McDonnell & Miller 51-2-M Mechanical Water Feeder & Low Water Cut Off, 35 PSI, 1″ NPT (Part# 135200)

Description

The McDonnell & Miller 51-2-M (Part Number 135200) is a combination mechanical water feeder and low water cut off engineered for reliable protection and automatic water makeup on low pressure steam and hot water boilers. By combining two critical boiler safety functions into a single, compact unit, the 51-2-M simplifies installation and reduces the number of connections required on the boiler.

The integrated low water cut off continuously monitors boiler water level and automatically interrupts the burner circuit when water drops to an unsafe level, protecting the boiler from dry-fire damage. The mechanical water feeder simultaneously restores water to the boiler as needed, maintaining proper operating levels without manual intervention.

Key Features

• Dual-function design: combines mechanical water feeder and low water cut off in one unit
• Suitable for low pressure steam and hot water boiler applications
• 35 PSI maximum vessel pressure rating
• 1″ NPT connections for straightforward piping integration
• Snap acting manual reset SPDT switch for positive, reliable burner circuit interruption
• Manual reset ensures operator awareness before returning boiler to service after a low water event
• Durable construction built for long-term boiler room service

Specifications

• Model: 51-2-M
• Part Number: 135200
• Brand: McDonnell & Miller (Xylem)
• Application: Low pressure steam and hot water boilers
• Maximum Vessel Pressure: 35 PSI
• Connection Size: 1″ NPT
• Switch Type: Snap acting, manual reset SPDT

Why Choose the McDonnell & Miller 51-2-M?

McDonnell & Miller has been a trusted name in boiler water level controls for over a century. The 51-2-M delivers the dependability and safety that boiler technicians and building engineers demand, combining proven mechanical water feeding with a positive-action manual reset cut off switch. The manual reset SPDT switch requires a deliberate operator action to restore burner operation after a low water shutdown, adding an important layer of safety accountability to any boiler system.