Description
The Lennox 12L37 is an OEM replacement L190-40F high limit switch engineered to protect your furnace from overheating conditions. When supply air temperatures exceed safe operating thresholds, this limit switch interrupts the burner circuit to prevent heat exchanger damage, component failure, and potential safety hazards — then automatically resets once temperatures return to normal operating range.
How It Works
The L190-40F designation identifies this switch’s operating parameters: it opens (trips) at 190°F to shut down the burner, and closes (resets) at 150°F once the system has cooled sufficiently — a 40°F differential that prevents rapid cycling and ensures stable, safe furnace operation.
Key Features
- OEM Lennox replacement part — direct fit for compatible Lennox furnace models
- Opens at 190°F to interrupt burner operation during overtemperature conditions
- Closes (resets) at 150°F — 40°F fixed differential for stable operation
- Automatic reset design for reliable, ongoing protection
- Protects heat exchanger, blower components, and connected equipment
- Built to Lennox OEM specifications for dependable performance and longevity
Specifications
- SKU: 12L37
- Model: L190-40F
- Brand: Lennox
- Open Temperature: 190°F
- Close Temperature: 150°F
- Differential: 40°F
- Type: High Limit Switch
- Reset Type: Automatic
Application
Designed for use in Lennox gas furnaces and heating systems requiring an L190-40F high limit control. Always verify compatibility with your specific furnace model before installation. Consult your equipment’s service manual or a qualified HVAC technician for proper installation and replacement procedures.
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