Trane Modular 20 to 35 Tons Wartungshandbuch
Operating Principals
SCXG-SVX01H-EN
73
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).
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.
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).
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 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-SVX01*-EN.
air-cooled condenser, model CXRC. For more information,
see the air-cooled condenser Installation, Owner, and
Diagnostic Manual, CXRC-SVX01*-EN.
Verify head pressure control, standard or optional.
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.
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.
Figure 60. CO
2
reset function, outside air vs. CO
2
Increasing
Concentration
Concentration
Maximum
Airflow
Airflow
Increasing
Reset Amount
Reset Amount
O.A CFM
Setpoint
Setpoint
Carbon Dioxide
Reset Start
Reset Start
Carbon Dioxide
Maximum Reset
Maximum Reset