Modine 3H0400780003 High Limit Switch Boiler Safety Controls & Aquastats - L220-40F

The Modine 3H0400780003 is a stalk-mount high limit switch designed as a critical safety component for Modine gas-fired unit heaters. This temperature limit switch continuously monitors heat exchanger temperatures and automatically interrupts the electrical circuit when temperatures exceed safe operating limits, preventing overheating damage and potential fire hazards.

Key Features:

• Opens at 220°F to shut down the heating system
• Automatically resets when temperature drops to 180°F (40°F differential)
• Stalk-mount design for direct placement in the heat stream
• Automatic reset operation for convenient safety protection
• Opens on temperature rise to prevent dangerous overheating conditions

This genuine Modine OEM replacement part is commonly used in 30,000, 45,000, and 125,000 BTU HD unit heater models. Replaces previous Modine part numbers 5H0757690001, 5H75769-1, 3H40078-3, and cross-references to FP 53658. Installing the correct OEM limit switch ensures your Modine heater operates safely and efficiently while maintaining compliance with safety standards.