PEX Installation

IM-PF 724596 0416
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16.4 Noise and water hammer in PEX systems
As with all plumbing materials under some
operating conditions, water hammer can occur in
PEX plumbing systems. The inherent exibility of
ViegaPEX Ultra drastically reduces the magnitude of
pressure surges compared with metallic plumbing
materials. Damage to plumbing components in a
PEX system due to these pressure surges is highly
unlikely, although noise can sometimes result.
Fortunately, there are solutions to minimize or
eliminate water hammer noise.
• Install xtures that are not water hammer prone.
As a general rule, two-handle xtures are less likely
to cause hammer than single-handle xtures. Single-
handle shower valves, which rotate to close and
therefore are difcult to close quickly, might be
good choices.
• Clamping or strapping more frequently may help
prevent tubing noise. It is important that the tubing
not be in contact with wallboard, forced air ducts
or other high-resonance articles. Insufciently
or improperly clamped or strapped tubing may
move during xture operation and hit against
these surfaces.
• Install a water hammer arrester at xtures where
noise is a problem. A water hammer arrester (AA
sized) installed as closely as possible to the xture
on the cold-water side only will eliminate the source
of the noise (the pressure wave). It should be noted
that even with an arrester, tubing that is clamped or
strapped insufciently may still hit against something
as it moves slightly when the water ow is stopped.
• Avoid operating xtures in such a way that causes
near instantaneous shutoff. Simply closing xtures in
a less abrupt manner can eliminate hammer noise.
16.5 Shower valves
PEX lines should only be run to the inlet connections of
tub/shower valves unless specically approved by the
valve manufacturer for other connections.
16.6 Electrical grounding
Neither ViegaPEX Ultra nor FostaPEX tubing may be
used as an electrical ground. Consult the NEC for
recommended grounding method when plastic pipe
is used.
16.7 Expanding foams
When penetrations must be sealed for air inltration
purposes, there are several options available. Use a
good grade of silicone, acrylic or siliconized acrylic
caulking. DO NOT use oil-based caulks. Most
canned expanding foams and open- or closed-cell pipe
insulation are good sealing materials and may be used
in direct contact with PEX tubing. Other materials may
be used provided they do not cause short- or long-term
damage to the PEX tubing.
16.8 Fire Stop compounds
Most building codes require the use of a re-
stopping compound when tubing penetrates a
re-rated wall. There are a number of re-stopping
compounds identied as water based, acrylic or
latex that have been listed for use with PEX tubing
that include but are not limited to the following.
• 3M Fire Protection — CP 25WB+ Caulk
• Tremco, Inc — TREMstop® IA
• Specied Technologies, Inc. — SpecSeal®
SSS 100 / SSS 102
• Passive Fire Protection Partners — Fire Stop
™
4800 DW / 4100 DW / 4100 NS / 3600 EX
It is the responsibility of the user to determine
the suitability of these or any products for the
intended application and install the compounds
in accordance with the product’s installation
instructions and listing.
16.9 Tubing expansion
ViegaPEX Ultra tubing, as with any PEX tubing,
expands and contracts with temperature changes
in the environment or the fluid inside the tubing.
The longer the tubing run and the higher the
temperature change, the more linear expansion
the system will experience. This expansion and
contraction can affect the appearance as well as
integrity of the system by putting stress on the
tubing, fittings, valves and fasteners.
When using expanding spray foam to insulate
walls in a structure, there are several options
available. Viega suggests using water-based or
urethane-based open-cell insulation only. DO NOT use
closed-cell spray foams. Closed-cell spray foams have
the potential to generate high temperatures during their
expansion process, especially when not applied
properly, which can damage PEX tubing. Always follow
the spray foam manufacturer’s installation instructions
and warnings.
Do not expose Viega products to any
foreign substance that includes but is
not limited to Volatile Organic Chemical
(VOC) compounds, paints, solvents,
glues, cleaners and disinfectants. Viega
products that are exposed to these
types of substances are at risk of having
failures (leaks).