High-Signal Integrity: Heavy-duty gauge wiring and secure connectors prevent intermittent communication errors between the thermostat and the control board

Built with a high-strength aluminum die-cast housing

This 3/8" NPT automatic vent limiter features a precision-machined ball check valve mechanism that permits free inhalation for sensitive diaphragm movement during normal operation but limits gas escape to within ANSI Z21

Common Questions What is the primary application for the A-4000-1037

ensuring seamless integration with existing safety circuits

Lennox 18K69 Limit Switch High-Signal Integrity: Heavy-duty gauge wiringThe Lennox 18K69 Limit Switch is a critical safety component designed for precise thermal management in Lennox electric furnaces and air handlers. This OEM replacement part, also identified as 18K6901, features an L150F L333F configuration, meaning it is set to "Open on Rise" when temperatures hit the 150F threshold and automatically resets when the system cools to 110F. For a technician in the field, this auto reset limit switch ensures the heating