White-Rodgers 3L09-7 Limit Switch

The White-Rodgers 3L09-7 is a precision-engineered board mount limit control designed for critical temperature monitoring in HVACR systems. This 1/2-inch bimetal disc limit switch features a 3.12-inch insertion length, making it a standard choice for furnace plenums and air handling units where accurate high-limit protection is mandatory. With a fixed open temperature of 175 degrees F and a close temperature of 145 degrees F, this automatic reset snap disc ensures reliable system cycling and prevents overheating. The open on rise switch action provides high-speed contact separation to safeguard electrical components. As a versatile OEM replacement limit switch, the 3L09-7 is compatible with various residential and light commercial heating equipment, offering a compact and cost-effective solution for field technicians performing preventative maintenance or emergency repairs.

Key Benefits:

• Precise Thermal Control: Fixed 175°F cutout and 145°F cut-in ensure consistent safety indexing without the need for manual adjustment.
• Durable Construction: Features a high-speed contact separation design for longevity in high-cycling HVAC environments.
• Universal Board Mounting: The 3.12" probe length and 1/2" disc size allow for seamless integration into existing control boards and plenums.
• Automatic Reset Functionality: Minimizes downtime by automatically restoring circuit continuity once the temperature falls below the 145°F threshold.

Common Questions:

What is the primary application for the 3L09-7?
This 175 degree limit switch is primarily used as a high-limit safety control in furnace systems, ensuring the unit shuts down if plenum temperatures exceed safe operating parameters.

Can this replace other 1/2" bimetal disc switches?
Yes, the 3L09-7 serves as a cross-reference for many 36T series controls. Always verify that the open/close temperatures and insertion length match your specific equipment requirements.

How does the "Open on Rise" action work?
In this configuration, the electrical contacts remain closed during normal operation and "snap" open when the temperature reaches 175°F, breaking the circuit to the gas valve or inducer motor.

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.