How Does a Flame Sensor Work?
The flame sensor functions by detecting the presence of a flame in the burner assembly. Here’s how it works:
- When the furnace turns on, the gas valve opens to release fuel.
- The igniter lights the gas, creating a flame.
- The flame sensor detects heat and generates a small electrical current.
- If the sensor detects a flame, it signals the control board to keep the gas valve open.
- If no flame is detected within a few seconds, the furnace shuts down to prevent gas buildup.
Signs of a Faulty Flame Sensor
Over time, a flame sensor can wear out or become dirty. Here are common signs of a failing flame sensor:
| Signs of Failure | Explanation |
| Short Cycling | The furnace turns on but shuts off quickly. |
| No Heat | The furnace refuses to start, leaving your home cold. |
| Cracked Porcelain | The ceramic insulator is damaged, affecting performance. |
| Corrosion or Soot Buildup | Dirt and rust prevent the sensor from working properly. |
How to Maintain Your Flame Sensor
Regular maintenance can extend the life of your flame sensor and keep your furnace running efficiently. Follow these steps:
Cleaning Your Flame Sensor
Dust and carbon buildup can cause a flame sensor to stop working. Cleaning it regularly helps avoid problems.
- Turn off power and gas to the furnace.
- Locate the flame sensor (near the burner assembly).
- Carefully remove the sensor.
- Use fine sandpaper or steel wool to clean off debris.
- Reinstall the sensor and restore power.
When to Replace a Flame Sensor
Sometimes, cleaning isn’t enough. You may need a new sensor if:
- The sensor has visible cracks or damage.
- It fails despite regular cleaning.
- The furnace keeps shutting off unexpectedly.
Why a Flame Sensor is Important
A furnace without a working flame sensor is a serious hazard. Gas buildup can lead to carbon monoxide poisoning or even explosions. This tiny device plays a huge role in keeping your home safe.
Conclusion
Your furnace’s flame sensor ensures safety by detecting a flame and shutting off gas when necessary. Regular maintenance, such as cleaning, can prevent issues. If your furnace short cycles or won’t start, check the sensor first. Keeping it in good condition will keep your furnace running safely and efficiently.