Description
Lennox 73W18 AUTO Limit Switch Overview
The Lennox 73W18 is an automatic reset limit switch engineered to protect furnaces and heating systems from dangerous overheating conditions. With an open setpoint of 150°F and an automatic reset point of 120°F, this limit switch continuously monitors supply-air or heat exchanger temperatures and interrupts the burner circuit whenever temperatures exceed the safe operating threshold — then automatically restores normal operation once temperatures return to the reset point.
Key Features
- AUTO (automatic) reset operation — no manual intervention required after a limit trip
- Open setpoint: 150°F — shuts down burner to prevent overheating
- Reset setpoint: 120°F — automatically restores operation when temperature normalizes
- Direct OEM replacement for compatible Lennox furnace models
- Reliable bimetal sensing element for accurate, repeatable temperature response
- Compact design for straightforward installation in existing limit switch locations
Why Limit Switches Matter
A properly functioning limit switch is a critical safety component in any forced-air heating system. If airflow is restricted — due to a dirty filter, blocked return, or failed blower — heat exchanger temperatures can rise rapidly. The 73W18 limit switch detects this rise and cuts power to the burner before damage occurs, protecting both the heat exchanger and the occupants of the building.
Application
- Designed as a direct OEM replacement for Lennox furnaces requiring a 120-150°F AUTO limit switch
- Suitable for residential and light commercial forced-air heating applications
- Always verify compatibility with your specific Lennox model before installation
Specifications
- Brand: Lennox
- Part Number / SKU: 73W18
- Switch Type: AUTO (Automatic Reset)
- Open Temperature: 150°F
- Reset Temperature: 120°F
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