TEMPERATURE CONTROL DURING ICE BUILD
—During ice build, the capacity control algorithm uses the
WATER/BRINE CONTROL POINT minus 5 F (2.7 C) to con-
trol the LEAVING CHILLED WATER temperature. The ECW
CONTROL OPTION (see CONFIG screen), the 20 mA
DEMAND LIMIT, and any temperature reset option are ig-
nored during ice build.
TERMINATION OF ICE BUILD — Ice build termination
occurs under the following conditions:
1. Ice Build Time Schedule — The ice build function ter-
minates when the current time is not designated as an ice
build time period.
2. Entering Chilled Water Temperature — Compressor op-
eration terminates based on temperature if the ICE BUILD
TERMINATION parameter on the CONFIG screen is set
to 0 (temperature only) and the ENTERING CHILLED
WATER temperature is less than the ICE BUILD SET-
POINT. If the ICE BUILD RECYCLE OPTION is set to
ENABLE, a recycle shutdown occurs and recycle start-
up is based on a LEAVING CHILLED WATER tempera-
ture greater than the WATER/BRINE CONTROL POINT
plus RECYCLE RESTART DELTA T (see SERVICE1
screen).
3. Remote Contacts/Ice Level Input — Compressor opera-
tion terminates when the ICE BUILD TERMINATION pa-
rameter is set to 1 (contacts only) and the remote contacts
are open. In this case, the contacts are used for ice level
termination control. The remote contacts can still be opened
and closed to start and stop the chiller if the current time
is not a time designated as an ice build period. If the cur-
rent time is designated as an ice build period, the contacts
are used to stop the ice build function.
4. Entering Chilled Water Temperature and Remote Con-
tacts — Compressor operation terminates when the ICE
BUILD TERMINATION parameter is set to 2 (both tem-
perature and contacts) and the previously described con-
ditions for ENTERING CHILLED WATER temperature and
remote contacts have occurred.
NOTE: Overriding the CHILLER START/STOP, WATER/
BRINE CONTROL POINT, and ACTIVE DEMAND LIMIT
values by CCN devices (with a priority less than 4) during
the ice build period is not possible. However, overriding can
be accomplished with CCN during two-chiller lead/lag
operation.
RETURN TO NON-ICE BUILD OPERATIONS — When
the ice build function terminates, the chiller returns to nor-
mal temperature control and start/stop schedule operation. If
the CHILLER START/STOP or WATER/BRINE CONTROL
POINT has been forced (with a priority less than 4), before
the start of ice build operation, then CHILLER START/STOP
and WATER/BRINE CONTROL POINT forces are removed;
that is, under these circumstances, the ice build operation
takes precedence over the force.
Attach to Network Device Control
— One of the
selections on the SERVICE menu is ATTACH TO NET-
WORK DEVICE. See Fig. 12. This table serves the follow-
ing purposes:
• uploads the occupancy schedule number (OCCPC03S), if
changed, as defined in the CONFIG screen (SCHEDULE
NUMBER).
• attaches the LID to any CCN device, if the chiller has been
connected to a CCN network. This may include other PIC
controlled chillers.
• uploads changes from a new PSIO or LID module or up-
graded software.
Figure 20 shows the ATTACH TO NETWORK DEVICE
table as it appears on the LID. The LOCAL entry is always
the PSIO module address of the chiller the LID is mounted
on. Whenever the controller identification of the PSIO is
changed, this change is reflected on the bus and address for
the LOCAL DEVICE of the ATTACH TO DEVICE screen
automatically.
Whenever the ATTACH TO NETWORK DEVICE table
is accessed, no information can be read from the LID on any
device until you attach one of the devices listed on the dis-
play. As soon as this screen appears, the LID erases infor-
mation about the module to which it was attached to make
room for information on another device. Therefore, a CCN
module must be attached when this screen is entered.
To attach to a device listed on this screen, highlight it us-
ing the SELECT softkey. Then press the ATTACH soft-
key. The message, UPLOADING TABLES, PLEASE WAIT,
flashes. The LID then uploads the highlighted device or mod-
ule. If the device address cannot be found, the message, COM-
MUNICATION FAILURE, appears. The LID then reverts to
the ATTACH TO NETWORK DEVICE screen. Try another
device or check the address of the device that did not attach.
The upload process time for each CCN module is different.
In general, the uploading process takes 3 to 5 minutes.
NOTE: Before leaving the ATTACH TO NETWORK DE-
VICE screen, select the LOCAL device. Otherwise, the LID
will be unable to display information on the local chiller.
ATTACHING TO OTHER CCN MODULES — If the chiller
PSIO has been connected to a CCN network or other PIC
controlled chillers through CCN wiring, the LID can be used
to view or change parameters on the other controllers. Other
PIC chillers can be viewed and set points changed (if the
other unit is in CCN control) if desired from this particular
LID module.
To view the other devices, access the ATTACH TO
NETWORK DEVICE table. Move the highlight bar to any
device number. Press the SELECT softkey to change to the
bus number and address of the module to be viewed. Press
the ENTER softkey. Press the EXIT softkey to return to
the ATTACH TO NETWORK DEVICE table. If the device
number is not valid, the message, COMMUNICATION FAIL-
URE, displays. Enter a new address number or check the
wiring. If the device is communicating properly, the mes-
sage, UPLOAD IN PROGRESS, displays and the new de-
vice can now be viewed.
Whenever there is a question regarding which CCN de-
vice the LID is currently showing, check the device name
descriptor on the upper left hand corner of the LID screen.
See Fig. 20.When the CCN device has been viewed, use the
ATTACH TO NETWORK DEVICE table to attach to the
PSIO that is on the chiller. From the ATTACH TO NET-
WORK DEVICE table , highlight LOCAL, and press the
SELECT softkey. Then, press the ATTACH softkey to up-
load the LOCAL device. The PSIO will upload.
NAME DESCRIPTOR
Fig. 20 — Example of Attach to Network
Device Screen
41
