White-Rodgers 3L09-24 Limit Switch

The White-Rodgers 3L09-24 is a professional-grade board mounted limit switch engineered for high-limit safety in residential and commercial furnaces. Built with a 1/2" bimetal disc, this control manages critical plenum temperatures by utilizing an open on rise switch action. It is factory-calibrated to a 190°F fixed open temperature and a 170°F fixed close temperature, ensuring a precise 20°F differential for reliable equipment protection. The 3.12" insertion length allows the sensing element to sit deep within the air stream for rapid response to over-temperature conditions.

Designed for seamless integration into HVAC circuit boards, the 3L09-24 limit control features an auto reset function, eliminating the need for manual intervention after the system cools to safe operating levels. This snap-disc limit switch is often found in high-efficiency forced-air systems where maintaining exact thermal boundaries is non-negotiable. Its robust construction provides high-speed contact separation to prevent arcing and ensure long-term switching reliability in demanding furnace limit switch applications.

• Optimal Thermal Sensitivity: The 1/2" bimetal disc provides rapid reaction times to temperature fluctuations, protecting the heat exchanger from damage.
• Standardized Fit: Featuring a 3.12" insertion length, this switch is a direct-fit for various OEM board-mount configurations.
• Automated Operation: The auto reset mechanism ensures the system resumes normal operation once temperatures descend to 170°F.
• Compact Board Mounting: Designed specifically for space-constrained control boards without compromising technical performance.

What is the difference between "Open on Rise" and "Close on Rise" for this model?
The White-Rodgers 3L09-24 is an "Open on Rise" switch, meaning it breaks the electrical circuit when the temperature hits 190°F to shut down the burner for safety.

Can this limit switch be used in a 24V or 120V circuit?
Yes, this control is rated for both low-voltage and line-voltage applications, commonly supporting 15 amps at 120 VAC and various pilot duty ratings.

Is the 3.12" insertion length compatible with my furnace plenum?
This length is standard for many mid-to-high efficiency furnaces. Always measure your existing probe to ensure the 3L09-24 reaches the proper section of the air stream.

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.