McDonnell & Miller 193-A-7B Controller

The McDonnell & Miller 193-A-7B (Part Number 164500) is a robust, float-operated combination low water cut-off and pump controller specifically engineered for commercial and industrial steam boiler applications. Designed to handle a maximum pressure of 150 PSI, this unit integrates a No. 7B potentiometer switch, which provides a 135-ohm proportional control signal to maintain a constant boiler water level by modulating the feed valve. Unlike standard head mechanisms, this model features alternate tappings to facilitate versatile equalizing piping and the installation of gauge glass and tri-cock sets directly into the water column.

For the veteran contractor, the 193-A-7B controller offers a magnetic repulsion mechanism that eliminates the need for bellows, significantly reducing the risk of mechanical failure in high-demand environments. This unit arrives ready for 1-inch NPT connections and is compatible with 120V or 240V systems. Its heavy-duty construction ensures precision in water level management, safeguarding the pressure vessel against dry-fire conditions while optimizing boiler feed pump control efficiency.

• Proportional Feed Control: The No. 7B switch ensures a steady water line by sending a precise 135-ohm signal to proportional valves.
• Integrated Water Column: Includes integral tappings for gauge glass and tri-cock installations, simplifying the boiler trim setup.
• Magnetic Repulsion Technology: Replaces traditional bellows for higher reliability and less frequent maintenance in industrial steam systems.
• Versatile Compatibility: Designed with alternate tappings for flexible mounting on various steam boiler configurations.

What is the primary function of the No. 7B switch?
The 7B switch is a potentiometer slide wire control used to provide a proportional signal to maintain exact water levels, rather than simple on/off pump control.

Can this unit be used for high-pressure applications?
Yes, it is rated for a maximum steam pressure of 150 PSI, making it suitable for both low and high-pressure commercial boiler systems.

How do I handle the manual reset on this model?
This specific 164500 model is typically configured for automatic reset; however, manual reset head mechanisms are available if code requires a technician's manual intervention after a low water condition.

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.