McDonnell & Miller 341900 Bellows Assembly

The McDonnell & Miller 341900 (Model SA47-104) is a critical replacement bellows assembly engineered specifically for Series 247 and Series 247-2 mechanical water feeders. As a veteran-grade low water cut-off component, this assembly facilitates the vital mechanical link between the float arm and the valve sealing mechanism. By utilizing a high-integrity large bellows design, it ensures a hermetic seal that prevents boiler water from entering the switch housing while allowing the float to react precisely to boiler water level fluctuations. This part is essential for maintaining the proportional feed action required in low-pressure steam and hot water systems, specifically where reliable automatic water feeder operation is a baseline requirement for system safety.

When performing a boiler feeder repair, technicians must ensure the bellows cup is properly seated in the head casting notch to maintain alignment. The SA47-104 bellows is designed to withstand standard operating pressures up to 25 psi, providing the flexibility needed for sensitive level sensing without sacrificing the structural rigidity required for industrial HVACR environments. Integrating this OEM McDonnell & Miller part restores the factory-spec movement of the valve linkage, ensuring your boiler safety controls function without lag or mechanical binding.

Key Benefits:

• Precision engineered for McDonnell & Miller 247 series compatibility, ensuring a perfect mechanical fit without field modifications.
• Constructed with a durable bellows cup to provide long-term protection against pressure spikes and thermal stress.
• Restores sensitive proportional water feeding, preventing short-cycling and maintaining optimal boiler efficiency.
• Critical for isolating electrical components from the hydronic system fluid, ensuring safe low water cut-off execution.

Common Questions:

How do I know if my McDonnell & Miller bellows needs replacement?
If you observe water leaking from the bellows housing or notice the feeder valve sticking despite a free-moving float, the bellows has likely lost its structural integrity or developed a pinhole leak. This requires immediate replacement to protect the switch assembly.

Is the SA47-104 compatible with Series 47 feeders?
No, the 341900 bellows assembly is specifically sized and threaded for the 247 Series. While they appear similar, the internal dimensions and stroke lengths are not interchangeable with the Series 47 components.

Does this assembly include the necessary gaskets for installation?
Technicians should always verify the inclusion of the head gasket (37-26) and bellows cup gaskets. It is industry best practice to replace all sealing surfaces whenever the head mechanism is disassembled for a bellows replacement.

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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.