52W29 Furnace Flame Sensor Replacement - For Lennox Armstrong & Ducane Furnaces - 2 Pack

52W29 Furnace Flame Sensor

Key Features

• Constructed with a metal alloy rod and a ceramic insulator for high-temperature durability and conductivity.
• Detects burner flame to allow safe and continuous furnace operation.
• Rod Length: 2-3/4 inches
• Connector Size: 3/16 inch

Replaces / Cross-Reference Part Numbers

• 52W29
• 52W2901
• 31L71
• 31L7101
• LB-74940A
• 28PV41
• 903600
• FLS52W29

Compatibility & Fitment

• Direct replacement for specific furnace models from Lennox, Armstrong, and Ducane.
• Confirmed fit for G40, G41, G50, and G51 series furnaces.
• Verify fitment by matching your original part number to the cross-reference list.

When to Replace

• The furnace cycles on but the burner shuts off after a few seconds.
• The furnace fails to produce heat or does not stay lit.
• The ceramic insulator on the existing sensor is cracked or broken.
• The metal rod is corroded, covered in carbon buildup, or physically damaged.

Installation Tips

• Disconnect all electrical power to the furnace before beginning service.
• Handle the new sensor by its ceramic base; avoid touching the metal rod with bare hands as skin oils can cause premature failure.
• Ensure the single mounting screw is secure but not overtightened to avoid cracking the ceramic.
• Position the sensor so the metal rod is properly enveloped by the burner flame during operation.