Carrier WeatherExpert 48N2 Controls, Start-up, Operation, Service And Troubleshooting Instructions

Also see for WeatherExpert 48N2: Installation instructions Installation instructions Controls, start-up, operation, service, and troubleshooting Installation instructions

Contents

Carrier WeatherExpert 48N2 Controls, Start-up, Operation, Service And Troubleshooting Instructions Manual pdf 91 page image

91The algorithm will calculate a Start Bias time in minutes us-ing the following equations:If (space temperature > occupied cooling set point)Start Bias Time = (space temperature – occupied cooling setpoint)* TCS.CIf (space temperature < occupied heating set point)Start Bias Time = (occupied heating set point – spacetemperature)*TCS.HWhen the Start Bias Time is greater than zero the algorithmwill subtract it from the next occupied time to calculate the newstart time. When the new start time is reached, the TemperatureCompensated Start mode is set (Operating ModesMODET.C.ST), the fan is started and the unit controlled as in an occu-pied state. Once set, Temperature Compensated mode will stayon until the unit goes into the Occupied mode. The Start BiasTime will be written into the CCN Linkage Equipment Table ifthe unit is controlled in DAV mode. If the Unoccupied Econo-mizer Free Cool mode is active (Operating ModesHVAC =“UNOCC FREE COOL”) when temperature compensatedstart begins, the Unoccupied Free Cool mode will be stopped.Carrier Comfort Network® (CCN) — It is possibleto configure the ComfortLink controls to participate as an ele-ment of the Carrier Comfort Network (CCN) system directlyfrom the local display. This section will deal with explainingthe various programmable options which are found under theCCN sub-menu in the Configuration mode.The major configurations for CCN programming are locat-ed in the local displays at ConfigurationIAQCCN. SeeTable 61.CCN Address (CCNA) — This configuration is the CCN ad-dress the rooftop is assigned.CCN Bus Number (CCNB) — This configuration is the CCNbus the rooftop is assigned.CCN Baud Rate (BAUD) — This configuration is the CCNbaud rate.CCN Time/Date Broadcast (TM.DT) — If this configurationis set to ON, the control will periodically send the time and dateout onto the CCN bus once a minute. If this device is on a CCNnetwork then it will be important to make sure that only onedevice on the bus has this configuration set to ON. If more thanone time broadcaster is present, problems with the time willoccur.NOTE: Only the time and date broadcaster can performdaylight savings time adjustments. Even if the rooftop is standalone, the user may want to set this to ON to accomplish thedaylight/savings function.CCN OAT Broadcast (OAT.B) — If this configuration is setto ON, the control will periodically broadcast its outside-airtemperature at a rate of once every 30 minutes.CCN OARH Broadcast (ORH.B) — If this configuration isset to ON, the control will periodically broadcast its outside airrelative humidity at a rate of once every 30 minutes.CCN OAQ Broadcast (OAQ.B) — If this configuration is setto ON, the control will periodically broadcast its outside airquality reading at a rate of once every 30 minutes.Global Schedule Broadcast (G.S.B) — If this configuration isset to ON and the schedule number (SCH.N) is between 65 and99, then the control will broadcast the internal time scheduleonce every 2 minutes.CCN Broadcast Acknowledger (B.ACK) — If this configu-ration is set to ON, then when any broadcasting is done on thebus, this device will respond to and acknowledge. Only one de-vice per bus can be configured for this option.Schedule Number (SCH.N) — This configuration determineswhat schedule the control may follow.SCH.N = 0 The control is always occupied.SCH.N = 1 The control follows its internal time sched-ules. The user may enter any numberbetween 1 and 64 but it will be overwrittento “1” by the control as it only has oneinternal schedule.SCH.N = 65-99 The control is either set up to receive to abroadcasted time schedule set to thisnumber or the control is set up to broadcastits internal time schedule (G.S.B) to thenetwork and this is the global schedulenumber it is broadcasting. If this is the case,then the control still follows its internal timeschedules.Accept Global Holidays? (HOL.T) — If a device is broad-casting the time on the bus, it is possible to accept the time yetnot accept the global holiday from the broadcast message.Override Time Limit (O.T.L) — This configuration allowsthe user to decide how long an override occurs when it is initi-ated. The override may be configured from 1 to 4 hours. If thetime is set to 0, the override function will become disabled.Timed Override Hours (OV.EX) — This displays the currentnumber of hours left in an override. It is possible to cancel anoverride in progress by writing “0” to this variable, therebyremoving the override time left.SPT Override Enabled? (SPT.O) — If a space sensor is pres-ent, then it is possible to override an unoccupied period bypushing the override button on the T55 or T56 sensor. Thisoption allows the user to disable this function by setting thisconfiguration to NO.T58 Override Enabled? (T58.O) — The T58 sensor is a CCNdevice that allows cooling/heating set points to be adjusted,space temperature to be written to the rooftop unit, and the abil-ity to initiate a timed override. This option allows the user todisable the override initiated from the T58 sensor by settingthis option to NO.Global Schedule Override? (GL.OV) — If the control is setto receive global schedules then it is also possible for the globalschedule broadcaster to call out an override condition as well.This configuration allows the user to disable the global sched-ule broadcaster from overriding the control.Alert Limit Configuration — The ALLM submenu isused to configure the alert limit set points. A list is shown inTable 62.SPT Low Alert Limit/Occ (SP.L.O) — If the space tempera-ture is below the configurable occupied SPT Low Alert Limit(SP.L.O), then Alert 300 will be generated and the unit will bestopped. The alert will automatically reset.SPT High Alert Limit/Occ (SP.H.O) — If the space tempera-ture is above the configurable occupied SPT High Alert Limit(SP.H.O), then Alert 301 will be generated and the unit will bestopped. The alert will automatically reset.SPT Low Alert Limit/Unocc (SP.L.U) — If the space tem-perature is below the configurable unoccupied SPT Low AlertLimit (SP.L.U), then Alert 300 will be generated and the unitwill be stopped. The alert will automatically reset.SPT High Alert Limit/Unocc (SP.H.U) — If the space tem-perature is above the configurable unoccupied SPT High AlertLimit (SP.H.U), then Alert 301 will be generated and the unitwill be stopped. The alert will automatically reset.EDT Low Alert Limit/Occ (SA.L.O) — If the space tempera-ture is below the configurable occupied evaporator dischargetemperature (EDT) Low Alert Limit (SA.L.O), then Alert 302will be generated and cooling operation will be stopped butheating operation will continue. The alert will automaticallyreset.