with a corresponding temperature range of 60 to 105 F
(15 to 41 C). The condenser entering water temperature
should be controlled below the specified design entering
water temperature to save on compressor kilowatt
requirements.
7. Cooler pressure and temperature also will vary with the
design conditions. Typical pressure range will be be-
tween 60 and 80 psig (410 and 550 kPa), with tempera-
ture ranging between 34 and 45 F (1 and 8 C).
8. The compressor may operate at full capacity for a short
time after the pulldown ramping has ended, even though
the building load is small. The active electrical demand
setting can be overridden to limit the compressor IkW, or
the pulldown rate can be decreased to avoid a high
demand charge for the short period of high demand
operation. Pulldown rate can be based on load rate or tem-
perature rate. It is accessed on the Equipment SERVICE
screen, RAMP_DEM table (Table 2, Example 20).
To Stop the Chiller
1. The occupancy schedule starts and stops the chiller
automatically once the time schedule is configured.
2. By pressing the STOP button for one second, the alarm
light blinks once to confirm the button has been pressed.
The compressor will then follow the normal shutdown
sequence as described in the Controls section. The chiller
will not restart until the CCN or LOCAL softkey is
pressed. The chiller is now in the OFF control mode.
IMPORTANT: Do not attempt to stop the chiller by
opening an isolating knife switch. High intensity
arcing may occur.
Do not restart the chiller until the problem is diagnosed
and corrected.
After Limited Shutdown —
No special preparations
should be necessary. Follow the regular preliminary checks
and starting procedures.
Preparation for Extended Shutdown —
The
refrigerant should be transferred into the pumpout storage
tank (if supplied; see Pumpout and Refrigerant Transfer
Procedures) to reduce chiller pressure and the possibility
of leaks. Maintain a holding charge of 5 to 10 lbs (2.27 to
4.5 kg) of refrigerant or nitrogen to prevent air from leaking
into the chiller.
If freezing temperatures are likely to occur in the chiller
area, drain the chilled water, condenser water, and the pump-
out condenser water circuits to avoid freeze-up. Keep the
waterbox drains open.
Leave the oil charge in the chiller with the oil heater
and controls energized to maintain the minimum oil reser-
voir temperature.
After Extended Shutdown —
Ensure the water sys-
tem drains are closed. It may be advisable to flush the water
circuits to remove any soft rust which may have formed. This
is a good time to brush the tubes and inspect the Schrader
fittings on the waterside flow devices for fouling, if
necessary.
Check the cooler pressure on the CVC default screen and
compare it to the original holding charge that was left in the
chiller. If (after adjusting for ambient temperature changes)
any loss in pressure is indicated, check for refrigerant leaks.
See Check Chiller Tightness section, page 46.
Recharge the chiller by transferring refrigerant from the
pumpout storage tank (if supplied). Follow the Pumpout and
Refrigerant Transfer Procedures section, this page. Observe
freeze-up precautions.
Carefully make all regular preliminary and running sys-
tem checks. Perform a Control Test before start-up. If the
compressor oil level appears abnormally high, the oil may
have absorbed refrigerant. Ensure that the oil temperature is
above 140 F (60 C) or above the cooler refrigerant tempera-
ture plus 50° F (27° C).
Cold Weather Operation —
When the entering con-
denser water temperature drops very low, the operator should
automatically cycle the cooling tower fans off to keep the
temperature up. Piping may also be arranged to bypass the
cooling tower. The PIC II controls have a low limit tower
fan output that can be used to assist in this control (terminal
11 and 12 on ISM).
Manual Guide Vane Operation —
It is possible to
manually operate the guide vanes in order to check con-
trol operation or to control the guide vanes in an emergency.
Manual operation is possible by overriding the target guide
vane position. Access the COMPRESS screen on the CVC
and scroll down to highlight TARGET GUIDE VANE
POS. To control the position, use the INCREASE or
DECREASE softkey to adjust to the percentage of guide
vane opening that is desired. Zero percent is fully closed;
100% is fully open. To release the guide vanes to automatic
control, press the RELEASE softkey.
NOTE: Manual control increases the guide vane openings
and overrides the pulldown rate during start-up. Motor cur-
rent above the electrical demand setting, capacity overrides,
and chilled water temperature below the control point over-
ride the manual target and close the guide vanes. For
descriptions of capacity overrides and set points, see the
Controls section.
Refrigeration Log —
A refrigeration log (as shown in
Fig. 30), is a convenient checklist for routine inspection and
maintenance and provides a continuous record of chiller
performance. It is also an aid when scheduling routine main-
tenance and diagnosing chiller problems.
Keep a record of the chiller pressures, temperatures, and
liquid levels on a sheet similar to the one in Fig. 30. Auto-
matic recording of PIC II data is possible by using CCN
devices such as the Data Collection module and a Build-
ing Supervisor. Contact a Carrier representative for more
information.
60
Summary of Contents for HERMETIC CENTRIFUGAL LIQUID CHILLERS 19XR
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