McDonnell & Miller 51S-2 Water Feeder/Low Water Cut-Off

The McDonnell & Miller 51S-2 Water Feeder/Low Water Cut-Off combines automatic water feeding with reliable low-water protection for boiler systems. Featuring a 1 inch threaded port and mechanical actuation, this water feeder delivers precise water level control and safe operation. Built to UL and CSA standards, it is designed for 120/240 VAC input and handles typical boiler pressures, ensuring dependable performance in residential or commercial heating setups.

Designed for durable, hands-off boiler protection, this unit handles potable water media with a temperature rating up to 120°F and a water pressure rating of 100 PSI (water) and 35 PSI (vessel). The inclusion of a Series 2 Switch provides reliable signaling to boiler controls for automatic shut-off when water is low. It supports a broad input supply and is built to meet stringent safety standards such as UL and CSA.

• 1 Inch Threaded Port for straightforward, secure installation
• Mechanical Actuation delivers precise water level control with minimal maintenance
• Series 2 Switch provides reliable signaling to boiler controls
• UL and CSA compliant for safety and industry approval
• 120/240 VAC input rating at 60 Hz; supports common voltages
• Full-load current: 10.2 A at 120V / 5.1 A at 240V
• Locked-rotor current: 61.2 A at 120V / 30.6 A at 240V
• Media handled: Water; Temperature rating up to 120°F; Pressure: 100 PSI (water), 35 PSI (vessel)