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Table 26A — Configuring Outdoor Air and Space Temperature Reset
*4 items skipped in this example.
Table 26B — Configuring Return Temperature Reset
*4 items skipped in this example.
Temperature Reset —
The control system is capable of
handling leaving-fluid temperature reset based on return cooler
fluid temperature. Because the change in temperature through
the cooler is a measure of the building load, the return tempera-
ture reset is in effect an average building load reset method.
The control system is also capable of temperature reset based
on outdoor-air temperature (OAT), space temperature (SPT), or
from an externally powered 4 to 20 mA signal. Accessory sen-
sors must be used for SPT reset (33ZCT55SPT). The Energy
Management Module (EMM) must be used for temperature
reset using a 4 to 20 mA signal. See Tables 25A and 25B.
To use Outdoor Air or Space Temperature reset, four vari-
ables must be configured. In the Configuration mode under the
sub-mode RSET, items CRST, RM.NO, RM.F and RT.DG
must be properly set. See Table 26A — Configuring Outdoor
Air and Space Temperature Reset. The outdoor air reset exam-
ple provides 0° F (0° C) chilled water set point reset at 85.0 F
(29.4 C) outdoor-air temperature and 15.0 F (8.3 C) reset at
55.0 F (12.8 C) outdoor-air temperature. The space tempera-
ture reset example provides 0° F (0° C) chilled water set point
reset at 72.0 F (22.2 C) space temperature and 6.0 F (3.3 C)
reset at 68.0 F (20.0 C) space temperature. The variable CRST
should be configured for the type of reset desired. The variable
RM.NO should be set to the temperature that no reset should
occur. The variable RM.F should be set to the temperature that
maximum reset is to occur. The variable RM.DG should be set
to the maximum amount of reset desired.
To use Return reset, four variables must be configured. In
the Configuration mode under the sub-mode RSET, items
CRST, RT.NO, RT.F and RT.DG must be properly set. See
Table 26B — Configuring Return Temperature Reset. This ex-
ample provides 5.0 F (2.8 C) chilled water set point reset at
MODE
(RED LED)
KEYPAD
ENTRY
SUB-
MODE
KEYPAD
ENTRY
ITEM
DISPLAY
ITEM
EXPANSION
COMMENT
Outdoor
Air
Space
CONFIGURATION
DISP
UNIT
OPT1
OPT2
RSET CRST 2 4
COOLING RESET
TYPE
2 = Outdoor-Air Temperature
4 = Space Temperature
(Connect to TB5-5,6)
RM.NO* 85 °F 72 °F
REMOTE - NO
RESET TEMP
Default: 125.0 F (51.7 C)
Range: 0° to125 F
RM.F 55 °F 68 °F
REMOTE - FULL
RESET TEMP
Default: 0.0° F (-17.7 C)
Range: 0° to 125 F
RM.DG 15 °F6 °F
REMOTE - DEGREES
RESET
Default: 0° F (0° C)
Range: –30 to 30 F
(–34.4 to -1.1 °C)
MODE
(RED LED)
KEYPAD
ENTRY
SUB-MODE
KEYPAD
ENTRY
ITEM DISPLAY
ITEM
EXPANSION
COMMENT
CONFIGURATION
DISP TEST ON/OFF TEST DISPLAY LEDs
UNIT TYPE X UNIT TYPE
OPT1 FLUD X COOLER FLUID
OPT2 CTRL X CONTROL METHOD
RSET CRST X COOLING RESET TYPE
0 = No Reset
1 = 4 to 20 mA Input (EMM required)
(Connect to EMM TB6-2,3)
2 = Outdoor-Air Temperature
3 = Return Fluid
4 = Space Temperature
(Connect to TB5-5,6)
RT.NO* XXX.X
∆
F
RETURN FLUID - NO
RESET TEMP
Default: 10.0
∆
F (5.6
∆
C)
Range: 0° to125 F COOLER
∆
T
RT.F XXX.X
∆
F
RETURN FLUID - FULL
RESET TEMP
Default: 0
∆
F (–17.8
∆
C)
Range: 0° to 125 F COOLER
∆
T
RT.DG XX.X
∆
F
RETURN - DEGREES
RESET
Default: 0
∆
F (0
∆
C)
Range: –30 to 30°F (–16.7 to 16.7 C)
ENTER
ENTER
ENTER ENTER
ENTER
ENTER
ENTER
ENTER
IMPORTANT: Care should be taken when interfacing with
other control systems due to possible power supply differ-
ences: full wave bridge versus half wave rectification. Con-
nection of control devices with different power supplies
may result in permanent damage. ComfortLink™ controls
incorporate power supplies with half wave rectification. A
signal isolation device should be utilized if the signal gen-
erator incorporates a full wave bridge rectifier.