McDonnell & Miller RB24-E Low Water Cut-Off 144692

SKU: 742707 Category:


The McDonnell & Miller RB24-E Low Water Cut-Off (LWCO) is a popular choice for protecting hot water boilers from the dangers of low water conditions. Here’s a breakdown of its key features and benefits:


  • Automatically shuts down the boiler burner if the water level falls below a safe threshold, preventing overheating and potential steam explosions.

Operating Principle:

  • Electronic: Utilizes a solid-state conductivity probe to detect water presence.
  • 24 VAC operation: Compatible with most residential boiler control systems.
  • Automatic reset: Resumes operation automatically once the water level rises to a safe point.


  • Brass threads: Ensure a leak-free and secure connection.
  • Integrated wrench flats: Simplify installation and prevent damage to the housing.
  • Self-cleaning probe: Minimizes maintenance needs and extends cleaning intervals.
  • Universal wiring harness: Adapts to different boiler models for “plug-and-play” installation.
  • Green power on LED: Indicates the LWCO is receiving power.
  • Red low water LED: Signals a critical water level condition and boiler shutdown.


  • Enhanced safety: Protects your boiler from low water hazards and potential explosions.
  • Reliable performance: Solid-state technology offers dependable operation with minimal moving parts.
  • Easy installation: Universal wiring harness and compact design simplify setup.
  • Automatic reset: Eliminates the need for manual intervention after a low water event.
  • Peace of mind: Provides constant monitoring and automatic response to water level changes.
  • Low maintenance: Self-cleaning probe reduces cleaning frequency.

Things to consider:

  • Compatibility: Ensure the RB24-E matches your boiler’s voltage requirements and control system compatibility.
  • Installation: Proper installation by a qualified technician is crucial for safety and optimal function.
  • Testing: Regular testing is recommended to ensure the LWCO is working correctly.

Overall, the McDonnell & Miller RB24-E Low Water Cut-Off is a reliable and versatile option for protecting your hot water boiler. Its combination of advanced technology, ease of use, and safety features makes it a popular choice for homeowners and professionals alike.

Additional information

Weight 1.47 lbs


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