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General
When installation is complete, but prior to putting the unit
into service, the following pre-start procedures must be
reviewed and verified correct :
1) Inspect all wiring connections to be sure they are clean
and tight.
Warning : Disconnect all electric power including remote
disconnects before servicing. Failure to disconnect pow-
er before servicing can cause severe personal injury or
death.
Caution : Check the tightness of all connections in the
compressor power circuits (disconnects, terminal block,
contactors, compressor junction box terminals, etc.).
Loose connections can cause overheating at the con-
nections and undervoltage conditions at the compres-
sor motor.
2) Verify that all refrigerant valves, as shown in figure 14,
are «OPEN».
Caution : Do not operate the unit with the compressor,
oil discharge and liquid line service valves «CLOSED».
Failure to have the «OPEN» may cause serious com-
pressor damage.
3) Check the power voltage to the unit at the main power
fused-disconnect switch. Voltage must be within the
voltage utilization range, given in table 1 and also
stamped on the unit nameplate. Voltage imbalance must
not exceed 2%. Refer to «Unit voltage imbalance», below.
4) Check the unit power phasing.
5) Check the condenser fans to be sure that they rotate
freely in the fan openings and that each is securely
attached to its fan motor shaft. Check fan rotation and
belt tensioning.
6) Energize the compressor sump heaters by closing the
unit main disconnects. If unit-mounted disconnects are
used, they must also be closed. If the unit does not have
the optinal control power transformer, 115 VAC power
must be filed supplied to terminals 1TB3-1 and 1TB3-2.
The chiller switch must be in the STOP/RESET position.
Caution : The compressor sump heaters must be ener-
gized for a minimum of 24 hours prior to unit opera-
tion, to prevent compressor damage caused by liquid
refrigerant in the compressor at start-up.
7) Energize the evaporator heat tape.
8) Fill the evaporator chilled water circuit. Refer to table 14
for evaporator liquid capacities. Vent the system while
it is being filled. Open the vent on the top of the evap-
orator during filling and close when filling is completed.
Caution : Do not used untreated or improperly treated
water. Equipment damage may occur.
Caution : Do not fill chilled water system unless the
evaporator heat tape has been energized.
9) Close the fused-disconnect switch (es) that supplies
power to the chilled water pump starter.
10) Start the chilled water pump to begin circulation of the
chilled water. Inspect all piping for leakage and make any
necessary repairs.
11) With chilled water circulating through the system, adjust
Pre-start procedures
12) Adjust chilled water flow switch (if installed) for prop-
13) Stop the chilled water pump.
Unit voltage power supply
Measure each leg of the supply voltage at the unit main
power fused-disconnect. If the measured voltage on any leg
is not within specified range, notify the supplier of the
power and correct the situation before operating the unit.
Unit voltage unbalance
Excessive voltage imbalance between the phases of a three-
phase system can cause motors to overheat and eventu-
ally fail. The maximum allowable imbalance is 2%. Voltage
imbalance is determined using the following calculations
:
% Imbalance = __________________
V ave = (V 1 + V 2 + V 3 ) /3
V x = phase with greatest difference from V ave (without
regard to sign).
For example, if the three measured voltages are 375, 389
and 388 volts, the average would be :
_______________ = 384
The percentage of imbalance is then :
______________ = 2.34%
This exceeds the maximum allowable (2%) by 0.34 per-
cent.
Water system flow rates
Establish a balanced chilled water flow through the evap-
orator. Chilled water flow rates below the minimum values
will result in laminar flow, which reduces heat transfer and
causes either loss of electronic expansion valve control or
repeated nuisance, low temperature cutouts. Flow rates
that are too high can cause tube erosion and damage to the
tube supports and baffles in the evaporator.
Water system pressure drop
Measure chilled water pressure drop through the evapo-
rator at the field-installed pressure taps on the system
water piping. See figure 8. Use the same gauge for each
measurement.
Pressure drop readings should be approximately those
shown in the pressure drop charts, figure 9.
23
water flow and check water pressure drop through the
evaporator are conform to the order specifications.
Refer to figure 9.
er operation.
Caution : Inadequate voltage to the unit can cause con-
trol components to malfunction and shorten the life of
relay contact, compressor motors and contactors.
(V x - V ave ) x 100
V ave
375+388+389
3
100 (375-384)
384
Caution : Once the evaporator is filled with water, the
evaporator heat tapes must be energized to protect the
evaporator from freezing and bursting if the outdoor air
temperature drops below freezing.
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