YORK INTERNATIONAL
59
FORM 150.40-NM25
FIG. 43 – WATER COOLING RANGE SELECT
(SET FOR
±
2°F CONTROL)
DUAL CIRCUIT UNITS
C. Subtract the Cooling Range from the RWT Setpoint:
i.e.: Design RWT Setpoint: 12.7°C
Design Cooling Range:– 5.6°C
7.1°C
Ü
“Computed Setpoint”
D. Determine whether the “Computed Setpoint” falls into
the temperature range of –9.9° to 0°C or 0° to 9.9°C.
1. If the “Computed Setpoint” falls into the tempera-
ture range from –9.9° to 0°C, place SW1 on the
Micro Logic Board to the OFF position (See Fig.
51). This places an imaginary minus sign into the
micro memory in front of the setpoint dialed into
the setpoint switches.
2. If the “Computed Setpoint” falls into the tempera-
ture range from 0° to 9.9°C place SW1 on the
Micro Logic Board to the ON position (See Fig.
51).
E. Place the two setpoint switches to the “computed”
setpoint. (See Fig. 44)
i.e.: 7,1 = 7.1°C from Step C if SW1 on the Micro
Logic Board is ON (Step C).
WATER COOLING
RANGE CODE
0
3.4°C
1
3.9°C
2
4.4°C
3
5.0°C
4
5.6°C
5
6.1°C
6
6.7°C
7
7.8°C
CHILLED WATER TEMPERATURE SETPOINT
AND COOLING RANGE SELECTION
METRIC ONLY
Return Water Temperature Control
Setpoints of –9.9° to 9.9°C can be programmed into the
panel if the Micro Logic Board is equipped with a
GEII.5M REV.2 EPROM (Fig. 51). Follow the steps be-
low to set up the panel switches prior to operating the
chiller.
A. Before any control panel switches are set, SW3 (Fig.
51) on the Micro Logic Board must be placed in the
OFF position for RWT control.
B. Determine what the desired RWT must be and fill in
the blanks below:
1. Design RWT Setpoint =
2. *Design Cooling Range =
(Temp. difference across cooler.)
*Select from these listed below: These are also listed on the control
panel.
CAUTION:
Selection of the Cooling Range should be
made according to the deviation from set-
point which can be tolerated and whether
more than normal system cycling of the load-
ers and compressors is experienced due to
a cooling range which is too tight (small).
Code 7, ± 2°F is recommended.
It is advisable, to assure that cycling problems do not
occur, to use LWT Control only if 6, 7, or 8 stages of
loading and unloading is present on the chiller. In addi-
tion, 6, 7, or 8 stage control from the Micro Logic Board
is initiated by placing SW5 ON. (See Page 66.)
NOTE: SW5 ON should only be selected if the chiller is
equipped with 5, 6, 7, or 8 stages.
System Loading & Unloading
See Pages 62-65 for loading and unloading points for
both return and leaving water temperature control.
LD01872
