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Connections and Manifold Distribution

Each PEX manufacturer uses slightly different types of connections. The product that I use, Wirsbo's Aquapex, works by slipping a reinforcing collar over cut ends and then expanding pipe openings with a special tool. After the opening is expanded, the tool is disengaged and a fitting can be quickly slipped in before the PEX material naturally contracts back to its original diameter (Figure 7).

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Figure 7. Wirsbo's PEX connects to brass fittings using a proprietary expansion tool bit (top). The cut end of the PEX is expanded, the fitting slides into place (bottom), and within seconds, the PEX contracts back to its original diameter. Rings placed outside the cut end ensure strong, leak-free connections.

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A wide variety of transition pieces are available for special connections, such as where the service entrance connects to PEX. Manifolds are often used to distribute the various primary supply lines just after the point where the main entrance line splits at the water heater. Stock manifolds are available or installers can assemble their own using common plumbing materials. Manifolds, however, are not required. They tend to be common on new construction where a separate line or home run is piped to every wet room in a house. On repipes, however, the idea is to limit the number of runs to minimize damage to finished surfaces. With just a few primary runs, it's usually possible to use common tee or wye fittings where secondary lines branch off or 90-degree elbows for getting around tight turns. Because PEX is vulnerable to UV light, it can't be used outdoors. And because it lacks rigidity, it also shouldn't be used for hose bibbs or shower risers. I use copper in these situations. Shower risers are not usually affected by aggressive water because they air out when they're not in use. And the hose bibbs are relatively easy to repair if they wear out prematurely. Garry Gage runs a plumbing company in Rialto, Calif.