LG GEN2 Series User manual

ROOFTOP DEDICATED
OUTDOOR AIR SYSTEMS (DOAS)
INSTALLATION AND OPERATION MANUAL
GEN2 Series (AR-DR)
Base Rooftop DOAS
500 to 18,000 CFM
GEN2 Series (AR-DE)
Energy Recovery Wheel Rooftop DOAS
1,000 to 18,000 CFM

Installation, Operation and Maintenance Manual
Please read and save these instructions for future reference. Read carefully before attempting to assemble, install,
operate or maintain the product described. Protect yourself and others by observing all safety information. Failure
to comply with these instructions will result in voiding of the product warranty and may result in personal injury
and/or property damage.
General SafetyInformation
Only qualified personnel should install and maintain this
system. Personnel should have a clear understanding of
these instructions and should be aware of general safety
precautions. Improper installation can result in electric
shock, possible injury due to coming in contact with
moving parts, as well as other potential hazards. Other
considerations may be required if high winds or seismic
activity are present. If more information is needed,
contact a licensed professional engineer before moving
forward.
1. Follow all local electrical and safety codes, as well
as the National Electrical Code (NEC), the National
Fire Protection Agency (NFPA), where applicable.
Follow the Canadian Electrical Code (CEC) in
Canada.
2. All moving parts must be free to rotate without
striking or rubbing any stationary objects.
3. Unit must be securely and adequately grounded.
4. Do not spin wheel faster than maximum cataloged
fan RPM. Adjustments to fan speed significantly
affect motor load. If the fan RPM is changed, the
motor current should be checked to make sure it is
not exceeding the motor nameplate amps.
5. Verify that the power source is compatible with the
equipment.
6. Never open access doors to the unit while it is
running.
WARNING
The roof lining contains high voltage wiring. To
prevent electrocution, do not puncture the interior or
exterior panels of the roof.
DANGER
•Always disconnect power before working on or near
this equipment. Lock and tag the disconnect switch
or breaker to prevent accidental power up.
•If this unit is equipped with optional gas accessories,
turn off gas supply whenever power is disconnected.
CAUTION
This unit is equipped with a compressed refrigerant
system. If a leak in the system should occur,
immediately evacuate the area. An EPA Certified
Technician must be engaged to make repairs or
corrections. Refrigerant leaks may also cause bodily
harm.
CAUTION
When servicing the unit, the internal components may
be hot enough to cause pain or injury. Allow time for
cooling before servicing.

Table ofContents
General Safety Information------------------------------------------------------------------------------------------------2
Unit Nomenclature-----------------------------------------------------------------------------------------------------------8
General Data------------------------------------------------------------------------------------------------------------------9
Receiving, Handling, Storage---------------------------------------------------------------------------------------------16
Product Overview------------------------------------------------------------------------------------------------------------18
- Cooling
- Heating
- Airflow Arrangement
- Safety Listing
- Models and Capacities
Subassemblies---------------------------------------------------------------------------------------------------------------19
Installation
Typical Unit Weights and Dimensions----------------------------------------------------------------------------------21
Service Clearances ---------------------------------------------------------------------------------------------------------22
Additional Clearances for Packaged DX-------------------------------------------------------------------------------23
Handling Concerns for Units with Package DX ----------------------------------------------------------------------23
Lifting----------------------------------------------------------------------------------------------------------------------------23
Roof Curb Mounting---------------------------------------------------------------------------------------------------------24
Optional Piping Vestibule--------------------------------------------------------------------------------------------------24
Ductwork Configurations---------------------------------------------------------------------------------------------------24
Rail Mounting and Layout--------------------------------------------------------------------------------------------------26
Recommended Electrical and Gas Supply Entry Locations ------------------------------------------------------26
- Gas Supply Piping
- Gas Connections
Piping Installation------------------------------------------------------------------------------------------------------------27
- Optional Coil Piping
- Condensate Drain Trap
- Condensate Overflow Switch
Electrical Information-------------------------------------------------------------------------------------------------------28
- Determine the Size of Main Power Lines
- Determine the Size of Electric Heater Wiring
- Provide the Opening(s) for the Electric Connections
- Connect the Power Supplies
- Wire the Optional Convenience Outlet
- Connect Field-Wired Low Voltage Components
- Field-Provided Disconnect
Control Center Operation ------------------------------------------------------------------------------------------------29
- Phase Monitor
- Variable Frequency Drive
- Supply Fan VFD Sequence
Optional Component Operation ----------------------------------------------------------------------------------------31
- Exhaust Fan VFD Sequence
- OA and Recirc Air Damper Sequence
- Exhaust Fan Only Power
- Vapor Tight Lights
- EC Condenser Fans
- Airflow Monitor

- VFD Compressor
- Frost Control
- Rotation Sensor
- Dirty Filter Sensor
- Microprocessor Control
- Unoccupied Recirculation Damper
- Vapor Tight Lights
- Hot Gas Bypass Valve
- Hot Gas Reheat Valve
Factory-Installed Refrigeration System Components----------------------------------------------------------------28
Start-Up –Unit-----------------------------------------------------------------------------------------------------------------29
- Model and Serial Number
- Pre-Start-Up Checklist
- Special Tools Required
- Start-Up Procedure
- Voltage Imbalance
- Start-Up Checklist
Start-Up –Components-----------------------------------------------------------------------------------------------------36
- Fan
- Supply Fan (Plenum Type)
- Fan Wheel Rotation Direction
- Supply/Exhaust Fan
- Vibration
- Discharge Air Temperature Sensor
- Airflow Monitor
- Optional Dirty Filter Switch
Optional Energy Wheel-------------------------------------------------------------------------------------------------------37
- Start-Up
- Drive Belt
- Adjust the Air Seals
- Sequence of Operation
- Maintenance
- Inspection
- Wheel Disassembly
- Cleaning
- Reassembly
- Energy Recovery Wheel Belt
- Energy Recovery Wheel Bearings
- Energy Recovery Wheel –Troubleshooting
Troubleshooting------------------------------------------------------------------------------------------------------------------51
- Alarms
- Microprocessor Controller
- Phase Monitor
- Variable Frequency Drive
- Optional Digital Scroll Compressor Controller
- Unit Refrigeration Circuit

Routine Maintenance-----------------------------------------------------------------------------------------------------------56
- Monthly
- Semiannually
- Annually
- Units with Packaged DX, Semiannually
Maintenance Procedure-------------------------------------------------------------------------------------------------------58
- Lubrication
- Dampers
- Gas Furnace
- Fan Motors
- Fan Wheel and Fasteners
- Internal Filter Maintenance
- External Filter Maintenance
- Coil Maintenance
Reference -------------------------------------------------------------------------------------------------------------------------60
- Venting Connection Locations
- Rated Airflow
Indirect Gas-FiredFurnaces as-FiredFurnaces
General Safety Information ---------------------------------------------------------------------------------------------------62
Receiving, Un-packaging, Storage ------------------------------------------------------------------------------------------63
Unit Identification---------------------------------------------------------------------------------------------------------------- 63
Furnace Model Number--------------------------------------------------------------------------------------------------------63
Burner Control Turndown -----------------------------------------------------------------------------------------------------63
Furnace Serial Number --------------------------------------------------------------------------------------------------------63
ETL Listing-------------------------------------------------------------------------------------------------------------------------63
Product Overview----------------------------------------------------------------------------------------------------------------63
Furnace Control Center--------------------------------------------------------------------------------------------------------64
- Furnace Control Center Components
- Typical Furnace Control Logic
Typical Furnace, Electrical and Control Components ------------------------------------------------------------------65
Gas-Fired Burner Turndown --------------------------------------------------------------------------------------------------66
- Electronic Modulation
- Combinations
- Available Turndown Control Options
Installation of Venting for Outdoor Units---------------------------------------------------------------------------------------67
Installation of Venting for Indoor Units-----------------------------------------------------------------------------------------67
Venting Methods---------------------------------------------------------------------------------------------------------------------68
Installation of Standard Indoor Venting----------------------------------------------------------------------------------------68
- Horizontal
- Vertical
Installation of Concentric Venting------------------------------------------------------------------------------------------------69
- Horizontal
- Vertical
- Two-Pipe Venting –Horizontal
- Two-Pipe Venting –Vertical
Installation of Control Wiring-------------------------------------------------------------------------------------------------------71
Installation of Discharge Air Sensor----------------------------------------------------------------------------------------------71
Installation of Gas Piping -----------------------------------------------------------------------------------------------------------72

- Gas Supply Requirements
- Connect the Supply Gas Line
- Installation of Additional Regulator
- Test the System for Leaks
- Gas Pressure Test Ports
Sequence of Operation----------------------------------------------------------------------------------------------------------76
- Start-Up / Standby
- Heat Mode
- Recovery from Lockout
Performance Data-----------------------------------------------------------------------------------------------------------------76
Start-Up –Furnaces (all units) -------------------------------------------------------------------------------------------------77
- 4:1 Turndown Electronic Modulation
- Adjust High Fire and Low Fire Settings
- Modulating Valve High Fire Setting
- Modulating Valve Low Fire Setting
- With High Turndown Electronic Modulation
Troubleshooting---------------------------------------------------------------------------------------------------------------------81
- Ignition Controller
- 4:1 Modulating with Stand-Alone Controller
- 4:1 Modulating with Microprocessor Controller
Reference: Controls----------------------------------------------------------------------------------------------------------------90
- Furnace Control with Microprocessor
Maintenance--------------------------------------------------------------------------------------------------------------------------91
- Combustion Blower Motor
- Burners and Orifices
- Heat Exchanger
- Flue Collector Box
- Electrical Wiring
- Gas Train
- Replacement Parts
Maintenance Log---------------------------------------------------------------------------------------------------------------------92
Controller
Overview--------------------------------------------------------------------------------------------------------------------------------95
- Keypad Description ----------------------------------------------------------------------------------------------------------------98
- Expansion Boards-------------------------------------------------------------------------------------------------------------------98
- Connecting to the Web UI---------------------------------------------------------------------------------------------------------98
- Service Password-------------------------------------------------------------------------------------------------------------------98
- Startup Settings----------------------------------------------------------------------------------------------------------------------98
- Expansion Board Addresses and Dip Switch Settings --------------------------------------------------------------------98
- IP Address-----------------------------------------------------------------------------------------------------------------------------99
- Main Board Terminal Connections----------------------------------------------------------------------------------------------99
- Expansion Board Terminal Connections---------------------------------------------------------------------------------------98
Software Backup and Restore-------------------------------------------------------------------------------------------------------100
AC Smart Setup-------------------------------------------------------------------------------------------------------------------------102
Navigation ------------------------------------------------------------------------------------------------------------------------------- 106
Unit Status Overview --------------------------------------------------------------------------------------------------------------108
Menu ---------------------------------------------------------------------------------------------------------------------------------------111

Sequence of Operation ---------------------------------------------------------------------------------------------------------------131
Large Controller Overview -----------------------------------------------------------------------------------------------------------136
Medium Controller Overview --------------------------------------------------------------------------------------------------------137
Expansion Board Overview ---------------------------------------------------------------------------------------------------------138
Furnace Overview 139
Controller
Set-Points Data Tables ----------------------------------------------------------------------------------------------------------------140
Network Settings Data Tables -------------------------------------------------------------------------------------------------------147
Alarm Data --------------------------------------------------------------------------------------------------------------------------------151
BACnet and MODBUS Points -------------------------------------------------------------------------------------------------------155
Unit Status Modes ----------------------------------------------------------------------------------------------------------------------167
Lon Talk Points --------------------------------------------------------------------------------------------------------------------------168
Appendix A: Remote Display ---------------------------------------------------------------------------------------------------------171
Appendix B: I/O Expansion Board Quick Start -----------------------------------------------------------------------------------172
Appendix C: Space Thermostat Quick Start --------------------------------------------------------------------------------------173
Appendix D: Greentrol Airflow Monitoring Quick Start --------------------------------------------------------------------------175
Appendix F: Factory Modbus Connections ----------------------------------------------------------------------------------------176

Unit Nomenclature
Family
AR = Air-Source Packaged Rooftop Unit,
R410A Refrigerant
Type
D = Dedicated Outdoor Air System (DOAS)
ERV Option
R = Base Unit
E = Energy Recovery Wheel
Chassis Size
02 =12
12 = 112
22 = 212
311 = 311
35 = 352
Cooling Capacity
03 = 3 Tons 15 = 15 Tons
04 = 4 Tons 17 = 17.5 Tons
05 = 5 Tons 20 = 20 Tons
60 = 60 Tons
70 = 70 Tons
06 = 6 Tons 25 = 25 Tons
07 = 7, 7.5 Tons 30 = 30 Tons
10 = 10 Tons 40 = 40 Tons
12 = 12.5 Tons 50 = 50 Tons
Series
A = First Series
AR
D
R
12
05
A
Rooftop Dedicated Outdoor Air System Engineering Manual

GENERAL DATA
Base Rooftop DOAS
Table 1: Base Rooftop DOAS
Model No.
AR-DR02-03A
AR-DR02-04A
AR-DR02-05A
AR-DR02-06A
AR-DR02-07A
Design Airflow (CFM)
620
770
960
1,050
1,240
ESP (in. wg)
2.5
2.5
2.5
2.5
2.5
Entering Air Summer
DB/WB (°F)
95/75
95/75
95/75
95/75
95/75
Entering Air Winter DB (°F)
0
0
0
0
0
Cooling Performance
Coil LAT DB/WB (°F)
54.9/54.8
55.1/55.0
55.0/54.9
54.9/54.8
55/54.9
Total Cooling Capacity
(MBH)
43.6
53.8
67.3
73.8
87.0
Sensible Cooling Capacity
(MBH)
26.8
33.2
41.4
45.4
53.6
Hot Gas Reheat Coil
Capacity (MBH)
35.3
41.7
48.4
52.3
57.9
Evaporator coil depth
(rows)
3
3
4
4
6
Number of compressors
1
1
1
1
1
Compressor Type(s)
Inverter scroll
Inverter scroll
Inverter scroll
Inverter scroll
Inverter scroll
Heating
Fuel
Natural Gas
Natural Gas
Natural Gas
Natural Gas
Natural Gas
Capacity Input (MBH)
75
75
100
100
150
Capacity Output (MBH)
60
60
80
80
120
LAT (°F)
89.6
72.2
77.2
70.5
89.6
Turndown Type
Modulating
Modulating
Modulating
Modulating
Modulating
Turndown Ratio
4:1
4:1
4:1
4:1
4:1
Supply Fan Data
Fan Quantity
1
1
1
1
1
Wheel Speed (RPM)
1900
1939
1991
2029
2113
Motor HP
3/4
3/4
1
1
1.5
Configuration
Outdoor Air Intake
End
End
End
End
End
Supply Air Discharge
Bottom
Bottom
Bottom
Bottom
Bottom
Weight (lbs)
1,064
1,070
1,095
1,098
1,153
Filtration
Hood
None
None
None
None
None
Supply
2" MERV 8
2" MERV 8
2" MERV 8
2" MERV 8
2" MERV 8
Note:
Capacity Data above may change if entering air temperatures, leaving air temperatures (LAT), or airflow rates are varied.
Take appropriate actions at the end of HVAC equipment life to recover, recycle, reclaim or destroy R410A refrigerant according to applicable
regulations (40 CFR Part 82, Subpart F) under section 608 of CAA.

GENERAL DATA
Base Rooftop DOAS
Table 1: Base Rooftop DOAS
Model No.
AR-DR12-05A
AR-DR12-07A
AR-DR12-10A
AR-DR12-12A
AR-DR12-15A
Design Airflow (CFM)
980
1500
1800
2250
2900
ESP (in. wg)
2
2
2
2
2
Entering Air Summer
DB/WB (°F)
95/75
95/75
95/75
95/75
95/75
Entering Air Winter DB (°F)
0
0
0
0
0
Cooling Performance
Coil LAT DB/WB (°F)
54.8/54.7
54.5/54.4
54.5/54
54.9/54.8
54.7/54.5
Unit LAT DB/WB (°F)
93.8
87.2
82.1
81.9
79.9
Total Cooling Capacity
(MBH)
68.2
105.4
128.3
155.6
202.9
Sensible Cooling Capacity
(MBH)
43.3
66.8
80.3
99.2
128.6
Hot Gas Reheat Coil
Capacity (MBH)
41.3
52.8
53.7
65.6
78.8
Evaporator coil depth
(rows)
4
5
4
6
6
Number of compressors
1
1
2
2
2
Compressor Type(s)
Digital scroll
Digital scroll
Digital scroll /
Standard scroll
Digital scroll /
Standard scroll
Digital scroll /
Standard scroll
Heating
Fuel
Natural Gas
Natural Gas
Natural Gas
Natural Gas
Natural Gas
Capacity Input (MBH)
100
200
200
250
300
Capacity Output (MBH)
80
160
160
200
240
LAT (°F)
75.6
98.8
82.3
82.3
76.6
Turndown Type
Modulating
Modulating
Modulating
Modulating
Modulating
Turndown Ratio
4:1
4:1
4:1
4:1
4:1
Supply Fan Data
Fan Quantity
1
1
1
1
1
Wheel Diameter (in)
14
14
14
14
18
Wheel Speed (RPM)
1809
1996
2133
2376
1716
Motor HP
1
1
1.5
1.5
3
Configuration
Outdoor Air Intake
End
End
End
End
End
Supply Air Discharge
Bottom
Bottom
Bottom
Bottom
Bottom
Weight (lbs)
2253
2325
2384
2487
2646
Filtration
Hood
None
None
None
None
None
Supply
2" MERV 8
2" MERV 8
2" MERV 8
2" MERV 8
2" MERV 8
Note:
Capacity Data above may change if entering air temperatures, leaving air temperatures (LAT), or airflow rates are varied.
Take appropriate actions at the end of HVAC equipment life to recover, recycle, reclaim or destroy R410A refrigerant according to applicable
regulations (40 CFR Part 82, Subpart F) under section 608 of CAA.