Carrier SINGLE PACKAGE ROOFTOP UNITS ELECTRIC COOLING/GAS HEATING 48EJ Installation And Service Instructions Manual

Also see for 48EJ: Installation, Start-Up and Service Instructions User manual

Contents

Table 18 — User Defined Set PointsSET POINTNAME FORMAT DESCRIPTION LIMITS DEFAULTOHSP xx.xF Occupied Heat Set Point 55 to 80 F 68 FOCSP xx.xF Occupied Cool Set Point 55 to 80 F 78 FUHSP xx.xF Unoccupied Heat Set Point 40 to 80 F 55 FUCSP xx.xF Unoccupied Cool Set Point 75 to 95 F 90 FSASP xx.xF Supply Air Set Point 45 to 70 F 55 FOATL xx.xF Hi OAT Lockout Temperature 55 to 75 F 65 FNTLO xx.xF Unoccupied OAT Lockout Temperature 40 to 70 F 50 FRTIO xx.x Reset Ratio 0 to 10 3LIMT xx.xF Reset Limit 0 to 20° F 10%MDP xxx% Minimum Damper Position 0 to 100% 20%LOWMDP xxx% Low Temperature MinimumDamper Position Override 0 to 100% 100%IAQS xxxx IAQ Set Point 1 to 5000 PPM 650 PPMUHDB xx.xF Unoccupied Heating Deadband 0 to 10° F 1° FUCDB xx.xF Unoccupied Cooling Deadband 0 to 10° F 1° FLTMP xxx% Low Temp. Min. Position 0 to 100% 10%HTMP xxx% High Temp. Min. Position 0 to 100% 35%PES1 xxx% CV Power Exhaust Stage 1 Point 0 to 100% 25%PES2 xxx% CV Power Exhaust Stage 2 Point 0 to 100% 75%LEGENDCV — Constant VolumeIAQ — Indoor Air QualityOAT — Outdoor-Air TemperatureIf thermostats are used to deenergize the G input, the con-trol board will turn off indoor fan without any delay and closeeconomizer dampers.When cooling, G must be energized before cooling canoperate. The control board determines if outdoor conditionsare suitable for economizer cooling using the standard out-door air thermistor. For economizer to function for free cool-ing, the enthalpy must be low, the outdoor air must equal toor less than the High Outdoor Air Temperature Lockout (de-fault is 65 F), the SAT (supply-air temperature) thermistor isNOT in alarm, and outdoor air reading is available. Whenthese conditions are satisfied, the control board will use econo-mizer as the first stage of cooling.When Y1 input is energized, the economizer will be modu-lated to maintain SAT at the defined set point. The default is55 F. When SAT is above the set point, the economizer willbe 100% open. When SAT is below the set point, the econo-mizer will modulate between minimum and 100% open po-sition. When Y2 is energized, the control will turn on com-pressor no. 1 and continue to modulate economizer as describedabove. If the Y2 remains energized and the SAT reading re-mains above the set point for 15 minutes, compressor no. 2will turn on. If Y2 is deenergized at any time, only the laststage of compression that was energized will be turned off.If outdoor conditions are not suitable for economizer cool-ing, the economizer will go to minimum position and cyclecompressor no. 1 and 2 based on demand from Y1 and Y2respectively. The compressors will be locked out when theSAT temperature is too low (less than 40 F for compressorno. 1 and less than 45 F for compressor no. 2.) After a com-pressor is locked out, it can restart after normal time guardperiod.The Time Guardt function maintains a minimum off timeof 5 minutes, a minimum ON time of 10 seconds, and aminimum delay before starting the second compressor of10 seconds.When heating, the heat stages respond to the demand fromW1 and W2 of the thermostat input. Heating and coolingwill be mutually locked out on demand on a first call basis.The heating and the cooling functions cannot be operatingsimultaneously.COOLING, VARIABLE VOLUME UNITS — On power up,the control module will activate the initialization softwareof the control board. The initialization software then readsDIP switch no. 1 position to determine CV or VAV opera-tion. Initialization clears all alarms and alerts, re-maps theinput/output database for VAV operation, sets maximum heatstages to 1 and sets maximum cool stages to 6. The controlreads DIP switch no. 3 and if open, then it sets the internalflag for expansion mode operation.The control board will determine if an interface (linkage)is active and if the unit will operate in a Digital Air Volume(DAV) mode. In a DAV system, the room terminals are equippedwith microprocessor controls that give commands to the baseunit module. If an interface is active, the control will replacelocal comfort set points, space and return air temperaturesand occupancy status with the linkage data supplied.The control board will determine occupancy status fromTime Schedules (if programmed), Remote Occupied/Unoccupied input, global occupancy, or DAV. If tempera-ture compensated start is active, the unit will be controlledas in the Occupied mode.NOTE: The temperature compensated start is a period of timecalculated to bring the unit on while unoccupied to reach theoccupied set point when occupancy occurs.The control board will set the appropriate operating modeand fan control. The control board will turn VFD on if Oc-cupied mode is evident.For units equipped with a start/stop switch only (no spacetemperature sensor), if unoccupied and valid return-air tem-perature reading is available (either from a sensor or DAV),the control will monitor return-air temperature against Un-occupied Heat and Cool set points.For units with a start-stop switch and a space temperaturesensor, the control board will start the VFD whenever SPTis outside of the set points (Unoccupied Heat or UnoccupiedCool). The VFD may also be started by nighttime thermostatvia remote Occupied/Unoccupied input or by a temperaturecompensated start algorithm. When VFD is running in a nor-mal mode, the control will start heating or cooling as re-quired to maintain supply-air temperature at the supply airset point plus the reset (when enabled). The reset value isdetermined by SAT (supply-air temperature) reset and/or spacetemperature reset algorithms. The space temperature reset isonly available when enabled through software.40