How to Make PEX Connections

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Cross-linked polyethylene (PEX) is growing quickly in acceptance as a supply pipe for residential plumbing.

 

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Overview

Cross-linked polyethylene (PEX) is growing quickly in acceptance as a supply pipe for residential plumbing. It’s not hard to understand why. Developed in the 1960s but relatively new to the United States, this supply pipe combines the ease of use of flexible tubing with the durability of rigid pipe. It can withstand a wide temperature range (from subfreezing to 180° F); it is inexpensive; and it’s quieter than rigid supply pipe.
PEX is flexible plastic (polyethylene, or PE) tubing that’s reinforced by a chemical reaction that creates long fibers to increase the strength of the material. It has been allowed by code in Europe and the southern United States for many years, but has won approval for residential supply use in most major plumbing codes only recently. It’s frequently used in manufactured housing and recreational vehicles and in radiant heating systems. Because it is so flexible, PEX can easily be bent to follow corners and make other changes in direction. From the water main and heater, it is connected into manifold fittings that redistribute the water in much the same manner as a lawn irrigation system.
For standard residential installations, PEX can be joined with very simple fittings and tools. Unions are generally made with a crimping tool and a crimping ring. You simply insert the ends of the pipe you’re joining into the ring, then clamp down on the ring with the crimping tool. PEX pipe, tools, and fittings can be purchased from most wholesale plumbing suppliers and at many home centers. Coils of PEX are sold in several diameters from 1⁄4" to 1". PEX tubing and fittings from different manufacturers are not interchangeable. Any warranty coverage will be voided if products are mixed.
PEX pipe is a relatively new water supply material that’s growing in popularity in part because it can be installed with simple mechanical connections.From: The Complete Guide to Plumbing, 978-1-58923-378-2

What You'll Need

Tools:

Tape measure
Felt-tipped pen
Full-circle crimping tool
Go/no-go gauge
Tubing cutter
PEX pipe
Manifolds
Protector plates
PEX fittings
Utility knife
Plastic hangers
Crimp ring

Materials:

Tape measure
Felt-tipped pen
Full-circle crimping tool
Go/no-go gauge
Tubing cutter
PEX pipe
Manifolds
Protector plates
PEX fittings
Utility knife
Plastic hangers
Crimp ring

 

Step 1

How to Make PEX Connections

Cut the pipe to length, making sure to leave enough extra material so the line will have a small amount of slack once the connections are made. A straight, clean cut is very important. For best results, use a tubing cutter.


Step 2

How to Make PEX Connections

Inspect the cut end to make sure it is clean and smooth. If necessary, deburr the end of the pipe with a sharp utility knife. Slip a crimp ring over the end.


Step 3

How to Make PEX Connections

Insert the barbed end of the fitting into the pipe until it is snug against the cut edges. Position the crimp ring so it is 1⁄8" to 1⁄4" from the end of the pipe, covering the barbed end of the fitting. Pinch the fitting to hold it in place.


Step 4

How to Make PEX Connections

Align the jaws of a full-circle crimping tool over the crimp ring and squeeze the handles together to apply strong, even pressure to the ring.


Step 5

How to Make PEX Connections

Test the connection to make sure it is mechanically acceptable, using a go/no-go gauge. If the ring does not fit into the gauge properly, cut the pipe near the connection and try again.


Step 6

How to Plumb a PEX Water-Supply System

Install copper manifolds (one for hot and one for cold) in an accessible location central to the fixtures. The manifold should have one outlet for each supply line it will support (fixtures that require hot and cold supply will need a separate outlet for each). Run supply lines from the water heater and water main to the copper manifolds. Connect the supply pipes to the manifolds with crimp fittings.


Step 7

How to Plumb a PEX Water-Supply System

A manifold may be attached vertically or horizontally, but it must be anchored with correctly sized hangers screwed to the framing members.


Step 8

How to Make PEX Connections

Starting at each fixture (and leaving at least 12" of extra pipe exposed), run appropriately sized PEX through holes in the framing to the manifolds. Pipes may be bundled together loosely with plastic ties. Protect the line with a nailing plate at each stud location. Be sure to leave some slack in the supply lines.


Step 9

How to Plumb a PEX Water-Supply System

Support the pipe with a plastic hanger near every floor or ceiling and midway up vertical runs. Also use hangers to guide pipe near the beginnings and ends of curves and near fittings. Use a plastic guide for sharp curves (inset). Do not bend PEX so sharply that it kinks.


Step 10

How to Plumb a PEX Water-Supply System

Cut each branch supply line to length (leave some extra in case you need to recrimp). Install shutoff valves for each outlet (most manifolds come with preattached valves). Connect the PEX branch supply lines to the shutoff valves. Label each pipe. Use
a short length of PEX and a plug to seal any unused outlets (inset).


 
 

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