Keeping Your Home Cool during the Sweltering, Summer Months

Understanding And Fixing Gas Furnace Flame Sensor Issues

by Anthony Graves

Gas furnaces are a common kind of residential heating system, especially in colder climates. However, like any mechanical system, they can encounter issues over time. One particular component that often causes problems is the flame sensor.

What Is A Gas Furnace Flame Sensor?

The flame sensor in a gas furnace plays a crucial role in ensuring safety and proper operation. Its function is detecting a flame when the gas burner ignites. If no flame is detected or if it becomes weak or unstable during operation, the sensor signals to shut off the gas supply as a safety measure.

A faulty or malfunctioning flame sensor can lead to various issues with your gas furnace. Common signs include frequent cycling on and off without heating adequately, inconsistent heat output, an unlit pilot light despite successful ignition attempts, or even complete system failure. Recognizing these signs can help prevent further damage.

Regular maintenance for your gas furnace is essential for keeping the flame sensor functioning optimally. Over time, dust particles and other debris can accumulate on its surface, affecting its ability to detect flames accurately. Routine cleaning and inspection by an HVAC professional can identify issues before they escalate.

How Does Your System's Flame Sensor Work?

You need to be familiar with the parts and operation of a gas furnace flame sensor to understand how it works. When the burner ignites at startup or during each heating cycle, an electrical current passes through an electrode rod, creating an ionized gas flame. The flame sensor is then responsible for detecting this ionization and sending a signal to the control board.

The flame sensor usually consists of a metal rod of stainless steel or another conductive material. It is positioned close to the gas burner, allowing it to sense the presence or absence of flames. When flames are present, they generate electrical conductivity between the sensor and the ground. This fluctuation in resistance allows the control board to determine if there is a stable flame.

What Causes Flame Sensor Problems?

Several factors can contribute to flame sensor problems in gas furnaces. One issue is the buildup of soot on the sensor's surface, interrupting its ability to accurately detect flames. Other potential causes include misalignment of the sensor's position relative to the burner or even loose electrical connections.

Maintaining your gas furnace will help reduce the likelihood of issues with the flame sensor. Schedule annual inspections by an HVAC professional who can thoroughly clean and inspect all components. Additionally, ensure proper ventilation around your furnace, change air filters regularly, and promptly address any issues with gas pressure or burner performance.

Contact a gas furnace repair professional near you to learn more.