PEX vs PEX-Al-PEX Pipe

Hydronic PEX

PEX is the acronym for "cross-linked polyethylene"

Cross-linked polyethylene pipe is not designed to be used in situations where  temperatures that exceed 200 degrees Fahrenheit!

Which is the limitation of cross linked polyethylene.

For applications where temperatures can exceed 200 degrees Fahrenheit use copper pipe

PEX for potable water does not require an "Oxygen Barrier".

Hydronic PEX (also referred to as Oxygen Barrier PEX) uses a coating that is applied to the surface of the PEX pipe which provides the oxygen barrier to the heat transfer fluid, used in the Hydronic heating system.

The coating is typically either clear or tinted red.

Hydronic PEX piping has to be protected from the sun!

As Ultra Violet rays will deteriorate the oxygen barrier!

In contrast PEX-Al-PEX is the acronym for PEX-Aluminum-PEX, which refers to the alternating layers of cross-linked polyethylene and aluminum used in the manufacturing process of the pipe.

The principle of the manufacturing process of PEX-Al-PEX is that the aluminum layer acts as the oxygen barrier for the heat transfer fluid being used in the Hydronic heating system.

Head Loss for PEX pipe is typically higher then PEX-Al-PEX pipe.

PEX pipe of 1" nominal O.D., actually measures 1.125" outside diameter, .863" inside diameter and a .125" wall thickness, with a 10 gpm flow rate has a 6.2 psi head loss per 100' of pipe compared to  1" PEX-Al-PEX with a 10 gpm flow rate and 2.49 psi head loss per 100' of pipe.

As such you have to use the 1-1/4" nominal O.D. much more expensive Hydronic PEX pipe to match the flow of 1" PEX-Al-PEX pipe.

PEX-Al-PEX