Unit installation

Operating
SCXF-SVX01K-EN 61
and when ambient conditions are favorable for
economizing. Inherent in unit controller is the ability to
suppress setpoint below 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/lb (adjustable 19-28 BTu/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).
Air-Cooled Condensers
Model SXRF units are designed for use with the remote air-
cooled condenser, model CXRC. For more information,
see the air-cooled condenser Installation, Owner, and
Maintenance Manual, CXRC-SVX01*-EN. See Table 24,
p. 34 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.