Install Instructions

41
IM-PR 566442 1114 (Design Manual)
∆L =
PEX expansion rate
100' x 10°F
x ∆T x tubing length ft
Where:
ViegaPEX and ViegaPEX Ultra expansion rate =
1.1" per 100' per 10°F
ViegaPEX Barrier tubing expansion rate =
0.96" per 100' per 10°F
∆T = Change in temperature (in °F)
For example:
40' of 1" ViegaPEX Barrier tubing going from
70°F to 130°F
∆L =
0.96"
1000
x 60° x 40' = 2.30"
∆L = 2.30"
no more than 50 ft. apart.
There are three types of expansion offsets recom-
mended for use with large-diameter PEX tubing:
100'
25'25' 50'
50' 50'
Viega recommends the use of expansion offsets. This
can be accomplished at a corner or by using offsets or
loops on straight tubing runs. Expansion compensa-
tors should be installed at the midway point of tubing
runs and should be spaced no more than 50 ft. apart.
Below is an example of required offsets for a 100-ft.
tubing run. Note that the expansion compensators are
Using a loop to accommodate
tubing expansion
Offsets also provide room for
tubing expansion
Allow some slack in all runs to prevent damage
from tubing contraction.
⅛" to
3
/
16
"
slack per foot
the corner expansion offset, the Z-type expansion
offset and the U-type expansion loop. A descrip-
tion, illustration and dimensional chart for each
type of offset is located in the following pages. See
Page 45 for FostaPEX recommendations.
Tubing fasteners:
Tubing fasteners perform two functions: providing
support for the tubing and guiding the tubing
during expansion and contraction. It is important
to keep this in mind when installing fasteners, as
an expansion compensator will not be effective if
the fasteners prevent linear movement of the piping
system.
Linear expansion:
To calculate linear expansion for PEX tubing use
the following formula:
1.10.2 PEX expansion compensation
ViegaPEX, ViegaPEX Ultra and ViegaPEX Barrier
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.
Tubing sizes smaller than ¾" generally do not require
expansion compensators with fittings and can easily
be bent into loops and offsets to absorb linear expan-
sion.
For unconstrained tubing runs (not within the floor)
Figure 1-32