Description
The McDonnell & Miller RB-122E is a residential-grade, automatic-reset low water cut off (LWCO) designed to protect hot water boilers from the hazards of low water conditions. Engineered by Xylem’s McDonnell & Miller brand — a trusted name in hydronic safety controls — this unit monitors boiler water levels and automatically shuts down the burner when water drops below a safe operating threshold, then resets automatically once water is restored to a safe level.
Key Features
- 120VAC operating voltage for standard residential electrical compatibility
- 3/4″ NPT connection for straightforward installation on hot water boiler systems
- Automatic reset operation — restores burner function once safe water level is re-established
- Built-in test switch for quick, on-demand system verification without draining the boiler
- Designed specifically for residential hot water boiler applications
- McDonnell & Miller / Xylem quality construction for long-term reliability
- Part Number: 144676
Why Low Water Cut Offs Matter
A low water cut off is a critical safety device for any hot water boiler system. Without adequate water, a boiler can overheat and suffer catastrophic damage — or worse, create a dangerous situation for building occupants. The RB-122E continuously monitors water levels and interrupts burner operation the moment water falls below the safe threshold, protecting your boiler investment and ensuring occupant safety.
Automatic Reset Convenience
Unlike manual-reset models that require a technician visit to restore operation, the RB-122E’s automatic reset feature allows the boiler to resume normal operation once the water level is safely restored. This minimizes downtime and service calls while maintaining the highest level of boiler protection.
Built-In Test Switch
The integrated test switch allows service technicians and homeowners to verify proper LWCO operation quickly and easily — without draining the system. Regular testing is recommended as part of a routine boiler maintenance program to confirm the safety control is functioning correctly.
Specifications
- Brand: McDonnell & Miller (Xylem)
- Model: RB-122E
- Part Number: 144676
- Voltage: 120VAC
- Connection Size: 3/4″ NPT
- Reset Type: Automatic
- Application: Residential Hot Water Boilers
- Feature: Built-In Test Switch
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