Copeland Comfort Control (White Rodgers) 3L09-17 Limit Switch

The White Rodgers 3L09-17 is a board-mounted 1/2" bimetal disc limit switch engineered for precision thermal protection in HVAC systems. Designed with an open on rise switch action, this fixed-setting temperature control features a 250°F fixed open temperature and a 225°F fixed close temperature, providing a 25°F differential crucial for preventing high-limit excursions and equipment cycling issues. This auto reset limit switch utilizes a 3.12" insertion length, making it a critical OEM replacement part for specific furnace and air handler configurations. It serves as the direct replacement for SHL518, ensuring seamless integration during furnace limit switch replacement. For service technicians, the robust construction provides reliable HVAC high limit control, ensuring circuit interruption when setpoints are exceeded. Its board-mounted design simplifies installation in tight control compartments while maintaining the specified thermal cutout accuracy required for safe combustion cycles and system longevity.

• Precise Thermal Calibration: Fixed 250°F trip point ensures reliable over-temperature protection.
• Automatic Reset Functionality: Switches back at 225°F, reducing unnecessary service calls for manual resets.
• Direct Compatibility: Engineered as the exact SHL518 replacement for simplified cross-referencing.
• Extended Insertion Length: 3.12" probe reaches deep into the heat exchanger airflow for accurate sensing.
• Bimetal Reliability: 1/2" disc technology offers consistent performance under high-cycle industrial conditions.

What causes a limit switch like the 3L09-17 to trip frequently?
Repeated tripping usually indicates restricted airflow, often due to a clogged filter, undersized ductwork, or a failing blower motor, causing the heat exchanger to exceed the 250°F threshold.

Can I use a different insertion length if the 3.12" probe is unavailable?
No. The insertion length is specific to the heat exchanger geometry. Using a shorter or longer probe will result in inaccurate temperature sensing and potential safety hazards.

How do I verify if the 3L09-17 is the correct part for my system?
Confirm the fixed open/close temperatures and the insertion length match your existing OEM specifications or technical manual before installation.

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.