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Start-Up/Shutdown/Recycle Sequence (Figure 25)
Local Start-Up
Local start-up (or a manual start-up) is initiated by pressing the LOCAL menu softkey which
is on the default LID screen. Local start-up can proceed when Time Schedule 01 is in
OCCUPIED mode, and after the internal 15-minute start-to-start timer and the stop-to-start
inhibit timer have expired.
The chiller start/stop status point on the Status01 table may be overridden to start,
regardless of the time schedule, in order to locally start the unit. Also, the remote contacts may
be enabled through the LID and closed to initiate a start-up.
Whenever the chiller is in LOCAL control mode, the PIC will wait for Time Schedule 01 to
become occupied and the remote contacts to close, if enabled. The PIC will then perform a
series of pre-start checks to verify that all pre-start alerts and safeties are within the limits
shown in Table 3. The run status line on the LID now reads ‘‘Starting.’’ If the checks are
successful, the chilled water/brine pump relay will be energized. Five seconds later, the
condenser pump relay is energized. Thirty seconds later the PIC monitors the chilled water and
condenser water flow switches, and waits until the
WATER FLOW VERIFY TIME
(operator
configured, default 5 minutes) to confirm flow. After flow is verified, the chilled water/brine
temperature is compared to
CONTROL POINT
plus
DEADBAND
. If the temperature is less
than or equal to this value, the PIC will turn off the condenser pump relay and go into a