The York S1-025-27747-009 Limit Switch is a critical OEM furnace safety control designed to maintain thermal integrity within high-performance heating systems

and aging compared to standard Buna-N or neoprene seals

ensuring consistent electrode performance even in high-demand environments

offering the stability required for modern multi-speed or single-stage configurations

Propane (LP) conversions require a different orifice size and specific LP conversion kits to account for higher gas density

Lennox 10P29 Thermocouple The York S1-025-27747-009 Limit SwitchThe Lennox 10P29 Thermocouple is a mission critical 30MV furnace flame sensor designed for standing pilot gas fired heating systems. This 30 inch universal thermocouple generates a millivolt signalapproximately 30 mV DCto maintain the connection with the Pilotstat safety control power unit. Engineered for versatility, it is an OEM level replacement for Lennox part numbers 78B72, 31C38, 11Z70, and 10P2901, as well as several Honeywell Q340A series