McDonnell & Miller 47-2 Feeder

The McDonnell & Miller 47-2 is a heavy-duty mechanical water feeder and low water cut-off (LWCO) engineered for steam and hot water boilers using a cold water feed. This dual-function control, part number 132800, features quick hook-up fittings to simplify integration into existing gauge glass tappings. Unlike electronic alternatives, this mechanical feeder provides proportional feed action and maintains a minimum safe water level independent of electrical service, ensuring the float-operated mechanism continues to manage water volume even during power outages. The integrated No. 2 switch provides a critical automatic reset safety function, interrupting the burner circuit if levels drop below the 1-inch threshold to prevent dry firing.

Designed for professional-grade reliability, the unit handles a maximum boiler pressure of 25 psi and a maximum water supply pressure of 150 psi. Serviceability is optimized through a quick-change replaceable cartridge valve and strainer, allowing technicians to clear sediment or replace internals without dismantling the entire iron body assembly. For contractors managing commercial boiler controls, the 47-2 remains the industry standard for mechanical make-up water management and dry-fire prevention.

Key Benefits:

• Mechanical Reliability: Proportional feeding continues to function regardless of electrical availability, protecting the heat exchanger from low-water conditions.
• Simplified Installation: Included quick hook-up fittings allow for direct 1/2-inch NPT connections to the boiler's gauge glass tappings.
• Maintenance-Friendly Design: The CTRD-101 cartridge and strainer kit can be serviced or replaced without breaking the piping.
• Integrated Safety: Two snap-acting SPDT switches provide both water feeding and low water cut-off protection in a single 29-lb cast iron housing.

Common Questions:

Can I upgrade a standard Model 47 to a 47-2 in the field?
Yes, a standard Model 47 feeder can be field-upgraded by adding the No. 2 switch to provide the low water cut-off function, identical to the factory 132800 configuration.

What is the maximum inlet water temperature for the 132800?
The unit is rated for a maximum inlet water temperature of 120°F (49°C), making it suitable for standard cold water supply lines.

Why is my boiler overfilling after the burner cycle ends?
This is often caused by sediment trapped in the valve and strainer assembly or a slow return of condensate. Ensure the strainer is cleaned during annual maintenance to prevent the proportional valve from sticking open.

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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.