Setpoint Menu - Carrier 30GX Installation, Operation And Maintenance Instructions

4.2.7 - SETPOINT menu

This menu displays the unit setpoints. These points can be
modified when the unit is in Local operating mode.
ITEM FORMAT DESCRIPTION
0 ±nn.n Cooling setpoint 1 in °C
1 ±nn.n Cooling setpoint 2 in °C
2* nn.n Heating setpoint in °C. Heat pump only.
3* nn.n Condensing setpoint 1 in °C.
4* nn.n Condensing or reclaim setpoint 2 in °C.
5 nnn Demand limit as %
6* n.n Cooling mode ramp in °C/minute
7* n.n Heating mode ramp in °C/minute. Heat pump only.
8* nn.n Voltage reset 0-10 V d.c. cooling mode - Voltage for zero reset
9* nn.n Voltage reset 0-10 V d.c. cooling mode - Voltage for max. reset
10* ±nn.n Delta T reset cooling - Delta T for zero reset
11* ±nn.n Delta T reset cooling - Delta T for maximum reset
12* ±nn.n Cooling reset - Maximum reset value in °C
13* nn.n Voltage reset 0-10 V d.c. heating mode - Voltage for zero reset
14* nn.n Voltage reset 0-10 V d.c. heating mode - Voltage for max. reset
15* ±nn.n Delta T reset heating - Delta T for zero reset
16* ±nn.n Delta T reset heating - Delta T for maximum reset
17* ±nn.n Heating reset - Maximum reset value in °C
Key:
n : numerical display
* : This item is displayed in certain unit configurations only.
Items 0-1 Cooling setpoint 1 & 2
This item lets you display and modify the
cooling setpoints. Cooling setpoint 2 is
generally used for ice storage.
See section 4.2.4, description of item 10
(active setpoint) and the conditions of
use for setpoints 1 and 2.
Item 2 Heating setpoint
This item is used for heat pumps only. It
can be used to display and modify the
heating setpoint.
See section 4.2.4, description of item 10
(active setpoint) and the conditions of
use for the heating setpoint.
Limiting values for the cooling and heating setpoints
SET POINT
Minimum cooling value
• Water
• Medium brine (low temperature)
• Low brine (verty low temperature)
Maximum cooling value
Maximum heating value
Minimum heating value
Item 3 Condensing setpoint
This item is used to display and modify
the condensing setpoint. It is used by the
system to control the fan stages or a
variable speed fan (air-cooled unit) or to
control condenser water valves (water-
cooled unit) when the unit is not in
reclaim mode (see section 4.2.4, item 14,
the conditions of use for the normal
condensing setpoint).
18
°F °C
38 3,3
14 -10
-4 -20
101 38,3
138 58.8
80 26,6
Item 4 Reclaim setpoint
This item is used to display and modify
the reclaim setpoint. As in item 3, it is
used to control condensation.
Limiting values for the condensing setpoints
CONDENSING SETPOINT
Minumum temperature
(corresponding pressure)
Maximum temperature
(corresponding pressure)
Item 5 Demand limit setpoint
This item is used to define the maximum
capacity that the unit is authorised to put
into operation when the demand limit
contact is closed and if reduction by
contact has been selected (see section
3.4.7, description of contact, and section
4.2.10, configuring the demand limit
method).
Range: 0 to 100 %
Items 6-7 Cooling/heating mode ramp
These items refer to the rates of
temperature drop (cooling mode) or
temperature rise (heating mode) in °C/
minute in the active heat exchanger
leaving water. These parameters are only
accessible if the ramp function is
validated in the configuration menu (see
section 4.2.10). When the capacity
loading of the unit is effectively limited
by the ramp, mode 11 is displayed in the
information menu (see section 4.2.4).
Range: 0.1 to 1.1°C/min
Items 8 to 17 Setpoint reset
In normal operating conditions, the unit
maintains a leaving water temperature at
the heat exchanger (i.e. evaporator in
cooling mode or condenser in heating
mode) which is more or less equal to the
active cooling or heating setpoint. This
setpoint is generally chosen by reference
to full load operating conditions. Under
partial load, it may be necessary to reset
the setpoint upwards (in cooling mode) or
downwards (in heating mode) in order to
optimise the unit performance.
The system uses the control point to
adjust the water leaving temperature:
• Control point = active setpoint + reset
(cooling mode)
• Control point = active setpoint - reset
(heating mode)
When the reset function is active (i.e.
when the calculated reset value is non-
zero) mode 9 is displayed (see section
4.2.4).
°F °C
(psig) (kPa)
96 35
(114) (788)
140 60
(229) (1558)