McDonnell & Miller RB-24E Wiring Harness

The McDonnell & Miller RB-24E (Part Number 144692) is a specialized 24Vac low water cut-off designed for residential hot water boiler applications. This 3/4 inch NPT probe-type LWCO features an automatic reset and an integrated test switch for streamlined diagnostic checks during routine maintenance. The inclusion of the universal wiring harness ensures straightforward integration into existing control circuits, significantly reducing field installation time for contractors. By monitoring the probe's electronic signal, the RB-24E prevents hazardous dry fire conditions, protecting the heat exchanger when water levels drop below the critical threshold. This unit is rated for a maximum pressure of 160 psi and a maximum water temperature of 250°F, making it a reliable boiler safety control for modern hydronic systems. Its compact design allows for installation in tight mechanical spaces, while the plug-in wire harness simplifies electrical connections without requiring manual terminal wiring.

Technical Specifications and Benefits

• Automatic Reset Functionality: Automatically restores boiler operation once the water level returns to a safe operating range above the probe.
• Universal Wiring Harness: Pre-terminated leads facilitate rapid RB-24E wiring to the transformer and gas valve or control board.
• Integrated Test Switch: Allows technicians to verify control logic and burner shutdown without draining the system.
• No Moving Parts: The electronic probe technology eliminates the mechanical failure points associated with traditional float-style cut-offs.
• Compact NPT Connection: Mounts directly into a 3/4 inch tee or boiler tapping for a secure, leak-proof fit.

Common Installation Questions

How do I troubleshoot an RB-24E that is not allowing the burner to fire?
Verify that the probe is clean and free of scale buildup. Ensure the McDonnell & Miller 144692 has a solid 24V supply and that the green LED indicates a safe water level. If the red LED remains lit despite a full system, check the probe-to-ground continuity.

Can the RB-24E be mounted horizontally?
Yes, the probe must be installed horizontally into the side of a pipe or boiler vessel, ensuring it is positioned above the minimum safe water level specified by the boiler manufacturer.

Wait, does this harness work with other RB series controls?
The provided universal wiring harness is specifically designed for the RB-24E and RB-24S models to interface with standard 24V boiler control circuits and 1/4 inch terminal connections.

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.