INSTALLATION
Commissioning
10
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6.10 Pipework
installation
Use copper or stainless steel pipes or corrugated stainless steel
hoses for the supply and return lines. Pipe diameter is dependent on
the length of the run and expected fl ow rates. Recommended pipe
diameter for systems of up to eight collectors is ¾˝. If the pipe run
is longer than 60 feet (18 m), a larger pipe diameter may be needed.
Flashing is recommended for pipe run penetrations into the roof. On
fl at roofs and roofs with shallow pitches, passing the pipes through
an external wall is recommended to avoid water leaks. Pipe hangers
must provide correct support and angle and must meet building
codes. Hangers must not compress insulation and should allow for
thermal contraction and expansion of the pipework. Installers must
comply with all local, state and national codes.
We recommend trimming pipes with pipe cutters to avoid creating
metal fi lings. Electrically ground the pipework in accordance with
electrical codes. Connect all pipework to the building’s ground over
the shortest possible distance.
All piping in the solar thermal loop must be properly supported
for the expected loads of the system. The piping supports must not
compress the pipe insulation.
The piping is to be run in such a way that the performance of any
fi re rated assembly is not reduced.
6.10.1 Soldered pipe
Soldered pipe must be hard-soldered using 95/5 lead-free solder.
6.10.2 Alternative piping
Piping made with locking ring fi ttings, press fi ttings, and corrugated
hoses must be sealed using suitable sealants. Seals must be resistant
to propylene glycol and temperatures up to 356°F (180°C).
6.11 Thermal
insulation
All exterior piping also requires UV and moisture protection. Insu-
lation must be resistant to temperatures up to 356°F (180°C).
A rigid aluminum sheath is recommended as protection for the
mineral wool. The EPDM hose can be fi nished with UV-resistant
paint. Where required, protect the thermal insulation against birds
or rodents. Insulate all lines of the solar loop. Apply the thermal
insulation after pressure testing and checking the system for leaks.
Extremely cold climates that experience nighttime winter temperatu-
res below -30°F (-34.4°C) may need thicker pipe insulation to prevent
pipe freeze-ups or slushing of the antifreeze mixture.
Minimum Insulation Thickness
Diameter of Pipe
Minimum thickness of insulation layer
Less than ¾˝
¾˝
¾˝ to 1 ¼˝
1˝
1 ¼˝ to 4˝
Identical to pipe diameter
Greater than 4˝
4
˝
7. Commissioning
7.1
Pressure and leak test
After the pipe work has been installed and the collectors have been
connected it will be necessary to pressure-test the system to detect
leaks before fi lling the solar loop with heat transfer fl uid. Propylene
glycol solutions can leak from much smaller gaps than can water; so
such testing is critical to assuring a successful installation. Recom-
mended test pressure is 80 psi. Thermal pipe insulation should be
installed only after the leak test has been successfully completed.
It is recommended that compressed air be used to test the system
for leaks, as it is very easy to make repairs and it will prevent loss of
solar medium, spills, property damage, and messy clean-up prob-
lems. Air is also capable of revealing very small leaks that water may
not reveal, through which propylene glycol will often leak. Leaks will
be evident from the sound of escaping air, observation of bubbles
emanating from fi ttings and other leak-prone components that are
coated with soapy water, and watching the pressure gauge over
time. Bear in mind that the pressure gauge will vary some based
on temperature of the air, so one must try to read the pressure
at nights when the system cools down to ambient temperature or
when covered.
7.2
Expansion tank pre-charge pressure
While the leak testing is being performed, the installer should set
the expansion tank’s pre-charge pressure. Make sure that the “wet”
side of the expansion tank (pipe connection) is vented to atmosphere.
Using a compressor, pre-charge the tank with air (or use pressurized
nitrogen) to a fi nal pressure of 5 psi (350 mbar) less than the target
system pressure. For example, if the fi nal target system (solar loop)
pressure is to be 50 psig (3.45 bar), fi ll the expansion tank to 45 psig
(3.1 bar), which is the recommended default value. When complete,
cap the Schrader valve fi tting and reattach the tank to the pump
station. Make sure the expansion tank always faces up (the Schrader
valve must bepointed down).
7.3
Charging & venting
!
WARNING:
Freeze tolerance limits are based upon an assumed set
of environmental conditions. This manual assumes prod-
uct installation in North America and the reasonable
range of weather conditions encountered there. Extend-
ed periods of cold weather, including ambient air tem-
peratures above the specifi ed limit, may cause freezing
in exposed parts of the system. It is the owner’s respon-
sibility to protect the system in accordance with Stiebel
Eltron’s instructions if the air temperature is anticipated
to approach the specifi ed freeze tolerance limit.
The solar heating system must be fi lled exclusively with the pre-
mixed propylene glycol heat transfer medium. Stiebel Eltron glycol
containers have been premixed and require no further treatment.
Never mix water with the heat transfer fl uid, otherwise the essential
characteristics and corrosion protection can no longer be guaran-
teed.
