The primary difference is the electrical enclosure

While dimensions suggest high-tonnage application

Durable Construction: Built to withstand the high-cycle demands of commercial HVAC and residential furnace environments

this HVAC safety switch integrates seamlessly with Carrier models including the 42WKN series air handlers

as the interlocking tooth design requires no lubrication

Belimo FSNF120-S Actuator Freon The primary difference is theThe Belimo FSNF120 S is a specialized fire and smoke damper actuator designed for life safety applications in HVAC systems. Operating on 120 VAC, this spring return actuator delivers 70 in lb of torque, ensuring reliable fail safe operation during power loss or smoke detection events. Built with a rugged high strength steel housing, it meets UL555 and UL555S requirements for smoke control. This model features two integrated SPDT auxiliary switches for