Lennox 73W18 Limit Switch
The Lennox 73W18 Limit Switch (Model 102857-05) is an essential OEM replacement part designed for high-precision thermal protection in residential and commercial heating cycles. This auto limit control switch features a STILT design and is specifically calibrated to actuate at 150°F (cut-out) and automatically reset at 120°F (cut-in), maintaining a strict 30-degree differential to protect the heat exchanger from overheating conditions. Built with a purple sleeve color for quick field identification and a left-hand orientation, this 5-inch Lennox furnace limit switch ensures seamless integration into the factory wiring harness. Field technicians rely on this part for its durable construction and L150-30F thermal rating, which is critical for restoring system safety and preventing furnace short cycling caused by restricted airflow or blower failure. It is compatible with a wide range of Lennox, Armstrong, and Ducane equipment, making it a versatile addition to any service truck's inventory for immediate HVAC repair and maintenance.
Key Benefits
- Precise Thermal Regulation: Features a factory-set 150 degree high limit trip point to prevent component damage and improve system safety.
- Automated System Recovery: Integrated auto-reset functionality at 120°F allows for system restoration without manual intervention once safe temperatures are reached.
- Simplified Field Identification: Distinctive purple sleeve and 102857-05 model number ensure correct part selection for Lennox, Concord, and Allied Air units.
- Rugged STILT Construction: The 5-inch overall length (OAL) and industrial-grade housing are engineered to withstand high-static environments and demanding furnace heat cycles.
Common Questions
What causes a Lennox 73W18 limit switch to trip frequently?
Frequent tripping is typically caused by restricted airflow. Check for a clogged air filter, blocked supply registers, or a failing blower motor. If airflow is optimal and the switch continues to open, the internal bimetal disc may be fatigued, requiring a replacement Lennox 73W18.
How do I verify if the 102857-05 limit switch is defective?
Using a multimeter, test for electrical continuity across the terminals while the switch is cool. Since this is a normally closed (NC) component, a lack of continuity at room temperature indicates the switch has failed and must be replaced.
Is this switch compatible with other HVAC brands?
Yes, while branded as a Lennox part, catalog number 73W18 is a direct replacement for various Allied Air, Armstrong, and Ducane models that utilize the 102857-05 specification across their furnace platforms.
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.
Original: $34.92
-65%$34.92
$12.22Lennox 73W18 Limit Switch
The Lennox 73W18 Limit Switch (Model 102857-05) is an essential OEM replacement part designed for high-precision thermal protection in residential and commercial heating cycles. This auto limit control switch features a STILT design and is specifically calibrated to actuate at 150°F (cut-out) and automatically reset at 120°F (cut-in), maintaining a strict 30-degree differential to protect the heat exchanger from overheating conditions. Built with a purple sleeve color for quick field identification and a left-hand orientation, this 5-inch Lennox furnace limit switch ensures seamless integration into the factory wiring harness. Field technicians rely on this part for its durable construction and L150-30F thermal rating, which is critical for restoring system safety and preventing furnace short cycling caused by restricted airflow or blower failure. It is compatible with a wide range of Lennox, Armstrong, and Ducane equipment, making it a versatile addition to any service truck's inventory for immediate HVAC repair and maintenance.
Key Benefits
- Precise Thermal Regulation: Features a factory-set 150 degree high limit trip point to prevent component damage and improve system safety.
- Automated System Recovery: Integrated auto-reset functionality at 120°F allows for system restoration without manual intervention once safe temperatures are reached.
- Simplified Field Identification: Distinctive purple sleeve and 102857-05 model number ensure correct part selection for Lennox, Concord, and Allied Air units.
- Rugged STILT Construction: The 5-inch overall length (OAL) and industrial-grade housing are engineered to withstand high-static environments and demanding furnace heat cycles.
Common Questions
What causes a Lennox 73W18 limit switch to trip frequently?
Frequent tripping is typically caused by restricted airflow. Check for a clogged air filter, blocked supply registers, or a failing blower motor. If airflow is optimal and the switch continues to open, the internal bimetal disc may be fatigued, requiring a replacement Lennox 73W18.
How do I verify if the 102857-05 limit switch is defective?
Using a multimeter, test for electrical continuity across the terminals while the switch is cool. Since this is a normally closed (NC) component, a lack of continuity at room temperature indicates the switch has failed and must be replaced.
Is this switch compatible with other HVAC brands?
Yes, while branded as a Lennox part, catalog number 73W18 is a direct replacement for various Allied Air, Armstrong, and Ducane models that utilize the 102857-05 specification across their furnace platforms.
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.
Product Information
Product Information
Shipping & Returns
Shipping & Returns
Description
The Lennox 73W18 Limit Switch (Model 102857-05) is an essential OEM replacement part designed for high-precision thermal protection in residential and commercial heating cycles. This auto limit control switch features a STILT design and is specifically calibrated to actuate at 150°F (cut-out) and automatically reset at 120°F (cut-in), maintaining a strict 30-degree differential to protect the heat exchanger from overheating conditions. Built with a purple sleeve color for quick field identification and a left-hand orientation, this 5-inch Lennox furnace limit switch ensures seamless integration into the factory wiring harness. Field technicians rely on this part for its durable construction and L150-30F thermal rating, which is critical for restoring system safety and preventing furnace short cycling caused by restricted airflow or blower failure. It is compatible with a wide range of Lennox, Armstrong, and Ducane equipment, making it a versatile addition to any service truck's inventory for immediate HVAC repair and maintenance.
Key Benefits
- Precise Thermal Regulation: Features a factory-set 150 degree high limit trip point to prevent component damage and improve system safety.
- Automated System Recovery: Integrated auto-reset functionality at 120°F allows for system restoration without manual intervention once safe temperatures are reached.
- Simplified Field Identification: Distinctive purple sleeve and 102857-05 model number ensure correct part selection for Lennox, Concord, and Allied Air units.
- Rugged STILT Construction: The 5-inch overall length (OAL) and industrial-grade housing are engineered to withstand high-static environments and demanding furnace heat cycles.
Common Questions
What causes a Lennox 73W18 limit switch to trip frequently?
Frequent tripping is typically caused by restricted airflow. Check for a clogged air filter, blocked supply registers, or a failing blower motor. If airflow is optimal and the switch continues to open, the internal bimetal disc may be fatigued, requiring a replacement Lennox 73W18.
How do I verify if the 102857-05 limit switch is defective?
Using a multimeter, test for electrical continuity across the terminals while the switch is cool. Since this is a normally closed (NC) component, a lack of continuity at room temperature indicates the switch has failed and must be replaced.
Is this switch compatible with other HVAC brands?
Yes, while branded as a Lennox part, catalog number 73W18 is a direct replacement for various Allied Air, Armstrong, and Ducane models that utilize the 102857-05 specification across their furnace platforms.
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.
