McDonnell & Miller 94-M Pump Controller

The McDonnell & Miller 94-M is proof of heavy-duty reliability for high-pressure steam applications, serving as a robust combination low water cut-off and pump controller. Designed specifically for steam boilers with a maximum pressure of 250 psi, this unit utilizes manual reset SPDT switches to ensure precise water level management and failsafe protection. The dual snap-acting switches prevent rapid cycling, reducing mechanical wear on your pump motor. As a direct replacement for part number 165900, it integrates seamlessly into existing low-pressure or high-pressure systems. Field technicians rely on the Series 94 for its proportional control capabilities and the security of a manual reset, which mandates a physical inspection before the burner can be restarted. Whether you are managing industrial process steam or complex commercial heating, the McDonnell & Miller 165900 provides the LWCO functionality required to protect the pressure vessel from dry-fire conditions.

• 250 PSI Pressure Rating: Engineered for high-pressure environments where standard controllers fail.
• Manual Reset Mechanism: Adds an essential layer of safety, requiring technician intervention after a low water event.
• Snap-Acting Switches: Ensures crisp electrical contact and prevents "chatter" in the pump circuit.
• Universal Application: Compatible with a wide range of industrial steam boilers requiring pump control and LWCO integration.
• Durable Float Design: High-quality construction resists scale buildup and ensures accurate buoyancy levels.

Common Questions

How do I wire the McDonnell & Miller 94-M for separate pump and burner circuits?
The dual SPDT switches allow for independent wiring. One switch typically manages the pump starter or contactor, while the second acts as the safety limit for the burner circuit, requiring a manual reset if the water level drops below the critical threshold.

What is the difference between the 94 and the 94-M versions?
The 'M' designation stands for Manual Reset. While both function as pump controllers, the 94-M prevents the burner from automatically restarting once the water level is restored, ensuring the operator can investigate the cause of the low water condition.

Can the McDonnell & Miller 165900 be used on hot water boilers?
This specific model is optimized for steam boiler water level control. For hot water systems, a probe-type or specialized low water cut-off is typically recommended unless the application specifically calls for float-actuated control.

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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.