MCDONNELL

About MCDONNELL

McDonnell & Miller is a manufacturer of liquid level and flow control devices for steam and hot water heating systems, with a history dating back to the early 20th century. The brand is known for its low water cut-offs, boiler water feeders, and level controls, which are used to maintain safe water levels in boilers and prevent dry-fire conditions. These devices are commonly found in commercial and industrial HVACR applications, including steam boilers, hydronic heating systems, and process equipment. The product line includes float-type low water cut-offs, probe-type controls, water feeders, and replacement parts such as head mechanisms, gaskets, and float blocks. Many McDonnell & Miller products carry FM Approval and UL Listing, indicating compliance with recognized safety standards. The devices are typically constructed with materials suitable for the temperatures and pressures encountered in steam and hot water systems, though specific ratings vary by model. 3G Electric supplies a range of McDonnell & Miller components, including low water cut-offs, level controls, water feeders, and replacement parts. These items are available for global shipment, supporting maintenance and repair operations for boiler systems. The catalog includes both complete control units and individual replacement components, such as head mechanisms, gaskets, and float blocks, which are used to restore function to existing equipment. 3G Electric provides access to these parts with specifications and manufacturer part numbers to assist in matching components to the appropriate application. The product range covers common replacement needs for steam and hot water boiler systems, including safety devices that shut off burners when water levels drop, automatic water feeders that maintain proper water levels, and level controls that monitor and regulate liquid levels in tanks and receivers. The availability of individual replacement parts allows for repair rather than full replacement of control units, which can be relevant for maintenance budgets and downtime reduction. 3G Electric's catalog includes McDonnell & Miller SKUs with details such as product type, manufacturer part number, and country of origin, facilitating identification and procurement. The brand's products are used in a variety of settings, from commercial buildings to industrial plants, wherever steam or hot water boilers require reliable water level management. The focus on safety and reliability is evident in the design of low water cut-offs, which are intended to prevent boiler damage and hazardous conditions. 3G Electric supports this line by stocking both common and hard-to-find replacement parts, enabling maintenance teams to address equipment issues efficiently. The combination of McDonnell & Miller's specialized product range and 3G Electric's distribution capabilities provides a resource for maintaining boiler system safety and performance.

Common Applications

• Commercial boiler rooms — McDonnell & Miller low water cut-offs (e.g., Part 69) for steam and hot water boilers to prevent dry-fire.
• Industrial steam systems — McDonnell & Miller water feeders (e.g., 51-S-HD) to maintain water level in low-pressure steam boilers.
• HVAC hydronic heating — McDonnell & Miller level controls (e.g., 63-M) for monitoring liquid levels in expansion tanks and receivers.
• Boiler maintenance and repair — McDonnell & Miller replacement head mechanisms (e.g., 94-HDLS) to restore function to existing controls.
• Process equipment — McDonnell & Miller float blocks (e.g., 64-B) for on/off control of pumps and valves based on liquid level.
• Steam boiler safety — McDonnell & Miller level control tappings (e.g., 63-B) to prevent low-water conditions in commercial and industrial systems.