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7.3 - flow control
evaporator flow switch and chilled water pump interlock
IMPORTANT: On 30XA units, the unit water flow switch
must be energised, and the chilled water pump interlock
must be connected. Failure to follow this instruction will
void the Carrier guarantee.
The water flow switch is installed on the evaporator water
inlet and adjusted by the control, based on unit size and
application. If adjustment is necessary, it must be carried
out by qualified personnel trained by Carrier Service.
Terminals 34 and 35 are provided for field installation of
the chilled water pump interlock (auxiliary contact for pump
operation to be wired on site).
7.4 - Evaporator water box bolt tightening
The evaporator (and condenser) are of the shell and tube
type with removable water boxes to facilitate cleaning. Re-
tightening or tightening must be done in accordance with
the illustration below.
Water box tightening sequence
legend
1
Sequence 1: 1 2 3 4
Sequence 2: 5 6 7 8
Sequence 3: 9 10 11 12
2
Tightening torque
Bolt size M16 - 171 - 210 Nm
NOTE: Before this operation we recommend draining the
circuit and disconnecting the pipes to be sure that the bolts
are correctly and uniformly tightened.
28
7.5 - frost protection
7.5.1 - standard machine
If the chiller or the water piping is in an area where the
ambient temperature can fall below 0°C it is recommended
to add an antifreeze solution to protect the unit and the
water piping to a temperature of 10 K below the lowest
temperature likely to be reached at the installation site.
Use only antifreeze solutions, approved for heat exchanger
duty. If the system is not protected by an antifreeze solution
and will not be used during the freezing weather conditions,
draining of the cooler and outdoor piping is mandatory.
Damage due to freezing is not covered by the warranty.
IMPORTANT: Depending on the climatic conditions in
your area you must:
•
Add ethylene glycol with an adequate concentration
to protect the installation up to a temperature of 10 K
below the lowest temperature likely to occur at the
installation site.
•
If the unit is not used for an extended period, it is
recommended to drain it, and as a safety precaution
add ethylene glycol to the heat exchanger, using the
water entering purge valve connection (a purge connec-
tion is available somewhere on the heat exchanger
water box in case the machine is not perfectly level).
•
At the start of the next season, refill the unit with water
and add an inhibitor.
•
For the installation of auxiliary equipment, the instal-
ler must comply with basic regulations, especially for
minimum and maximum flow rates, which must be
between the values listed in the operating limit table
(application data).
7.5.2 - Optional evaporator frost protection (30Xa)
In cases where it is not possible to apply the recommenda-
tions in paragraph 7.5.1, the units can be equipped with
heaters to protect the evaporator against frost (option 41A
or 41B).
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