Dual Chiller Control For Parallel Applications; Dual Chiller Pump Control For Parallel - Carrier AquaForce 30XV140 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

set point error will be reset downwards by 4° F (2.2° C) pro-
vided that the lead capacity is not zero.
Each dual chiller application, Parallel and Series, is de-
scribed separately below.
DUAL CHILLER CONTROL FOR PARALLEL APPLI-
CATIONS — To configure the master chiller for parallel
applications, see Table 24. To configure the slave chiller for
parallel applications, see Table 25.

DUAL CHILLER PUMP CONTROL FOR PARALLEL

CHILLER APPLICATIONS — Parallel chiller control with
dedicated pumps is recommended. The chiller must start and
stop its own water pump located in its own piping. If pumps are
not dedicated for each chiller's piping, chiller isolation valves
are required; each chiller must open and close its own isolation
valve through the control. Figures 25-28 show typical pump ar-
rangements for dual chiller parallel applications.
Although not recommended, it is possible to configure the
system with no individual pump control. In applications where
the unit is configured for fresh water (Main Menu 
Configuration Menu Service Parameters, Evaporator Fluid
Type=1 [Fresh Water]), and Set Point temperature is close to
the lower limit of the fresh water range, it is possible for
changeable leaving water conditions as the chilled water flow
rate drops to an operating unit, causing the leaving chilled wa-
ter temperature to drop and initiate the evaporator freeze pro-
tection override. Constant flow applications may alleviate this
issue. In constant water flow applications, the master chiller
should be the primary control source for the chilled water
pump. The slave chiller should have override capability. In the
event of a communication failure between the master and slave
chillers, the slave chiller will operate as a stand-alone machine
and therefore must be able to enable the chilled water pump.
DUAL CHILLER CONTROL FOR SERIES CHILLER
APPLICATIONS — When chillers are configured to work
in series mode no additional chilled water supply sensor is
required. The master chiller will be installed downstream of
the slave chiller (the slave chiller outlet fluid is the master
inlet fluid). If pump control is required, it will be controlled
by the master chiller.
To configure the master chiller for series applications, see
Table 26. To configure the slave chiller for series applications,
see Table 27.
28