Simplify your supply
Discover the most innovative line of electronic low water cut off devices available today, including the world's first configurable device
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Small but powerful boiler control
Introducing the GuardDog® RB-24SE, which packs a whole lot of control into a compact device, making it ideal for tight spaces.
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A boiler control workhorse
Introducing the GuardDog® RB-122E, a sturdy, reliable primary cut-off device for residential and commercial hot water boilers.
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Simplify Boiler Control with boilerwize®
The industry's first-ever configurable low water cut off device, boilerwize® is a universal control that can be configured for any application.
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A Tradition of Safety and Quality
McDonnell & Miller has pioneered innovation in boiler safety for industrial, commercial and residential applications for over a century.
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A century of innovation
2024 marked 100 years of McDonnell & Miller's commitment to manufacturing safety devices for steam and hot water boilers - and 100 years of paving the way for the future of low water cut off devices. Explore McDonnell & Miller's century-long story of pioneering innovations.
About Xylem's McDonnell & Miller brand
Xylem's McDonnell & Miller brand has been a trusted name in boiler control and safety for over a century. Founded in 1924, the company pioneered innovations in low water cut-off technology and continues to lead in the engineering and manufacturing of safety devices for steam and hot water boilers. Known for products like the GuardDog® series, McDonnell & Miller delivers reliable, compact, and efficient solutions for residential and commercial applications, helping ensure system safety and performance across HVAC and plumbing systems.