Lennox VOSB Installation Instructions Manual

©2019 Lennox Industries Inc. Dallas, Texas, USA

VRF

THIS MANUAL MUST BE LEFT WITH THE OWNER
FOR FUTURE REFERENCE

These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.

WARNING

Improper installation, adjustment, alteration, ser­vice or maintenance can cause property damage,
personal injury or loss of life.

Installation and service must be performed by a li­censed professional HVAC installer, service agency
or the gas supplier.

Failure to follow safety warnings and these instruc­tions exactly could result in property damage, dan­gerous operation, serious injury, or death.

Any additions, changes, or conversions required in
order for the appliance to satisfactorily meet the ap­plication needs must be made by a licensed profes­sional HVAC installer (or equivalent) using factory-

specied parts.

Do not use this system if any part has been under

water. A ood-damaged appliance is extremely dan-

gerous. Immediately call a licensed professional
HVAC service technician (or equivalent) to inspect
the system and to replace all controls and electrical
parts that have been wet, or to replace the system, if
deemed necessary.

CAUTION

As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and wear gloves and
protective clothing.

To ensure proper system performance and reliability,
Lennox does not recommend operation of VRF sys­tems during any phase of construction. Construction
debris, low temperatures, harmful vapors, and opera-

tion of the unit with misplaced lters can damage the

units. Failure to follow these guidelines will result in the
warranty being voided.

INSTALLATION
INSTRUCTION

VOSB Outside Air Ducted Units

VRF SYSTEMS -- Indoor Units
507896-02
06/2019

IMPORTANT

The Clean Air Act of 1990 bans the intentional venting

of refrigerant (CFC’s and HCFC’s) as of July 1, 1992.

Approved methods of recovery, recycling or reclaiming
must be followed. Fines and/or incarceration may be
levied for non-compliance.

General

The VOSB outside air ducted indoor units are matched
with an outdoor heat recovery or heat pump unit to

create a VRF (variable refrigerant ow) system that uses

R-410A refrigerant. VOSB indoor units are designed for
indoor installation only.

Refer to the Product Specication bulletin (EHB) for
the proper use of these indoor units with specic heat

pumps, heat recovery units, mode switching devices,
branch pipes, line sets and controls.

Shipping and Packing List

Check the components for shipping damage. If you nd

any damage, immediately contact the last carrier.

Package 1 of 1 contains the following:

1 - Assembled high-static, concealed duct unit

1 - Digital Display Panel

2 - Refrigerant piping insulation sleeves

1 - Flexible condensate connector (VOSB036-054)

1 - Hose clamp (VOSB036-054)

1 - Condensate connection pipe (VOSB072-096)
(Packed in Supply side of cabinet.)

1 - Roll tape for condensate pipe (VOSB072-096)

1 - Condensate overow connection harness

1 - 120 Ohm End of Line Resistor

1 - Installation manual

1

Safety Requirements

!

WARNING

ELECTRICAL SHOCK, FIRE, OR EXPLOSION HAZARD.
Do not touch the unit or the controller if your hands are wet.
DO NOT spray water on the indoor unit for any reason.

Do not replace a fuse with a fuse of a di󰀨erent rating. Do not use a jumper wire to replace a fuse. Do not insert

your hands, tools or any other item into the air intake or air outlet at either the indoor or outdoor unit.
Do not allow children to operate the system.

Model Number Identication

V OS B 036 H 4 - 3 P

Brand/Family

V = Variable Refrigerant Flow (VRF)

Unit Type

OS = Outside Air Ducted Indoor Models

Major Design Sequence

Nominal Cooling Capacity - Btuh

B = 2nd Generation

036 = 36,000 Btuh
048 = 48,000 Btuh
054 = 54,000 Btuh
072 = 72,000 Btuh
096 = 96,000 Btuh

Refrigerant Type

4 = R-410A

Cooling E󰀩ciency

H = High E󰀩ciency

Voltage

P = 208/230V-1 phase-60hz

Controls Protocol

3 = Phase 3

NOTE - Only Lennox VRF indoor units will work with Lennox VRF outdoor units and associated mechanical
equipment. Lennox Mini Split indoor units are similar in appearance but must not be connected to a Lennox VRF

refrigerant circuit. Please refer to model numbers to conrm compatibility. Model numbers for Lennox VRF units

start with a “V” and model numbers for Lennox Mini-Splits start with a “M”.

System Piping

CAUTION

VRF system piping is customized for each installation.
The LVSS piping report is an engineered design that
must be followed. The piping diagram or diagrams
included within the LVSS report have been prepared
based on the information provided to the Lennox VRF
applications department.

When the indicated lengths change from the gures

stated within the report, it is imperative that prior to the
commencement of the refrigerant pipe work installation,
Lennox VRF applications department are informed of
these proposed changes.

Upon receipt of this new information the Lennox VRF

applications department will conrm any changes that

may be applicable to this installation. If changes are
required, a new piping diagram will be produced and will
supersede all other previously provided documents.

Failure to provide this information regarding changes

to the original design may lead to insu󰀩cient capacity,

equipment failure, warranty being made void and the
refusal to commission the system.

When using as part of a VRF Heat Recovery system,
refer to the specic pipe connection details located in

the Mode Selection Box installation manual and the
detailed drawing on page 16 of this manual.

NOTICE

2

Unit Dimensions - Inches (mm)

SECTION A-A

VOSB036, 048, 054

SECTION D-D

BRACKETS FOR

SUSPENDING (4)

29-1/8

25-1/8

(740)

(638)

PRIMARY

DRAIN

CONNECTION

(Either Side)

AUXILIARY

DRAIN

CONNECTION

(Either Side)

45-1/4 (1149)

AIR FLOW

TOP VIEW

SECTION C-C

3-5/8 (92)

15-5/8

(397)

5-3/8

7-1/4

(137)

(184)

LIQUID PIPE

GAS PIPE

ELECTRICAL

CONTROL

BOX

SECTION B-B

RETURN
AIR DUCT
OPENING

29-1/8 (740)

23-7/8 (606)

AUXILIARY

DRAIN

CONNECTION

(Either Side)

1-5/8 (41)

7-1/2

4-7/8

(191)

(124)

AIR FLOW

LEFT SIDE VIEW

SECTION D-D

1 (25)

PRIMARY

DRAIN

CONNECTION

(Either Side)

SUPPLY
AIR DUCT
OPENING

(Supply Air

Duct Opening)

9-3/4
(248)

5-3/8
(137)

2-1/2 (64)

TOP OF UNIT

51-1/4 (1302)

47-1/2 (1207)

36-5/8 (930)

(Supply Air Duct Opening)

(Bottom of Unit)

SUPPLY AIR SIDE

SECTION C-C

TOP OF UNIT

RETURN AIR

DUCT OPENING

42-1/4 (1073)

(Return Air Duct Opening)

(Bottom of Unit)

RETURN AIR VIEW

SECTION A-A

16-1/2

(419)

13-3/8 (340)

(Return Air

Duct

Opening)

SUPPLY
AIR DUCT
OPENING

FACTORY­MOUNTED

LIFT PUMP

AUXILIARY

DRAIN

CONNECTION

(Either Side)

GAS PIPE

AIR FLOW

RIGHT SIDE VIEW

SECTION B-B

LIQUID PIPE

PRIMARY

DRAIN

CONNECTION

(Either Side)

RETURN
AIR DUCT
OPENING

3

Unit Dimensions - Inches (mm)

SECTION A-A

VOSB072, 096

RETURN
AIR DUCT
OPENING

20-7/8

(530)

38-1/4 (972)

32-7/8 (835)

AIR FLOW

LEFT SIDE VIEW

SECTION D-D

SECTION D-D

SUPPLY
AIR DUCT
OPENING

38-1/4

34-5/8

(972)

(879)

(Supply Air

Duct Opening)

2 (51)

14-7/8

(378)

6

(152)

(Supply Air Duct Opening)

50 (1270)

AIR FLOW

TOP VIEW

SECTION C-C

TOP OF UNIT

56-3/4 (1441)

36-7/8 (937)

(Bottom of Unit)

SUPPLY AIR SIDE

SECTION C-C

12-1/8

(308)

BRACKETS FOR
SUSPENDING (4)

GAS
PIPE

LIQUID

PIPE

ELECTRICAL

CONTROL

BOX

SUPPLY
AIR DUCT
OPENING

19-7/8

(505)

SECTION B-B

LIQUID PIPE

AIR FLOW

RIGHT SIDE VIEW

SECTION B-B

2-3/4

(70)

GAS PIPE

RETURN
AIR DUCT
OPENING

DRAIN

CONNECTION

5-1/2
(140)

TOP OF UNIT

RETURN AIR

DUCT OPENING

44-1/8(1120)

(Bottom of Unit)

RETURN AIR VIEW

SECTION A-A

4

(76)

3

13-1/2

(343)

Clearances

Refer to Figure 1 for minimum clearance requirements.

Wall

Wall

20” (508 mm) Minimum Service Clearance

Air

Flow

DUCTED

UNIT

24” (610 mm)

24” (610 mm)

Minimum

Service

Clearance

Minimum
Service
Clearance

TOP VIEW

Ceiling

24” (610 mm) Minimum Clearance

1” (25 mm) Minimum Clearance

CeilingSuspended

FRONT VIEW

NOTE - No part of the suspended ceiling, or other supports not directly associated with the indoor unit installation,

can be xed to, or touch the indoor unit, in any form. Minimum clearances must be observed at all times.

NOTE - Horizontal installation only.

Figure 1. Minimum Installation Clearances

5

Unit Placement

WARNING

Do not install the unit in an area where ammable

materials are present due to risk of explosion resulting
in serious injury or death.

Check suitability of structure to which the unit support

mechanism will be xed to. If structure is not capable

of carrying the weight of the unit, unit may fall causing
personal injury or equipment damage.

Use the provided and specied components when

installing equipment. Failure to do so may result in
unit falling, water leaking or electrical shocks, causing
personal injury or equipment or property damage.

Consider the possibility of earthquakes in your area
when installing the equipment. If the unit is not correctly
secured, it may fall, causing personal injury or equipment
damage.

Safely dispose of packing materials, which include
nails, wood and other sharp objects, as well as plastic
wrapping. Children playing with plastic wrap or bags risk

the danger of su󰀨ocation.

CAUTION

Do not place items which may be damaged by water
under or around the unit.

The unit should be installed at least 8 feet above the

oor (if possible) to ensure maximum performance and

comfort.

AVOID

Do not install the unit in the following locations:

• Areas near commercial kitchen exhaust hoods where
odors and grease may enter the air stream.

• Areas near ue and/or exhaust vents where ue
gasses, waste gasses, or debris may enter the air
stream.

• Areas exposed to petrochemicals or petrochemical
products

• Areas exposed to salt or other corrosive materials or
caustic gasses

• Areas exposed to extreme voltage variations (such as
factories

• Tightly enclosed areas that may impede service of the
unit

• Areas exposed to fossil fuels (such as oil or gas in

kitchens)

• Areas exposed to strong electromagnetic forces

• Areas exposed to acids or alkaline detergents (laundry

rooms)

DO:

• Locate the unit so that it is not exposed to direct
sunlight

• Ensure the structural ceiling can support the weight
of the unit.

• Select a location where condensate line will have the
shortest run to a suitable drain per local codes.

• Allow su󰀩cient space around unit for proper operation
and maintenance

• Install unit a minimum of 3 feet away from any antenna,

power cord (line) radio, telephone, security system, or

intercom. Electrical interference and radio frequencies

from any of these sources may a󰀨ect operation

6

Installation

It is important to locate the unit where it can be accessed
for service in the future. Refer to unit dimensions on Pages
3-5 for exact locations of suspension brackets, return air
and supply air openings.

1. Make sure that the structural ceiling or slab is able
to support the weight of the indoor unit. It may be
necessary to add extra support.

2. Install suspension rods in the structural
ceiling or concrete slab in a suitable location.
If the structural ceiling is constructed of concrete,

install anchors to accept four ⅜” threaded rods to

suspend the indoor unit. If the structural ceiling
includes wooden joists, use angle iron or Unistrut

channel xed securely in place to accept the ⅜”

threaded rods. NOTE - Threaded rod (requirement
of Lennox warranty program) is the ONLY acceptable
method of suspending the unit; do not use chains or
straps. See Figure 2.

⅜” THREADED

CONCRETE CEILING

USING ANCHORS

ANCHOR

ANGLE IRON

BOLTED IN

PLACE ACROSS

WOODEN JOISTS

⅜” THREADED

ROD

ANGLE IRON

WOODEN JOISTS

WOODEN JOIST

Figure 2. Suspending Methods

3. Slide one nut and one washer onto each threaded rod.

Use electrical tape to keep the washer from failing o󰀨.
Position the nuts slightly above the nal resting place

of the four suspension brackets. See Figure 3.

⅜” THREADED

ROD

INDOOR UNIT

SUPPLY AIR

OPENING

LEVELING

FRONT VIEW

NUT

Figure 3. Suspension Hardware

ROD

ACROSS

When unit is
level, tighten

nut to secure

position of

suspension

bracket on

SUSPENSION

BRACKET

rod.

⅜” THREADED

ROD

FIELD-PROVIDED

ISOLATION GROMMET

WASHER

LEVELING

NUT

SUSPENSION

BRACKET

Figure 4. Isolation Grommet

4. Use either a mechanical lifting device or a minimum of
two people to raise the unit and insert the threaded rods
into the suspension brackets on the unit base. Slide
a washer and then a nut onto each rod below each
suspension bracket. Use the leveling nut (beneath

suspension bracket) to adjust the unit to the correct

height. Remove the electrical tape holding the upper
washers and nuts in place and tighten each of the four
nuts above the brackets down onto the brackets. This
will ensure that the unit remains level.

5. It is recommended to install a eld-provided isolation
grommet as shown in Figure 4 to prevent transmission
of vibration from unit to structural ceiling.

6. If the unit is being installed in an application that includes

a sheet rock (plasterboard) ceiling, it is required that

an access panel be installed in a suitable location.
This will also allow access for future maintenance
(requirement of Lennox warranty program).
Access is required during the commissioning process
to test the condensate disposal system and to check
the local disconnect.

7. The unit is factory-congured for the supply air to be

delivered from the front and the return air lter at the

rear of the unit.

INSTALLATION GUIDELINES

• It is recommended to install a eld-provided isolation
grommet as shown in Figure 4 to prevent transmission
of vibration from unit to structural ceiling.

• Provide separate support for the weight of the duct
system. Duct system must not be supported by the
indoor unit.

• Use exible joints (canvas) at the point where the duct
connects to the unit on both ends. Material must meet
all local and national code requirements.

• When unit is being installed in a location where even
the slightest noise would be a problem (meeting room

or other very quiet space), design duct system to avoid

transmission of vibration to the structure to the extent
possible.

• When sizing the return air lter grille, a minimum
surface area of 200 sq. in. per ton is recommended.

7

Return Air Filter

Return Air Filter

The factory-supplied return air lter is segmented to allow

it to be separated if needed to remove it from the unit in
tight spaces. The segments are connected with hook &
loop (Velcro-style) straps. See Table 1 for lter dimen­sions.

Filter
removal
tab

Figure 5. Segmented Factory-Supplied

Return Air Filter

Remove Return Air Filter Instructions

1. Loosen the screw that secures the lter retaining
bracket and slide the bracket away from the unit.

2. Grasp the lter removal tab and slide the lter out.

Filter removal tab

Figure 7. Slide Out Filter

Figure 6. Loosen Filter Retaining Bracket

Table 1. Filter Dimensions

Indoor Unit Model Filter Dimensions Each Section of Filter Dimensions

VOSB036, 048, 054

VOSB072, 096

42-5/8 x 13-1/4 x 3/8 in.

1083 x 336 x 10 mm

44-1/2 x 13-1/4 x 3/8 in.

1130 x 336 x 10 mm

External Static Pressure

External Static Pressure setting on wired controller

• Use high speed air ow for selection and design.

• Set the external static pressure (ESP) on wired
controller, the setting value should not be 0.2 in.w.g

(50Pa) higher than the actual external static pressure

of the duct.

Hook & Loop Strap

Figure 8. Filter Partially Removed

3. Reverse these steps to reinstall the lter. Be sure
to reinstall the receiver if it was detached during the

lter removal.

14-1/8 x 13-1/4 x 3/8 in.

359 x 336 x 10 mm

14-3/4 x 13-1/4 x 3/8 in.

375 x 336 x 10 mm

8

Refrigerant Piping Connections

WARNING

Refrigerant leaks are unlikely; however, if a refrigerant
leak occurs, open a door or windows to dilute the

refrigerant in the room. Turn o󰀨 the unit and all other

appliances that may cause a spark. Call a licensed

professional HVAC technician (or equivalent) to repair

the leak.
Use only R410A refrigerant to charge this system. Use
of other refrigerant or gas will damage the equipment.
Do not allow air or other contaminants to enter system
during installation of refrigerant piping. Contaminants
will result in lower system capacity and abnormally high
operating pressures and may result in system failure or
explosion.
Insulate all refrigerant piping.
Refrigerant pipes may be very hot during unit operation.
Do not allow contact between wiring and bare copper
pipes.
After refrigerant piping connections have been
completed, check the system for leaks per
commissioning instructions.

WARNING

Danger of re. Bleeding the refrigerant

charge from only the high side may result
in pressurization of the low side shell and
suction tubing. Application of a brazing torch
to a pressurized system may result in ignition
of the refrigerant and oil mixture. Check the
high and low pressures before applying heat.

IMPORTANT

Refrigerant lines must be clean, dry, refrigerant-grade
copper lines. Air handler coils should be installed

only with specied line sizes for approved system

combinations.

Handle refrigerant lines gently during the installation

process. Sharp bends or kinks in the lines will cause
restrictions.

IMPORTANT

Only use brazing rods/sticks which are suitable/
recommended for air conditioning pipework installations

- Do Not Use Soft Solder.

IMPORTANT

The compressor in the unit this air handler is matched

with contains PVE oil (Polyvinyl ether). PVE oil is
formulated for hydrouorocarbon (HFC) refrigerants,

such as R410A, which this system contains. While it may
have some miscibility properties with mineral-based oil

and POE oil (Polyolester), it is not recommended to mix

PVE oil with any other type of refrigerant oil.

CAUTION

Brazing alloys and ux contain materials which are

hazardous to your health.
Avoid breathing vapors or fumes from brazing operations.

Perform operations only in well-ventilated areas.
Wear gloves and protective goggles or face shield to

protect against burns.
Wash hands with soap and water after handling brazing

alloys and ux.

CAUTION

Purge low pressure nitrogen [1 to 2 psig (6.0 to 12.8

kPA)] through the refrigerant piping during brazing. This

will help to prevent oxidation and the introduction of
moisture into a system.
To prevent the build-up of high levels of nitrogen when
purging be sure it is done in a well ventilated area.

9

• Refrigerant lines must be connected by a qualied
technician in accordance with established procedures.

• Field provided piping consists of two HVAC/R rated
copper lines connected to the indoor unit.

• Final equipment connections must be brazed

connections. Compression or other types of ttings
are not permitted for nal connections.

• All refrigerant piping shall be free of defects, debris,
and oil.

• Copper-phosphorous brazing alloys are to be used to
join all pipework connections where applicable.

• Always ow/purge nitrogen to avoid oxidation while
brazing.

• Always use an appropriate heat absorption compound
to protect the unit and internal sensors from conductive
heat while brazing.

1. The seal on the unit refrigerant piping connections
should remain in place until the last possible moment.
This will prevent dust or moisture from getting into the
refrigerant piping before it is connected.

2. Prior to brazing remove rubber air grommets from
indoor unit refrigerant line ports.

3. Slowly loosen one of the rubber plugs to release the
factory nitrogen charge. Remove the rubber plug from
both liquid and gas lines.

4. Connect the liquid and gas lines to the evaporator coil.

5. Reinstall the rubber grommets into the refrigerant
piping panel.

6. Insulate both pipes individually.

Table 2. Refrigerant Piping Connections

Indoor Unit Size

(Btuh)

36,000

48,000

54,000

72,000

96,000

Liquid Line Vapor Line

3/8” 5/8”

3/8” 7/8”

Sealing the Unit

Seal the unit so that warm air is not allowed into the
cabinet. Warm air introduces moisture, which results in
condensation problems.

This is especially important when the unit is installed in an
unconditioned area.

If installed in an unconditioned space, sealant should be
applied around the electrical wires, refrigerant tubing, and
condensate lines where they enter the cabinet.

WARNING

There must be an air-tight seal between the unit and the

return air plenum. Use berglass sealing strips, caulking,

or equivalent sealing method between the plenum and
the air handler cabinet to ensure a tight seal. Return
air must not be drawn from a room where this unit or

any gas-fueled appliance (i.e. water heater) or carbon
monoxide-producing device (i.e. wood replace) is

installed.

10

Condensate Piping Connections

VOSB036-054 indoor units have a factory-installed

condensate lift pump capable of 28 inches (711 mm) of lift

and one gravity drain connection on each side of the unit.
If using gravity drain, select one connection to use and
leave the unused connection port sealed.

Seal and plug the lift pump connection port
when using a gravity drain connection port.
Disconnect the factory-installed lift pump that is connected
to the CN labeled PUMP..

VOSB072-096 indoor units have one gravity drain
connection.

CAUTION

Make sure that drain piping is properly routed and
insulated in order to prevent both leaks and condensation.
Follow these instructions exactly to ensure proper
drainage and unit operation.

1. Use the provided hose clamp to secure the

provided exible condensate drain connector

and insulating sleeve to the drain line stub
on the side of the indoor unit. See Figure 9.

NOTE - Take care not to over-tighten the hose clamps

this may damage the drain line stub.

036 SHOWN

RETURN

AIR DUCT

SUPPLY

AIR DUCT

OPENING

AUXILIARY

DRAIN

CONNECTION

(EITHER SIDE VOSB036-054)

INDOOR

UNIT

(BOTTOM OF UNIT)

AIR FLOW

FLEXIBLE DRAIN

CONNECTOR

1” I.D.

(EITHER SIDE VOSB036-054)

(ONE SIDE VOSB072--96)

OPENING

PRIMARY

DRAIN

CONNECTION

PVC DRAIN

PIPE

3. See Figure 10 for applications including a single unit
and a single gravity drain. In this case, ensure that
the drain line is properly sloped (no less than 1/4 inch

per foot) and condensate lines are routed to ensure

moisture is drained away from the indoor unit.

Structural Ceiling

Suspension Rods

Indoor Unit

Do not operate unit without condensate drain trap.

NOTE - Drain line should be sloped 1/4 inch per foot (18 mm per m)
AWAY from unit and should be supported as needed to prevent sagging.

Do not overtighten drain fitting.

Anti-siphon vent must extend above the
height of the coil drain pan by 2” (51 mm).

1 ft.

(305 mm) max

Clean Out
Do not glue

3”

3”

3 ft.

(1 m)

Support

straps

Drain line

Figure 10. Sloped Condensate Gravity Drain

Single Unit

IMPORTANT

Drain should have a slope of at least 1/4 inch per foot
and should be approved corrosion-resistant pipe.

4. See Figure 12 for applications including multiple units
and a single gravity drain. In this case, ensure that
the drain line is properly sloped (no less than 1/4 inch

per foot) and condensate lines are routed to ensure

moisture is drained away from the indoor unit. See

5. See Figure 11 for applications including a single unit
using the factory-mounted lift pump.

STRUCTURAL CEILING

SUSPENSION RODS

8 in.

(203 mm)

DRAIN LINE

3 ft. (1 m)

SUPPORT

STRAPS

Max. 18 in.

CONDENSATE

LINE STUB

1” O.D.

HOSE CLAMP

INSULATION

Figure 9. Condensate Drain Connection

IMPORTANT

You must conrm operation of every drain and pump in

the system as part of the commissioning procedure.

2. Make a water-tight connection between the eld-

provided condensate drain line and the exible
condensate connector (1” I.D.).

Figure 11. Condensate Drain with Lift Pump

Single Unit

6. See Figure 13 for applications including multiple units
using the internal lift pump to provide lift into a single,
correctly sized main drain. In this case, ensure that
the main drain line is properly sloped, no less than

1/4 inch per foot (6 mm per 305 mm), and that each

individual drain is connected to the main drain exactly
as shown.

11

Install an anti-siphon vent for each trap - must extend above
the height of the coil drain pan by 2” (51 mm).

Suspension

Rods

Clean Out

Indoor Unit tinU roodnItinU roodnI

3”

3”

Install a trap for each indoor unit.

Do not operate unit without condensate drain trap.

Do not overtighten drain fitting.

Figure 12. Sloped Condensate Gravity Drain

8 in.

2~3-15/16 in.

Indoor Unit

INDIVIDUAL DRAIN OUTLET FROM EACH INDOOR UNIT

(Must be connected to internal pump and must be routed to

main drain as shown.)

Max. 18 in.

(305 mm) max

Clean Out

Vent

3”

3”

NOTE - Drain line should be sloped 1/4 inch per foot (18 mm per m)
AWAY from unit and should be supported as needed to prevent sagging.

Clean Out

3”

3”

Multiple Indoor Units

8 in. 8 in.

2~3-15/16 in.

Max. 18 in.

(Sloped at 1/4” per foot (6 mm per 305 mm) AWAY

from unit and should be supported as needed to prevent sagging.)

tinU roodnItinU roodnI

MAIN DRAIN

1 ft.

Vent

2~3-15/16 in.

3 ft.

(1 m)

Support

straps

Max. 18 in.

Figure 13. Condensate Drain with Lift Pump

Multiple Indoor Units

7. In all cases, drain should be as short as possible and
should not have any droops or kinks that would restrict

condensate ow and shall be constructed using an

approved pipe. All drains should contain traps. There
must be a 2-inch space between the end of the

8. After system installation is complete, the
condensate drain line must be checked for leaks

and if a condensate pump has been tted, it must

be checked to ensure proper operation. This
check is part of the commissioning procedure.

condensate drain and the nal termination point

(ground, open drain, etc.) to ensure that the line
will drain freely.

Table 3. Condensate Pump Accessory Options

Capacity Brand Model Name Model # Cat #

Lennox VRF Drain Pump Kit V8DRNP05 17U32 - 18 in -

VOSB072-096

Blue
Diamond

MegaBlue X87-835 14T71 13.2 66.5 ft 23 ft

*Optional pump maximum suction lift is measured from the pump outlet.

Max Flow

Rate

(gal per hr)

Max

head

Max
suction
lift*

12

Table 4. Condensate Connection Sizes

Cut wire here

using solder
or butt joints

Model

VOSB Outside Air
Ducted

Condensate
Life Pump
Factory
Mounted

Yes - 036-054
No - 072/096

Condensate
Pump Lift
Measurement

18 “ Yes

Using an External Water Level Switch

1. Disconnect the closed circuit loop connection
labeled WATER.

2. Connect the provided overow harness accessory to
the WATER connection. See Figure 14.

3. See unit wiring diagrams for location of the WATER
connection.

The connection has 5 VDC current, do not supply eld

voltage.

Table 3 lists available external condensate pump
accessories. See Table 4 for connection sizes.

Condensate Pump
Facility on Indoor
PCB Board

INDOOR
UNIT
MAIN
BOARD

WATER

Connect to
pump here

WATER

Condensate
Outlet of
Indoor Unit

1” O.D.
1-5/8” O.D.

adapter pro­vided

L1

L2

Flexible Drain Con­nection (supplied
with unit)

1” I.D.

GREEN

G

PUMP
CONNECTIONS

G

L2

L1

NC

COM

NO

OPTIMAL

0.5A

Wiring Connections

WARNING

Isolate the power supply before accessing unit electrical
terminals.

Install unit so that unit disconnect is accessible.

Follow all local and national codes, as well as this
installation instruction, during installation. Do NOT
overload electrical circuit, as this may lead to failure and

possible re.

Use specied wiring and cable to make electrical

connections. Clamp cables securely and make sure that
connections are tight to avoid strain on wiring. Insecure
wiring connections may result in equipment failure and

risk of re.

Wiring must be installed so that all cover plates can be
securely closed.

Do not attempt to repair a damaged power cord.
Do not modify the power cord in any way. Do not
attempt to extend the length of the power cord or use
an extension cord with this appliance. Do not share the
single power outlet with any other appliances.

• Indoor and outdoor unit equipment must each be on
their own a dedicated breaker.

• Indoor units must have a dedicated service disconnect.
Switches are acceptable; however it must be a double
pole switch that disconnects L1 and L2.

Figure 14. External Water Level Switch Connection

CAUTION

This unit must be properly grounded and protected by a
circuit breaker. The ground wire for the unit must not be
connected to a gas or water pipe, a lightning conductor
or a telephone ground wire.
Do not connect power wires to the outdoor unit until
all other wiring and piping connections have been
completed.
Install all wiring at least 3 feet away from televisions,
radios or other electronic devices in order to avoid the
possibility of interference with the unit operation.
Do not install the unit near a lighting appliance that

includes a ballast. The ballast may a󰀨ect remote control

operation.

In the U.S.A., wiring must conform with current local

codes and the current National Electric Code (NEC). In

Canada, wiring must conform with current local codes and

the current Canadian Electrical Code (CEC).

Refer to unit nameplate for minimum circuit ampacity and
maximum overcurrent protection size.

NOTE - Two-conductor stranded shielded cable must be
used for the communication wiring. This is necessary to
ensure proper system communication and operation.

13

1. Remove the screws that secure the control box cover.
Remove the cover and place it to the side where it will
not be damaged.

2. Locate the terminal strip in the control box. Connect

the power wiring (sized per NEC/CEC and local codes)

and communications cable (two-conductor shielded

cable). Refer to unit nameplate for rated voltage.

3. If the indoor unit is the nal unit in a group that is wired
in series, install the provided resistor across terminals
P and Q.

Indoor units and mode selection boxes on the same
refrigeration circuit should have a common power
supply but must have an independent disconnect switch
installed adjacent to each item of equipment for servicing
and maintenance purposes. Indoor unit and mode
selection box power supply MUST not be taken from the
outdoor unit. Always follow NEC/CEC and Local Codes.

208/230V 1Ph 60Hz

Power supply

Dedicated
breaker

208/230V 3Ph 60Hz

or 460V 3Ph 60Hz

Power supply

L2L1

L1 L2

L1 L2 L3

L1 L2 L3

Mode Selection Box Indoor unit

L2 L3L1

Service
Disconnect

Outdoor Unit (Main Unit)

L1 L2 L3

L1 L2 L3

L1 L2 L3

Outdoor Unit (Sub1 unit)

Service
Disconnect

L1 L2 L3

Indoor unit Indoor unit

L1 L2 L3

L1 L2 L3

Service
Disconnect

Outdoor Unit(Sub2 Unit)

L1 L2 L3

Fuse

L1 L2

Service
Disconnect

Fuse

L1 L2

Service
Disconnect

Fuse

L1 L2

Service
Disconnect

L1 L2

Fuse

Service
Disconnect

Figure 15. Typical Power Wiring Diagram (VRF Heat Recovery System Shown)

14

Outdoor unit Outdoor unit

(main unit)

(sub1 unit)

Outdoor unit

(sub2 unit)

P Q H1 H2X YO AK1 K2

Outdoor Unit Communication Terminal Block

(PQ)

P Q

(H1 H2 )

Install a terminating resistor (Ω120) on terminals P&Q on the indoor unit

(H1 H2 ) (H1 H2 )

(PQ)

(PQ)

(PQ)

MS

Box

(PQ)

MS

Box

(PQ)

which is furthest from the outdoor unit.

P Q

MS Box Communication

Terminal Block

HA HB 12V COM P Q

Indoor Unit Communication Terminal Block

Ground drain wire or
cable shield
to MS Box
and Outdoor Unit chassis

All Drain Wires will connect from outdoor unit chassis to mode selection box chassis at the end of
the signal run.

18 GA., stranded, 2-conductor, shielded control wire (polarity sensitive).

Typical Wiring Diagram, NEC/CEC and Local Codes apply.

NOTE - Each communication wire from the MS box should follow the refrigerant piping for that port.

Figure 16. Typical Communication Wiring Diagram (VRF Heat Recovery System)

15

Outdoor unit

(main unit)

Outdoor unit

(sub1 unit)

Outdoor unit

(sub2 unit)

(H1 H2 )

(H1 H2 )

(H1 H2 )

P Q H1 H2X YO AK1 K2

Outdoor Unit Communication Terminal Block

(PQ)

HA HB 12V COM P Q

Indoor Unit Communication Terminal Block

(PQ)

P Q

Install a terminating resistor (Ω120) at the last indoor unit terminals P and Q of the daisy chain.

All shields of shielded cable connect to

chassis GROUND terminal at Indoor Units.

18 GA., stranded, 2-conductor, shielded control wire (polarity sensitive).

Typical Wiring Diagram, NEC/CEC and Local Codes apply.

Ground cable shield

to Indoor Unit chassis

Figure 17. Typical Communication Wiring Diagram (VRF Heat Pump System)

Tightening torque for the terminal screws

• Use the correct screwdriver for tightening the terminal
screws.

• If the terminal screws are over tightened, screws
might be damaged.

• Refer to Table 5 for the tightening torque of the
terminal screws.

IMPORTANT

DO NOT adjust DIP switch settings. Settings may only
be adjusted by a trained technician as part of the com­missioning procedures.

Table 5. Terminal Screw Tightening Torque

Tightening torque (lb-ft)

Terminal base of
remote controller/Signal

transmission wire (X2M)

Terminal base of power

supply (X1M)

Grounding terminal (M4) 1.06-1.43

• After wiring, conrm all connections are correct; Then
turn on power supply to the unit.

0.58-0.72

0.87-1.06

16

Error code

E0

E1

E2

E3

E4

E5

E6

E7

EC

Vco2

COM

XT2

HA HB 12V COM QP

Error code

U4

F8

Eb

Ed

EE

FE
A0

D8

WHITE
BLUE
RED

BLACK

YELLOW
GRAY

Error Content

Mode conflict

Communication error between indoor and main outdoor unit

T0 (Inlet air temperature sensor) malfunction

T2 (Middle of evaporator sensor) malfunction

T2B (Outlet of evaporator sensor) malfunction

T2A (Inlet of evaporator sensor) malfunction

DC fan motor error

EEPROM failure

TA (Outlet air temperature sensor) malfunction

To wired
controller
comm. bus

To wired
controller
power

To outdoor/
indoor/MS
units
comm. bus

CO2

78

sensor

Error Content
MS self-inspection error

MS error

EEV malfunction

Outdoor unit fault
High water alarm

No address
Emergency stop

Remote off

CS

FAN

HHE interface

( Current range: 0-1A)

Voltage range: 0-24V AC/DC)

(

CTON

HTON

4 5 6

Code

FM
T0
T2A
T2B

T2
TA

XP1-5

ON/OFF
SWITCH

CN50

“ +5V GND +12V ”
ONLY USED
FOR TESTING

Title

Indoor fan motor

Inlet air temperature sensor
Inlet of evaporator sensor

Outlet of evaporator sensor
Middle of evaporator sensor

Outlet air temperature sensor

Connectors

DC motor
drive board

CN13

CN3

N=3

Code

XS1-5

XT1-2

PUMP

CS

ALARM

EEV

Title

Connectors

Terminals
Pump motor

Water level switch
Warning lamp

Electronic expansion valve

SVD Solenoid valve

NOTE:

1. Refer to manual for
communication wiring

2. Please use the 2-conductor
shielded twisted cable for
communication

FAN

FM

Display Board

XS4

T2B

XS3

T1/T0

XS2

T2

XS1

T2A

TA

XP4

XP3

XP2

XP1

EEV

XS5

RED

WHITE

CALB K

EULB

ACKLB

XP5

CN9

CN15

CN14

CN26

CN6

CN2{L_IN}

CN4{N_IN}

GND
Vco2

CN8

CN11 CN5 CN52

CN12

CN30

EARTH

CN54

Main Board

CN3 CN18

CN20

N=4

LACKB

G/Y

DER

XT1

L1 L2

ALARM

PUMP

POWER IN

NOTE:

Component in dash line is optional or field wiring

Typical wiring diagram. Refer to wiring diagram on the unit for actual wiring.

Figure 18. VOSB036H4-3, VOSB048H4-3, & VOSB054H4-3

Typical Wiring Diagram

CN24

SVD

17

Error code

E0

E1

E2

E3

E4

E5

E6

E7

EC

To wired
controller
comm. bus

To wired
controller
power

To outdoor/
indoor/MS
units
comm. bus

Error Content

Mode conflict

Communication error between indoor and main outdoor unit

T0 (Inlet air temperature sensor) malfunction

T2 (Middle of evaporator sensor) malfunction

T2B (Outlet of evaporator sensor) malfunction

T2A (Inlet of evaporator sensor) malfunction

DC fan motor error

EEPROM failure

TA (

Outlet air

temperature sensor) malfunction

NOTE:

1. Refer to manual for communication wiring

2. Please use the 2-conductor shielded twisted
cable for communication

HA HB 12V COM QP

WHITE
BLUE
RED

BLACK

YELLOW
GRAY

XT2

Vco2

CO2

78

sensor

COM

CN15

CN14

XP5

XS4

XS3

XS2

XS1

XP4

XP3

XP2

XP1

XS5

RED

WHITE

CALB K

EULB

ACKLB

CN9

CN2{L_IN}

CN4{N_IN}

GND

Vco2

CN26

CN6

CN8

Display Board

T2B

T1/T0

T2

T2A

TA

EEV

Error code

U4

F8

Eb

Ed

EE

FE
A0

D8

CN11 CN5

CN12

CN30

EARTH

Error Content
MS self-inspection error

MS error

EEV malfunction

Outdoor unit fault
High water alarm

No address

Emergency stop
Remote off

CS

FAN

CTON

HTON

HHE interface

( Current range: 0-1A)

Voltage range: 0-24V AC/DC

(

CN54

CN52

Main Board

CN50

4 5 6

“ +5V GND +12V ”
ONLY USED
FOR TESTING

CN3 CN28

ON/OFF
SWITCH

)

CN27

CN18

N=3

Code

Indoor fan motor

FM
T0

Inlet air temperature sensor
Inlet of evaporator sensor

T2A

Outlet of evaporator sensor

T2B

T2

Middle of evaporator sensor

Outlet air temperature sensor

TA

Connectors

XP1-6

DC motor
drive board

CN13

N=3

CN24

CN57+

CN58-

CN20

CN29

Title

CN3

RED

BLACK

BLUE

XP6XS6

DC motor
drive board

FAN

FM

Rectifier Bridge

-

~

Code

XS1-6

Connectors

XT1-2

Terminals
Pump motor

PUMP

Water level switch

CS

Warning lamp

ALARM

Electronic expansion valve

EEV

SVD Solenoid valve

CN3

CN13

Lorem ipsum

~

+

BLUE

Title

FAN

FM

N=4

LACKB

G/Y

DER

XT1

L1 L2

ALARM

PUMP1

PUMP2

SVD

POWER IN

NOTE:

Component in dash line is optional or field wiring

Typical wiring diagram. Refer to wiring diagram on the unit for actual wiring.

Figure 19. VOSB072H4-3 and VOSB096H4-3 Typical Wiring Diagram

Dip-switch setting:

See Table 6 for allowed indoor to outdoor unit combinations.

Use the SW8-1 dip switch to set whether or not the all of the indoor units in the system are VOSB units or if there is a
mix of indoor units in the system.

0 - All indoor units in the system are VOSB.

1 - VOSB and common indoor units mix in one system.

Table 6. VOSB Indoor Unit to Outdoor Unit Allowed Connection Ratio

Outdoor Unit Indoor Unit

IDU/ODU
Connection Ratio

VOSB/ODU
Connection Ratio

Heat Pump VOSB Only ≤100% ≤100%

Heat Pump VOSB + other indoor units ≤100% ≤30%

Heat Recovery VOSB Only NOT ALLOWED NOT ALLOWED

Heat Recovery VOSB + other indoor units ≤100% ≤30%

18

Relocate T0 Return Air Sensor

Relocate the unit return air from inside the unit to a loca­tion within the conditioned zone whenever the return is
pulling air from above the ceiling or if fresh air is being
introduced and mixed into the return. The T0 sensor can­not accurately read the space temperature under these
conditions if the sensor remains located inside of the unit.

This sensor can be extended with 18 AWG stranded
shielded cable.

1. Identify the T0 connection on the main board - CN4.

(white wires soldered to PCB)

Figure 22. Cut the Black Wire

4. Prepare the 18 AWG stranded shielded extension
cable.

5. Solder the extension cable to the black wire on each

end or use the VRF accessory V0SNSR00P (13G99)

to splice in the extension cable.

6. Locate the return air thermistor to the conditioned
area of which the indoor unit serves.

Figure 20. Identify T0 Sensor Connection on PCB

2. Identify where the white wire is plugged into the black
wire.

Figure 23. Sensor Thermistor

IMPORTANT

Avoid installing sensor in high load or heat loss areas
such as exterior walls or walls that are against uncondi­tioned spaces, near entry doors and windows, or where
direct sunlight may be present.

Figure 21. Identify White Plug into Black Wire

3. Cut the black wire between the plug and the sensor
thermistor. Leave adequate room for making wiring
connections on each end.

19

Error code

E0

E1

E2

E3

E4

E5

E6

E7

EC

Error Content

Mode conflict

Communication error between indoor and main outdoor unit

T0 (Inlet air temperature sensor) malfunction

T2 (Middle of evaporator sensor) malfunction

T2B (Outlet of evaporator sensor) malfunction

T2A (Inlet of evaporator sensor) malfunction

DC fan motor error

EEPROM failure

TA (Outlet air temperature sensor) malfunction

To wired
controller
comm. bus

To wired
controller
power

To outdoor/
indoor/MS
units
comm. bus

CO2
sensor

Error code

U4

F8

Eb

Ed

EE

FE
A0

D8

XT2

HA HB 12V COM QP

WHITE
BLUE
RED

BLACK

YELLOW
GRAY

Vco2

78

COM

Error Content
MS self-inspection error

MS error

EEV malfunction

Outdoor unit fault
High water alarm

No address
Emergency stop

Remote off

CS

FAN

HHE interface

( Current range: 0-1A)
(

Code

XP1-5

CN50

CTON

HTON

4 5 6

Voltage range: 0-24V AC/DC)

“ +5V GND +12V ”
ONLY USED
FOR TESTING

Title

Indoor fan motor

FM
T0

Inlet air temperature sensor
Inlet of evaporator sensor

T2A

Outlet of evaporator sensor

T2B

T2

Middle of evaporator sensor

TA

Outlet air temperature sensor

Connectors

ON/OFF
SWITCH

DC motor
drive board

CN13

N=3

XS1-5

XT1-2
PUMP

ALARM

CN3

Code

Title

Connectors

Terminals
Pump motor

Water level switch

CS

Warning lamp

Electronic expansion valve

EEV

SVD Solenoid valve

NOTE:

1. Refer to manual for
communication wiring

2. Please use the 2-conductor
shielded twisted cable for
communication

FAN

FM

Display Board

XS4

T2B

XS3

T1/T0

XS2

T2

XS1

T2A

TA

XP4

XP3

XP2

XP1

EEV

XS5

RED

WHITE

CALB K

ACKLB

CN15

XP5

CN9

CN6

EULB

CN2{L_IN}

CN4{N_IN}

CN14

CN26

XT1

GND
Vco2

CN8

DER

L1 L2

CN11 CN5 CN52

CN12

CN30

EARTH

N=4

LACKB

G/Y

CN54

Main Board

CN3 CN18

ALARM

CN20

PUMP

POWER IN

NOTE:

Component in dash line is optional or field wiring

Typical wiring diagram. Refer to wiring diagram on the unit for actual wiring.

Figure 24. Identify T0 Sensor on Wiring Diagram

White plug

CN4

Black wire

18 AWG stranded shielded cable

CN24

SVD

Black wire

White wire

Figure 25. Typical Wiring Connections

Setting Blower Operation

Blower cycling can be congured to determine indoor

operation.

• Default operation is indoor unit blower OFF when the
indoor unit is in thermo OFF.

• Settings can be adjusted in the -3P controller and

cannot be congured at the indoor unit PCB.

Thermistor

Solder or connect with V0SNSR00P

• Consult the specic controller manual for detailed
blower setting information.

NOTE - Ensure the blower is set to the ON position when
using an electrical duct heater.

20

Mounting the Receiver/Display

The VOSB unit receiver/display must be eld-connected

and mounted. Mounting slots are available on the bottom
of the electrical control box.

1. Remove receiver from accessories package.

2. Insert the two xed plastic mounting brackets on the

back of the receiver (Figure 26) into the two slots on
the bottom of the electrical control box (Figure 25) and

slide to secure it.

3. Connect the 10-conductor wire of the receiver to the
unit control board. Pass the wire though the cable
path. See Figure 27.

Cable path

Slots

Electrical

control box

Figure 27. Receiver Mounting Location

Fixed plastic

mounting

brackets

10-conductor wire

(to unit control board)

Figure 26. Receiver

If it is necessary to position the receiver a distance from the
unit, use the optional extension cable kit V0CTRL93P-1

(cat # 14R84).

Network Address and Commissioning

After the system has been installed, each indoor
unit must be assigned an address as part of the
commissioning procedure.

21

Spot Check Instructions

Use the Spot Check Performance table below and the
Manual button on the unit receiver to view diagnostic
information the indoor unit.

Table 7. Spot Check Performance Identication Table

No. Content Recorded Value/Date

0 Normal display

1 Communication address of indoor unit

2 Indoor unit capacity (horsepower)

3 Network address of indoor unit

4 The actual setpoint temperature

5 The actual indoor temperature T1

6 The middle coil temperature T2

7 The coil inlet temperature T2A

8 The coil outlet temperature T2B

9 The discharge temperature TA

10 The actual superheat temperature

11

12 The actual subcool temperature

13 Error Code

14 Indoor software version

15 End (--)
This Spot Check Performance table is located on the unit service panel.

The diagnostic information can also be obtained using the wired remote controller.

The target subcool (heating) /superheat (cooling)

temperature

22

Troubleshooting

Digital Display

The indoor unit is equipped with a receiver that has a
digital display that provides an error code. Refer to the
table to view the error codes. The error code will replace
the temperature setting displayed on the receiver. If more
than one error has occurred, the codes will alternate so
that all codes are shown.

Figure 28. Receiver/Display

Make note of the code (E1, EE, etc.), then reset the

display by pressing the ON/OFF button on the unit
controller. Press the ON/OFF button a second time
to reapply power to unit. If the code is still displayed,
disconnect and restore power at the unit disconnect
switch or circuit breaker. If the problem was temporary,
the code will not reappear. If the error code reappears
after power has been broken and restored at the
disconnect switch or circuit breaker, call VRF Technical
Support 1-844-438-8731.

Table 8. Fault Code Display on Indoor Unit Receiver

Error Code Description

FE No address

E0 Mode conict

E1 Communication error between indoor and main outdoor unit

E2 T0 (Room temperature sensor) malfunction

E3 T2 (Middle of evaporator sensor) malfunction

E4 T2B (Outlet of evaporator sensor) malfunction

E5 T2A (Inlet of evaporator sensor) malfunction

E6 DC fan motor error

E7 EEPROM failure

Eb EXV malfunction

EC TA (Discharge temperature sensor) malfunction

Ed Outdoor unit Fault

EE High Water Alarm

A0 Emergency stop

D8 Remote o󰀨

U4 MS self-inspection error

F8 MS error

Table 9. Fault Code Display on Controller

Error Code Description

F0 Communication/Address error between indoor units and wired controller

F1 Communication/Wiring error between indoor units and wired controller

E2 Controller temperature sensor error

23

Technical Support

1-844-GET-VRF1

(1-844-438-8731)

[e-mail]

www.LennoxVRF.com

Download the app

from the Apple App Store or the Google Play store.

24