York MILLENNIUM YCAL0043SC Manual page 133

LITERATURE SUPPLEMENT
Subject: Recommended Operating Guidelines for YCAL Chillers
GENERAL
By observing a few recommended operating guidelines, compressor cycling can be reduced and optimum chilled
liquid temperature control can be achieved when operating YCAL chillers in both water and brine systems.
MINIMUM WATER VOLUME
Minimum water volume in the chilled water system should be 5.0 gallons per ton. Chilled liquid volumes below
this minimum will definitely suffer from chilled liquid temperature control problems and compressor cycling.
Chilled liquid volumes in the range of 7-11 gallons/ton are generally recommended as the industry standard and
will provide the best chilled liquid temperature control with minimum compressor cycling.
MINIMUM LEAVING CHILLED LIQUID CONTROL RANGE PROGRAM SETTINGS
For optimum chilled liquid temperature control, and reduced compressor cycling, leaving chilled liquid setpoint
control range settings should be equal to or greater than the minimum ranges specified in the Table 1 below.
These recommended settings vary according to the number of compressors in the chiller and the chilled liquid
differential actually measured across the evaporator when the chiller is fully loaded. Typically, chilled liquid
system designs utilize an evaporator temperature differential design of 10 ºF, but measurements should be made
to assure that the chiller flows meet design and if not, the minimum control range may need to be varied
accordingly. Use the table below for programming the control range when "leaving" chilled liquid control is
selected.
Number of
Compressors In
the Chiller
2
3
4
6
TABLE 1 - MINIMUM SETPOINT RANGES
YORK INTERNATIONAL
Form No.: 150.62-NM2 (LS2)
Supersedes: None
File with: 150.62-NM2 (699)
Recommended Programmed Leaving Chilled Liquid Setpoint
º
5 F Evap Diff
º
± 2.0 F
º
± 1.8 F
º
± 1.4 F
º
± 1.4 F
Control Range
º
10 F Evap Diff
º
± 2.2 F
º
± 2.0 F
º
± 1.8 F
º
± 1.4 F
201
º
15 F Evap Diff
º
± 2.5 F
º
± 2.5 F
º
± 2.5 F
º
± 1.8 F
1