McDonnell & Miller 61 Low Water Cut-Off 140100 20PSI

Original price was: $689.96.Current price is: $473.59.

4 in stock

SKU: 38306 Category:


The McDonnell & Miller 61 Low Water Cut-Off (LWCO) is a crucial safety device for steam boilers, safeguarding against the dangers of low water conditions and potential explosions. 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 damage.

Operating Principle:

  • Float-activated: A float inside the boiler rises and falls with the water level, triggering a switch when it drops too low.
  • Dual mercury switches: One for low water cut-off (boiler shutdown) and the other for alarm or feeder control (optional).
  • Multiple pressure ratings: Available for boilers with maximum pressures up to 20 psi.


  • Adjustable BX outlet: Adapts to various installation configurations.
  • Dual precision switches: Ensure reliable operation of the low water cut-off and alarm or electric water feeder.
  • Packless bellows: Eliminate potential leak points for increased safety and reliability.
  • 1″ NPT equalizing pipes and blow down valve required: Facilitate proper system operation and maintenance.


  • Enhances safety: Protects your boiler from low water hazards and potential explosions.
  • Reliable performance: Proven design and robust construction ensure years of dependable service.
  • Versatility: Compatible with various boiler models and pressure ratings.
  • Additional control options: The included dual switches allow for alarm or feeder activation on low water conditions.
  • Ease of installation: Designed for straightforward setup with the necessary connections.

Things to consider:

  • Compatibility: Choose the model with the appropriate pressure rating for your boiler.
  • Installation: Proper installation by a qualified boiler 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 61 Low Water Cut-Off is a valuable safety device for your steam boiler. Its reliable performance, versatility, and ease of use make it a popular choice for protecting your boiler and ensuring safe operation.


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