McDonnell & Miller 2-M 110100 Switch

The McDonnell & Miller 2-M (110100) is a heavy-duty, SPDT manual reset switch engineered for field installation on Series 47, 247, 51, 51-S, 53, and 63 boiler water feeders. As a low water cut-off switch, this component provides critical burner protection by interrupting the circuit if water levels drop below the safe operating line. Designed for versatility in commercial and residential steam systems, the 110100 switch features dual voltage compatibility, operating efficiently at 120Vac or 240Vac with a pilot duty rating of 125VA. The manual reset functionality ensures that a technician must inspect the boiler and address the low-water condition before the burner can be restarted, preventing potential dry-fire damage. Built with a robust snap-action mechanism, the McDonnell & Miller 2-M switch handles high electrical loads with 10.2A FLA at 120V and 5.1A FLA at 240V, making it a standard choice for contractors looking to upgrade existing automatic feeders with integrated manual reset safety controls.

Key Benefits

• Universal Field Compatibility: Direct-fit replacement or upgrade for Series 47, 247, 51, 51S, 53, and 63 water feeders.
• Enhanced System Safety: The manual reset lock-out requires professional intervention after a low-water event, ensuring root cause diagnosis.
• Dual Voltage Support: Flexible wiring terminal configuration supports 120Vac/240Vac applications without extra transformers.
• Reliable Snap Action: Durable SPDT switch internals provide precise opening and closing of burner and alarm circuits.
• Integrated Alarm Logic: Features separate terminals to trigger a low water alarm while simultaneously cutting burner power.

Common Questions

What is the difference between the McDonnell & Miller 2 and 2-M switches?
The No. 2 switch is an automatic reset model, whereas the 2-M (110100) requires a physical manual reset after a low-water trip to ensure system safety and code compliance.

Can this 110100 switch be used as a standalone low water cut-off?
No, the 2-M is a component switch designed to be mounted onto a float-operated feeder or control head that provides the mechanical movement required to trip the switch.

Is the 2-M switch compatible with both steam and hot water boilers?
Yes, provided it is installed on a compatible McDonnell & Miller feeder or control that is rated for the system's specific pressure and temperature requirements.

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.