Xylem 157S-M Low Water Cut-Off and Pump Controller with Manual Reset

The Xylem McDonnell & Miller 157S-M is a combination float-operated low water cut-off and pump controller designed for commercial and industrial steam boiler applications. This control features mercury-free snap action switches, making it environmentally friendly and eliminating special handling or disposal requirements.

Key Features:

• Mercury-free snap action switches for environmentally safe operation
• Manual reset functionality for enhanced safety control
• Integral water column with float chamber for reliable water level monitoring
• Monel bellows construction provides superior corrosion resistance
• Two 120 volt bi-metal snap switches with SPDT (single pole, double throw) configuration
• Single pole, single throw switch for pump control operation
• Single pole, double throw switch for low water cut-off and alarm actuation
• Fully enclosed junction box protects control from dust and dirt while allowing easy wiring access
• Maximum operating pressure of 150 PSI (10.5 kg/cm²)
• 1 inch NPT tapped connection for installation
• 1/2 inch NPT tappings provided for gauge glass and tri-cocks

The 157S-M is suitable for commercial and industrial low or high pressure boiler applications and can be used for boilers of any steaming capacity. The manual reset feature requires operator intervention after a low water condition, providing an additional layer of safety. Replacement head mechanisms are available and completely interchangeable with Series 150 and 157 controls already installed in the field.