33H78 Lennox L130-20F, Limit Switch

The Lennox 33H78 L130-20F Limit Switch is a genuine OEM safety-critical temperature sensor designed for residential gas furnaces, air handlers, and HVAC heating units. Operating as a high-limit safeguard with an Open on Rise switch action, this premium snap-disc style switch continuously monitors internal heat exchanger temperatures to prevent hazardous overheating conditions.

The switch features a fixed cut-out temperature of 130°F (54°C), instantly breaking the electrical circuit to shut off the gas valve or heating elements if the system exceeds safe limits. Once ambient conditions cool down by a fixed 20°F differential to its cut-in temperature of 110°F (43°C), the internal bimetal disc automatically resets to restore system continuity and allow normal heating cycles to safely resume.

• Automatic Reset Functionality: Features an auto-reset layout that restores electrical connection once the internal chamber cools down to 110°F.

• Genuine OEM Precision: Engineered directly by Lennox to preserve the original factory specifications, safety ratings, and performance of your heating equipment.

• Vital System Safeguard: Protects your furnace's heat exchanger from thermal stress, cracks, and severe component damage by enforcing strict high-limit thermal thresholds.

• Streamlined Replacement: Built with a standard two-pin electrical terminal configuration and a rigid integrated mounting flange for an exact, hassle-free drop-in installation.