173
JOHNSON CONTROLS
SECTION 7 – UNIT CONTROLS
FORM 150.67-NM1
ISSUE DATE: 4/28/2017
7
PROGRAM KEY
There are several operating parameters under the PRO-
GRAM key that are programmable. These setpoints can
be changed by pressing the PROGRAM key, and then
the ENTER/ADV key to enter Program Mode. Continu-
ing to press the ENTER/ADV key will display each op-
erating parameter. While a particular parameter is being
displayed,the↑(UP)and↓(DOWN)arrowkeyscanbe
used to change the value. After the value is changed, the
ENTER/ADV key must be pressed to enter the data into
memory. Table 15 shows the programmable limits and
default values for each operating parameter.
Following are the displays for the programmable val-
ues in the order they appear:
d D I S C H A R G E P R E S S U R E
C U T O U T = 3 9 5 P S I G
DISCHARGE PRESSURE CUTOUT is the discharge
pressure at which the system will shutdown as moni-
tored by the optional discharge transducer. This is a
software shutdown that acts as a backup for the me-
chanical high pressure switch located in the refrigerant
circuit. The system can restart when the discharge pres-
sure drops 40 PSIG (2.76 barg) below the cutout point.
If the optional discharge pressure transducer is not in-
stalled, this programmable safety would not apply. It
should be noted that every system has a mechanical
high pressure cutout that protects against excessive
high discharge pressure regardless of whether or not
the optional discharge pressure is installed.
S U C T I O N P R E S S U R E
C U T O U T = 80 . 0 P S I G
The SUCTION PRESSURE CUTOUT protects the
chiller from an evaporator freeze-up. If the suction
pressure drops below the cutout point, the system will
shut down. Typically, the cutout should be set to 80
PSIG (5.52 Bars) form water cooling.
* The minimum discharge pressure allowed is 235 PSIG. The Fan Differential Off Pressure High Limit will be lowered (reduced) to
prevent going below 235 PSIG based on where the fan control On Pressure is programmed.
PROGRAM VALUE MODE LOW LIMIT HIGH LIMIT DEFAULT
DISCHARGE PRESSURE CUTOUT —
325 PSIG 575 PSIG 570 PSIG
22.4 BARG 39.6 BARG 39.3 BARG
SUCTION PRESSURE CUTOUT
WATER COOLING
80.0 PSIG 120.0 PSIG 80.0 PSIG
5.52 BARG 8.27 BARG 5.52 BARG
GLYCOL COOLING
42.0 PSIG 70.0 PSIG 44.0 PSIG
2.9 BARG 4.83 BARG 3.03 BARG
LOW AMBIENT TEMPERATURE
CUTOUT
STANDARD AMBIENT
25.0 °F 60.0 °F 25.0 °F
-3.9 °C 15.6 °C -3.9 °C
LOW AMBIENT
0 °F 60.0 °F 25.0 °F
-17.8 °C 15.6 °C -3.9 °C
LEAVING CHILLED LIQUID
TEMPERATURE CUTOUT
WATER COOLING — —
36 °F
2.2 °C
GLYCOL COOLING
-1.0 °F 36.0 °F 36.0 °F
-18.3 °C 2.2 °C 2.2 °C
ANTI-RECYCLE TIMER — 300 SEC. 600 SEC. 600 SEC.
FAN CONTROL ON PRESSURE
(NOT APPLICABLE TO A YCRL)
—
360 PSIG 485 PSIG 385 PSIG
24.8 BARG 33.4 BARG 26.5 BARG
FAN DIFFERENTIAL OFF PRESSURE —
80 PSID 160 PSID 125 PSID
5.51 BARD 11.03 BARD* 8.62 BARD
TOTAL NUMBER OF COMPRESSORS
SINGLE SYSTEM 2 3 3
DUAL SYSTEM 4 6 6
NUMBER OF FANS PER SYSTEM 2 4 3
UNIT/SYSTEM TRIP VOLTS CURRENT FEEDBACK 0.5 VOLTS 4.5 VOLTS 2.5 VOLTS
REMOTE UNIT ID — 0 7 0
TABLE 14 - PROGRAM KEY LIMITS AND DEFAULT
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