The second commonly used system is the expansion method. This method is used with a proprietary expansion tool and pex tubing which has memory built into the tubing. This method is known as the Wirsbo/Uponor system. The system starts with the Pex-A tubing (Engle). This tubing is hot formed and has the best memory of all 3 tubing types. This method is considered the best method by professionals but because it is a proprietary method it is typically not considered the best method by the “do it yourself” crowd.
The system uses the proprietary tubing, rings, fittings and expansion system.
How this method works is first the plumber slides a ring over the tube. Then the expander tool is inserted into the tube. If it is 1/2 tubing then the expander collar is 1/2 inch. The tube is mechanically expanded. The fitting is inserted and the tube shrinks back down to the original size. Within 10 seconds, the fitting can be pressurized and be ready to go.
Utilizing this system has pretty much the best guarentee of any system used. Since all components of the system are proprietary Wisbo/Uponor are confident to offer a 25 year guarentee if installed by a trained Uponor plumber.
The tubing used is known as Aguapex. The fittings are called ProPex.