Used for years in Europe and now gaining popularity in the United States, cross-linked polyethylene pipe (PEX) provides an easy-to-install alternative to standard copper pipe. PEX is lightweight and flexible, making it suitable for running new water lines through existing floors and walls. It withstands freezing extremely well, and will not produce the banging, clattering noises often made by copper lines. PEX connects easily to existing copper lines using simple, push-together fittings that eliminate the need for making difficult soldered joints.
Cut the PEX pipe to the required length using the PEX clamping pipe cutter. Make the cut as square as possible and perpendicular to the length of the pipe. This will ensure a tight connection with the PEX fitting.
Use the standard pipe cutter to cut a clean end on the copper pipe, also making sure the cut is as square and perpendicular as possible. A jagged or twisted metal edge will not make a clean seal with the PEX fitting.
Lightly sand the edges of both cuts with emery paper to remove any burrs or jagged points. Do not over-sand. The burr inside copper or PEX tubing can also be removed with the burr scraper found on most pipe cutters.
Use the ruler and pen to make marks on both pipes 1 inch from the cuts you made, indicating how far down the pipe you need to push the fitting. This distance may vary depending upon the brand of fitting. Double-check the fitting's specifications to make sure you use the right distance.
Holding the copper pipe securely, push one side of the PEX push-together fitting firmly onto the end of the pipe until its edge reaches the pen mark. This indicates that you've made a full connection between pipe and fitting.
Take the end of the PEX pipe and push it firmly into the other side of the fitting, again making sure that the fitting edge reaches the pen line.
Turn on the water to the line and check for leaks. If the PEX transition fitting leaks, shut off the water and use the PEX fitting release tool to remove the fitting from both pipes. Make sure the edges are clean and square, re-sanding lightly if needed, then push both the PEX and copper pipes back into the fitting.