During burner on testing, the resistance of a CAD cell should be within which range?

During burner on testing, the resistance of a CAD cell should be within which range?

• A. 0-100 ohms
• B. 300-900 ohms
• C. 1000-2000 ohms
• D. 150-350 ohms

Answer: (B)

A CAD cell acts as a flame sensor—the resistance changes with flame-driven light energy. When the burner is burning, the flame signals the control, and the cad cell should show a mid-range resistance that the system expects to see. The typical reading during burner operation is about 300 to 900 ohms, indicating the sensor is responding properly to the flame. Readings outside this range usually point to a sensor wiring issue, dirt or misalignment, or a faulty sensor, which can cause the control to misinterpret flame presence. While exact values can vary by manufacturer, 300–900 ohms is a common target range.

A CAD cell acts as a flame sensor—the resistance changes with flame-driven light energy. When the burner is burning, the flame signals the control, and the cad cell should show a mid-range resistance that the system expects to see. The typical reading during burner operation is about 300 to 900 ohms, indicating the sensor is responding properly to the flame. Readings outside this range usually point to a sensor wiring issue, dirt or misalignment, or a faulty sensor, which can cause the control to misinterpret flame presence. While exact values can vary by manufacturer, 300–900 ohms is a common target range.