McDonnell & Miller 47-2-M Reset

The McDonnell & Miller 47-2-M (Part Number 132900) is a heavy-duty mechanical water feeder and low water cut-off combination engineered for commercial and residential steam boiler maintenance. Designed for use on low pressure steam boilers with a maximum steam pressure of 25 psi and a maximum water pressure of 150 psi, this unit features Quick Hook-Up fittings for simplified gauge glass installation. The dual manual reset SPDT switches provide reliable low water cut-off protection and alarm actuation, preventing dry-fire conditions that lead to heat exchanger failure. For applications involving hot water boilers, the 47-2-M ensures consistent water levels through its proportional feed action. This mechanical controller uses a continuous cold water feed to maintain the critical water line, making it a standard specification for contractors prioritizing system longevity. Whether replacing an existing 132900 water feeder or performing a new install, this unit provides robust mechanical redundancy for float-operated safety circuits.

• Quick Hook-Up Design: Simplifies installation by utilizing existing gauge glass tappings for faster field service.
• Manual Reset Safety: Two snap-acting SPDT switches require manual intervention after a low-water event, ensuring the technician can investigate the cause of the drop.
• Proportional Feeding: Delivers precise makeup water volume to match the boiler's steaming rate, reducing thermal shock.
• Debris Management: Includes a large-capacity strainer to protect the valve seat from sediment and pipe scale.

Common Installation Questions

How do the manual reset switches improve system safety compared to automatic resets?
The manual reset requirement forces an inspection of the system if water levels drop below the safe operating point, preventing the boiler from cycling under fault conditions that might be missed with an automatic reset.

Can the McDonnell & Miller 47-2-M be used on both steam and hot water systems?
Yes, while primarily found on steam applications, it is rated for hot water boilers provided the operating pressures do not exceed 25 psi for steam or 150 psi for water cycles.

What is the purpose of the Quick Hook-Up fittings?
These fittings allow for "pipeless" installation into the gauge glass tappings, significantly reducing the labor hours required for mounting and ensuring the float chamber is at the correct hydraulic level.

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.