
All connections in the PEX piping runs shall be
approved by the PEX manufacturer for potable
water piping.
•
The system shall have a pressure-only relief valve
installed at the drainback tank location or shall be
vented to the atmosphere. The pressure rating for
the relief valve shall be no less than 25 psi and no
more than 50 psi.
The collector loop pipe sizing must be adequate-
ly sized to handle the design flow rates for the
collector(s). SunEarth recommends ¾” nominal
diameter pipe sizes for two collector systems and
½” nominal diameter pipe sizes for two collector
systems, except for the return piping from the col-
lector to the drainback reservoir, this should always
be ¾” or larger.
CAUTION:
The solar loop piping from the
collector(s) to the drainback tank must be no less
than 3/4” TYPE-M copper tube to allow air to
migrate up the tube ensuring full draining of the
collector(s) and tubes.
It may be necessary to increase the pipe size for lon-
ger pipe runs or reduce the pipe size for shorter runs
or higher efficiency pumps. The pipe must be large
enough that the velocity of the water in the pipe does
not exceed 4 ft/s. Hot water flowing at over 4 ft/s
in a pipe will erode the pipe and reduce system life.
When more than one collector is used in the system,
the collectors should be plumbed in a reverse return
piping arrangement in order to maintain equal flows
through all collectors in the array during normal
operation.
To ensure proper drainage of the collector array
and solar loop piping the lines must be adequately
sloped to drain back to the drainback reservoir.
Figure 6 illustrates correct and incorrect methods of
plumbing the solar collector array. Note that water
will trap in the “U” section of piping as illustrated
in the drawing marked incorrect thus making it sus-
ceptible to freeze damage.
Piping in new solar installations can be covered with
dirt, grease, solder flux or other impurities that may
P.9
Supply Line
1” CC CAP
1” CC COUPLING
1” x ¾” CC 90° ELBOW OR COUPLING
RETURN LINE
1” x ¾” CC 90° ELBOW OR COUPLING
1” CC CAP
1” CC COUPLING
COLLECTOR PLUMBING - SLOPED TO DRAIN
fig. 6