Carrier 19XL - Manual (Page 98)

chilled water sensor should be installed. If this sensor is not installed, the return chilled water
sensor of the downstream chiller must be relocated to the return chilled water pipe of the
upstream machine.
To properly control the common supply point temperature sensor when chillers are piped in
parallel, the water flow through the shutdown chillers must be isolated so that no water bypass
around the operating chiller occurs. The common point sensor option must not be used if water
bypass around the operating chiller is occurring.
Machine Communication Wiring
Refer to the machine’s Installation Instructions, Carrier Comfort Network Interface section for
information on machine communication wiring.
Lead/Lag Operation
The PIC control provides the ability to operate 2 chillers in the LEAD/LAG mode. It also
provides the additional ability to start a designated standby chiller when either the lead or lag
chiller is faulted and capacity requirements are not met. The lead/lag option operates in CCN
mode only. If any other chiller configured for lead/lag is set to the LOCAL or OFF modes, it will
be unavailable for lead/lag operation.
Note: Lead/lag configuration is viewed and edited in Lead/Lag, under the Equipment Configu-
ration table of the Service menu. Lead/lag status during machine operation is viewed in
the MAINT04 table in the Control Algorithm Status table.