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88 SCXG-SVX01B-EN
Table O-GI-10. Remote Air-Cooled Condenser Refrigerant Connection Sizes - English
inches (Metric, mm)
Unit Circuit 1 Circuit 1 Circuit 2 Circuit 2
Size Liquid Line Discharge Line Liquid Line Discharge Line
CXRC 20, 25, 29, 30
5
/
8
1
1
/
8
5
/
8
1
1
/
8
(16) (29) (16) (29)
Standard Two-Position Damper Interface
Units with the two-position damper
interface are provided with a 0-10 VDC
control output suitable for controlling a
field-provided modulating actuator. In
occupied mode, the output drives to the
maximum position.
Airside Economizer Interface
Units with airside economizer interface
are equipped with the necessary control
sequences to allow using outside air for
the first stage of cooling, in occupied or
unoccupied mode and when ambient
conditions are favorable for economizing.
Inherent in the unit controller is the ability
to suppress the setpoint below the
normal unit setpoint. This allows the
building to improve comfort levels when
possible, and at the same time, optimize
building mechanical cooling operation for
peak operating efficiency. An outside air
temperature and relative humidity
sensor are provided for field installation
to monitor reference enthalpy.
Economizer operation enables when the
outside air enthalpy is less than 25 BTU’s/
lb. (adjustable 19-28 BTU’s/lb.). During
occupied mode, the outside air damper
opens to 15% (adjustable 0-100%) for
ventilation purposes. Also, the ability to
alter the outside air damper position to
compensate for VAV supply air
modulation is inherent in the unit controls,
and can be enabled by the operator. An
analog 2-10 VDC output (adjustable (0-10
VDC) is provided to modulate the field-
provided 30 second damper actuators
(adjustable 1-255 seconds).
Airside Economizer Interface with
Comparative Enthalpy
Units with airside economizer interface
and comparative enthalpy are equipped
with the necessary control sequences to
allow using outside air for the first stage
of cooling, in occupied or unoccupied
mode and when ambient conditions are
favorable for economizing. Inherent in the
unit controller is the ability to suppress
the setpoint below the normal unit
setpoint. This allows the building to
improve comfort levels when possible,
and at the same time, optimize building
mechanical cooling operation for peak
operating efficiency. A factory-installed
control board, with outside and return air
temperature and relative humidity
sensors, are provided for monitoring
outside and return air. The sensors are
field installed. Economizer operation
enables when the outside air enthalpy is
3 BTU’s/lb. less than the return air
enthalpy. During occupied mode, the
outside air damper opens to 15%
(adjustable 0-100%) for ventilation
purposes. Also, the ability to alter the
outside air damper position to
compensate for VAV supply air
modulation is inherent in the unit
controls, and can be enabled by the
operator. An analog 2-10 VDC output
(adjustable (0-10 VDC) is provided to
modulate the field-provided 30-second
damper actuators (adjustable 1-255
seconds).
Figure O-GI-6. CO
2
Reset Function, Outside Air vs. CO
2
.
Air-Cooled Condensers
SXRG units are designed for use with the
remote air-cooled condenser, model
CXRC. For more information, see the air-
cooled condenser Installation, Owner, and
Diagnostic Manual,
CXRC-SVX01A-EN.
See Table O-GI-10 for CXRC refrigerant
connection sizes.
Condenser fans will stage per a user-
defined setting. If the condenser is
equipped with head pressure control (air
modulation on last stage of condenser
capacity), the condenser airflow will
modulate to maintain condensing
temperature setpoint. Condensing
temperature is determined by sensors
located at each condenser coil.
Owner
General
Information