Carrier 48TCA04---A12 appendix Oat ≤ Spt

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When in the occupied mode and the indoor relative humidity is greater then the Occupied High Humidity setpoint, then the H3_EX_RV output point will be energized. When in the unoccupied mode and indoor relative humidity is greater then the Unoccupied High Humidity setpoint, then the H3_EX_RV output point and supply fan output will be energized. There is a fixed 5% hysteresis that the indoor relative humidity must drop below the active setpoint to end the dehumidification mode and deenergize the H3_EX_RV output. If the PremierLink controller is in the unoccupied mode, then the fan relay will deenergize if there is no other mode requiring to the fan to be on. This function will not energize mechanical cooling as a result of the indoor relative humidity exceeding either setpoint.

A high humidity alarm will be generated if the indoor relative humidity exceeds the high humidity setpoint by the amount configured in the Control Humidity Hysteresis in the ALARMS table for 20 minutes. The alarm will return to normal when the indoor relative humidity drops 3% below the active humidity setpoint.

Economizer — The economizer dampers are used to provide free cooling and indoor air quality if optional CO2 sensor is installed and when the outside conditions are suitable. Temperature control is accomplished by controlling the SAT to a certain level determined by the Economizer PID Loop by calculating a submaster reference (ECONSR) value. This algorithm will calculate the submaster reference temperature (ECONSR) based on OAT and enthalpy conditions and cooling requirements. The ECONSR value is then passed to the Economizer Submaster Loop, which will modulate dampers to maintain SAT at ECONSR level.

The following conditions are required to determine if economizer cooling is possible:

S Indoor fan has been on for at least 30 seconds S Enthalpy is low

S SAT reading is available S OAT reading is available S SPT reading is available

S OAT ≤ SPT

SOAT < OATMAX (OATMAX default is 75_F) S Economizer position is NOT forced

If any of the above conditions are not met, the ECONSR will be set to its MAX limit of 120_F and the damper will go to its configured minimum position. The minimum damper position can be overridden by the IAQ routine described later in this section.

The calculation for ECONSR is as follows:

ECONSR = PID function on (setpoint - SPT), where:

setpoint = ((OCSP+STO) + (OHSP+STO))/2 when NTLO (Unoccupied Free Cool OAT Lockout) < OAT < 68_F

setpoint = (OCSP+STO) - 1 when OAT ≤ NTLO setpoint = (OHSP+STO) + 1 when OAT ≥ 68_F

The actual damper position (ECONPOS) is the result of the following calculation. Values represented in the right side of the equation can be found in the SERVICE configuration table descriptions in this manual. Note that that the OAT is taken into consideration to avoid large changes in damper position when the OAT is cold:

ECONPOS = SubGain x (ECONSR-SAT) + CTRVAL where SubGain = (OAT - TEMPBAND) / (ESG + 1)

If the OAT < DXLOCK (DX Cool Lockout setpoint) then the damper will be modulated to maintain the SAT at the ECONSR value.

If the OAT is between DXLOCK and 68_F (DXLOCK < OAT < 68_F) and additional cooling is required, the economizer will close the to minimum position for three minutes, the economizer integrator will then be reset to 0 and begin modulating to maintain the SASP after the stage has been energized for about 90 seconds. This will allow the economizer to calculate a new ECONSR that takes into account the cooling effect that has just been turned on and not return to the value require before the cooling was added. This will prevent the economizer from causing premature off cycles of compressors while maintaining the low SAT temperature setpoint for the number of stages active. In addition to preventing compressor short cycling, by using return air across the evaporator coil just after the compressor has started allows for increased refrigerant flow rates providing for better oil return of any oil washed out during compressor start-up.

If the OAT > 68_F and OAT < SPT and the number of DX stages requested is > 0 by the staging algorithm, then ECONSR is set to its minimum value 48_F and the damper will go to 100% open.

If the Auxiliary Relay is configured for exhaust fan (AUXOUT = 1) in the CONFIG configuration table and Continuous Power Exhaust (MODPE) is Enable in the SERVICE configuration table, then the AUXO output (HS3) will be energized whenever the PremierLink controller is in the occupied mode. If the MODPE is disabled then AUXO output will be energized based on the Power Exhaust Setpoint (PES) in the SETPOINT table.

Heating — The heat stages are controlled by the Heating Control Loop, which is used to calculate the desired SAT needed to satisfy the space. It will compare the SPT to the Occupied Heat Setpoint (OHSP) + the T56 slider offset (STO) when occupied and the Unoccupied Heat Setpoint (UHSP - Unoccupied Heating Deadband) if unoccupied to calculate a Staged Heat Submaster Reference (SHSR). The heat staging algorithm compares the SHSR to the actual SAT to calculate the required number of heating stages to satisfy the load. This loop runs every 40 seconds. The following conditions must be met in order for this algorithm to run:

S Indoor fan has been ON for at least 30 seconds.

S Cool mode is not active and the time guard between modes equals zero.

S Mode is occupied or the Temperature Compensated Start or Heat mode is active.

48TC

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Contents Safety Considerations Table of ContentsWhat to do if you smell gas Unit Arrangement and AccessRoutine Maintenance GeneralSeasonal Maintenance Supply Fan Belt-Drive Supply FAN Blower SectionCondenser Coil Maintenance and Cleaning Recommendation CoolingCondenser Coil One-Row Coil Periodic Clean Water RinseRoutine Cleaning of Coil Surfaces Remove Surface Loaded FibersEvaporator Coil Metering Devices Refrigerant System Pressure Access PortsCleaning the Evaporator Coil Evaporator CoilNo Charge To Use Cooling Charging ChartsPuronr R-410A Refrigerant Refrigerant ChargeSize Designation Nominal Tons Reference Cooling Charging ChartsCooling Charging Charts C08229 C08437 C08438 C08439 Problem Cause Remedy Cooling Service AnalysisCompressor Condenser-Fan AdjustmentTroubleshooting Cooling System Convenience OutletsUnit Connect Primary Transformer Smoke DetectorsSystem ControllerSmoke Detector Locations SensorFiop Smoke Detector Wiring and Response Completing Installation of Return Air Smoke SensorSensor and Controller Tests Sensor Alarm TestSensor Alarm Test Procedure Controller Alarm TestTo Configure the Dirty Sensor Test Operation Controller Alarm Test ProcedureDirty Controller Test Procedure Dirty Sensor Test ProcedureDetector Cleaning Troubleshooting Relief Device Protective DevicesGAS Heating System Compressor ProtectionLiquid Propane Supply Line Pressure Ranges Fuel Types and PressuresNatural Gas Supply Line Pressure Ranges Natural Gas Manifold Pressure RangesCombustion-Air Blower Flue Gas PassagewaysMain Burners Cleaning and AdjustmentCheck Unit Operation and Make Necessary Adjust- ments Burners and IgnitersBurner Ignition Limit SwitchOrifice Replacement LED Error Code DescriptionLED Indication Error Code Description Red LED-Status Orifice Sizes IGC ConnectionsAltitude Compensation* A04-A07 Cont. Altitude Compensation* A08-A12LP Orifice Troubleshooting Heating System Minimum heating entering air temperatureAltitude Compensation* A04-A06 Low NOx Units Problem Cause Remedy Heating Service AnalysisIGC IGC Board LED Alarm CodesPremierLink Controller Premierlinkt ControlPremierLink Wiring Schematic 55 Space Temperature Sensor Wiring PremierLink Sensor Usage Space Sensor Mode56 Internal Connections Thermostat ModeLctb Indoor CO2 Sensor 33ZCSENCO2 Connections PremierLink Filter Switch Connection RTU-MP Control System Recommended CablesColor Code Recommendations RTU-MP Multi-Protocol Control Board RTU-MP System Control Wiring Diagram Outputs RTU-MP Controller Inputs and OutputsRTU-MP T-55 Sensor Connections Space Temperature SPT SensorsIAQ Sensor SEN J4-2 COM J4-3 24 VAC Connecting Discrete Inputs Power Exhaust outputCommunication Wiring Protocols RTU-MP Troubleshooting LEDs on the RTU-MP show the status of certain functions LEDsTroubleshooting Alarms BACnet MS/TP AlarmsRTU-MP Driver Code Name Meaning Basic Protocol TroubleshootingModbus Manufacture DateEconoMi$er IV Component Locations Economizer SystemsEconoMi$er IV Wiring EconoMi$er IV Input/Output Logic EconoMi$erOutdoor Dry Bulb Changeover Supply Air Temperature SAT SensorOutdoor Air Lockout Sensor EconoMi$er IV Control ModesOutdoor Enthalpy Changeover Return Air Temperature or Enthalpy Sensor Mounting LocationExhaust Setpoint Adjustment Indoor Air Quality IAQ Sensor InputMinimum Position Control Demand Control Ventilation DCV Damper MovementThermostats Occupancy ControlDifferential Enthalpy CO2 Sensor ConfigurationEconoMi$er IV Sensor Usage EconoMi$er IV PreparationWiring Diagrams 48TC Typical Unit Wiring Diagram Power A06, 208/230-3-60 48TC Unit Wiring Diagram Control A06 START-UP, General PRE-START-UPVentilation Continuous Fan CoolingMain Burners HeatingPerform System Check-Out Field Service TestSTART-UP, Premierlink Controls START-UP, RTU-MP ControlConfiguration Input 1 Function InputsInput Space Sensor TypeCooling, Unit With EconoMi$er Operating SequencesBase Unit Controls Cooling, Units Without Economizer Heating, Units Without EconomizerPremierLink Control Heating With EconoMi$er48TC Available Cooling Stages OAT ≤ SPT 48TC 48TC Scheduling Loadshed Command Gas and Electric Heat UnitsRTU-MP Sequence of Operation Linkage ModesBAS On/Off Always Occupied Default OccupancyLocal Schedule BACnet SchedulePower Exhaust EconomizerIndoor Air Quality Fastener Torque Values Demand LimitTorque Values Position Number Appendix I. Model Number SignificanceModel Number Nomenclature Serial Number FormatPhysical Data Cooling Tons Appendix II. Physical Data48TC*A08 48TC*A09 48TC*A12 Physical Data CoolingPhysical Data Heating LOW General Fan Performance Notes Appendix III. FAN PerformanceTon Horizontal Supply Ton Vertical SupplyCFM RPM BHP Medium Static Option High Static Option 48TC**05 48TC**05 Phase Ton Horizontal Supply1486 48TC**05 Phase Ton Vertical Supply1493 15061482 48TC**0648TC**06 Phase Ton Vertical Supply 48TC**06 Phase Ton Horizontal Supply48TC**07 Phase Ton Horizontal Supply1122 1162 11071124 1103 11431093 1133 4971099 11161273 5791263 1247Unit MOTOR/DRIVE Motor Pulley Turns Open Combo Pulley AdjustmentType Appendix IV. Electrical DataIFM Range RLA LRAFLA Appendix IV. Electrical DataFull IFM RangeEFF at RLA LRAType DISC. Size Combustion PowerNOM IFM No P.E FAN Motor ExhaustNOM Unbalanced 3-Phase Supply VoltageWiring Diagrams Appendix V. Wiring Diagram List48TC*A04 Outdoor Circuiting Appendix VI. Motormaster Sensor LocationsCatalog No 48TC---2SM 48TC*A09/12 Outdoor CircuitingPreliminary Information Unit START-UP Checklist

48TCA04---A12 specifications

The Carrier 48TCA04---A12 is a high-efficiency rooftop air conditioning unit designed for commercial and industrial applications. Known for its reliability and performance, this model features advanced technologies that cater to diverse climate control needs.

One of the standout features of the Carrier 48TCA04---A12 is its excellent energy efficiency, which adheres to the stringent standards set by the U.S. Environmental Protection Agency. The unit utilizes a highly efficient scroll compressor combined with state-of-the-art heat exchanger technology, allowing it to operate with minimal energy consumption while providing powerful cooling capabilities.

The unit comes equipped with a robust and durable design, built to withstand various environmental conditions. Its weather-resistant cabinet is constructed from high-quality materials, ensuring long-lasting performance even in harsh climates. Additionally, the unit features a galvanized steel structure with a powder-coated finish, further enhancing its resistance to corrosion and wear.

In terms of technologies, the Carrier 48TCA04---A12 incorporates advanced controls that promote optimal performance. The unit supports Carrier's smart connectivity options, facilitating remote monitoring and adjustments via smart devices. This feature ensures convenient energy management and allows maintenance teams to access performance data, leading to proactive service interventions.

Another important characteristic of this unit is its quiet operation. The design includes sound-reducing insulation and a well-engineered airflow system, minimizing noise levels to create a more comfortable indoor environment. This is particularly important for commercial spaces such as offices and retail environments, where a tranquil atmosphere is critical for customer satisfaction and productivity.

The Carrier 48TCA04---A12 also offers diverse application flexibility, making it suitable for various locations, from small retail stores to large warehouses. With several tonnage options available, users can select a model that perfectly aligns with their specific cooling needs. Additionally, the unit can be easily integrated with existing HVAC systems, providing a seamless solution for upgrading or retrofitting older installations.

To sum up, the Carrier 48TCA04---A12 rooftop air conditioning unit stands out due to its exceptional energy efficiency, durable construction, advanced technology, and quiet operation, making it a reliable choice for commercial and industrial cooling solutions. Its flexibility and smart technology integrations ensure that it meets a wide range of climate control requirements effectively.
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