Lennox 75W15 Limit Switch

The Lennox 75W15 Limit Switch is a high-performance L165-30F limit switch designed as a genuine OEM replacement for residential and commercial heating equipment. Engineered to function as a critical safety control, this Lennox furnace limit switch operates as a normally closed (NC) snap-disc limit control that opens at 165°F and resets at 135°F. This automatic-reset component is essential for preventing heat exchanger damage by interrupting the gas valve circuit if internal plenum temperatures exceed safe operating parameters. Professionals will recognize the Lennox 75W15 as a direct cross-reference for part number 102857-08, ensuring exact electrical and mechanical compatibility without the need for field modifications. With its 5" overall length (OAL) and orange-sleeved wiring leads, this STILT-type limit control integrates seamlessly into Lennox HVAC systems, maintaining system integrity and safeguarding against airflow-related overheating faults.

Key Benefits

• Precision Thermal Protection: Actuates at a fixed 165°F to prevent thermal stress and heat exchanger failure.
• Direct OEM Compatibility: Replaces Lennox 102857-08 and Allied 102857-08 part numbers with factory-spec accuracy.
• Automatic Reset Functionality: Closes the circuit once temperatures drop to 135°F, allowing for restored system operation after the fault is cleared.
• Robust STILT Design: Features a durable 5-inch probe for accurate temperature sensing within the furnace plenum.

Common Questions

Is the Lennox 75W15 a manual or automatic reset switch?
The Lennox 75W15 is an auto-reset limit switch. It will automatically re-engage the heating circuit once the internal temperature drops below its 135°F reset point, provided the initial cause of overheating has been resolved.

What are the symptoms of a failing L165-30F limit switch?
A faulty limit switch often results in the furnace "short cycling," where the burners shut off but the blower continues to run. If your system triggers a high limit error code or fails to ignite despite adequate airflow, the switch should be tested for continuity.

Can I use the 75W15 in place of a 102857-08?
Yes, these parts are identical. The Lennox 75W15 is the official catalog number used for the 102857-08 replacement part, maintaining identical mounting and electrical specifications.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.