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7.3 - Flow control
Evaporator flow switch and chilled water pump interlock
IMPORTANT: On 30XQ units, the unit water flow switch must be energized, 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) is of the shell and tube type with removable water boxes to facilitate cleaning.
Retightening or tightening must be done in accordance with the illustration below.
Water box tightening sequence
Legend:
Sequence 1: 1, 2, 3, 4 2 Tightening torque
Sequence 2: 5, 6, 7, 8 Bolt size M16 - 171 - 210 Nm
Sequence 3: 9, 10, 11, 12
Sequence 4: 13, 14, 15, 16
NOTE: Before this operation we recommend draining the circuit and disconnecting the pipes to be sure that the bolts
are correctly and uniformly tightened.
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 ℃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.
For 30XQ series units, antifreeze module are designed as standard configuration to prevent cooler damage. But the water
system fittings outside unit still need other antifreeze solutions. If the system 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 connection is available
somewhere on the heat exchanger water box in case the machine is not perfectly level).
36
Carrier Yileng - Shanghai, China
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