PEX-Aluminum-PEX, or PEX-AL-PEX, is PEX tubing with an embedded layer of aluminum. The aluminum serves as an oxygen barrier and keeps the tubing rigid. PEX-AL-PEX undergoes less linear expansion than standard PEX tubing. PEX-AL-PEX has a larger diameter than standard PEX, and does not work with the same fittings.
There are few options for fittings with PEX-AL-PEX. Standard PEX-AL-PEX tubing only works with PEX-AL-PEX compression fittings and Uponor’s MLC press fittings.
Viega’s FostaPEX PEX-AL-PEX is not sized the same as standard PEX-AL-PEX. FostaPEX only works with Viega’s PEX Press fitting system. PEX Press fittings are also compatible with standard PEX tubing, but not PEX-AL-PEX.
