This thermal disc switch is built for durability in high-cycle environments

ensuring seamless field swaps for legacy HVAC systems

Replacement intervals generally range from 3 to 6 months depending on local environmental factors and odor concentrations

Optimized for accurate gas flow measurement

electromechanical switching component engineered for high-current management in HVAC heating circuits

McDonnell & Miller 63-M Low Water Cut Off 30067439-890 This thermal disc switch isThe McDonnell & Miller 63 M (Part Number 143100) is a heavy duty, float operated mechanical low water cut off designed for superior reliability in both hot water and steam boiler applications. Built for contractors who require a dependable safety interface, this unit features a manual reset mechanism and a robust No. 2 dual switch assembly. These switches provide simultaneous low water cut off protection and a dedicated circuit for an electric water