McDonnell & Miller 157S-RBP-MD Hi-Pressure Level / Low-Water Control (Part 176503)

Overview

The McDonnell & Miller 157S-RBP-MD is a combined high-pressure level control and low-water cut-off / pump controller designed for use in boilers of various steaming capacities. It uses snap-action switches for reliable, mechanical feedback. Key features include Monel bellows for corrosion resistance, maximum operating pressure up to 150 PSI, alternate tapping options, and dual conductance probes for low-water detection and alarm actuation. Part number 176503. nationalpumpdepot.com+3BoilerWAREhouse+3National Pump Supply+3

Key Features & Benefits

• Rated for 150 PSI maximum pressure, suitable for many high-pressure boiler systems.

• Monel bellows provide excellent resistance to corrosion in harsh boiler water environments.

• Dual snap-action switches: one SPST (single pole, single throw) for pump control, another SPDT (single pole, double throw) for low-water cutoff / alarm.

• Includes alternate tappings to accommodate different mounting or pipe layouts

• Equipped with two integral conductance probes to sense water levels more reliably.

Technical Specifications

Applications

• Boiler systems of any steaming capacity that require reliable level detection and low-water protection.

• Industrial and commercial boilers where high-pressure (up to 150 PSI) service is needed.

• Situations where corrosion and wet conditions demand durable materials (Monel bellows).

• Use cases needing both pump control and alarm/low-water cut-off functions integrated into a single device.

Installation & Best Practices

• Mount in a location with access to water level where the conductance probes can sense accurately and avoid deposits that impede conductivity.

• Ensure system piping pressure does not exceed 150 PSI.

• Install so snap switches are accessible for testing and maintenance.

• Follow manufacturer instructions for manual reset where applicable.

• Use alternate tapping ports if needed to align with boiler geometry or piping layout.

• Perform regular inspection/cleaning of bellows, probes, and contacts to ensure reliable operation.

Why Buy From Apex Controls

Apex Controls offers the genuine McDonnell & Miller 157S-RBP-MD level control (Part 176503) with verified OEM specifications. You’ll benefit from accurate product fit, reliable parts, and expert technical support — helping ensure boiler safety, operational reliability, and compliance.