LG DOAS User manual

DEDICATED OUTDOOR AIR SYSTEM (DOAS)
INSTALLATION AND OPERATION MANUAL
Variable Refrigerant Flow DOAS Units
ARND20BDAT2
ARND20BDAR2 (no preheat)

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LG Electronics U.S.A., Inc., Englewood Cliffs, NJ.All rights reserved. “LG Life’s Good” is a registered trademark of LG Corp.
2
Dedicated Outdoor Air System (DOAS) Installation and Operation Manual
Do not throw away or destroy this manual.
Please read carefully and store in a safe place for future reference.
The instructions included in this manual must be followed to prevent product malfunction, property damage, injury, or death to the user or
other people. Incorrect operation due to ignoring any instructions will cause harm or damage.
The level of seriousness is classified by the symbols described below.
Alist of safety precautions begins on page 4.
TABLE OF SYMBOLS
This symbol indicates a potentially hazardous situation which, if not avoided, may result in death, serious
injury, property damage or equipment damage.
This symbol indicates additional helpful information such as an explanation, a comment, or a clarication
about the subject.
This symbol indicates a recommendation or tip. Recommendations instruct the user to apply the suggested
practice to ensure the best operating results to achieve the maximum benet of the product. Tips contain
practical information that may help the user solve a problem or describe actions that may save time.

TABLE OF CONTENTS
Table Of Symbols ..................................................................................2
Safety Precautions................................................................................4
Location Selection.................................................................................8
General Installation Instructions.........................................................11
Piping....................................................................................................12
Electrical...............................................................................................15
Low Voltage Communications ...........................................................16
Duct Connections................................................................................17
Wiring Diagrams..................................................................................18
Start-Up................................................................................................22
DOAS Start-Up Checklist....................................................................50
Operation..............................................................................................51
Maintenance.........................................................................................52
Maintenance Log.................................................................................53
Who To Call ForAssistance ...............................................................55

Due to our policy of continuous product innovation, some specifications may change without notification.
LG Electronics U.S.A., Inc., Englewood Cliffs, NJ.All rights reserved. “LG Life’s Good” is a registered trademark of LG Corp.
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Dedicated Outdoor Air System (DOAS) Installation and Operation Manual
SAFETY PRECAUTIONS
The instructions below must be followed to prevent product malfunction, property damage, injury or death to the user or other people.
Incorrect operation due to ignoring any instructions will cause harm or damage. The level of seriousness is classified by the symbols
described below.
All electric work must be performed by a licensed electrician
and conform to local building codes or, in the absence of local
codes, with the National Electrical Code NFPA 70/ANSI C1-1993
or current edition, and the instructions given in this manual.
If the electrical work is not performed properly, it may result in fire,
electric shock, physical injury and/or death.
The customer should not install, remove, or re-install the unit.
There is risk of fire, electric shock, physical injury and/or death.
The dealer or an authorized technician should install the unit.
Improper installation by the user may result in water leaks, fire,
electric shock, physical injury and/or death.
For re-installation of an installed unit, always contact the dealer
or an authorized technician.
There is risk of fire, electric shock, physical injury and/or death.
Be very careful when transporting the product.
DOAS weight and size preclude one person carrying the unit. Use
two or more people to transport the product without the assistance of
mechanical transport equipment. There is a risk of personal injury.
Do not handle DOAS without the use of gloves and protective
clothing. The product may have sharp edges.
There is a risk of personal injury.
Dispose the packing materials safely.
Destroy the structure of plastic packaging and boxes to prevent
children from playing with them. There is a risk of injury, suffocation
and / or death to humans, animals and wildlife.
Do not install the unit on an unstable structure.
It may result in the failure of the structure, property damage,
equipment damage, and / or personal injury or death.
R410A refrigerant creates toxic gases when burned. Do not
store or use flammable products near the unit.
There is risk of product failure, fire, and physical injury and/or death.
Replace all control box and panel covers after completing work.
Failure to do so may result in dust or water infiltration, causing fire,
electric shock, physical injury and/or death.
Always wear safety glasses and work gloves when installing
the product. A rapid release of R410A refrigerant may cause
frostbite.
Do not use oxygen, acetylene or air in place of refrigerant and
dry nitrogen for leak testing.
There is a risk of explosion resulting in physical injury and/or death.
Properly insulate all cold surfaces when installing this product.
Uninsulated cold surfaces may generate condensate that may drip
and cause water damage to wall and floors.
This product is engineered to be used for conditioning of
outdoor air only. It is not to be used in applications that require
precision cooling or heating such as data centers, food preser-
vation, wine coolers, refrigeration and / or freezer applications.
There is risk of property damage.
Provide field-installed electrical isolation devices to protect
sensitive equipment sharing a power source with this product.
Provide sufficient protection against the effects of
electromagnetic fields (EMF) and electrical noise.
Inverter equipment, private power generators, high-frequency
medical equipment, or radio communication equipment may cause
the air conditioner to malfunction.
Provide sufficient electrical system protection against
lighting strikes.
The risk is loss of warranty, product damage, and / or complete loss
of the product.
Ductwork and other installed airflow restriction devices such as
filters shall not exceed the rated maximum static pressure limits
of the DOAS fan assembly.
Doing so may cause product malfunction.
This symbol indicates a potentially hazardous situation which, if not avoided, may result in death, serious
injury, property damage or equipment damage.
This symbol indicates additional helpful information such as an explanation, a comment, or a clarication
about the subject.
This symbol indicates a recommendation or tip. Recommendations instruct the user to apply the suggested
practice to ensure the best operating results in order to achieve the maximum benet of the product. Tips
contain practical information that may help the user solve a problem or describe actions that may save time.
Roughing-In

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Safety Precautions
SAFETY PRECAUTIONS
Roughing In, Continued
Do not store or use gasoline or other flammable vapors and
liquids in the vicinity of the DOAS unit.
Doing so could result in fire, physical injury and/or death.
Do not work in a closed area where refrigerant or nitrogen
gases may be leaking.
Vapors may be present and can result in physical injury and/or
death.
Always use a pressure regulator to control incoming pressures
when pressure testing.
Excessive pressure may result in product damage, physical injury or
death.
Do not install this product outdoors or where it will be directly
exposed to coastal conditions.
Air from the ocean may cause the condenser and evaporator fins to
corrode, which may cause product malfunction.
Do not install this product in a location that is noise sensitive.
Provide additional acoustical treatment as needed.
The risk may be occupant discomfort.
When installing refrigerant piping, consider pipe expansion and
use flare connections.
Improper pipe installation may lead to pipe fatigue, failure, and a
rapid release of refrigerant, frostbite, suffocation, physical injury, and
/or death.
Verify the piping system has been properly evacuated (<500
ppm), and the system’s refrigerant charge is correct before
commissioning and after any repair is made.
Improper system evacuation and / or an improper refrigerant charge
may cause product malfunction.
Power Wiring
The information contained in this manual is intended for use by
a qualified, experienced service technician familiar with safety
procedures, and who is equipped with the proper tools and test
instruments.
Failure to carefully read and follow all instructions in this manual can
result in equipment malfunction, property damage, personal injury
and/or death.
This equipment uses high voltage electricity. Only a qualified,
experienced electrician should wire this system. Never assume
that the electrical power has been disconnected.
Verify with a meter.
Failure to follow all guidelines, properly respect electricity, use
industry best grounding practices, follow suggested wiring instruc-
tions, local, and NEC codes can lead to electrical shock, physical
injury, seizures, and/or death.
Use a properly sized circuit protective device. Using an
undersized protective device will lead to equipment malfunc-
tion. Installing an oversized protective device may cause burns,
fire, and death.
There is risk of fire, electric shock, explosion, physical injury and/or
death.
Properly secure power wires and communications cables at
connectors to eliminate wire strain.
Inadequate connections may generate heat, cause a fire and
physical injury and/or death.
Verify all power, ground, and communications wires and cables
are properly terminated before applying power to the product.
Securely tighten all wire terminations.
Improper and/or loose wire and communications cable terminations
may cause product malfunction, fire, physical injury and/or death.
Turn power off at the unit disconnect before servicing.
Electrical shock can cause physical injury and/or death.
When servicing controls, ensure all wires are labeled properly
prior to disconnecting.
Wires labeled incorrectly could cause product malfunction, fire,
physical injury and/or death.
Properly replace all controls.
Failure to replace controls could result in fire and/or explosion.
Do not overload the VFD motor. The overload ampere setting
must not exceed 115% of the electric motors FLA rating as
shown on the motor nameplate.
There is risk of fire, electric shock, explosion, physical injury and/or
death.
Verify the DOAS unit is operational after servicing. Secure all
doors with a door latch or nut and bolt.

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6
Dedicated Outdoor Air System (DOAS) Installation and Operation Manual
GENERAL DATA
Table 1: Dedicated OutdoorAir System General Data Dedicated OutdoorAir System
ARND20BDAT2 ARND20BDAR2
Cooling Mode Performance
Capacity (Btu/h) 143,100 143,100
Heating Mode Performance
Capacity (Btu/h) (Main Coil) 59,900 59,900
Capacity (Btu/h) (Reheat Coil) 45,900 45,900
EnteringAir
Cooling Max (°F DB/WB) 122/78 122/78
Heating Min (°F DB) 2.5 41
Unit Data
Refrigerant Type1R410A R410A
Refrigerant Control EEV EEV
Sound Power dB(A) 84 84
Net Unit Weight (lbs) 725 600
Shipping Weight (lbs) 825 700
Communication Cable24 x 18 4 x 18
Fan
Type Backward Curved Plenum Backward Curved Plenum
Motor 1 1
Motor/Drive ECM/Direct ECM/Direct
Airflow Rate (CFM) 2000 2000
External Static Pressure (in wg) 1.65 1.65
Airflow Range (CFM) 1200 - 2000 1200 - 2000
Piping (Main Coil)
Liquid Line (in, OD) 1/2 1/2
Vapor Line (in, OD) 1-1/8 1-1/8
Piping (Reheat Coil)
Liquid Line (in, OD) 1/2 1/2
Vapor Line (in, OD) 1-1/8 1-1/8
Condensate
Condensate Line (in, OD) 1 NPT 1 NPT
Actual discharge air temperatures may vary from discharge air temperature set-point due to changes in outdoor air processing loads.
EEV - Electronic Expansion Valve ECM - Electronically Commutated Motor
Power wiring is field supplied and must comply with the applicable local and national codes.
This data is rated 0 ft. above sea level, with 25 ft. of refrigerant piping per coil.
Main Coil Cooling capacity rating obtained with entering air of 95°F DB/75°F WB and leaving air of 52.9°F
DB, 52.5°F WB.
Main Coil Heating capacity rating obtained with entering air of 44°F DB and leaving air of 75°F DB.
Reheat Coil Heating capacity rating obtained with entering air of 54°F DB and leaving air of 86°F DB.
1Take appropriate actions at the end of HVAC equipment life to recover, recycle, reclaim or
destroy R410Arefrigerant according to applicable regulations (40 CFR Part 82, Subpart F)
under section 608 of CAA.
2All communication cable to be minimum 18AWG, 4-conductor, stranded, shielded and must
comply with applicable and national code.
Power Supply (V/Hz/Ø): 208-230/60/3.

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Installation Instructions
REFRIGERANT SAFETY
ASHRAE Standards 15-2010 and 34-2010 offer guidelines that address refrigerant safety and the maximum allowable concentration of
refrigerant in an occupied space. Refrigerant will dissipate into the atmosphere, but a certain volume of air is required for this to occur safely.
For R410Arefrigerant, the maximum allowable concentration of refrigerant is twenty-six (26) lbs. per 1,000 cubic feet of an occupied space.
Buildings with twenty-four (24) hour occupancy allow half of that concentration.
ASHRAE Standards 15 and 34 assume that if a system develops a leak, its entire refrigerant charge will dump into the area where the leak
occurs. To meetASHRAE Standards 15 and 34, calculate the refrigerant concentration that may occur in the smallest room volume on the
system, and compare the results to the maximum allowable concentration number. Also consult state and local codes in regards to
refrigerant safety.
Verify the maximum refrigerant concentration level for spaces served by DOAS meets the concentration limit for the application.

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LG Electronics U.S.A., Inc., Englewood Cliffs, NJ.All rights reserved. “LG Life’s Good” is a registered trademark of LG Corp.
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Dedicated Outdoor Air System (DOAS) Installation and Operation Manual
LOCATION SELECTION
Selecting the Best Location
Placement of the unit relative to ductwork, electrical and plumbing must be carefully considered. Use flexible gasket material to seal the duct
to the unit.
Verify floor, foundation or suspension support can sustain the total unit weight, including accessories. The unit must be level on both
horizontal axis to support the unit and reduce noise and vibration.
Allow adequate space for piping access and panel removal. To ensure proper access for field service, maintain minimum clearances for field
piping and other obstructions. Refer to Table 2 and Figure 1. Condensate drain connections are located on the access side of the unit.
Follow local building codes for additional service clearance requirements.
Suspended Unit Mounting Details
DOAS units are equipped for suspended installations. The unit should be lifted into position by supporting the unit with skid used for shipping.
Carefully install the DOAS unit to prevent damage to the cabinet and ensure the unit is installed level.Additional installation provisions may
be necessary depending on the job specifications. The specifying engineer or installing contractor are responsible for ensuring the
installation of the DOAS is structurally sound. Refer to Figure 2 and Figure 3 for recommended suspended installation methods.
Access Side Clearance1All Other Sides
36 inches 6 inches
Table 2: Dedicated OutdoorAir System Clearances
Figure 1: Minimum Clearance Required for UnitAccess
X
(
See Table 2
)
Front
Back
Left Right
1Dimension X on Figure 1.
Clearance Requirements

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Installation Instructions
LOCATION SELECTION
Figure 2: Series Platform Suspension Installation
Figure 3: Series Parallel Beam Suspension Installation
Mounting Details
DOAS unit can be installed using either platform suspension (Figure 2) or parallel beam suspension (Figure 3) as shown below.
Air
Flow
Avoid Interference with
Condensate Drain
Field-Provided
Isolation
as Required
Field-Provided
Suspension Rods
(as required).
Avoid Interference
with Access Doors.
Secure to
Field-Provided
Beams
Air
Flow
Avoid Interference with
Condensate Drain
Field-Provided
Suspension Rods
(as required).
Avoid Interference
with Access Doors.
Secure to
Field-Provided
Metal Plate
Field-Provided
Isolation as Required

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Dedicated Outdoor Air System (DOAS) Installation and Operation Manual
LOCATION SELECTION
Unit Orientation and Control Component Location
Figure 4: Unit Orientation
Filter, coil and wiring access doors are on the right side as designated by the unit orientation and fan access door is on the left side. The back will
always be the same side as the lter and outdoor air opening. The front will always be the side opposite the lter and
outdoor air opening.
DOAS TOP VIEW
Connections and
Service Access on
Right Side for Right-
Hand Orientation
Supply Air
(Front)
Left Hand Side
Right Hand Side
Outdoor Air
(Back) AIR FLOW

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Installation Instructions
GENERAL INSTALLATION INSTRUCTIONS
Receiving the Unit
• Check the unit for damage that may have occurred during transit.
• If damage is found, note it on the carrier’s freight bill and request an inspection by the carrier’s agent immediately.
• Check the name plate to ensure the correct model sizes and voltages were received and match and satisfy the job requirements.
• In order to protect the warranty, if repairs need to be made to damaged goods then the factory should be notified before any repair action is
taken. Certain equipment alterations, repairs and manipulation of equipment without consent from the manufacturer may void the product
warranty.
Failure to observe the following instructions will result in premature failure of the DOAS and possibly void your warranty.
Upon receipt, check the shipment for items that ship loose such as lters and remote sensors. Review
order and shipment documentation to identify potentially loose shipped items. These items may have
been placed inside the unit cabinet for security. Installers and owners should secure all doors with locks
or nuts and bolts to prevent unauthorized access.
Figure 5: Lockable Handle
Storage
The DOAS cannot be stored outdoors. If installation does not occur immediately following delivery,
store the equipment in a dry protected area away from construction traffic and in the proper
orientation as marked by the packaging. Prior to storing the unit, secure all loose-shipped items.
Handling the Unit
Before lifting the unit, ensure all shipping material has been removed. If spreader bars, blocking or
other lifting devices are used, take extra care to ensure the cabinet, coil and fans are not damaged.

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Dedicated Outdoor Air System (DOAS) Installation and Operation Manual
PIPING
Figure 6: Drain Trap
Condensate Drain Piping
Condensate drain trapping and piping must conform to all applicable codes.Ap-trap and drain line must be installed. The p-trap cannot
exceed 6 inches from the drain connection. The lines need to be the same pipe size or larger than the drain connection, include a p-trap, and
pitch downward toward the drain.An air break should be used with long condensate line runs.
Failure to install p-traps can result in an overow of condensate water. This can lead to product
damage or property damage. Draw-through cooling coils will have a negative static pressure in
the drain pan area. This can cause an un-trapped drain to back up due to the air being pulled up
through the condensate drain piping.
The value of pressure in the drain pipe should be at least equal to the absolute value of
the negative static pressure in the drain pan plus one inch. Follow the procedure below to
calculate the static pressure.
Calculating Static Pressure
1. Add the pressure drops of all components upstream of the drain plan. This includes the
cooling coil.
2. Add the return duct static pressure. Include the dirt allowance pressure drop for the
filters to account for the worst-case scenario.
Draw-Through
Drain Pan Pressure Trap Dimensions
Negative Static X Y
(inches of water) (inch) (inch)
-0.50 1.50 0.75
-1.00 2.00 1.00
-1.50 2.50 1.25
-2.00 3.00 1.50
-2.50 3.50 1.75
-3.00 4.00 2.00
-3.50 4.50 2.25
-4.00 5.00 2.50
Table 3:DOAS Drain Trap Dimensions
The absolute value of the fan inlet pressure will always be greater than or equal to the absolute value of the static pressure in the drain pan or
draw-through units so the fan inlet pressure is a safe value to use for the drain pan static pressure.
Condensate Drain Piping

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Piping
PIPING
Refrigerant Piping
The installing contractor is responsible for piping the condensing unit to the air handling unit.Acceptable piping sizes can be determined by
using LATS software.
Refrigerant Piping Guidelines
• Pipe sizes must be selected to meet installation conditions and not based on the connection sizes at the evaporator or condensing unit.
• Only cleanACR tubing should be used and all piping should follow any applicable codes.
• The air handling unit coils are pressurized and the copper caps must be punctured to permit a gradual escape of pressure prior to
unsweating the caps.
• To avoid exposing the coils to moisture, immediately couple the tubing to the DOAS unit.
• When making solder connections, ensure the dry nitrogen flows through the lines when the copper is heated to prevent oxidization inside of
the copper.
• When piping is complete, the interconnecting piping and the air handling unit must be leak checked and evacuated to 500 microns or less.
This will allow condenser shutoff valves to open and allow refrigerant to flow to the air handling unit.
• The DOAS should be charged based on the manual calculation of refrigerant charge, based on coil refrigerant volumes.
• The refrigerant reheat coil is to be connected to a separate outdoor unit than the main coil outdoor unit. Ensure not to cross circuits in the
reheat systems.
Aproperly installed pipe system will have sufficient support so that pipes will not sag during the life of the system.As necessary, place
supports closer for segments where potential sagging could occur. Maximum spacing of pipe supports shall meet local codes.
Piping Guidelines
Figure 7: Pipe Support at DOAS Unit
A
B
A+ B ~ 12" – 19"
Max. 12"
~ 12" – 19"
Figure 8: Typical Pipe Support Location - Change in Pipe Direction
Refrigerant Pipe Connections
• DOAS units come with brazed connections.
Refrigeration system components contain very small capillary tubes, small orices, electronic expansion valves, oil separators, and heat
exchangers that can easily become blocked.
While brazing, ALWAYS follow these guidelines:
• Keep pipe supplies capped, clean, and store in a dry location.
• Use a tubing cutter, do not use a saw to cut pipe. De-burr and clean all cuts before assembly. Blow clean the pipe with dry nitrogen prior to
assembly.
• Do not use flux, soft solder, or anti-oxidant agents. Use a 15% silver phosphorous copper brazing alloy to avoid overheating and produce
good flow.
• Protect refrigerant shut-off valves electronic expansion valves, unit case, insulation, and control components from excessive heat by using
a wet rag or a heat barrier spray product while brazing.
• While brazing, always use a dry nitrogen purge operating at a minimum pressure of three (3) psig and maintain a steady flow.

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LG Electronics U.S.A., Inc., Englewood Cliffs, NJ.All rights reserved. “LG Life’s Good” is a registered trademark of LG Corp.
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Dedicated Outdoor Air System (DOAS) Installation and Operation Manual
Pipe Insulation
• Insulate all cold surfaces sufficiently to prevent moisture from forming.All pipes must be insulated and each pipe must be wrapped
separately.
• Use field-provided half (1/2) of an inch thick (or better) closed cell insulation. The thickness may need to be increased based on ambient
conditions and local codes.
• All refrigerant and condensate piping including field-provided isolation ball valves and flexible pipe connection kits provided by LG should
be wrapped.
• All insulation joints should be glued with no air gaps between insulation segments, and between insulation segments and the unit case.
Insulation material shall fit snugly against the refrigeration pipe with no air space between the pipe surface and the surrounding insulation.
Figure 9: Typical piping Diagram
PIPING
Piping Insulation

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Electrical
Electrical
• Verify the unit name plate matches the power supply.
• The unit is provided with a single point power wiring connection. The connection terminals are made to the main terminal block.A complete
wiring diagram including factory and field wiring can be found inside the control compartment door.
• Route power and control wiring separately. Do not run the power and control signal wires in the same conduit.
• All units require field supplied electrical overcurrent and short circuit protection. The device must not be sized larger than the maximum
overcurrent protection (MOP) shown on the nameplate.
• Local codes may require a disconnect switch to be within sight of the unit. The disconnect switch should not be installed on the DOAS unit.
• The electrical supply can enter the unit through the bottom or the side of the controls compartment.
• Asingle point connection to a terminal block is provided with the unit. High voltage conductors must be placed in the control panel in a
separate opening and separate conduit from low voltage conductors.
• To pass a wire through the wall or roof of the unit, cut an opening and pass the conduit through it. Follow the procedure below to safely cut
an electrical opening.
Field cut openings must be a minimum of 6 inches away from all components and wiring to prevent damage caused by drilling or cutting.
Cutting an Electrical Opening
If a reciprocating saw is used to make the cut-out, ensure that the metal shavings from the foam part do not separate from the foam. If the foam
is separated, it can result in structural damage of the part.
1. Select the location for the opening. Ensure the conduit will not interfere with the operation of any components, prevent door access or
prevent a panel from being removed.
Three phase voltage imbalance will cause motor overheating and premature failure. The maximum allowable imbalance is 2.0%. Voltage imbal-
ance is dened as 100 times the maximum deviation from the average voltage divided by the average voltage.
2. Drill a pilot opening all the way through the foam panel.
3. Using a hole saw, cut the opening through the metal on both sides of the foam area.
ELECTRICAL
Table 4: Dedicated OutdoorAir System Electrical Data
Model Voltage
Range MCA MOP Power Supply
Hz Volts Phase
ARND20BDAT2 187-253 96 100 60 208-230 3
ARND20BDAR2 (no preheat) 187-253 8 15 60 208-203 1
MCA= Minimum Circuit Ampacity MOP = Maximum Overcurrent Protection
Power wiring cable is field provided and must comply with the applicable local and national codes.
4. Using a knife, cut the foam from the opening.
5. Install the conduit.
6. After the conduit is installed in the opening, caulk the sides with an industrial grade silicone sealant or a duct seal compound.
If a larger opening is needed for additional duct connections not provided by the factory, it is imperative that the foam be completely sealed.
Insulation covers must be fabricated from sheet metal to cover the foam at the cut. The edges and corners that are not covered need to be
sealed using silicone caulking or a duct seal compound.
• Size supply conductors based on the unit minimum current ampacity (MCA). Supply conductors must be rated at a minimum of 75°C.
• Wire power leads to the unit’s terminal block or main disconnect.All wiring beyond this point has been completed by the factory and cannot
be modified without effecting the unit’s agency and/or safety certification.
• The supply voltage must be within the minimum and maximum range displayed on the unit nameplate. The available short circuit current
should not exceed the short circuit current rating (SCCR) shown on the unit nameplate.
• Check the voltage imbalance at the unit disconnect. Contact your local power company for line voltage corrections.
• The installing contractor must check for proper motor rotation and check blower motor amperage listed on the motor nameplate is not
exceeded.

Due to our policy of continuous product innovation, some specifications may change without notification.
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Dedicated Outdoor Air System (DOAS) Installation and Operation Manual
LOW VOLTAGE COMMUNICATIONS
Outdoor/DOAS Unit Communications Cable Installation Guidelines
Outdoor/DOAS Unit Communications Cable Installation Guidelines
Three phase voltage imbalance will cause motor overheating and premature failure. The maximum allowable imbalance is 2.0%. Voltage imbal-
ance is dened as 100 times the maximum deviation from the average voltage divided by the average voltage.
Polarity matters. When connecting the communications cable conductors at each Multi V system component, be careful the conductor
connected to the DOAS (A) terminal on the outdoor unit is connected to the 10 terminals at eachAHU control terminal. Likewise, the conduc-
tor connected to the DOAS (B) terminal on the outdoor unit must be connected to the 11 terminals at eachAHU control terminal. Cross con-
necting between the “A” and “B” terminals will cause a communications error and the system will not run (see Figure 10).
The minimum distance required between power wires and the communications cable is voltage/amperage dependent and in cases where either
are relatively high the minimum distance may be more than two (2) inches. Refer to the respective LG Multi V Outdoor Unit Engineering Manual
on www.lg-vrf.com for detailed information.
CEN BSODU B
ODU Connected to DOAS Main Coil
CEN AIDU AIDU BSODUACEN BSODU B
ODU Connected to DOAS Reheat Coil
CEN AIDU AIDU BSODUA
COMM1(2) COMM2(2) RS485A(2) RS485B(2)
COMM1(2) COMM2(2) RS485A(2) RS485B(2)
Figure 10: DOAS Wiring Connection to Outdoor Unit
• Keep communications cables away from line voltage wiring, lighting ballasts, and other devices emitting EMF energy. Maintain a minimum
of two (2) inches between line voltage wires and communications cables.
• Field provide a minimum of 18-4AWG, stranded and shielded, PVC or vinyl jacket communications wiring between the DOAS units and outdoor units.
• The outdoor/DOAS unit communications cable must be run between components in a daisy chain configuration.
• Ground the shield of the communications cable at the OUTDOOR UNIT END ONLY.
Don’ts
• Star and Wye communications cable configurations are not acceptable
• Never splice communication cables
• Never use wire caps

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Electrical
Duct Connections
• Attach duct to flanges provided on the unit. The installer is responsible for sealing ducts to the flanges to prevent water leaks.
• Ductwork should be sized in accordance with theASHRAE Handbook. Ductwork should be installed in accordance with NFPA
Standard 90A.
• When attaching duct to the unit, use a flexible/compressible material rated for duct connections.Athree inch flexible connector for
both outdoor air and supply duct connections is recommended.
DUCT CONNECTIONS

Due to our policy of continuous product innovation, some specifications may change without notification.
LG Electronics U.S.A., Inc., Englewood Cliffs, NJ.All rights reserved. “LG Life’s Good” is a registered trademark of LG Corp.
18
Dedicated Outdoor Air System (DOAS) Installation and Operation Manual
WIRING DIAGRAM
DOAS Model ARND20BDAT2 with Preheat

Due to our policy of continuous product innovation, some specifications may change without notification.
LG Electronics U.S.A., Inc., Englewood Cliffs, NJ.All rights reserved. “LG Life’s Good” is a registered trademark of LG Corp. 19
Electrical
WIRING DIAGRAM

Due to our policy of continuous product innovation, some specifications may change without notification.
LG Electronics U.S.A., Inc., Englewood Cliffs, NJ.All rights reserved. “LG Life’s Good” is a registered trademark of LG Corp.
20
Dedicated Outdoor Air System (DOAS) Installation and Operation Manual
DOAS Model ARND20BDAR2 without Preheat
WIRING DIAGRAM