A new PEX compression adapter made of PP-R and lead-free brass allows installers to easily transition between Aquatherm and PEX in potable water and radiant systems. The new lead-free adapter is manufactured to meet ASTM F1960. A new male-end design allows installers to fuse directly into fusion outlets, making it quicker and easier to install. The PEX adapter is available in ½-, ¾-, and 1-inch diameters. Unlike the existing Aquatherm PEX crimp adapter, which has a socket connection and requires fusion to pipe, the new compression adapter has a street connection that can be welded directly into an Aquatherm fitting, providing greater ease of use. It uses an expander ring and clamp connection.