analog to digital converter . . . . . . . . . . . . . . . 4 - UPGNet

351579-YTS-B-0608free cooling is available (economizer operation) and the otherone for mechanical cooling only. First, when free cooling isavailable ("economizer suitable"), the SAT control algorithm isas described in the Economizer Operation section later in thisdocument, except the programmed Economizer First StageSetpoint and Economizer Second Stage Setpoint are replacedby the programmed VAV Upper Cooling SAT Setpoint and VAVLower Cooling SAT Setpoint.When free cooling is not available, the SAT control is performedby the following control algorithm: Minimum compressor offtimes (ASCD) of 5 minutes and minimum on times of one to tenminutes [default is three] are maintained and the cycling rate ofthe compressors will not exceed maximum 6 cycles/hour. TheSAT is controlled in a ±5 °F band around the active SATsetpoint. A compressor is allowed to turn on only if the currentSAT minus the Predicted SAT Drop is more than 5 °F.SUPPLY DUCT PRESSURE CONTROL ALGORITHMThe Supply Duct pressure is controlled to a specified setpoint (seeparagraph Duct Pressure Setpoint, section Option Operationearlier in this document). An appropriate closed loop control PIalgorithm is used to control the supply duct static pressure bymodulating Inlet Guide Vanes, or the supply fan VFD.MORNING WARM UP / VAV OCCUPIED HEATINGCONTROL ALGORITHMSTARTING MORNING WARM UPNon-networked systems: The MWU (Morning Warm Up) optionis enabled by setting the option parameter and establishing astart and end Occupied time period in the control’s Occupied 1weekly schedule.MWU (Morning Warm Up) is initiated upon all transitions fromUnoccupied to Occupied mode. The system clock is used toidentify, for the Morning Warm Up, a 1 hour period before actualoccupancy begins (also see Intelli-Start). If the MWU option isdisabled, the occupancies should be scheduled at their regulartime.An Occupied Override signal will initiate a warm up of up to twohours (the setpoint value of the Unoccupied Override TimePeriod). It is important to note that the unit is still operating in anUnoccupied mode for the first hour after the occupied Overrideinput is turned on. Reference the Weekly and Holiday Schedule,Tables 11 and 12.Figure 7: SAT Control BandMORNING WARM UP / VAV OCCUPIED HEATING FUNCTIONMorning Warm Up controls the RAT to a preprogrammedMorning Warm Up RAT Setpoint. An appropriate closed loopcontrol algorithm is used to control heat stages to accomplishthis. The algorithm uses a dead band (i.e. control RAT betweenthe MWU RAT Setpoint and two degrees below the setpoint).Table 11: Weekly ScheduleHOLIDAY SCHEDULEStage Up If SAT is Above SetpointBy + 5.0 0 F, or More, For 5 Minutes+ 5.0 0 FActive SAT Setpoint- 5.0 0 FStage Down If SAT is Above SetpointBy - 5.0 0 F, or More, For 5 MinutesTimes Mon Tues Wed Thu Fri Sat SunOccupied 1 00:00 00:00 00:00 00:00 00:00 00:00 00:00Unoccupied 1 00:00 00:00 00:00 00:00 00:00 00:00 00:00Occupied 2 00:00 00:00 00:00 00:00 00:00 00:00 00:00Unoccupied 2 00:00 00:00 00:00 00:00 00:00 00:00 00:00• If the Start Time is programmed to zero, the default is all day.• The Number of Days will be programmed from 0-99.• The Start Date is programmed by Month-Day-Year.• When the Start Date is 00-00-0000, that Holiday is ignored.• When the Time is 00:00, the Time is equal to 12:00 a.m.,the beginning of the day.34 Johnson Controls Unitary Products