Free Technical Information for Building Inspectors, Contractors and Consumers. Code and Manufacturer's Information Resource
PEX
WHAT's THE CODE SAY? :
Cross-linked polyethylene plastic (PEX) piping shall:
* Comply with the adopted code
*be installed in accordance with the manufacturer's instructions
End cuts shall be cut square and free of burrs.
Crimp rings shall be 1/8-inch to 1/4-inch from end of tubing.
Crimp rings shall not have multiple crimps.
Crimp ring shall be perpendicular to centerline of tubing.
Check each crimp with GO/NO-GO GAUGE.
Incorrectly crimped fittings shall be cut out and replaced.
Contraction: allow 1/8-inch slack per foot of PEX tubing.
PEX may be loosely bundled (NOT TAPED).
Do not bend PEX tubing tighter that the recommended minimum
bending radius.
Install a minimum 18-inches of metallic or other approved material
piping between water heater and PEX tubing.
JOINTS AND CONNECTIONS
GENERAL RECOMMENDATIONS
PEX must be free of gouges, cuts, deep scratches, tar, kinks, grease, flux, and fading or discoloration.
Protective sleeves or bushings shall be used with metal studs.
Use clamps or straps at tubing bends directly from connections.
Horizontal support shall be 32-inches minimum.
Vertical tubing shall be supported at every floor, and at the mid-point between floors.
Supports/clamps shall not restrict the movement of PEX tubing.
Supports/clamps shall not pinch, cut, kink, or damage tubing.
Use only hangers and straps recommended for plastic tubing.
Tubing passing through slabs or foundations shall have a protective sleeve.
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Tubing must be anchored securely enough to support the tubing, yet relaxed enough to allow the tubing to expand and contract. 1) Along horizontal runs, install supports every 32” or less. 2) Along vertical runs, install supports every 48”, at each floor, and as a mid-story guide.
PIPE SUPPORT SPACING
WOOD STUD INSTALLATION
When PEX is installed through wood studs striker plates should be installed to protect
tubing during construction and drywall installation (see illustration).
The tubing does not require sleeving when installed in wood studs if adequate clearance is
provided. Should concern exist regarding chaffing or movement steel stud installation
practices may be utilized.
PENETRATING FOUNDATION WALLS
It is recommended when entering or exiting a foundation that a rigid piping material be
used to protect the tubing from being pinched or chaffed during expansion and contraction
of the foundation material.
INSTALLING PEX IN A SLAB
1) Secure tubing to wire mesh or rebar using plastic ties at the intervals necessary to keep
the tubing from floating up during the pour.
2) When PEX enters or exits a slab the tubing should be sleeved to provide protection.
Pipe insulations rigid plastic conduit may be used. If 90° metal bend supports are utilized at
a slab penetration these also should be sleeved.
3) If the tubing runs through an expansion joint, it must be sleeved or dipped below the joint and sleeved.
4) Fittings should not be buried directly in the slab or underground. A single continuous run of tubing should be used from entry to exit.
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Installation
PEX pipes are a lot cheaper than that copper pipes that had been previously used in plumbing systems and also present distinct advantage when it comes to installing PEX pipe. As PEX pipes are more flexible, it is easier to install them than other materials and also requires fewer connections and fittings to keep it in place.
For example, in order for the pipe to turn a corner, it would have been necessary to connect two lengths of pipe at a 90 degree angle in the past. However, PEX pipe will bend around the corner without causing a weakness in the system. As a result, it takes very little time to install in comparison to metal or rigid piping.
There are only 5 steps to follow when installing PEX pipe:
1. Measure the area that the piping system has to cover. It may be logical to follow the previous system. When installing the PEX pipe cut it to size, measuring carefully and taking into account that it can go round corners and thus very few connections are needed. Make sure that all edges are even before moving on.
2. Lay the pipes where they will eventually be fitted so that any discrepancies in size can be dealt with immediately.
3. If all is well with the layout, insert the first PEX pipe into a standard fitting to begin the system. The fitting will probably already be present. If not, choose a PEX adaptor to ensure that an airtight seal is formed around the pipe before proceeding.
4. Once the airtight seal is in place, bend or connect the rest of the PEX pipe until the system is in place. If connecting one length of pipe to another, use a copper crimp ring. The fitting is slotted inside the pipe and the copper crimp ring is inserted over the pipe. It is them fastened using PEX crimp tools. The connection should be tight and unmovable before you move onto the next length.
5. Finally, run water through the pipes to make sure that the connections are tight and that there are no overall weaknesses before using it as a main system. This gives you chance to detect and problems and solve them before the system is put into use
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For more information go to :
http://www.ppfahome.org/pex/faqpex.html
