American Standard Brand [Lifetime Warranty] 52W29 Furnace Flame Sensor Replacement - Compatible with Lennox Armstrong & Ducane Furnaces - Replaces 52W2901 LB47940A 31L71 31L7101
52W29 furnace flame sensor with mounting bracket and white ceramic insulator in branded BlueStars packaging.
52W29 furnace flame sensor showing dimensions of 4.1 inches and 5.4 inches for compatibility check.
52W29 furnace flame sensor with ceramic insulator and mounting bracket shown in a lifestyle product graphic.
Diagram of 52W29 furnace flame sensor highlighting the sensor head, ceramic casing, mounting bracket, and metal rod.
Close-up of 52W29 furnace flame sensor with mounting bracket and ceramic insulator.
Compatibility chart for 52W29 furnace flame sensor listing compatible furnace models.
52W29 furnace flame sensor shown with technician performing maintenance and list of common heating repair symptoms.
Installation guide showing steps to replace a 52W29 furnace flame sensor.
52W29 furnace flame sensor replacement part with mounting bracket and electrical terminal.
52W29 furnace flame sensor with mounting bracket and white ceramic insulator in branded BlueStars packaging.
52W29 furnace flame sensor showing dimensions of 4.1 inches and 5.4 inches for compatibility check.
52W29 furnace flame sensor with ceramic insulator and mounting bracket shown in a lifestyle product graphic.
Diagram of 52W29 furnace flame sensor highlighting the sensor head, ceramic casing, mounting bracket, and metal rod.
Close-up of 52W29 furnace flame sensor with mounting bracket and ceramic insulator.
Compatibility chart for 52W29 furnace flame sensor listing compatible furnace models.
52W29 furnace flame sensor shown with technician performing maintenance and list of common heating repair symptoms.
Installation guide showing steps to replace a 52W29 furnace flame sensor.
52W29 furnace flame sensor replacement part with mounting bracket and electrical terminal.
Lifetime Warranty

[Lifetime Warranty] 52W29 Furnace Flame Sensor Replacement - Compatible with Lennox Armstrong & Ducane Furnaces - Replaces 52W2901 LB47940A 31L71 31L7101

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52W29 Furnace Flame Sensor

Key Features

  • Monitors burner flame to ensure safe furnace operation.
  • Direct replacement for the original manufacturer's part.
  • Overall length: 5.25 inches.
  • Sensing rod length: 2.75 inches.
  • Constructed with a high-temperature resistant metal rod and ceramic insulator.

Replaces / Cross-Reference Part Numbers

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

Compatibility & Fitment

  • Fits specific gas furnace models from Lennox, Armstrong, and Ducane.
  • Compatible with furnace series including G40, G41, G50, G51, G60, G61, and G71.

When to Replace

  • Furnace ignites but shuts down after a few seconds.
  • Furnace fails to heat consistently or at all.
  • The sensor rod is visibly corroded, cracked, or has heavy carbon buildup that cannot be cleaned.

Installation Tips

  • Disconnect all electrical power to the furnace before servicing.
  • Handle the component by its metal bracket to avoid damaging the ceramic insulator.
  • Ensure the sensor rod is properly positioned in the flame path for correct operation.
  • Verify a secure wire connection before restoring power.
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  • WIDE COMPATIBILITY

    WIDE COMPATIBILITY

    Compatible with many models of Lennox, Ducane and Armstrong Furnaces
  • DURABLE MATERIAL

    DURABLE MATERIAL

    This part is made of high-quality metal material with ceramic porcelain for superior conductivity and high reliability.
  • SAVING SOLUTION

    SAVING SOLUTION

    Enjoy the great feeling when your furnace is repaired and works properly like before, BlueStars brings DIY solutions to help you deal with any trouble
  • IMPORTANT NOTE

    IMPORTANT NOTE

    This is a replacement part designed to be compatible with certain appliances. Any brand names mentioned are used solely to indicate compatibility.
CONNECTING LIVES, ENERGIZING MOMENTS

CONNECTING LIVES, ENERGIZING MOMENTS

Brand Model Number
G40DF, G40UH 45, 45X, 70, 70X, 90, 90X, 110, 110X, 135, 155
G41UF 45, 70, 90, 110, 135; G43UF: 45, 70, 90, 90H, 110, 110H, 135 (G50DF) 45, 45X, 70, 70X, 90, 90X, 110, 110X, 135
G50UH 45, 45X, 70, 70X, 90, 90X, 110, 110X, 135, 155, I70, I70X, I90. I90XI 110, I110X, I135
G50UHI I70, I70X, I90, I90X, I110, I110X, I135
G51MP 45, 70, 90, 110, 135
G60DF 45, 45X, 70, 70X, 90, 110, 135, V70, V70X, V90, V90X, V110, V110X, V135
G60DFV V70, V70X, V90, V90X, V110, V110X, V135
G60UH 45, 45X, 70, 70X, 90, 90X, 110, 110X, 135, V70, V70X, V90, V90X, V110, V110X, V135
G60UHV V70, V70X, V90, V90X, V110, V110X, V135
61MP 45, 70, 90, 110, 135, V45, V70, V90, V91, V110, V111, V135; 61MPV: V45, V70, V71, V90, V91, V110, V111, V135

FAQ

The 52W29 flame sensor verifies that the burner flame is actually present during ignition and heating operation. If the sensor does not detect flame, the control board shuts off gas flow as a safety measure to prevent unburned fuel from accumulating.
This flame sensor is commonly associated with Lennox, Armstrong, and Ducane furnaces. Search context also links it to several furnace series including G40, G41, G50, G51, G60, G61, and G71. Because furnace parts can vary by exact model and revision, match your original part number and furnace model before ordering.
Known part numbers and cross-references for this flame sensor include 52W29, 52W2901, 31L71, 31L7101, LB-74940A, and 28PV41. The safest match is the number printed on your original sensor or listed on your furnace parts diagram.
Typical symptoms include the burners lighting briefly and then shutting off within a few seconds, the furnace trying multiple ignition cycles, intermittent heat, or a furnace that starts but will not stay running. A dirty sensor can cause the same symptoms, so cleaning the rod with a fine abrasive pad is often worth trying before replacement.
On most furnaces, replacement is a straightforward service task. It usually involves shutting off power to the furnace, removing the access panel, disconnecting the sensor wire, taking out one mounting screw, swapping the sensor, and reinstalling the wire. A nut driver or screwdriver is typically all that is needed, and the job often takes about 10 to 20 minutes.
Before replacing the sensor, check whether the existing sensor is simply coated with oxidation or carbon buildup. Also inspect the wire connection, burner ground path, burner flame quality, and the sensor mounting area. Weak grounding, dirty burners, or ignition problems can mimic a failed flame sensor and cause the new part to behave the same way.
The most common issue is contamination on the sensor rod from normal combustion byproducts. Over time, oxidation and deposits reduce the sensor's ability to prove flame. Less commonly, the ceramic insulator can crack, the rod can wear down, or wiring and grounding issues can interfere with the flame signal.