Installation Guide
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What Is PEX? Why Use PEX?.............................................................................................2
Tools.................................................................................................................................4-12
Fittings..........................................................................................................................13-16
PEX Tubing...............................................................................................................17-18
Plumbing Systems....................................................................................................19-21
Manifolds...........................................................................................................................22-23
INSTALLATION MANUAL
PEX
Which PEX tubing to choose?
PEX-A is the most flexible of all PEX tubing types, has little or no coil memory and gives installer an ability to repair kinks with a heat gun. It has
been in use for over 50 years (which is longer than other types) with few publicly known issues (3), which is a good indicator of reliability. There are
two important downsides to this type. First and foremost is a high rate of chemical leaching – from 50% to over 200% higher than PEX-B (2), which
is a major concern for plumbing applications. Second is the price, which coupled with fittings and tools may become as much as 2-3 times higher
than PEX-B or PEX-C options. While a leading PEX-A manufacturer claims that their tubing has highest resistance to crack propagation, independent
testing (2) shows that PEX-B actually shows the same or higher resistance to long-term oxidation which appears to be the primary reason for crack
formation in the pipes and their subsequent failure. A lower bending radius in PEX-A (6 times the OD vs. 8 times the OD for PEX-B & C) is helpful, but
offers little practical advantage in most cases.
PEX-B is a clear winner in terms of price vs. both other types. It has been in use for over 40 years with no known issues, given that a typical warranty
for any type of PEX is only 20-25 years. It also has a higher bursting pressure than PEX-A and a similar or better resistance to oxidation - a very
important factor for plumbing installations. The major downside of PEX-B is its’ stiffness and coil memory (tendency to return to the original shape
of coil). While there’s little difference in smaller sizes such as 1/2”, larger pipe diameters, especially 1”, can be noticeably harder to bend. Any kinks
(which are very rare in our experience, but still occur) made during the installation can only be repaired by installing a coupling and cannot be
repaired with a heat gun like PEX-A.
Oxygen Barrier PEX (PEX-B) tubing has been designed to prevent diffusion of oxygen into hydronic radiant heating systems. A layer of polymer is
laminated to the outside surface which is highly resistant to the passage of oxygen. Oxygen Barrier PEX tubing is good for hydronic radiant heating,
cooling, and snow melting systems using water or water/glycol mix. The tubing may be installed in concrete, gypsum based lightweight concrete,
sand, asphalt, in or under wood flooring, or behind wallboard or plaster. Oxygen Barrier PEX tubing may also be used as transfer lines for baseboard
heating systems with a maximum operating temperature of 200° F @ 100 psi.
For hot and cold water plumbing as well as for open-loop heating systems, both PEX-A and PEX-B are evident choices, yet the latter offers a more
attractive combination of better health safety, higher durability and lower price.