McDonnell & Miller 63 142400 Low Water Cut-Off

Original price was: $709.83.Current price is: $629.57.

6 in stock

SKU: 38307 Category:


The McDonnell & Miller 63 142400 Low Water Cut-Off (LWCO) is a popular choice for protecting your steam or hot water boiler from the dangers of low water conditions. Here’s a breakdown of its key features and benefits:


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

Operating Principle:

  • Float-activated: A float inside the boiler rises and falls with the water level, triggering a switch when it drops too low.
  • Single mercury switch: Cuts off power to the burner on low water detection.
  • Multiple pressure ratings: Available for systems with maximum pressures up to 50 psi.


  • Heavy-duty construction: Durable cast iron body for long-lasting performance.
  • Optional manual reset: Allows for restarting the boiler after addressing the low water condition.
  • No. 2 switch included: Can be used for additional controls like alarm or electric water feeders.
  • Tapped 1″ FIP connection: Simplifies connecting an equalizing pipe.
  • Blow down valve required: Helps maintain the boiler by purging sediment buildup.


  • Enhances safety: Protects your boiler from the critical hazards of low water operation.
  • Reliable performance: Proven design and robust construction ensure years of dependable service.
  • Versatility: Suitable for both steam and hot water boilers with various pressure ratings.
  • Additional control options: The included No. 2 switch allows for flexible boiler management.
  • Easy maintenance: Accessible blow down valve simplifies boiler system maintenance.

Things to consider:

  • Compatibility: Choose the model with the appropriate pressure rating for your boiler.
  • Installation: Proper installation by a qualified technician is crucial for safety and optimal function.
  • Maintenance: Regular inspection and testing are necessary to ensure the LWCO is working correctly.

Overall, the McDonnell & Miller 63 142400 Low Water Cut-Off is a valuable safety device for your steam or hot water boiler. Its reliable performance, versatile options, and ease of maintenance make it a popular choice for protecting your boiler and ensuring safe operation.

Additional information

Weight 13.28 lbs


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