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4.
Prevent from getting mixed air into the system
Install the air purge valves at proper positions so that the air
purge of the entire equipment system is possible.
Operation of units with air mixed may lead to deterioration in
performance, actuation of protective devices, or damage of
heat exchanger tubes.
Pay attention to the flow velocity inside the water system,
position of the expansion tank, and to the position of air
purges along the piping, so that cavitations do not occur.
This machine is designed on the precondition that circulating
water is used. Use of once-through water may lead to
damage of the heat exchanger tubes due to dissolved
oxygen or free carbonate in chiller water (hot water) systems.
When using the unit in a heat recovery application, additional
care must be taken that water flow rate does not get
excessive. In the same application, a deaeration treatment
unit must be installed.
Do not allow aeration along the cooling water system as
shown in the following diagram.
Aerating water causes the dissolved oxygen to increase, and
pollutants in the atmosphere condensed in the water cause
the water to become corrosive.
1
2
1
Discharge pipe
2
Inlet pipe
5.
Observing the operation range of the unit
Observe the maximum operating water pressure of the unit.
Pay attention so that the cooling water inlet temperature
reaches 25°C or more.
When you use the unit during intermediate season and
winter season, control the cooling water supply water
temperature by using a thermostat for the cooling water inlet
and a 3-way mixing valve.
Pull-down time of this machine (time required for cooling from
ordinary temperature to reach the recommended operating
range) is within 1 hour under no load condition.
Make sure to prevent the water flow from becoming to high.
To assure proper operation of the unit a minimum water
volume is required in the system and the water flow through
the evaporator must be within the operation range as
specified in
Table
2.
Table 2: Minimum water volume
Minimum water
Model
EWWD440
EWWD600
EWWD850
When it is impossible to secure the minimum holding water
quantity, increase of thermo differential value is required. For
how to change the differential value, see
page 14
and
"Target temperature and low load stop related
settings screen" on page
6.
Prevent corrosion of water piping and of the unit interior
Do not install the earth of the electric equipment to the water
piping. Corrosion due to electric corrosion may occur.
If piping is to be put underground, be extremely careful and
take dust preventive measures.
EWWD440~850AAYNNO**
Packaged water-cooled water chillers
4PW25558-1B
1
2
Water quantity inside the
volume (l)
evaporator (l)
2660
105
3710
110
5020
157
"Settings screen" on
22.
Avoid execution of piping in such a way that a draft line is
formed inside the condenser or evaporator while the unit is
operating or stops.
In case of semi hermetic chilled water system with a thermal
storage tank, perform periodic replacement of water and
cleaning and inspection of the bottom of the thermal storage
tank (once every 1 or 2 years).
A new concrete heat storage tank will give off ions, and it is
not seldom that pH of the heat storage tank water rises
above 10. If pH rises above the standard, the rate at which
copper corrodes increases. The water must be changed
before the pH reaches that level.
If a heat storage tank is used for a prolonged period,
springing and leaking of water could occur due to cracks in
the heat storage tank. Water leaks pose no serious problem
for water quality, but if seawater or dirty underground water
springs, it could cause an outbreak of microorganisms in the
water of the heat storage tank, thus producing slime in the
system. It could also cause calcium carbonate to adhere.
Make sure to perform periodic water quality inspections,
especially as to water quality of the cooling water. Insufficient
water quality may result not only in performance deterioration
of the unit but also in damage to the heat exchanger tubes.
CAUTION
Use
chilled
complies with the water quality standard as in
chapter
"Water quality specifications" on page
Deterioration of water quality may lead to water
leakage and damage to the heat exchanger tubes.
7.
Freeze-up protection
The complete water circuit, inclusive all piping, must be
insulated to prevent condensation and reduction of the
cooling capacity.
Protect the water piping against water freezing during winter
period (e.g. by using glycol solution or heatertape).
CAUTION
Do not confuse the connection of outlet and
inlet of the water piping.
Do not confuse the inlet and outlet of the
chilled water and connection position of the
condenser water.
Normal operation may get impossible.
It may lead to breakdown including freezing
fracture of heat exchanger tubes.
8.
Preventing excessive increase of chilled water and condenser
water temperature
The water pressure should not exceed the maximum
working pressure of 10 bar.
NOTE
Provide adequate safeguards in the water circuit
to make sure that the water pressure will never
exceed the maximum allowable working pressure.
(hot)
water/cooling
water
Installation and operation manual
that
8.
9
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