Carrier Touch Pilot Control Series Control Manual

8.14 - BACnet (option 149)The BACnet/IP communication protocol is used by the buildingmanagement system or the programmable controllers tocommunicate with the Touch Pilot interface. It is activated if theoptional BACnet activation key (dongle) is present on the electroniccontrol board.This option may be ordered and installed on site. The BACnetprofile of the Touch Pilot interface is B-ASC.For more information about BACnet, please refer to the BACnetdocument included with the control or contact ManufacturerService Agency.8.15 - Dry cooler (option 154)19PV units have been specially designed to optimise the operationof split installations, using air-cooled condensers as the chiller heatrejection system.19PV units can control a Carrier dry cooler to cool down thecondenser water loop. This air exchanger includes all compatiblecontrol electronics.8.15.1 - Condensing pressure controlThe control configuration of this functionality must be done bya specially trained and qualified engineer during the unitinstallation. The Manufacturer supplies specific documentation forthis operation to the trained engineers.The Touch Pilot control system includes logic to permit the controlof different fixed and variable-speed fan variants.Touch Pilot continuously optimizes system operation to obtain thebest system efficiency by controlling the number of fans requiredfor any thermal load and outside temperature conditions.8.15.2 - Condensing setpointThe condensing setpoint is adjustable in the Setpoint menu(SETPOINT).Condensing setpointMinimum value 27°CDefault value 35°CMaximum value 49°CThe condensing setpoint can be reset by reference to the outsidetemperature to optimize the operation of the condensing system.To set the condensing setpoint reset, the following adjustmentsare necessary:- hr_sel (Heating Reset Select) set to “1” (OAT) in the ResetConfiguration menu (RESETCFG).- oat_crno (OAT no reset value), oat_crfu (OAT full reset value)and hr_deg (heating reset degree value) must be set in theReset Configuration menu (RESETCFG). See also section8.4.2 for more information about reset control.8.16 - Dry cooler free cooling (option 313)19PV units may come with the free cooling option that enablesthe control of a Carrier dry cooler. The chiller and the dry coolerhave to be connected through a LEN RS-485.Units fitted with a dry cooler provide the “free cooling” functionalitywhich means that the chilled water system directly exchangesheat using the air-to-water heat exchanger (“dry cooler”).For chillers with this option, the Touch Pilot control may use lowoutside air temperature to cool down the water loop and satisfythe cooling demand.The dry cooler is used not only to assist in producing cooling waterto meet the current cooling demand but it also allows for reducingenergy consumption.The dry cooler comes with up to 20 fans, i.e. fixed-speed or variable-speed fans, which can be installed in different configurations. TheTouch Pilot control distinguishes between two types of fan controlfor a dry cooler free cooling option, where the first one embracesthe use of fan staging and the second one includes the use ofvariable-speed fans. Mixed configuration can also be used (fixedand variable-speed fan control at the same time).8.17 - Master/Slave controlThe control system allows for master/slave control of two unitslinked by the network. The master unit can be controlled locally,remotely or by network commands, while the slave unit remainsin Network mode.All control commands to the master/slave assembly (start/stop,setpoint selection, heating/cooling control, load shedding, etc.)are handled by the unit which is configured as the master.The commands are transmitted automatically to the slave unit.If the master chiller is turned off, while the master/slave functionis active, then the slave chiller will be stopped. Under certaincircumstances, the slave unit may be started first to ensure thatthe run times of the two units are equalised.In the event of a communication failure between the two units,each unit will return to an autonomous operating mode untilthe fault is cleared. If the master unit is stopped due to an alarm,the slave unit is authorised to start.IMPORTANT: Master/slave assembly can be configured onlyby service technicians.8 - STANDARD CONTROL OPERATIONS AND OPTIONS29