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8. Water pipe installation
Please observe the following precautions during installation.
8.1. Precautions during installation
• The water pressure resistance of the water pipes in the heat source unit is
2.0MPa [290psi].
• Use the reverse-return method to insure proper pipe resistance to each unit.
• Provide some joints and bulbs around inlet/outlet of each unit for easy
maintenance, checkup, and replacement.
• To protect the heat source unit, install a strainer on the circulating water inlet
pipe within 1.5 m [4-7/8in] from the heat source unit.
• Install a suitable air vent on the water pipe. After flowing water through the
pipe, vent any excess air.
• Water may collect in the low-temperature sections of heat source unit. Add a
drainage pipe to the drain valve at the base of the unit to drain the water.
• Install a back flow-prevention valve on the pump and a flexible joint to
prevent excess vibration.
• Use a sleeve to protect the pipes at the point where they go through a wall.
• Secure the pipes with metal fitting, positioning them in locations to protect
pipes against breakage and bending.
• Do not confuse the water intake and outlet valves.
• 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 transmission 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 sealing tape as follows.
1 Wrap the joint with sealing tape following the direction of the threads
(clockwise), do not wrap the tape over the edge.
2 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 tight against each
thread.
3 Do not wrap the 1.5th through 2nd farthest threads away from the pipe
end.
• Hold the pipe on the unit side in place with a spanner when installing the
pipes or strainer. Tighten screws to a torque of 150 N . m (1500kg·cm).
• When connecting heat source unit water piping and on site water piping,
apply liquid sealing material for water piping over the sealing tape before
connection.
Example of heat source unit installation (using left piping)
[Fig. 8.1.1] (P.3)
Main circulating water pipe
A
Shutoff valve
C
Refrigerant pipes
E
Water inlet (lower)
G
8.2. Insulation installation
As long as the temperature range of the circulating water is kept to average
temperatures year-round (30 °C [86 °F] in the summer, 20 °C [68 °F] in the
winter), there is no need to insulate the indoor piping. Insulation should be
installed in the following situations:
• On any heat source piping.
• Indoor piping in cold-weather regions where frozen pipes are a problem.
• When air coming from the outside causes condensation to form on piping.
• On any drainage piping.
8.3. Water processing and water quality
control
To preserve water quality, use the closed type of cooling tower. When the
circulating water quality is poor, the water heat exchanger can develop scales,
leading to a reduction in heat-exchange power and possible corrosion. Pay
careful attention to water processing and water quality control when installing
the water circulation system.
• Removing of foreign objects or impurities within the pipes.
During installation, make sure that foreign objects, such as welding
fragments, sealant particles, or rust, do not enter the pipes.
24
Shutoff valve
B
Water outlet (upper)
D
Y-type strainer
F
Drain pipe
H
• Water Quality Processing
1 Depending on the quality of the cold-temperature water used in the air
conditioner, the copper piping of the heat exchanger may corrode.
Regular water quality processing is recommended.
Cold water circulation systems using open heat storage tanks are
particularly prone to corrosion.
When using an open-type heat storage tank, install a water-to-water heat
exchanger, and use a closed-loop circuit on the air conditioner side. If a
water supply tank is installed, keep air contact to a minimum, and keep
the level of dissolved oxygen in the water no higher than 1mg/ℓ.
2 Water quality standard
Items
pH (25°C) [77°F]
Electric conductivity (mS/m) (25°C) [77°F]
(μ s/cm) (25°C) [77°F]
Chloride ion
(mg Cl-/ℓ)
Sulfate ion
(mg SO4
Standard
items
Acid consumption (pH4.8)
(mg CaCO
Total hardness
(mg CaCO
Calcium hardness (mg CaCO
Ionic silica
(mg SiO
Iron
(mg Fe/ℓ) 1.0 or less
Copper
(mg Cu/ℓ) 1.0 or less
Sulfide ion
(mg S
Refer-
ence
Ammonium ion
(mg NH
items
Residual chlorine
(mg Cl/ℓ) 0.25 or less
Free carbon dioxide
(mg CO
Ryzner stability index
Reference : Guideline of Water Quality for Refrigeration and Air Conditioning
Equipment. (JRA GL02E-1994)
3 Consult with a specialist about water quality control methods and
calculations before using anti-corrosive solutions.
4 When replacing a previously installed air conditioning device (even when
only the heat exchanger is being replaced), first conduct a water quality
analysis and check for possible corrosion.
Corrosion can occur in cold-water systems even if there has been no
prior signs of corrosion.
If the water quality level has dropped, adjust water quality before
replacing the unit.
8.4. Pump interlock
The heat source unit may become damaged if it is operated with no water
circulating through the pipes.
Interlock unit operation and the water-circuit pump. Use the terminal
blocks for interlocking (TB8-1, 2, 3, 4) that can be found on the unit.
In the case of a pump interlock circuit signal connection to the TB8-3, 4, remove
the short-circuit wire. Also, use pressure valve 63PW with a minimum current of
5mA or less to prevent miss detection due to poor connection.
Pump interlock cords of parts of appliances for heat source use shall not be
lighter than polychloroprene sheathed flexible cord (design 245 IEC 57).
[Fig. 8.4.1] (P.3)
Short-circuit wire (Connected before delivery from manufacturer)
A
Pump interlock circuit connection (field-supplied)
B
[Fig. 8.4.2] (P.3)
This circuit is for interlocking of the heat source unit operation and the water-
circuit pump.
Heat source unit
A
To next heat source unit
C
X
: Relay
TM1, 2 : Timer relay (closes after elapsing the set time when it is
powered, while opens promptly when it is not powered)
52P
: Magnetic contactor for water circuit pump
MP
: Water circuit pump
MCB
: Circuit breaker
* Remove the short circuit wire between 3 and 4 when wiring to TB8.
* Use an insulated ring terminal to connect the wiring to TB8.
Low to mid-range
Tendency
temperature water system
Recirculating
water
Make-up
Corrosive
[20<T<60°C]
water
[68<T<140°F]
7.0 ~ 8.0
7.0 ~ 8.0
30 or less
30 or less
[300 or less]
[300 or less]
50 or less
50 or less
/ℓ)
50 or less
50 or less
2-
50 or less
50 or less
/ℓ)
3
/ℓ)
70 or less
70 or less
3
/ℓ)
50 or less
50 or less
3
/ℓ)
30 or less
30 or less
2
0.3 or less
0.1 or less
not to be
not to be
/ℓ)
2-
detected
detected
/ℓ) 0.3 or less
0.1 or less
+
4
0.3 or less
/ℓ) 0.4 or less
4.0 or less
2
–
–
Control panel (field-supplied)
B
Scale-
forming
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