McDonnell & Miller 94-HDLS Pump Controller

The McDonnell & Miller 94-HDLS (Part Number 165302) is a heavy-duty head mechanism only designed for high-pressure steam applications. Engineering for commercial and industrial steam boilers, this component serves as a direct replacement for the internal guts of Series 94 and 194 combination low water cut-off and pump controller units. This specific model is provided less switch, allowing technicians to utilize existing compatible switch assemblies or customize the configuration based on specific onsite wiring requirements. Capable of handling a maximum pressure of 250 PSI, the 165302 head mechanism features a robust 10-bolt flange design that ensures a leak-proof seal under extreme thermal cycling. By utilizing magnetic repulsion to actuate the control, it eliminates the need for bellows, significantly reducing the mechanical failure points common in high-pressure environments. This part is critical for maintaining precise boiler water level control, ensuring the feed pump cycles correctly and the burner circuit is protected against dry-firing conditions.

Key Benefits for Contractors

• High-Pressure Capability: Specifically rated for steam systems up to 250 PSI, making it ideal for large-scale industrial process steam.
• Bellows-Free Design: Uses magnetic repulsion technology to eliminate mechanical bellows, preventing the most common cause of leaks and control failure.
• Service Efficiency: The head-mechanism-only design allows for a "drop-in" replacement on existing float chambers without the need to break or re-pipe the main equalizing lines.
• Universal Boiler Compatibility: Engineered to maintain a consistent water level regardless of steaming capacity or pressure fluctuations.
• Industrial Grade Build: Features a 10-bolt flange for superior gasket compression and structural integrity in high-demand environments.

Common Questions

Can I use the 94-HDLS for a system with 15 PSI?
Yes, while it is rated for a 250 PSI max pressure, it functions effectively in low-pressure commercial applications where a more rugged, long-lasting low water cut-off mechanism is preferred.

Does the 165302 include the No. 5 switch?
No, the 94-HDLS is a "Less Switch" (LS) model. It is intended for field service where the existing switch is operational or where a specific custom switch is being installed separately.

What is the primary cause of float failure in these units?
In high-pressure systems, rapid pressure drops can sometimes cause a float to collapse or "crush." Regular boiler blow-down procedures are essential to clear sediment from the chamber and ensure the float moves freely.

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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.