White-Rodgers 3L09-6 Limit Switch

The White-Rodgers 3L09-6 Limit Switch is a professional-grade 1/2 inch bimetal disc thermal control engineered for high-reliability HVAC high limit protection. This board-mounted component features precise open on rise switch action, calibrated to trigger at a 170°F fixed open temperature and automatically reset at 130°F. Designed with a 3.12-inch insertion length, it ensures deep penetration into the plenum for accurate air temperature sensing, making it a critical safety device for protecting furnace heat exchangers from overheating. As a veteran-grade snap disc thermostat, the 3L09-6 utilizes high-speed contact separation to prevent arcing and ensure a long service life in demanding residential and light commercial heating cycles. This HVAC flame rollout switch alternative or plenum limit control is compatible with a wide range of OEM furnace control boards, offering a 40°F differential that prevents short-cycling. Whether you are performing a service call on a malfunctioning blower or upgrading a legacy system, this White-Rodgers limit control delivers the exact thermal response required to maintain system safety and operational integrity.

• Precise Thermal Calibration: Fixed 170°F cut-out and 130°F cut-in points ensure consistent safety monitoring with no field adjustments required.
• Industrial Build Quality: Features a 1/2" bimetal disc design for rapid and reliable snap-action switching under heavy thermal loads.
• Optimized Insertion Depth: The 3.12-inch probe length provides accurate sensing of core airstream temperatures in manifold and plenum applications.
• Universal Board Mounting: Designed for easy integration into standard furnace control circuits and electronic board configurations.
• Automatic Reset Functionality: Restores circuit continuity once the temperature drops below critical thresholds, reducing unnecessary nuisance lockouts.

• Is the White-Rodgers 3L09-6 suitable for high-voltage circuits? Yes, this limit switch is rated for 120V to 240V AC applications, making it versatile for most residential furnace and air handler control circuits.
• What causes a 170-degree limit switch to trip repeatedly? Frequent tripping usually indicates restricted airflow due to a clogged filter, an undersized duct system, or a failing blower motor, necessitating a full plenum temperature rise test.
• Can this snap disc be used as a replacement for other brands? It serves as a high-quality replacement for many Therm-O-Disc style 36T controls; however, always verify the temperature setpoints and insertion length match the original manufacturer’s 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.