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Flame Sensor Kit LB-74940A, 52W29

SKU: 52W29

$17.36each

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Description

Lennox 52W29 Flame Sensor Kit (LB-74940A) is an OEM flame sensing kit used on selected Lennox gas furnaces to monitor burner flame presence and allow the control board to safely prove flame during operation.

Key Features:

  • OEM Lennox flame sensor kit, part number 52W29 (LB-74940A)
  • Designed to detect burner flame and signal the furnace control board
  • Includes flame sensor assembly and associated hardware as supplied in the kit
  • Replacement part matched to specific Lennox furnace models listed in Lennox documentation

Compatibility & Applications:

  • Intended for use on Lennox gas furnaces that specify 52W29 / LB-74940A in the official parts list
  • Used when diagnostic codes or service checks indicate a failed or weak flame sensor signal
  • Suitable for residential forced air gas furnaces where the original flame sensor has become contaminated, cracked, or otherwise unreliable

Installation & Operation Notes:

  • Disconnect power to the furnace and shut off gas supply before servicing
  • Follow Lennox service instructions for accessing the burner compartment and removing the existing flame sensor
  • Install the new flame sensor in the same mounting location and orientation, reusing or replacing mounting hardware as supplied in the kit
  • Route and connect the sensor lead to the control board flame sensor terminal as originally configured
  • After installation, restore power and gas, then verify proper ignition sequence and stable flame sensing through a complete heat cycle

Maintenance & Troubleshooting:

  • Inspect the flame sensor during annual furnace maintenance for signs of buildup or damage
  • Light surface deposits can sometimes be cleaned using the procedure approved by the furnace manufacturer, but heavily worn or cracked sensors should be replaced
  • Persistent flame sense or lockout issues after sensor replacement may indicate burner, grounding, or control board problems that require further diagnosis

Certifications & Compliance:

  • Meets ARI 780/790 Standard

User Reviews & Q&A Summary:

  • Common theme is "correct part" for the intended replacement, with users reporting it worked as expected after installation
  • Review feedback frequently mentions straightforward installation for a direct replacement
  • Value and fulfillment are recurring positives (good deal/price and fast shipping)

Product Highlights

Product Highlight: Electrical Rating0.25 A @ 0.25 to 12 Vdc, 5.1A @ 240 Vac, 8A @ 120 Vac      Product Highlight: DifferentialFixed     Product Highlight: Switch ActionSPST, Contacts Break on Temp Rise     Product Highlight: MountHorizontal, Vertical     Product Highlight: Height5-5/8"     Product Highlight: Depth (Inches)2-1/8" Depth

Specs

Application:

High Limit

Low Limit

Bulb Size:

3/8" x 2-7/8"

Capillary Length:

3"

Switch Action:

SPST

Contacts Break on Temp Rise

Electrical Rating:

0.25 A @ 0.25 to 12 Vdc

5.1A @ 240 Vac

8A @ 120 Vac

Electrical Ratings (ALR):

48A @ 120 Vac

30.6A @ 240 Vac

Max Temp Differential:

2°F

Differential:

Fixed

Max Ambient Temp (°F):

150°F

Height:

5-5/8"

Width:

2"

Depth (Inches):

2-1/8"

Well Included:

No

Mount:

Horizontal

Vertical

Temperature Range (F):

40°F to 180°F