McDonnell & Miller 6667 Head Mechanism 153825 For 67, 69, & 469

Original price was: $447.69.Current price is: $339.57.

3 in stock

SKU: 38365 Category:


The McDonnell & Miller 6667 Head Mechanism is a replacement part for specific models of the company’s Low Water Cut-Off (LWCO) devices in steam boilers. It plays a crucial role in ensuring boiler safety by:


  • Replacing the head portion of the LWCO, containing vital components like the float chamber, mercury switch(es), and external connections.
  • Enabling quick and easy service without disrupting boiler piping or draining the system.


  • Simplified maintenance: Allows for efficient repairs or replacements without complex disassembly, minimizing downtime and labor costs.
  • Reduced downtime: Keeps your boiler operational with minimal interruption during maintenance.
  • Cost-effectiveness: Replacing the head mechanism is often more economical than purchasing a whole new LWCO unit.
  • Durable construction: Built with high-quality materials for reliable performance and long-lasting operation.


The 6667 Head Mechanism is compatible with certain models within the McDonnell & Miller Series 61, 67, 69, 70, and 767 controls. It’s crucial to ensure you choose the correct model for your specific LWCO unit to ensure proper fit and functionality.

Things to Consider:

  • Compatibility: Verify the 6667 Head Mechanism matches your specific LWCO model and pressure rating.
  • Installation: While potentially doable for DIYers with technical expertise, consulting a qualified boiler technician is highly recommended for safe and proper installation, especially considering the critical safety function of the LWCO.
  • Limited functionality: Only replaces the head portion, requiring the existing LWCO body and other components to be functional.

Overall, the McDonnell & Miller 6667 Head Mechanism is a valuable tool for simplifying maintenance and repairs on compatible LWCO models. Its ease of use, reduced downtime, and cost-effectiveness make it a popular choice for boiler owners and technicians looking for a quick, efficient, and affordable solution to maintain boiler safety and performance.

Additional information

Weight 1.67 lbs


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