2-1
2. OPERAING PRECAUTIONS
(1) Stop timing of auxiliary equipments
During the dilution cycle operation of the Chiller, the chilled water pump (both the primary side and
the secondary side) and air handling unit must be operated for the necessary time. The Chiller has a
little cooling capacity even if it is in the dilution cycle operation. Do not stop the air handling unit
before the necessary time to prevent possible chilled water freezing.
Connect the operation signal wires from the chiller to the chilled water pump and cooling water
pump. Each pump must be automatically operated by the chiller signal.
(2) Freeze protection of chilled water, hot water and cooling water
In winter, ensure that the chilled and cooling water in the pipes does not freeze during chiller
shutdown.
There is a possibility of chilled water freezing by a remaining cooling capacity within 1 hour after the
Chiller stops completely.
(3) Chilled water flow through the chiller
Don’t flow chilled water over 40% of the rated value at the chiller starting. Otherwise, chiller will not
start because it cannot check the flow switch contact switching from off to on.
(4) Temperature of cooling water during operation
Keep the cooling water entering temperature above 21
o
C / 69.8
o
F and above 24
o
C / 75.2
o
F for a
process setting machine.
During the start-up process however, a lower temperature is allowable until the operating condition
becomes normal.
If the chiller operates during intermediate season or in winter, provide an automatic three-way
control valve to the bypass piping of cooling tower.
When the chiller operates during intermediate season or in winter, there is a possibility of safety stop
with alarm in the case that cooling water inlet temperature does not reach the rated condition within
30 min. after starting chiller operation.
(5) Power supply during the shutdown period
Don’t cut the power supply during the shutdown period.
Refer to “2-2.Precautions after the chiller shutdown”.
(6) Control procedures for auxiliary equipments
Refer to “2-3 Control procedures for auxiliary equipments”.
(7) Action after the power fail recovery
Refer to “2-4 Action in case of the power failure”.
(8) Periodic check of safety devices
Safety devices need periodic check for safety use. We recommend performing these by our service
engineer. The contents of periodic check are indicated in section 5.
(9) Monitoring of the operating condition
In case the chilled water outlet temperature is not lowered to the set value for a while, the heat input
may not be sufficient or the chilled water may be overloaded. In order to prevent any damage or
failure to the Chiller in such cases, make sure to check the operating conditions and the state of
Chiller.
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