Description
The Trane SWT3938 is an OEM high limit switch designed to protect Trane furnaces and heating systems from overheating conditions. Engineered to Trane’s exacting specifications, this L135F-30F limit switch monitors supply air or heat exchanger temperatures and interrupts the burner circuit when unsafe temperature thresholds are reached — safeguarding equipment, heat exchangers, and occupants alike.
How It Works
The limit switch continuously senses temperature within the furnace plenum or heat exchanger area. When temperatures rise to the open setpoint, the switch opens the control circuit, shutting down the burner. Once temperatures fall and the reset differential is satisfied, the switch automatically resets and restores normal operation — providing reliable, automatic protection with no manual intervention required.
Key Features
- OEM Trane replacement limit switch — direct fit for compatible Trane furnace models
- L135F-30F designation: opens at 135°F, resets after a 30°F differential
- Automatic reset operation for continuous, uninterrupted protection
- Interrupts burner circuit to prevent heat exchanger damage and overheating
- Built to Trane OEM quality standards for long-term reliability
- Essential safety component for residential and light commercial Trane heating systems
Specifications
- SKU: SWT3938
- Brand: Trane
- Type: High Limit Switch
- Designation: L135F-30F
- Open Temperature: 135°F
- Differential: 30°F
- Reset Type: Automatic
Application
The SWT3938 is a direct OEM replacement for Trane furnaces requiring an L135F-30F high limit switch. Always verify compatibility with your specific Trane model number before installation. Proper limit switch function is critical to system safety and longevity — replace worn or failed switches promptly to maintain code compliance and protect your equipment investment.
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