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83
8. SYSTEM DESIGN GUIDE
WR2-Series-575V
8-2. Water piping work
pH (25°C[77°F])
Electric conductivity
Chloride ion
(mg Cl
-
/
)
Sulfate ion
(mg SO
4
2-
/
)
Acid consumption (pH4.8)
(mg CaCO
3
/
)
Total hardness
(mg CaCO
3
/
)
Calcium hardness (mg CaCO
3
/
)
Ionic silica
(mg SiO
2
/
)
Iron
(mg Fe/
)
Copper
(mg Cu/
)
Sulfide ion
(mg S
2-
/
)
Ammonium ion
(mg NH
4
+
)
Residual chlorine
(mg Cl/
)
Free carbon dioxide
(mg CO
2
/
)
Ryzner stability index
Standard
items
Refer-
items
Items
Lower mid-range
temperature water system
7.0 ~ 8.0
30 or less
[300 or less]
50 or less
50 or less
50 or less
70 or less
50 or less
30 or less
1.0 or less
1.0 or less
not to be
detected
0.3 or less
0.25 or less
0.4 or less
–
7.0 ~ 8.0
30 or less
50 or less
50 or less
50 or less
70 or less
50 or less
30 or less
0.3 or less
0.1 or less
not to be
detected
0.1 or less
0.3 or less
4.0 or less
–
Tendency
Recirculating
water
[68<T<140°F]
[20<T<60°C]
Make-up
water
Corrosive
Scale-
forming
Reference : Guideline of Water Quality for Refrigeration and Air Conditioning
Equipment. (JRA GL02E-1994)
(mS/m) (25°C[77°F])
(μS/cm) (25°C[77°F])
ence
/
[300 or less]
Shutoff
valve
Main circulating
water pipe
Water inlet (lower)
Water outlet
(upper)
Drain pipe
Refrigerant
pipes
Shutoff valve
Y-type
strainer
Installation example of heat source unit
Although the water piping for the CITY MULTI WR2 system does not differ from that for ordinary air conditioning systems,
pay special attention to the items below in conducting the piping work.
1) Items to be observed on installation work
• The water pressure resistance of the water pipes in the heat
source unit is 2.0MPa [290psi].
• In order to equalize piping resistance for each unit, adapt
the reverse return system.
• Mount a joint and a valve onto the water outlet/inlet of the
unit to allow for maintenance, inspection and replacement
work. Be sure to mount a strainer at the water inlet piping
of the unit. (The strainer is required at the circulation
water inlet to protect the heat source unit.)
* The installation example of the heat source unit is shown right.
• Be sure to provide an air relief opening on the water piping
properly, and purge air after feeding water to the piping system.
• Condensate will generate at the low temperature part inside
the heat source equipment. Connect drain piping to the drain
piping connection located at the bottom of the heat source
equipment to discharge it outside the equipment.
• Mount a backflow prevention valve and a flexible joint for
vibration control onto the pump.
• Provide a sleeve to the penetrating parts of the wall to
prevent the piping.
• Fasten the piping with metal fitting, arrange the piping not
to expose to cutting or bending force, and pay sufficient
care for possible vibration.
• Be careful not to erroneously judge the position of the inlet
and outlet of water.
(Lower position : Inlet, Upper position : Outlet)
• When connecting heat source unit water piping and water
piping on site, apply liquid sealing material for water
piping over the sealing tape before connection.
• This unit doesn’t include a heater to prevent freezing within tubes.
If the water flow is stopped on low ambient, drain the water out.
• The unused knockout holes should be closed and the
refrigerant pipes, water pipes, power source and transmis-
sion wires access holes should be filled with putty.
• The drain plug is installed on the back of the unit at factory for
field-connection of the drain pipes on the front of the unit.
Move the plug to the front to connect the drain pipes on the
back. Verify that there are no leaks from pipe connections.
• For installing two units, install water pipes in parallel to each other
so that the water flow rate through both units will be equal.
• Wrap the sealing tape as follows.
Wrap the joint with sealing tape in the direction of the threads
(clockwise), and do not let the tape run over the edge.
Overlap the sealing tape by two-thirds to three-fourths of
its width on each turn. Press the tape with your fingers so
that it is pressed firmly against each thread.
Leave the 1.5th through 2nd farthest threads away from
the pipe end unwrapped.
• Hold the pipe on the unit side in place with a spanner
when installing the pipes or strainer. Tighten screws to a
torque of 150N·m.
• Consider the circulating-water temperature and the water
pressure range when deciding on the piping specifications.
2) Thermal insulation work
Thermal insulation or anti sweating work is not required for the
piping inside buildings in the case of the CITY MULTI WR2
system if the operating temperature range of inlet water stays
within the temperature near the normal (summer : 30°C[86°F],
winter : 20°C[68°F]).
In case of the conditions below, however, thermal insulation is required.
• Use of well water for heat source water
• Outdoor piping portions
• Indoor piping portions where freezing may be caused in winter
• A place where vapor condensation may be generated on piping
due to an increase in dry bulb temperature inside the ceiling
caused by the entry of fresh outdoor air
• Drain piping portions
3) Water treatment and water quality control
To preserve water quality, use the closed type of cooling
tower for WY/WR2. In the case that an open type cooling
tower is employed or the circulating water quality is
inferior, scale will adhere onto the water heat exchanger
leading to the decreased heat exchange capacity or the
corrosion of the heat exchanger. Be sufficiently careful for
water quality control and water treatment at the installa-
tion of the circulation water system
• Removal of impurities inside piping
Be careful not to allow impurities such as welding
fragment, remaining sealing material and rust from mixing
into the piping during installation work.
• Water treatment
The water quality standards have been established by the
industry (Japan Refrigeration, Air Conditioning Industry
Association, in case of Japan) for water treatment to be
applied.
a)
b)
c)
0000006382.BOOK 83 ページ ２０２１年７月１９日 月曜日 午後４時１４分
