Firestat HVAC Duct Limit Switches, a Division of Senasys, are designed to protect HVAC systems by detecting and responding to abnormal temperature rises. Proudly made in the USA, these switches feature a helix bi-metal sensor that triggers a snap action SPST switch, shutting down heating, ventilation, and air conditioning equipment when temperatures exceed set limits. Commonly installed in air ducts of apartment complexes, industrial buildings, and multi-unit facilities, Firestat switches ensure safety by preventing overheating or potential fire hazards. Built for reliability and long-lasting performance, they include a manual reset to restore normal operation after high-temperature events.