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Manifold System

Almost all PEX plumbing is installed using the "home-run" system, where separate hot and cold supply lines for each fixture run back to a central manifold. Several companies supply manifolds for these systems (see "Sources of Supply," page 31), but I prefer to make my own manifolds out of copper and brass components (see Figure 1).

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Figure 1. Standard manifolds are available from PEX suppliers (left), but the author prefers to make his own from copper pipe and brass fittings (right). My shop-built or site-built manifolds cost less than the store-bought brands, give me more flexibility, and are easier to modify if the customer wants to add runs later on. And since I make my manifolds from common materials that are readily available, I don’t have to worry that parts won’t be available if I need them five or ten years from now. Each manifold has a hot and cold main, with fittings as needed for each fixture. We pair up the hot and cold supply for each sink or shower opposite each other, and clearly label each line to show which fixture it serves. Some brands of PEX come in a variety of colors so hot and cold lines can be color-coded; alternatively, we simply mark hot and cold lines with red and blue tape. Each line has its own shutoff valve at the manifold, as well as the usual shutoff valve at the fixture. The hot and cold manifold mains also have individual shutoff valves in case we need to make a repair or expand the system.

Cutting PEX

PEX is best cut with a special scissors-type cutter with a sharp blade (Figure 2).

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Figure 2. PEX tubing can be cut with a special scissorslike tool (left), or simply with a sharp pocketknife. A crisp, square cut is critical for a lasting joint.

With a slight rotation while you squeeze the handles, you have a perfect square cut. Several PEX manufacturers supply various versions of this tool.