Ay Mcdonald 4423-390 Pex-a Poly Insert Tee

Product Description

The AY MCDONALD 4423-390 is a PEX-A poly insert tee fitting used to create branch connections in PEX-A tubing systems. With a 0.5-inch by 0.5-inch by 0.75-inch configuration, this tee allows a run line to continue at the same diameter while expanding the branch outlet to 0.75 inches. The poly insert design is compatible with PEX-A expansion-style installations and provides a corrosion-resistant alternative to brass fittings. Plumbers and pipefitters use this type of fitting in residential and light commercial water distribution, radiant heating, and hydronic systems.

This fitting is suited for installations where a PEX-A main line needs to be teed off with a larger-diameter branch, a common configuration in domestic hot and cold water supply runs. The insert-style design seats inside the PEX-A tubing and is typically secured using a PEX expansion tool and expansion rings rather than crimp rings. It is appropriate for in-wall, under-slab, and mechanical room applications where a durable, non-metallic fitting is preferred.

Key Features

• Poly insert construction resists corrosion and scale buildup in water distribution systems
• 0.5 x 0.5 x 0.75 inch reducing tee configuration allows branch upsizing without additional reducers
• Designed for use with PEX-A tubing and the expansion-style connection method
• Lightweight polymer body suitable for concealed and mechanical room installations

Compatibility

Designed as an OEM-style replacement and new-installation fitting for PEX-A tubing systems using the expansion connection method.

Installation Notes

Installation should be performed by a licensed plumber in accordance with local plumbing codes and the IPC. Shut off the water supply and depressurize the line before cutting into existing tubing. Use a calibrated PEX expansion tool sized to the tubing diameter when seating expansion rings. Do not use this fitting with PEX-B or PEX-C tubing without verifying manufacturer compatibility, as insert dimensions and connection methods differ.