McDonnell & Miller 157S-RL Controller

The McDonnell & Miller 157S-RL (Part Number 176902) is a heavy-duty combination low water cut-off and pump controller designed explicitly for steam boilers with an integral water column. This model features alternate tappings including 1/2" NPT connections for gauge glass and tri-cocks, providing versatile installation options for commercial and industrial applications. Built with a Monel bellows for superior corrosion resistance and a snap-acting SPDT switch, the 157S-RL ensures reliable performance under high-temperature conditions. Supporting a maximum pressure of 150 psi, this float-operated controller utilizes an automatic reset mechanism to manage pump cycles and safely shut down burners during low-water events. For contractors requiring a mercury-free switch assembly, this unit provides precise level control and alarm actuation, maintaining critical safety standards for high-pressure steam systems.

• Dual Switch Logic: Features one SPST switch for dedicated pump control and one SPDT switch for low water cut-off and alarm signaling.
• Enhanced Durability: The Monel bellows construction resists harsh boiler chemicals and high-heat environments.
• Flexible Piping: Included alternate tappings simplify the addition of secondary site glass and diagnostic accessories.
• High Pressure Capacity: Field-proven to handle up to 150 psi, making it suitable for a wide range of industrial steaming capacities.
• Integral Water Column: Simplifies mounting by providing a float chamber that serves as its own water column.

• What is the difference between the 157S and the 157S-RL? The RL suffix specifically denotes the inclusion of alternate tappings for gauge glass and tri-cock mounting, which aren't standard on base models.
• Can this unit be used for both 120V and 240V systems? Yes, the McDonnell & Miller 176902 is rated for both 120V and 240V AC electrical configurations.
• Does this model require manual reset after a low water trip? No, this specific model features an automatic reset; for manual reset versions, look for the 'M' suffix (e.g., 157S-RL-M).

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.