JOHNSON CONTROLS
111
SECTION 6 - OPERATION
FORM 201.30-ICOM1 (519)
ISSUE DATE: 05/22/2019
6
TABLE 37 - SETPOINT VALUES
PROGRAM VALUE MODE LOW LIMIT HIGH LIMIT DEFAULT
Leaving Chilled Liquid Temp Setpoint
Water Cooling
38.0°F 60.0°F 44.0°F
3.3°C 15.6°C 6.7°C
Glycol Cooling
8.0°F 70.0°F 44.0°F
-13.3°C 15.6°C 6.7°C
Leaving Chilled Liquid Temp Control Range Cooling
1.5°F 2.5°F 2.0°F
0.8°C 1.4°C 1.1°C
Maximum Remote Temp Reset Cooling
2°F 40°F 20°F
1°C 22°C 11°C
Leaving Condenser Liquid Temp Setpoint Heat Pump
86°F 160.0°F 131°F
30°C 71.1°C 55°C
Leaving Condenser Liquid Temp Control
Range
Heat Pump
1.5°F 38.0°F 2.0°F
0.8°C 3.3°C 1.1°C
Maximum Remote Temp Reset Heat Pump
2°F 40°F 20°F
1°C 22°C 11°C
Another operator-programmable setpoint, control
range (CR), defines how far above and below the
LCHLT setpoint the chiller will stop compressors, or
the entire unit, and restart them to maintain LCHLT
within the range. The programmable CR defines the
setpoint high and low limits as shown in Figure 54 on
page 111. In this example, LCHLT setpoint is 44°F
(6.6°C) and the CR is 2°F (-16.6°C).
FIGURE 54 - SETPOINT HIGH AND LOW LIMITS DEFINED BY CONTROL RANGE (CR)
48°F --------------------------------------------------
46°F ---------
Setpoint + CR ( Setpoint High Limit)
----------
Programmed
44°F ----------
Setpoint
---------------------------------
Control (Cooling) Range
42°F ---------- ----------
Setpoint – CR (Setpoint Low Limit)
40°F
38°F --------------------------------------------------
--------------------------------------------------
LD16433
The chiller intent is to control LCHLT (or Leaving
Condenser Water Temperature in the heat pump ap-
plication), to the operator-programmable setpoint. The
programmable range depends whether the chiller is set
for water cooling or glycol (brine) cooling. The chiller
uses a proportion and rate control in effort to main-
tain LCHLT exactly at setpoint. The compressor VSD
speed is manipulated by the control to achieve this.
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