There are a number of safety features that protect your furnace from potentially dangerous problems, which can damage both it and you. One of the most important features is the flame sensor. Here’s what it does and why it’s necessary.

How the Flame Sensor Works

Your furnace burns natural gas to produce heat: The gas valve opens and combustion begins. However, if there’s no flame, the gas begins to build up in the unit, eventually leaking into your home. Carbon monoxide is dangerous when inhaled, and it can cause serious illness and even death.

Whenever the furnace calls for more gas, it’s the job of the flame sensor to be sure there’s an actual flame present to burn off the gas. If, when the valve opens, no flame is detected, the valve shuts off again after 10 seconds. It will then try twice more, and if still no flame is detected, the system is shut down completely.

After a shutdown, you’ll likely need to call your HVAC technician to reset the furnace and get it working again. They can also check to see why your furnace has no flame and fix the issue so it can function normally again.

Flame Sensor Issues

Over time, soot from the flames can build up on your flame sensor, causing it to malfunction. Dirt covering the sensor can make the flame difficult to detect, even if it’s there. Likewise, your sensor may become cracked or otherwise broken, which will prevent it from doing its job properly. Rather than risk gas buildup, the system will simply shut down, requiring a reset.

Most of these problems can be prevented with annual maintenance. Your HVAC technician will clean the soot off the sensor and ensure it’s working properly. If there are cracks or other damage, the technician can fix them at the beginning of the season before they cause problems, ensuring your furnace runs safely and efficiently for years to come.

To learn more about how your furnace works and to make sure it’s running properly, contact us at Mowery Heating, Cooling and Plumbing. We keep Indianapolis homes comfortable and efficient.

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