McDonnell & Miller 193 Controller

The McDonnell & Miller 193 (Part Number 163400) provides heavy-duty combination low water cut-off and pump control for commercial and industrial steam boilers. Engineered for high-pressure systems with a 150 PSI maximum pressure rating, this unit features dual snap-acting SPDT switches to ensure precise differential control and reliable burner shut-down. The proportional action of the float mechanism maintains tight water level tolerances, preventing hazardous dry-fire conditions and optimizing boiler feed pump cycles. Designed for longevity in harsh mechanical rooms, the 193 series utilizes a bellows seal to isolate the switch assembly from the steam chamber, eliminating common failure points found in lower-tier controllers. For contractors managing steam heating systems, this controller is the standard for automatic water feeders and safety limit integration, providing the rugged sensing performance required for continuous-duty applications.

• Snap-Acting Switches: Dual SPDT switches offer independent control for pump operation and low water cutout.
• High-Pressure Rating: Rated for up to 150 PSI steam pressure, suitable for high-pressure process steam.
• Universal Compatibility: Standard 1-inch NPT connections allow for direct replacement in boiler water level control piping.
• Field-Proven Reliability: The robust float-and-bellows design ensures mechanical accuracy without the failure rates of probe-type sensors in high-sediment environments.

Common Questions

What is the difference between the McDonnell & Miller 93 and 193?
The Model 193 includes a larger float chamber and is specifically designed for high-pressure applications up to 150 PSI, whereas the Model 93 is typically rated for lower pressure steam systems.

How do you wire the SPDT switches for a burner circuit?
The 163400 controller switches are wired in series with the burner's safety circuit. When the water level drops below the minimum safe threshold, the switch opens, breaking the 120V or 24V signal to the burner controller to prevent equipment damage.

Can this unit be used for both pump control and low water alarm?
Yes, the dual-switch configuration allows one set of contacts to manage the steam boiler pump controller and the other to act as a safety cutoff or to trigger an external alarm for the operator.

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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.