JOHNSON CONTROLS
68
FORM100.50-EG12 (918)
COOLING OPERATION
Zone Sensor Control
If a zone sensor controls the unit, the single package unit controller shall maintain the
zone temperature setpoint. This setpoint is user selectable at the single packaged unit
User Interface.
When a zone sensor is used for control, the single package unit controller will monitor
the temperature within the space and control the unit accordingly. A closed-loop staging
algorithm is used to stage compressors up and down as required to maintain the desired
zone temperature setpoint. If the unit is equipped with an economizer, outside air condi-
tions are continuously monitored by the control to determine if conditions are suitable for
economizing. If conditions are suitable for economizing, the single package unit controller
will modulate the outside air damper in addition to staging compressors up and down to
maintain the zone temperature setpoint.
HEATING OPERATION
Zone Sensor Control
If a zone sensor controls the unit, the single package unit controller shall maintain all zone
temperature setpoints. These setpoints are user selectable at the single package unit
user interface.
When a zone sensor is used for control, the single package unit controller will monitor
the temperature within the space and control the unit accordingly. A closed-loop staging
algorithm is used to stage heating steps up and down as required to maintain the desired
zone temperature setpoint. If the unit is equipped with an economizer, outside air condi-
tions are continuously monitored by the control to determine if conditions are suitable for
economizing. If conditions are suitable for economizing, the single package unit controller
will modulate the outside air damper in addition to staging heating steps up and down to
maintain the zone temperature setpoint.
Controls (Cont'd)
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