Matco-norca dun-759mlf 3/4 Inch Mxc Dielectric Union

Product Description

The MATCO-NORCA dun-759mlf is a 3/4-inch dielectric union designed to isolate dissimilar metals in a piping system and prevent galvanic corrosion at the joint. It features a male-by-coupling (MxC) end configuration, making it suited for connecting copper, steel, or other metallic pipe materials where electrochemical separation is required. Dielectric unions like this one are standard components in residential and commercial plumbing and mechanical systems, particularly at water heater connections and where ferrous and non-ferrous piping meet. Licensed plumbers and pipefitters install this fitting as part of code-compliant piping assemblies.

This fitting is commonly used at domestic water heater inlets and outlets, boiler supply and return connections, and other points in a plumbing or hydronic heating system where two different pipe metals join. The 3/4-inch size covers the most common residential and light-commercial water heater connection size. The MxC configuration accommodates threaded male pipe on one end and a coupling connection on the other, providing installation flexibility in tight or retrofit situations.

Key Features

• Dielectric insulation isolates dissimilar metals to prevent galvanic corrosion
• 3/4-inch size fits the most common residential water heater and boiler connection diameter
• Male-by-coupling (MxC) end configuration for versatile installation in threaded piping systems
• OEM-style replacement or new-installation fitting for plumbing and hydronic applications

Compatibility

Designed as an OEM-style replacement or new-installation dielectric union for residential and light-commercial plumbing and hydronic heating systems requiring a 3/4-inch MxC dielectric connection.

Installation Notes

Installation should be performed by a licensed plumber in accordance with the applicable edition of the International Plumbing Code (IPC) or local plumbing code. Shut off the water supply and relieve system pressure before disassembling any piping joint. Use thread sealant or PTFE tape rated for potable water on all threaded connections. Do not overtighten the union nut, as excessive force can crack the dielectric sleeve and compromise electrical isolation.

Technical Specifications

• Size: 3/4 inches
• End Configuration: Male x Coupling (MxC)
• Type: Dielectric Union
• UPC: 082647092426

Standard Information

• Brand: MATCO-NORCA
• Manufacturer Part Number: dun-759mlf