Carrier 48HC 04-28 Controls, Start-up, Operation And Troubleshooting

Also see for /50HC 04-28: Manual

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Carrier 48HC 04-28 Controls, Start-up, Operation And Troubleshooting Manual pdf 34 page image

34new start time. When the new start time is reached, the Tem-perature Compensated Start mode is set, the fan is started andthe unit controlled as in an occupied state. Once set, Tempera-ture Compensated mode will stay on until the unit goes into theOccupied mode. The Start Bias Time will be written into theCCN Linkage Equipment Table if the unit is controlled in DAVmode. If the Unoccupied Economizer Free Cool mode is activewhen temperature compensated start begins, the UnoccupiedFree Cool mode will be stopped.NOTE: The maximum minutes Start Bias can be is 180.Carrier Comfort Network® (CCN) ConfigurationIt is possible to configure the ComfortLink control to partici-pate as an element of the Carrier Comfort Network (CCN) sys-tem directly from the local display. This section will deal withexplaining the various programmable options which are foundunder the CCN sub-menu in the Configuration mode.The major configurations for CCN programming are located inthe local displays at ConfigurationCCN. See Appendix A.CCN Address (CCN.A)This configuration is the CCN address the rooftop is assigned.CCN Address (CCN.B)This configuration is the CCN bus the rooftop is assigned.CCN Baud Rate (BAUD)This configuration is the CCN baud rate.CCN Time/Date Broadcast (BRODB.TIM)If this configuration is set to ON, the control will periodicallysend the time and date out onto the CCN bus once a minute. Ifthis device is on a CCN network then it will be important tomake sure that only one device on the bus has this configura-tion set to ON. If more than one time broadcaster is present,problems with the time will occur.NOTE: Only the time and date broadcaster can perform daylightsavings time adjustments. Even if the rooftop is stand alone, theuser may want to set this to ON to accomplish the daylight/savingsfunction.CCN OAT Broadcast (BRODB.OAT)If this configuration is set to ON, the control will periodicallybroadcast its outside-air temperature at a rate of once every 30minutes.Global Schedule Broadcast (BRODB.GS)If this configuration is set to ON and the schedule number(SCH.N) is between 65 and 99, then the control will broadcastthe internal time schedule once every 2 minutes.CCN Broadcast Acknowledger (BRODB.ACK)If this configuration is set to ON, then when any broadcasting isdone on the bus, this device will respond to and acknowledge.Only one device per bus can be configured for this option.Schedule Number (SCH.OSCH.N)This configuration determines what schedule the control mayfollow.SCH.N = 0The control is always occupied.SCH.N = 1The control follows its internal time schedules. The user mayenter any number between 1 and 64 but it will be overwritten to“1” by the control as it only has one internal schedule.SCH.N = 65-99The control is either set up to receive to a broadcasted timeschedule set to this number or the control is set up to broadcastits internal time schedule (B.GS) to the network and this is theglobal schedule number it is broadcasting. If this is the case,then the control still follows its internal time schedules.Accept Global Holidays? (SCH.OHOL.G)If a device is broadcasting the time on the bus, it is possible toaccept the time yet not accept the global holiday from thebroadcast message.Override Time Limit (SCH.OOV.TL)This configuration allows the user to decide how long an over-ride occurs when it is initiated. The override may be config-ured from 1 to 4 hours. If the time is set to 0, the override func-tion will become disabled.Timed Override Hours (SCH.OOV.EX)This displays the current number of hours left in an override. Itis possible to cancel an override in progress by writing “0” tothis variable, thereby removing the override time left.SPT Override Enabled? (SCH.OOV.SP)If a space sensor is present, then it is possible to override anunoccupied period by pushing the override button on the T55or T56 sensor. This option allows the user to disable this func-tion by setting this configuration to NO.Demand LimitDemand Limit Control may override the cooling algorithm tolimit or reduce cooling capacity during run time. The term De-mand Limit Control refers to the restriction of machine capaci-ty to control the amount of power that a machine will use. Thiscan save the owner money by limiting peaks in the power sup-ply. Demand limit control is intended to interface with an ex-ternal network system. This is through a CCN Loadshed POCDevice or writing to network points.To limit stages through network writes, the points Run Sta-tusCOOLMAX.C and Run StatusHEATMAX.H areforced on the network through CCN points MAXCSTGS andMAXHSTGS respectively. Force these to the desired maxi-mum stages of cooling/dehumidification and heating, respec-tively.When there is no force on these points, they automatical-ly reset to allow all cooling/dehumidification and heating stag-es to be used. These points are reset at power-on/reset (POR).When using the Loadshed POC to do Demand Limiting, thecool and heat stage limits under both Redline and Loadshedconditions can be set individually with configuration decisions.If the active stages is greater then the loadshed or redline con-figurations when a loadshed or redline command is given, theunit will remove stages.ConfigurationCCNLDSHS.GRPThis is the Loadshed Group Number and corresponds to theloadshed supervisory devices that resides elsewhere on theCCN network and broadcasts loadshed and redline commandsto its associated equipment parts. This variable will default tozero which is an invalid group number. This allows the load-shed function to be disabled until configured.ConfigurationCCNLDSHR.MXCThis configuration tells the unit the maximum cooling stagesallowed to be on during a redline condition.ConfigurationCCNLDSHS.MXCThis configuration tells the unit the maximum cooling stagesallowed to be on during a loadshed condition.ConfigurationCCNLDSHR.MXHThis configuration tells the unit the maximum heating stagesallowed to be on during a redline condition.ConfigurationCCNLDSHS.MXHThis configuration tells the unit the maximum heating stagesallowed to be on during a loadshed condition.The two Demand Limiting methods can be active simultaneous-ly. The lowest cool and heat stage limits imposed by either meth-od are applied, and these “effective stage limits” are shown inthe points CSTGLIMT (Run StatusCOOLLMT.C) andHSTGLIMT (Run StatusHEATLMT.H), respectively. In