McDonnell & Miller 42-1 Replacement Casting

When you are in the field servicing a Series 42S Low Water Cut-Off, a cracked or compromised housing is a non-negotiable repair. The McDonnell & Miller 42-1 Replacement Casting is the exact OEM specification body required to restore the structural integrity of your boiler pump controller. This heavy-duty cast iron replacement part is engineered specifically for the 42S Series, ensuring a precise fit with the head mechanism and bellows assembly. As a veteran technician knows, maintaining the pressure vessel's integrity is critical in steam boiler safety applications. This casting is designed to handle standard operating pressures up to 50 psi. Whether you are dealing with a commercial LWCO or an industrial setup, using this 42-1 casting eliminates the alignment issues found with substandard aftermarket alternatives. Designed for long-term durability in high-heat environments, this housing provides the stable foundation needed for accurate float operation and pump control signaling.

Key Benefits:

• OEM Compatibility: Precision-machined for a seamless fit with McDonnell & Miller 42S head assemblies.
• Rugged Construction: High-grade iron casting built to withstand the thermal cycling of steam systems.
• System Reliability: Restores the float chamber to original factory tolerances for consistent water level monitoring.
• Standardized Ports: Features the factory-correct tappings for equalizing pipes and blow-down valve integration.

Common Questions:

Does this casting include the head gasket?
This item is the 42-1 replacement casting only. It is best practice to install a new CO-12 head gasket whenever the head mechanism is separated from the body to ensure a pressure-tight seal.

Can I use this with an older Series 42 mercury switch model?
While the 42-1 is the primary casting for the 42S series, compatibility with older mercury-style 42 units may vary based on the bellows design. Most technicians upgrade to the 42S head assembly when replacing the casting on retired mercury units.

What is the maximum operating pressure for this housing?
This casting is rated for steam boiler applications with a maximum operating pressure of 50 psi (3.5 kg/cm²).

This item is not eligible for free shipping.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.