Trane SWT1278 Limit Switch

The Trane SWT1278 Limit Switch is a critical safety component designed for precise thermal regulation within furnace supply plenums and industrial heating configurations. Engineered for high-reliability performance, this fixed-temperature limit control features a 150°F opening setpoint (150op) to prevent heat exchanger overheating and a 120°F closing setpoint (120cl) for circuit reset. As a veteran-grade OEM replacement part, the SWT1278 is essential for mitigating risks associated with restricted airflow and cracked heat exchangers, ensuring the system shuts down the gas valve if internal temperatures exceed safe operating parameters. The bimetal snap-action disc provides a crisp, positive break to avoid nuisance tripping in demanding HVACR environments. This furnace high limit switch is built to withstand harsh cabinet conditions, maintaining sensitive calibration over thousands of cycles to protect both the equipment and the structure from thermal damage.

• Precise Thermal Calibration: Calibrated for a 150°F open and 120°F close, ensuring tight operational Windows for HVAC safety controls.
• OEM Compatibility: Designed specifically for Trane and American Standard equipment, ensuring exact fit and terminal alignment.
• Enhanced System Protection: Prevents premature heat exchanger fatigue by maintaining strict temperature limits during the heating cycle.
• Industrial-Grade Durability: Robust construction minimizes contact pitting and drift, providing stable high-limit protection.

Is the SWT1278 compatible with other brands?
While primarily an OEM part for Trane, this switch can be used in other applications requiring a 150/120 setpoint; however, mount spacing and terminal orientation must be verified against the existing limit control.

What causes this switch to trip frequently?
Frequent tripping typically indicates restricted return airflow, a dirty furnace filter, or an oversized burner orifice. If the switch fails to reset at 120°F, the internal bimetal disc may be fatigued.

Can I use a higher temperature limit if this one keeps opening?
No. Never increase the limit setpoint above the manufacturer's specification. Doing so bypasses a critical safety function and significantly increases the risk of heat exchanger failure.

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.