Engineering Manual o.. - HVAC.Amickracing

AIR HANDLING SYSTEM CONTROL APPLICATIONSHEATING, COOLING, HUMIDIFICATION, AND DEHUMIDIFICATION CONTROLWITHOUT DEAD-BANDSFunctional Description2052EAN.C.RASA528824211150SPACE23.5835OAN.O.N.C.32ONNORMAL1ON13.52516REHEAT1223.5SUPPLY AIRTEMPERATURESETPOINT4114COOLINGDEMAND013359783PERCENTOPEN49 101816 130 1002715 SUPPLYFAN2611 0OACW13 4024131745100ECONOMIZER DECISION.REFER TO PREVIOUSECONOMIZER OPTIONS8 6OA MINIMUM SETPOINT(NOTE: THE TEST ANDBALANCE INITIALVALUE FOR PROPERVENTILATION IS 22)2822CONTROLPROGRAMCOOL COILLEAVING AIRTEMPERATURESETPOINT131921 45HUMIDIFIERVALVE POSITION023HUMIDI-FICATIONDEMAND5502250100100ItemNo.FunctionM151801-3 Control system energizes when fan is turnedon (See FAN SYSTEM START-STOPCONTROL).4-6 Manual positioning value determinesminimum ventilation mixing damper position.7 Operator information, outdoor air temperature.8 Economizer enables free cooling when OA issuitable.9 Operator information, MA temperature.10,27 Heating coil valve modulates to keep reheatcoil entering air from getting too low.11-16 Space temperature PI loop resets setpoint ofreheat coil SA PI loop to maintain constantspace temperature.17,18 Chilled water valve modulates in sequencewith mixing dampers as required to maintainSA PI setpoint.19 Chilled water coil leaving air temperaturelowered if required for dehumidification.20-26 Space humidity PI control loop modulateshumidifier valve to maintain space relativehumidity, subject to an SA high limithumidity PI loop.27 Control program coordinates ventilation,heating, cooling, humidification,dehumidification, and fan interlocks.252ENGINEERING MANUAL OF AUTOMATIC CONTROL