Lennox 73W20 Limit Switch

The Lennox 73W20 Limit Switch is a critical safety component designed for precise thermal regulation within Lennox residential furnaces and HVAC systems. As an OEM Lennox replacement part, this L175-30F limit control features a fixed set point, engineered to open the electrical circuit at 175°F and automatically reset when temperatures drop to 145°F. This SPST (Single Pole Single Throw) switch utilizes a 5-inch stilt mounting insertion depth to monitor internal heat exchanger temperatures accurately, preventing dangerous overheating conditions during restricted airflow or component failure.

For technicians servicing Allied, Armstrong, or Ducane equipment, the 73W20 limit switch is the direct furnace high limit sensor replacement for legacy part number 102857-07. Its robust construction ensures long-term reliability in high-cycle environments, providing the exact mechanical specs required for HVAC safety switch compliance. Ensure the brown sleeve and left-hand orientation match your existing configuration for a seamless drop-in fit.

Key Benefits

• Precise Thermal Protection: Engineered with a 175°F trip point to safeguard the heat exchanger from structural damage.
• Automatic Reset Functionality: Closes the circuit once temperatures return to a safe 145°F, minimizing system downtime.
• Direct OEM Compatibility: Replaces Lennox part number 73W20 and 102857-07 across multiple furnace product lines.
• Critical Safety Compliance: Maintains the necessary safety protocols for Lennox, AirEase, and Ducane heating units.

Common Questions

What does the L175-30F designation mean on this switch?
The "L175" indicates the switch is a "Limit" type that opens at 175°F. The "30F" signifies the differential, meaning it will reset once the temperature drops 30 degrees below the trip point (at 145°F).

Can I use a shorter insertion length switch as a substitute?
No. The 5-inch stilt mount is calibrated to detect temperature at a specific depth within the heat exchanger. Using an incorrect length can lead to delayed tripping and unsafe operation.

Is this switch compatible with other brands besides Lennox?
Yes, this is an OEM part used extensively in Allied Air brands, including Armstrong Air, Concord, and Ducane systems that specify part number 102857-07.

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.