Water Pipe Installation; Precautions During Installation; Insulation Installation; Water Processing And Water Quality Control - Mitsubishi Electric PQHY-P-YHM-A Serie Manual De Instalación

8. Water pipe installation

City Multi WY/WR2 Series pipes are similar to other air-conditioning pipes,
however, 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
1.0MPa. (2.0MPa for the high water pressure models)
• 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.
• In order to protect the heat source unit, install a strainer on the circulating
water inlet pipe within 1.5 m from the heat source unit.
• Install a suitable air vent on the water pipe. After sending water through the
pipe, be sure to vent the excess air.
• Compressed water may form in the low-temperature sections of heat source
unit. Use a drainage pipe connected to the drain valve at the base of the unit
to drain the water.
• Install a back fl ow-prevention valve on the pump and a fl exible joint to
prevent excess vibration.
•
Use a sleeve to protect the pipes where they go through a wall.
• Use metal fi ttings to secure the pipes, and install them so that they have
maximum protection against breakage and bending.
• Do not confuse the water intake and outlet valves.
•
This unit doesn't have any heater to prevent freezing within tubes. When the
water fl ow is stopped on low ambient, take out the water from tubes.
• The unused knockout holes should be closed and the opening of refrigerant
pipes, water pipes, power source and transmission wires should be fi lled
with putty and so on to prevent from rain. (fi eld construction)
• The drain plug is installed on the unit rear at factory shipment for fi eld-
connection of the drain pipes on the front of the unit. Relocate the plug to the
unit front to connect the drain pipes on the back of the unit. Check that there
are no leaks from pipe connections.
• For 2-unit combination, install water pipes in parallel to each other so that
the water fl ow rate through both units will be equal.
• Wrap the sealing tape as follows.
1 Wrap the joint with sealing tape in the direction of the threads
(clockwise), and do not let the tape run 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 fi ngers so that it is pressed fi rmly
against each thread.
3 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 150 N . m.
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 (upper)
G
Water outlet fl ange (lower)
I

8.2. Insulation installation

With City Multi WY/WR2 Series piping, as long as the temperature range of
the circulating water is kept to average temperatures year-round (30 °C in
the summer, 20 °C in the winter), there is no need to insulate or otherwise
protect indoor piping from exposure. You should use insulation in the following
situations:
• 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.
• Any drainage piping.
8.3. Water processing and water quality
control
To preserve water quality, use the closed type of cooling tower for WY/WR2.
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 of
the hea exchanger. Please pay careful attention to water processing and water
quality control when installing the water circulation system.
18
Shutoff valve
B
Water outlet (lower)
D
Y-type strainer
F
Drain pipe
H
Water inlet fl ange (upper)
J
• Removal of foreign objects or impurities within the pipes.
During installation, be careful that foreign objects, such as welding
fragments, sealant particles, or rust, do not enter the pipes.
• Water Quality Processing
1 Depending on the quality of the cold-temperature water used in the
airconditioner, the copper piping of the heat exchanger may become
corroded.
We recommend regular water quality processing.
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 contact with air 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
Sulfi de 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 Please consult with a water quality control specialist about water quality
control methods and water quality calculations before using anti-
corrosive solutions for water quality management.
4 When replacing a previously installed air conditioning device (even when
only the heat exchanger is being replaced), fi rst 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, please adjust water quality
suffi ciently 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.
Be sure to 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 fl exible cord (design 245 IEC 57).
[Fig. 8.4.1] (P.3)
Short-circuit wire (Connected before delivery from manufacturer)
A
B Pump interlock circuit connection
[Fig. 8.4.2] (P.3)
This circuit is for interlocking of the heat source unit operation and the mater-
circuit pump.
Heat source unit
A
To next unit
C
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.
Lower 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
6.0 ~ 7.0 –
Site control panel
B
Scale-
forming