Daikin DPS Installation And Maintenance Manual

Also see for DPS: Installation and maintenance manual Installation and maintenance manual Installation manual Installation and maintenance manual

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Daikin DPS Installation And Maintenance Manual Manual pdf 107 page image

Cooling(See page 41 for more information)Entering the Cooling Operating StateThe unit enters the Cooling operating state from the Fan Onlyoperating state when the control temperature rises above theOccupied Cooling Set Point by more than half the OccupiedCooling Dead Band and the discharge air temperature is abovethe discharge cooling setpoint by more than half the OccupiedCooling Dead Band The unit transitions from Cooling to Fanonly when the control temperature falls below the OccupiedCooling Set Point by more than half the Occupied CoolingDead Band The unit will also transition from the Cooling to Fanonly operating state if Cooling operation is disabled due to OAambient lockoutDAT ControlIn the Cooling state, compressors are modulated to maintainthe Discharge Air Temperature at the Discharge CoolingSetpointZone ControlIn the Cooling state, compressors are turned ON andmodulated to maintain the control temperature at the OccupiedCooling SetpointWhen Dehumidification is active, compressors are modulatedto maintain the leaving coil temperature at the minimum leavingcoil setpointProject AheadThis section describes the Projected Control Temperatureused to turn on and off stages of heating and cooling for ZoneControl units It is not used in DAT Control unitsIn Zone Control cooling and heating operation, the ProjectedControl Temperature, reduces overshoot as the zonetemperature approaches a setpoint after startup It does thisby causing stages to stop increasing before the actual controltemperature reaches the setpoint The rate of change of thecontrol temperature is calculated once per minute by thecontroller and equals the change during the last sixty secondsThis rate of change is multiplied by the Effective Project AheadTime and is added to the current control temperature The rateof change may be negative or positive so the Projected ControlTemperature may be higher or lower than the actual controltemperature This value, the Projected Control Temperature, isthe temperature that would exist after the Project Ahead Timepasses if the control temperature were to continue to changeat the same rate for the Effective Project Ahead Time TheEffective Project Ahead Time is set equal to the Cooling ProjectAhead Time when the unit is in the Cooling state The EffectiveProject Ahead Time is set equal to the Heating Project AheadTime when the unit is in the Heating state It is set equal tozero under all other conditions causing the Projected ControlTemperature to equal the actual control temperatureDischarge Air Temperature SetpointReset - CoolingThe Cooling DAT Setpoint may be reset for units with DATCooling Control The reset type may be set to one of thefollowing:• None: Discharge Cooling Spt is user adjustable• Network: Discharge Cooling Spt is equal to the NetworkDAT Clg Setpoint when it is valid• Space: Discharge Cooling Spt is based on the SpaceSensor• Return: Discharge Cooling Spt is based on the Return AirSensor• OAT: Discharge Cooling Spt is based on the Outdoor AirTemperature• Ext mA: Discharge Cooling Spt is determined by a 0-20mA signal• Ext V: Discharge Cooling Spt is determined by a 0-10VDC signal• Airflow: Discharge Cooling Spt is based on the airflow asindicated by the variable frequency drive speedReset reverts from Return to None when a Return Air Sensoropens or shorts Reset reverts from Space to None when aSpace Sensor opens or shorts Reset reverts from OAT toNone when an Outdoor Air Sensor opens or shortsWhen Space, Return, OAT, Airflow, Ext mA, or Ext V isselected, the Discharge Cooling Spt equals the Max Clg Sptwhen the selected value equals the Max Clg Spt @ valueSimilarly, the Discharge Cooling Spt equals the Min Clg Sptwhen the selected value equals the Min Clg Spt @ valueWhen Space, Return, OAT, or Airflow is selected, the resetschedule should be set so that the DAT Cooling setpointdecreases as the selected temperature increases as shown inthe graph belowFigure 19: Cooling Setpointoperator ’s guIdewww DaikinApplied com107 OM 1141-3 • MICROTECH UNIT CONTROLLER