Carrier 48AY020-060, 48EW, 48EY024-068, 48AW, 48EK, 48AK, 48AJ Heat Interlock Relay Wiring, COM Common

Page 83

GAS HEATING, VARIABLE AIR VOLUME (VAV) UNITS — All of the gas heating control is performed through the integrated gas control (IGC) board. The control module board serves only to initiate and terminate heating operation.

NOTE: The unit is factory-configured for disabled occupied heating. DIP switch 5 is used to enable occupied heating (DIP switch 5 set to OPEN).

Variable Air Volume (VAV) occupied heat is controlled by return-air temperature (RAT) using a 5k thermistor located just below the outdoor-air dampers. A VAV unit without a space temperature sensor is also controlled by RAT. A VAV unit with a space temperature sensor has Unoccupied Heat controlled by space temperature (SPT).

The control module board is powered by 24 vac. When there is a call for heating (either Morning Warm-Up, Unoccu- pied, or Occupied modes), power is sent from the control mod- ule board to W on each of the IGC boards and W2 of the main gas valve. When heating, the control module board will ener- gize a field-supplied heat interlock relay output to drive the VAV terminal boxes wide open. The HIR is not required on a DAV system. See Fig. 59. In the Occupied mode the indoor-fan motor will be operating and the outdoor-air dampers will be in the minimum position. In the Unoccupied mode the indoor-fan motor will be off, but will energize 45 seconds after the call for heat and the outdoor-air dampers will move to the IAQ Unoccupied position (generally set to zero in the Unoccupied mode). The duct pressure sensor will signal to the variable fre- quency drive to operate at full speed since all terminals have been driven open. An LED on the IGC board will be on during normal operation. A check is made to ensure that the rollout switches and limit switches are closed and the induced-draft motors are not running. The induced-draft motors are then en- ergized and when speed is proven with the hall effect sensor on the motor, the ignition activation period begins. The burners will ignite within 5 seconds.

When ignition occurs the IGC board will continue to moni- tor the condition of the rollout and limit switches, the hall effect sensor, and the flame sensor.

If the call for heat lasted less than 1 minute, the heating cy- cle will not terminate until 1 minute after heat became active. When heating is satisfied, the power will be interrupted to the IGC board and W1 and W2 of the main gas valve. If the unit is controlled through a room sensor, the indoor fan will be operat- ing in the Occupied mode and turned off after 45 seconds in the Unoccupied mode.

STAGED GAS UNIT HEATING — The Staged Gas Control option offered on 48EJ,EK,EW,EY024-068 and 48AJ,AK,AW, AY020-060 units adds the capability to control the rooftop unit’s gas heating system to a specified Supply Air Tempera- ture Set Point for purposes of tempering a cool mixed-air con- dition. The gas heating system employs multiple heating sec- tions. Each section is equipped with a two-stage gas valve. The gas valves are sequenced by a factory-installed staged gas con- troller (SGC) as required to maintain the user-specified Supply Air Set Point. Up to eleven stages of heating control are avail- able, based on quantity and heating capacity sizes of the indi- vidual heat exchanger sections provided in the base unit. In addition to providing system control for tempering heat opera- tion, the new SGC also controls Demand Heat sequences for both First-Stage (W1) and Second-Stage (W2 or full-fire) operation.

Tempering of supply air is desirable when rooftop units are operating in ventilation mode (economizer only operation) at low outdoor temperatures. At low outdoor temperatures, the mixed air temperature (combination of return-from-space tem- perature and outdoor/ventilation air temperature) may become too low for the comfort of the occupants or for the terminal reheat systems. The tempering function adds incremental steps of heat capacity to raise the temperature of the mixed air up to levels suitable for direct admission into the occupied space or to levels consistent with reheat capabilities of the space termi- nals. Refer to Table 37 for the staged gas heating control sys- tem components. Refer to Table 38 for the heating system con- troller (SGC) inputs. The heating system controller (SGC) out- puts consist of six relays (K1 through K6) which control the individual gas valves.

 

TRAN2

B

COM

CB4

SECONDARY

3.2 AMPS

24 VOLT

BASE MODULE

CONTROL BOARD

INDOOR FAN RELAY COM

T

30

T29

T

28

LEGEND

CB — Circuit Breaker

COM — Common

HIR — Heat Interlock Relay

T — Terminal

TRAN — Transformer

HIR

FIELD

INSTALLED

(HN61KK040)

(24V, 9.5VA)

Fig. 59 — Heat Interlock Relay Wiring

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Contents Installation, Start-Up Service Instructions Instructions on Make Unit Duct ConnectionsRoof Curb 48AJ,AK020-030 and 48EJ,EK024-034 Units Roof Curb 48AJ,AK034-050 and 48EJ,EK038-048 Units Roof Curb 48AJ,AK060 and 48EJ,EK054-068 Units Page Base Unit Dimensions 48AJ,AK020-030 Base Unit Dimensions 48AJ,AK035-050 Base Unit Dimensions 48AJ,AK060 Base Unit Dimensions 48AW,AY020-030 Base Unit Dimensions 48AW,AY035-050 Base Unit Dimensions 48W,AY060 Base Unit Dimensions 48EJ,EK024-034 Base Unit Dimensions 48EJ,EK038-048 Base Unit Dimensions 48EJ,EK054-068 Base Unit Dimensions 48EW,EY024-034 Base Unit Dimensions 48EW,EY038-048 Base Unit Dimensions 48EW,EY054-068 AT Each Corner % 48EJ,EW,EK,EYD030 Rigging Weights 48AJ,AK,AW,AY UnitsAT Each Corner % 48EJ,EW,EK,EYD024 48EJ,EW,EK,EYD028Unit 48AJ,AK,AW,AY Physical Data 48AJ,AK,AW,AY UnitsQuantity Rows...Fins/in Unit 48EJ,EK,EW,EY Physical Data 48EJ,EK,EW,EY Units06D537 06EA250 06EA265 Quantity...Type Ckt 1, Ckt Operating Weights Air Distribution Thru-the-Bottom Evaporator Fan Motor DataCombustion Fan Housing Location Install Flue HoodStages 48A,E Series Staged Gas ImplementationNumber of Stages Model Number Position Heat Size Htstgtyp Thermistor Designations Supply-Air Thermistor Connections Indoor Air Quality Sensor Configuration Make Electrical Connections DIP CCNCOM SIORLA LRA Unbalanced 3-Phase Supply VoltageElectrical Data 48AJ,AK,AW,AY Units Min MaxQty 30.8/28.0 180.5/177.7 225/225 236.3/230.9 MCA Mocp EW,EY Electrical Data 48EJ,EK,EW,EY UnitsRange Exhaust FAN Motor FLA LRAFLA LRA MCA Mocp EW,EY 54.0 23.6 41.6 RLA FLANEC GND Ground Field Power Wiring ConnectionsIFC CCBEquip GNDOFC Indoor-Fan Relay Terminal Block Carrier Comfort Network Indoor-Fan CircuitCCN IFC Pesc Color Code Recommendations CCN Connection Approved Shielded CablesSpace Temperature Averaging Wiring Make Outdoor-Air Inlet AdjustmentsAdding Seal Strip to Top of Hood Sides Adding Seal Strip to Sides of Hood Top Mounting Flange Mounting Angle With Tabs Attached to Filter Track Assembly Differential Enthalpy Control and Sensor Control Control Point Curve APPROX. DEG Psychrometric Chart for Enthalpy ControlBarometric Relief Damper and Power Exhaust Mounting Details 120.5 119.5 48EJ,EK,EW,EY058-068 Unit Size80.5 79.5 48EJ,EK,EW,EY024-054 Motormaster III Sensor Location 48EJ,EK,EW,EY054-064 Side Return Air Conversion Field ModificationsSTART-UP In. wg Pressure Control Signal VFD SET PointParameter Group Default Value Carrier Default Program Parameter ValuesMotor Standard Efficiency High Efficiency Typical Factory Wiring Optional Field Wiring Building Pressure Signal Level Closed DIP Switch ConfigurationSetting OpenAirflow DIP Switch Factory SettingsFan Performance, 48AJ,AK020-030 Vertical Discharge Units 18,000 Fan Performance, 48AJ,AK035 Vertical Discharge Units16,000 17,00017,000 18,000 19,000 20,000 Fan Performance, 48AJ,AK040,050 Vertical Discharge Units19,000 20,000Fan Performance, 48AJ,AK060 Vertical Discharge Units 11,000 12,000 13,000 14,000 15,000 Fan Performance, 48AW,AY020-030 Horizontal Discharge Units13,000 14,000 15,000 16,000 17,000 18,000 Fan Performance, 48AW,AY035 Horizontal Discharge Units17,000 18,000 16,000 17,000 18,000 19,000 20,000 Fan Performance, 48AW,AY040,050 Horizontal Discharge Units19,000 20,000 26,000 27,000 Fan Performance, 48AW,AY060 Horizontal Discharge UnitsFan Performance, 48EJ,EK024,034 Vertical Discharge Units 15,000 16,000 17,000 18,000 19,000 20,000 Fan Performance, 48EJ,EK038,044 Vertical Discharge Units19,000 20,000 Available External Static Pressure in. wg Rpm Bhp 000 1066 1096 1125000 1086 11.10 1114 11.61 1141 12.14 Fan Performance, 48EJ,EK048 Vertical Discharge UnitsRpm Bhp 10,000 949 13.81 970 14.54 990 15.26 Fan Performance, 48EJ,EK054-068 Vertical Discharge Units20,000 21,000 22,000 23,000 24,000 25,000 26,000 27,000 Fan Performance, 48EW,EY054-068 Horizontal Discharge Units26,000 27,000 Available External Static Pressure in. wg 10,000 956 12.99 976 13.66 996 14.32ESP Airflow LOW Speed Medium Speed High SpeedAir Quality Limits Motor LimitationsSequence of Operation Software Control Link Points User Defined Set PointsPage COM Common Heat Interlock Relay WiringInput Description Staged Gas System ComponentsStage Gas System Inputs/Outputs Function LocationNavigator Display Menu Structure Navigator DisplayCondition Occupied Morning Temperature Software HeatVersion Enabled DEG. F ResetField-Supplied Smoke Detector Wiring Stages Smoke Control ModesCooling Capacity Staging Table, CV Units with 2 Compressors Device Pressurization Smoke Purge Evacuation Fire ShutdownService Typical Gas Heating Section Manufacturer Lubricant LubricationCondenser-Fan Adjustment Evaporator Fan Service and ReplacementBelt Tension Adjustment To adjust belt tension Evaporator-Fan Motor ReplacementCooling Charging Chart 48EJ,EK,EW,EY024-034 Gas Valve AdjustmentCooling Charging Chart 48EJ,EK,EW,EY054-068 Protective Devices 20 HP 208/230-3-60 Voltage WireIndoor Voltage Wire 06D-537 208/230-3-60 Following fan motors have twoTypical 48EK VAV 24-V Control Circuit Typical CV 24-V Control Circuit Typical 48EK VAV 115-V Control Circuit Typical 48EJ CV 115-V Control Circuit 101 102 Troubleshooting Typical Refrigerant Circuiting 48AJ,AK,AW,AY027,030 Typical Refrigerant Circuiting 48AJ,AK,AW,AY035 Typical Refrigerant Circuiting 48EJ,EK,EW,EY038,044 Typical Refrigerant Circuiting 48AJ,AK,AW,AY040,050 Typical Refrigerant Circuiting 48EJ,EK,EW,EY048 Typical Refrigerant Circuiting 48EJ,EK,EW,EY054 Typical Refrigerant Circuiting 48AJ,AK,AW,AY060 Typical Refrigerant Circuiting 48EJ,EK,EW,EY064 Typical Refrigerant Circuiting 48EJ,EK,EW,EY068 IGC Control Heating and Cooling Control Board LED Alarms IGC Control Board LED AlarmsIAQ O Channel Designations Base Module CVO Channel Designations Base Module VAV Terminal no AssignmentService Training START-UP Checklist General
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48EJ, 48AJ, 48AK, 48EK, 48AY020-060 specifications

The Carrier 48EJ, 48AW, 48EK, 48AJ, and 48EY024-068 are cutting-edge rooftop air conditioning units designed for commercial applications. These models are renowned for their reliability, energy efficiency, and innovative technologies aimed at providing optimal indoor comfort.

One of the standout features of these units is their advanced cooling and heating capabilities. They employ a multi-stage compressor system that allows for precise temperature control, accommodating various load requirements. This flexibility is particularly beneficial in commercial settings where the cooling load can fluctuate throughout the day.

Energy efficiency is paramount in today’s environmental landscape, and Carrier has ensured that these models meet stringent efficiency standards. They incorporate high-efficiency scroll compressors, which significantly reduce energy consumption while delivering powerful performance. The units are also equipped with variable speed fans that adjust airflow based on demand, further optimizing energy use.

In terms of construction, these rooftop units feature a robust design that enhances durability and longevity. The cabinet is constructed to withstand harsh weather conditions, ensuring reliable performance year-round. Additionally, the units are equipped with corrosion-resistant coatings, particularly useful in coastal environments where salt exposure can be a concern.

The Carrier 48EJ, 48AW, 48EK, 48AJ, and 48EY models utilize advanced controls and connectivity features, allowing for easy integration into building management systems. This connectivity enables remote monitoring and control, facilitating quick response to changing conditions and simplifying maintenance tasks.

Noise reduction is another key characteristic of these models. They are designed with sound-absorbing insulation and low-noise fan blades to ensure quiet operation, making them suitable for noise-sensitive environments such as schools and hospitals.

These units are also available with various options for air filtration and dehumidification. The use of high-efficiency air filters enhances indoor air quality by trapping dust, pollen, and other airborne particles. Enhanced dehumidification capabilities ensure that spaces remain comfortable even in humid conditions.

In conclusion, the Carrier 48EJ, 48AW, 48EK, 48AJ, and 48EY024-068 rooftop units are engineered to offer exceptional performance, energy efficiency, and durability. With their advanced technologies and user-friendly features, they stand out as reliable solutions for meeting diverse commercial cooling and heating needs, making them a popular choice for many businesses.