Engineering Manual o.. - HVAC.Amickracing

AIR HANDLING SYSTEM CONTROL APPLICATIONSHEATING SYSTEM CONTROL PROCESSSPACE CONTROL OF HEATING, ECONOMIZER (FREE COOLING), AND HUMIDIFICATIONFunctional DescriptionSPACE4453RA52CONTROLPROGRAM82876NC58852SA13129152523.52210COOLHEATN.O.1OA83N.C.NORMALONSUPPLY AIRTEMPERATURESETPOINTSPACEHEATINGDEMAND1713002144113100011ECONOMIZER DECISION.REFER TO PREVIOUSECONOMIZER OPTIONS18CONTROLPROGRAM 222019CONTROLPROGRAMSUPPLY AIRTEMPERATURESETPOINT13SPACECOOLINGDEMAND10027OA MINIMUM SETPOINT(NOTE: THE TEST AND BALANCE INITIALVALUE FOR PROPER VENTILATION IS 22)016M15175ItemNo.Function1,2 Control system energizes when fan is turnedon (See FAN SYSTEM START-STOPCONTROL).3-5 Space humidity PI loop controls humidifiervalve if space humidity falls to setpoint.6,7 SA humidity high limit PI loop throttleshumidifier valve if duct humidity rises abovesetpoint.8 Control program coordinates space andhumidifier leaving air humidity control andfan interlock.9-11 Space temperature heating PI loop inputs toSA temperature heating reset schedule.12 SA temperature PI loop inputs to heating andmixed air control programs.13 Hot water valve modulates to maintain SAtemperature setpoint.14 Control program coordinates space and SAheating control and fan interlock.15,16 Space temperature cooling PI loop inputs to SAtemperature cooling reset schedule.17 Mixing dampers modulate to maintain SAtemperature setpoint.18 Economizer decision program determines whenOA is suitable to assist with cooling demand.19 Mixing dampers minimum ventilation value.20 Control program coordinates space and supplycooling control, ventilation control, and faninterlock.246ENGINEERING MANUAL OF AUTOMATIC CONTROL