YORK INTERNATIONAL 27
FORM 150.40-NM25
SINGLE CIRCUIT UNITS
F. Set the Cooling Range Switch to the coded number
which represents the desired cooling range selected
in Step B.
i.e.: Code “4” = 5.6°C from Step B (See Fig. 20)
FIG. 20 – WATER COOLING RANGE SET AT 4 (5.6°C)
G.Verify the actual design RWT Setpoint by placing the
Display Select switches to 0,5. The actual design set-
point will be displayed along with a “
–
” sign if the set-
point is negative. (See Fig. 21.)
i.e.: 12.7 will be displayed (from Step C) if the Display
Select Switches are set to 0,5. (See Fig. 21).
FIG. 19 – TEMP. SELECT SWITCHES SET AT 7, 1
(7.1°C “COMPUTED SETPOINT”)
H. System Limitations: With a minimum Cooling Range
of 3.4°C and a maximum “Computed Setpoint” of
9.9°C, a maximum RWT setpoint of 13.3°C can only
be achieved.
Maximum RWT setpoints for various cooling ranges
can be computed by adding the cooling range to
9.9°C.
With a maximum Cooling Range of 7.8°C and a mini-
mum “Computed Setpoint” of –9.9°C, a minimum
RWT setpoint of –2.1°C can only be achieved. Mini-
mum RWT setpoints for various cooling ranges can
be computed by adding the cooling range to –9.9°C.
I. See page 29 for determining loading and unloading
points.
LEAVING WATER TEMPERATURE (LWT) CONTROL
Follow the steps below to set up the panel switches prior
to operating the chiller.
NOTE: YORK does not recommend utilizing LWT Con-
trol with single circuit units, as cycling and tem-
perature fluctuations may result.
A. Before any control panel switches are set, SW3 on
the Micro Logic Board must be placed in the ON po-
sition for LWT control.
B. Determine what system conditions must be met and
fill in the blanks below:
1. Desired LWT Setpoint = .
2. *Desired Cooling Range = .
(Temp. difference across cooler)
*Select the Cooling Range from the chart below.
FIG. 21 – DATA DISPLAY SWITCHES SET AT 0, 5
CODE RANGE
0
+ 0.55°C
1
+ 0.67°C
2
+ 0.78°C
3
+ 0.84°C
4
+ 0.89°C
5
+ 1.00°C
6
+ 1.05°C
7
+ 1.11°C
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 is experienced due to a cooling range
which is too small. The factory recommends
that Code 7 be used to avoid cycling.
LD01858
LD01859
LD01860
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