Carrier 48FC Series Controls, Start-up, Operation And Troubleshooting

Also see for 48FC 04: Installation instructions

Carrier 48FC Series Controls, Start-up, Operation And Troubleshooting Manual pdf 15 page image

15system demand to be reduced. When the demand hits the off switchstages the system demand will be set to NO DEMAND. Theseswitch stages are in the SETTINGSSET POINTSTEMPDEMAND CONFIG submenu.The cooling and heating demand level up configurations (COOLDMD LEVEL UP and HEAT DMD LEVEL UP) will restrict asystem demand increase if the demand trend is less than the levelup configuration. These level up configurations will also increasethe system demand if the demand trend is greater than it for greaterthan the Time guard 2 (DEMAND TIMEGUARD2).The system demand will increase if it has remained at the samestate for greater than Time Guard 3 (DEMAND TIMEGUARD3).Cool SetpointHeat SetpointLCONLHONHCONHHONLHOFLCOFDecreaseDemandDecreaseDemandSPACE TEMPa48--- 10313Fig. 9 -- Space Sensor System Demand Switch StatesRAT DemandWhen the unit control type is configured for return air sensor(UNIT CONTROL TYPE = RAT SEN) the level 5 demand inTable 8 will be determined the same as space sensor but using thereturn air temperature (RETURN AIR TEMP) instead of the spacetemperature (SPACE TEMPERATURE).Humidity DemandWhen the unit is configured for either a Humidistat input(HUMSTAT CHANNEL) or Space Humidity Sensor (SPRHSENS CHANNEL) the level 5 demand in Table 8 will include adetermination of dehumidification demand.HumidistatWhen receiving an active input from the Humidistat(HUMIDISTAT), dehumidification will be demanded.Space Relative HumidityOn units with a relative humidity sensor, when the received valueof space relative humidity (SPRH LEVEL) has exceed thehumidity set point (SPRH SET POINT), dehumidification will bedemanded. This demand will remain until the space relativehumidity has fallen below the humidity set point by more than thehumidity set point deadband (SPRH DEADBAND). This wouldcome from the space humidity sensor, or building network.Occupancy DeterminationThe building’s occupancy is affected by a number of differentfactors. Occupancy affects the unit set points and the operation ofthe economizer. The factors affecting occupancy are listed belowfrom highest to lowest priority.Level 1 PriorityLevel 1 classification is a force/write to occupancy and can occurtwo ways. Listed in order of priority: force on OCCUPIED, and aLinkage write. The CCN point OCCUPIED is forced via anexternal device such as a ComfortIDt controller or a service tool:when OCCUPIED is forced to YES, the unit is consideredoccupied, when OCCUPIED is forced to NO, the unit isconsidered unoccupied. If the unit is being controlled by Linkage,the occupancy is communicated and mapped to OCCUPIED as aninput. Linkage does not force the point only write to it, therefore aforce applied to OCCUPIED will override it.If OCCUPIED is not being forced or written to, proceed to thelevel 2 priority.Level 2 PriorityLevel 2 is considered occupant interaction, and consists of TimedOverride and Remote Occupancy Switch. A timed override buttonpress will override a remote occupancy switch if both are installedfor operation.While using the programmed schedule, occupancy can betemporarily switched from unoccupied to occupied by pressing theoverride button for approximately 3 seconds on the T--55, T--56, orT--59 space temperature sensor. The length of the override periodwhen pressing the override button is determined by the OverrideTime Limit (TIMED OVR LENGTH). The hours remaining inoverride is displayed as Timed Override Hours (TIMED OVRHOURS). This point can also be changed from the local display ornetwork to set or change the override period length.Remote Occupancy Switch (REMOTE OCC SWITCH) can beforced or configured for operation based on an actual switch. Thephysical switch should be configured to either Normally Open orNormally Closed when the user would like to control theoccupancy with an external switch. This switch is field--supplied(24v, single pole, single throw [SPST]). There are two possibleconfigurations for the remote occupancy switch:1. (REMOTE OCC TYPE = 0) Normally Open Switch2. (REMOTE OCC TYPE = 1) Normally Closed SwitchIf the switch is configured to No Switch (REMOTE OCC CHAN =None), the switch input value will be ignored and software willproceed to level 3 priority. For each type of switch, the appropriateconfiguration and states are listed in the table below.TYPE OF SWITCH SWITCHCONFIGURATIONSTATE OF SWITCHAND STATE OFOCCUPANCYOccupied whenClosed or Unoccupiedwhen OpenNormal Open (0)Open and UnoccupiedClosed and OccupiedOccupied when Openor Unoccupied whenClosedNormal Closed (1)Open and OccupiedClosed andUnoccupiedLevel 3 PriorityThe following occupancy options are determined by the state ofOccupancy Schedule Number (SCHEDULE NUMBER) and theGlobal Schedule Broadcast (BROADCAST SCHEDL?).1. (SCHEDULE NUMBER = 0) The unit is alwaysconsidered occupied and the programmed schedule isignored. This is the factory default.2. (SCHEDULE NUMBER = 1- 64) Follow the localprogrammed schedule. Schedules 1 to 64 are local withinthe controller. The unit can only store one local scheduleand therefore changing this number only changes the title ofthe schedule table.3. (SCHEDULE NUMBER = 65- 99) Follow the globalprogrammed schedule. If the unit is configured as a GlobalSchedule Broadcaster (BROADCAST SCHEDL? = YES),the unit will follow the unit s programmed schedule andbroadcast the schedule so that other devices programmed tofollow this schedule number can receive the schedule. If theunit is not programmed as a Global Schedule Broadcaster(BROADCAST SCHEDL? = NO), the unit will receivebroadcasted schedules from a unit programmed to broadcastthis schedule number.