Carrier 48AK Installation, Start-up And Service Instructions Manual

Also see for 48AJ: Installation instructions Operation and service guide Started guide Operating and service guide

Contents

33• control of one stage of heat to maintain return-air tem-perature at heating set point during occupied periods• provide a variable frequency drive high voltage relayoutput to enable VFD• control of heat interlock relay• IAQ (Indoor Air Quality) sensor• OAQ (Outdoor Air Quality) sensor• DX compressor lockout occurs at 45 F outdoor air tem-perature and is factory-enabled on units with serial num-ber 0600F or later. This feature may be disabled throughthe use of a computer• compressor Time Guard® override (power up, minimumoff and on times)With the addition of a remote start/stop switch heating orcooling is enabled during unoccupied periods as required tomaintain space temperature to within unoccupied set points.Occupied heating is enabled or disabled by the position ofDIP (dual in-line package) switch no. 5.Additional features may be provided with Electronic Ac-cess to Unit Control Board. These features are:• additional control board diagnostics• electronic expansion board features (if installed)• control of the economizer damper and indoor fan toobtain unoccupied free cooling• 365-day timeclock with backup (supports minute, hour,day, month, and year)• holiday table containing up to 18 holiday schedules• occupancy control with 8 periods for unit operation• support a set of display, maintenance, configuration, ser-vice, and set point data tables for interface with BuildingSupervisor, ComfortWORKS®, or Service Tool softwareor accessory remote enhanced display• CCN IAQ/OAQ (outdoor air quality) participationWhen a VAV unit with a space temperature sensor is access-ed via a computer, the following additional features areavailable:• ability to initiate timed override from T-55 sensors• temperature compensated start to calculate early starttime before occupancy• provide space temperature reset to reset the supply air setpoint upward when the temperature falls below the occu-pied cooling set pointAn electronic expansion board may be field-installed to pro-vide the following features:• fan status• filter status• field-applied status• demand limiting• alarm light• fire unit shutdown• fire pressurization• fire evacuation• fire smoke purgeWhen the unit is connected to the CCN (Carrier ComfortNetwork), the following features can be utilized:• CCN demand limit participation• modulated power exhaust override• ability to use multiple space temperature sensors (multi-ples of 4 and 9 only) to average space temperature (CVand VAV only)A field-supplied T-55 space temperature sensor can be add-ed to monitor room temperature and provide unoccupied over-ride capability (1 hour).When the unit is equipped with a field-supplied spacetemperature sensor and a remote contact closure (remotestart/stop) the occupied default set points will monitor unitoperation. The occupied default set points are 55 F (supply-airtemperature) cooling and 68 F (return-air temperature) heating.See Fig. 26 for remote start/stop wiring.NOTE: For units without a space temperature sensor andwhich have not had the base unit control board accessed viasoftware to set an occupancy schedule, the remote start/stopclosure will allow the unit to operate in the pre-configuredoccupied default set points of 55 F (supply-air temperature)cooling and 68 F (return-air temperature) heating. Without anoccupancy schedule, the unit will control to the unoccupieddefault set points of 90 F (return-air temperature) cooling and55 F (return-air temperature) heating.Features with Network Applications — The base controlboard provides, as standard, a connection for use with a CarrierComfort System and can also be integrated into a Carrier Com-fort Network (CCN). When the unit is accessed via a PCequipped with ComfortWORKS, Building Supervisor, or Ser-vice Tool software or Remote Enhanced Display accessory, thefollowing features can be accessed:• on-board timeclock can be programmed• occupancy schedules can be programmed• unit set points can be changed• alarms can be monitoredThis access is available on the base control board via aRJ-11 phone jack or a 3-wire connection to the communicationbus. See Fig. 27. The internal timeclock has a 10-hour mini-mum back-up time to provide for unit power off for servicingunit or during unexpected power outages. For complete CarrierComfort System (CCS) or Carrier Comfort Network (CCN)features and benefits, refer to the product literature.Step 9 — Make Electrical ConnectionsPOWER WIRING — Units are factory wired for the voltageshown on the unit nameplate.When installing units, provide a disconnect per NEC(National Electrical Code) of adequate size (MOCP [maximumovercurrent protection] of unit is on the informative plate). Allfield wiring must comply with NEC and all local codes and re-quirements. Size wire based on MCA (minimum circuit amps)on the unit informative plate. See Fig. 28 for power wiring con-nections to the unit power terminal block and equipmentground.The main power terminal block is suitable for use with alu-minum or copper wire. See Fig. 28. Units have circuit breakersfor compressors, fan motors, and control circuit. If required bylocal codes, provide an additional disconnect switch. Whenev-er external electrical sources are used, unit must be electricallygrounded in accordance with local codes, or in absence of localcodes, with NEC, ANSI (American National Standards Insti-tute) C1-latest year.FIELD POWER SUPPLY — Unit is factory wired for volt-age shown on unit nameplate. See Table 7 and 8 for electricaldata.Field wiring can be brought into the unit from bottom(through basepan and roof curb) or through side of unit (cornerpost next to control box).A 31/2-in. NPT coupling for field power wiring and a 3/4-in.NPT coupling for 24-v control wiring are provided in basepan.In the side post, there are two 21/2-in. (48A020-030 and48E024-034) or 3-in. (48A035-060 and 48E038-068) knock-outs for the field power wiring. See Fig. 5-16. If control wiringis to be brought in through the side of unit, a 7/8-in. diameterhole is provided in the condenser side post next to the controlbox.If disconnect box is mounted to corner post, be careful notto drill any screws into the condenser coil.