McDonnell & Miller 94-HD Pump Controller

The McDonnell & Miller 94-HD Pump Controller (Part Number 165300) is a high-performance replacement head mechanism engineered for heavy-duty commercial and industrial steam boiler applications. Designed specifically for Series 94 and Series 194 units, this combination low water cut-off and pump control manages liquid levels in systems with a maximum pressure of 250 PSI. This assembly includes the No. 5 snap-acting SPDT switch, providing reliable dual-functionality for burner safety and feed pump activation. By utilizing magnetic repulsion to actuate the switches, this mechanism eliminates the need for bellows, significantly reducing the risk of mechanical failure in high-pressure environments. This "head only" design allows technicians to perform a full internal rebuild of the level control without removing the existing 1-1/4 inch NPT casting from the piping, minimizing downtime and labor costs during boiler maintenance. Its 10-bolt flange configuration ensures a secure, pressure-tight seal for consistent performance across any steaming capacity.

• Magnetic Repulsion Technology: Eliminates bellows for increased reliability in 250 PSI steam applications.
• Dual-Function Control: Integrated low water cut-off and pump controller in a single 165300 assembly.
• No. 5 SPDT Switch: Features snap-acting, automatic reset switches for precise burner and pump sequencing.
• Simplified Serviceability: Allows for total internal replacement without disrupting the primary boiler piping.
• High Pressure Rating: Robust construction rated for industrial steam systems up to 17.6 kg/cm².

Common Questions

Is the mounting gasket included with the 165300 head mechanism?
Standard replacement head mechanisms typically require a 92-68 flange gasket for installation. It is recommended to verify gasket presence or source one separately to ensure a proper star-pattern torque seal of 17-21 ft-lbs.

Can I use this to replace a 94-M manual reset head?
The 94-HD is an automatic reset model. While it fits the same Series 94 body, it will change the system operation from manual to automatic reset. Always verify local boiler codes before changing the reset functionality of a safety control.

What is the benefit of the snap-acting switch over older mercury versions?
The snap-acting SPDT switches in this 94-HD model provide a more positive electrical contact and eliminate the environmental hazards and vibration sensitivity of legacy mercury bulbs.

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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.