• 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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  • A Century of Innovation with McDonnell & Miller

    This year marks 100 years of McDonnell & Miller as a leader in engineering and manufacturing safety devices for steam and hot water boilers.

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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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GuardDog® RB-24SE Low Water Cut Off

More efficiency in a smaller footprint.

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GuardDog® RB-122-E Low Water Cut Off

Reduced costs plus worry-free reliability.

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100th Anniversary!

100 years of dependability and innovation.

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Flow Switch - FS6

A full line of flow switches.

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