To Stop The Chiller; After Limited Shutdown; Preparation For Extended Shutdown; After Extended Shutdown - Carrier 19DV Series Installation, Operation And Maintenance Instructions

start-up. There will be an alarm if compressor is ON and the bearing pressure drop is less than 68.9 kPa diff for 10
seconds.
5. The moisture indicator sight glass on the refrigerant motor cooling line should indicate single phase refrigerant
flow and a dry condition.
6. The condenser pressure and temperature varies with the chiller design conditions. Typically the pressure will
range from -10.3 to 120.6 kPa. with a corresponding temperature range of 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
between 50.8 kPa to -35 kPa, with temperature ranging between 1.1 and 7.2°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
kW, 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 temperature rate and is viewed at MAINTENANCE MENU
>> CAPACITY CONTROLS >> RAMP_DEM (Ramping Demand Limit Value). Configuration done in General
Config and rate done in Service Parameters.
9. Both the high and low float chamber have two sight glasses that look into the float chamber to confirm the floats
are not stuck open or closed. When the chiller is operating, the top sight glass is empty and the bottom sight glass
is full.

7.4 To stop the chiller

The occupancy schedule starts and stops the chiller automatically once the time schedule is configured. The unit
can be stopped manually using the HMI by pressing the green Start/Stop icon. The Unit Start/Stop screen is
displayed. Press Confirm Stop. The compressor will then follow the normal shutdown sequence as described in
the Start- Up/Shutdown/Recycle Sequence section. 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.
If the chiller is stopped by an alarm condition, do not restart the chiller until the problem is diagnosed and
corrected.

7.5 After Limited Shutdown

No special preparations should be necessary. Follow the regular preliminary checks and starting procedures.

7.6 Preparation for Extended Shutdown

If freezing temperatures are likely to occur in the chiller area, drain the chilled water, condenser water, and the
pumpout condenser water circuits to avoid freeze-up. Keep the waterbox drains open. Ensure that chiller is
powered up so purge can automatically remove non-condensables from the low pressure chiller system during the
shutdown. It is recommended not to store the refrigerant in the unit if below freezing temperatures are anticipated
or if the extended shutdown extends past a normal seasonal shutdown. In that case both refrigerant and water
side should be purged with positive pressure of dry nitrogen.

7.7 After Extended Shutdown

Ensure the water system drains are closed. It may be advisable to flush the water circuits to remove any soft rust
that 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.
Match the actual to the recorded nitrogen pressure prior to the extended shutdown to determine if a leak is
present.
Check the cooler pressure on the HMI panel and compare it to the original holding charge that was left in the
chiller. If (after adjusting for ambient pressure changes) any change in pressure is indicated, check for refrigerant
leaks. See Check Chiller Tightness section.
If charge was removed, recharge the chiller by transferring refrigerant from the pumpout storage tank (if supplied).
Carefully make all regular preliminary and running system checks.

7.8 Cold Weather Operation

When the entering condenser water temperature drops below 12.8 °C, 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 used
to maintain a minimum refrigerant pressure differential during an inverted start condition. The PIC5+ controls have
a low limit tower fan output that can be used to assist in this control with IOB 4 installed.
IMPORTANT: A field-supplied water temperature control system for condenser water should be installed.
The system should be able to maintain the leaving condenser water temperature at design conditions.
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