Lennox VOSB Series User manual

1
INSTALLATION
INSTRUCTION
VRF SYSTEMS -- Indoor Units
507896-02
06/2019
THIS MANUAL MUST BE LEFT WITH THE OWNER
FOR FUTURE REFERENCE
Shipping and Packing List
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.
VOSB Outside Air Ducted Units
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
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
WARNING
Improper installation, adjustment, alteration, ser-
vice or maintenance can cause property damage,
personal injury or loss of life.
Installation and service must be performed by a li-
censed professional HVAC installer, service agency
or the gas supplier.
Failure to follow safety warnings and these instruc-
tions exactly could result in property damage, dan-
gerous operation, serious injury, or death.
Any additions, changes, or conversions required in
order for the appliance to satisfactorily meet the ap-
plication needs must be made by a licensed profes-
sional 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 sys-
tems 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.
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.
©2019 Lennox Industries Inc. Dallas, Texas, USA
VRF

2
Model Number Identication
Safety Requirements
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.
WARNING
!
V OS B 036 H4 - 3 P
Brand/Family
V = Variable Refrigerant Flow (VRF)
Unit Type
OS = Outside Air Ducted Indoor Models
Major Design Sequence
B = 2nd Generation
Cooling E󰀩ciency
H = High E󰀩ciency
Refrigerant Type
4 = R-410A
Controls Protocol
3 = Phase 3
Voltage
P = 208/230V-1 phase-60hz
Nominal Cooling Capacity - Btuh
036 = 36,000 Btuh
048 = 48,000 Btuh
054 = 54,000 Btuh
072 = 72,000 Btuh
096 = 96,000 Btuh
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.
NOTICE
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.
System Piping
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”.

3
Unit Dimensions - Inches (mm)
TOP VIEW
SECTION A-A
BRACKETS FOR
SUSPENDING (4)
AUXILIARY
DRAIN
CONNECTION
(Either Side)
SECTION C-C
SECTION B-B
SECTION D-D
PRIMARY
DRAIN
CONNECTION
(Either Side)
AIR FLOW
3-5/8 (92)
45-1/4 (1149)
29-1/8
(740) 25-1/8
(638) 15-5/8
(397) GAS PIPE
LIQUID PIPE
ELECTRICAL
CONTROL
BOX
7-1/4
(184)
5-3/8
(137)
5-3/8
(137)
36-5/8 (930)
(Supply Air Duct Opening)
9-3/4
(248) 16-1/2
(419)
47-1/2 (1207)
51-1/4 (1302)
LEFT SIDE VIEW
SECTION D-D
AIR FLOW
RETURN
AIR DUCT
OPENING
SUPPLY
AIR DUCT
OPENING
RIGHT SIDE VIEW
LIQUID PIPE
GAS PIPE
AIR FLOW
SECTION B-B
SUPPLY
AIR DUCT
OPENING
AUXILIARY
DRAIN
CONNECTION
(Either Side)
PRIMARY
DRAIN
CONNECTION
(Either Side)
RETURN
AIR DUCT
OPENING
SECTION C-C
SUPPLY AIR SIDE
TOP OF UNIT
RETURN AIR VIEW
SECTION A-A
TOP OF UNIT
2-1/2 (64)
(Bottom of Unit)
(Bottom of Unit)
29-1/8 (740)
23-7/8 (606)
7-1/2
(191) 4-7/8
(124)
1 (25)
1-5/8 (41)
(Supply Air
Duct Opening)
PRIMARY
DRAIN
CONNECTION
(Either Side)
AUXILIARY
DRAIN
CONNECTION
(Either Side)
42-1/4 (1073)
(Return Air Duct Opening)
13-3/8 (340)
(Return Air
Duct
Opening)
RETURN AIR
DUCT OPENING
FACTORY-
MOUNTED
LIFT PUMP
VOSB036, 048, 054

4
Unit Dimensions - Inches (mm)
TOP VIEW
SECTION A-A
BRACKETS FOR
SUSPENDING (4)
SECTION C-C
SECTION B-B
SECTION D-D
DRAIN
CONNECTION
AIR FLOW
LIQUID
PIPE
GAS
PIPE
ELECTRICAL
CONTROL
BOX
RIGHT SIDE VIEW
GAS PIPE
LIQUID PIPE
AIR FLOW
SECTION B-B
SUPPLY
AIR DUCT
OPENING
RETURN
AIR DUCT
OPENING
6
(152) 36-7/8 (937)
(Supply Air Duct Opening)
2 (51)
14-7/8
(378)
38-1/4
(972) 34-5/8
(879)
19-7/8
(505)
2-3/4
(70)
3
(76)
44-1/8(1120)
13-1/2
(343)
38-1/4 (972)
32-7/8 (835)
56-3/4 (1441)
50 (1270)
12-1/8
(308)
5-1/2
(140)
LEFT SIDE VIEW
SECTION D-D
AIR FLOW
RETURN
AIR DUCT
OPENING
SUPPLY
AIR DUCT
OPENING
20-7/8
(530)
RETURN AIR VIEW
SECTION A-A
TOP OF UNIT
(Bottom of Unit)
(Supply Air
Duct Opening)
RETURN AIR
DUCT OPENING
SECTION C-C
SUPPLY AIR SIDE
TOP OF UNIT
(Bottom of Unit)
VOSB072, 096

5
Clearances
Refer to Figure 1 for minimum clearance requirements.
20” (508 mm) Minimum Service Clearance
24” (610 mm)
Air
Flow
24” (610 mm)
Minimum
Service
Clearance
TOP VIEW
DUCTED
UNIT
FRONT VIEW
24” (610 mm) Minimum Clearance
Ceiling
Wall
Wall
1” (25 mm) Minimum Clearance
CeilingSuspended
Minimum
Service
Clearance
Figure 1. Minimum Installation Clearances
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.

6
Unit Placement
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
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.

7
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.
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.
Figure 2. Suspending Methods
ANGLE IRON
BOLTED IN
PLACE ACROSS
WOODEN JOISTS
WOODEN JOIST
⅜” THREADED
ROD
ANGLE IRON
ACROSS
WOODEN JOISTS
ANCHOR
CONCRETE CEILING
USING ANCHORS
⅜” THREADED
ROD
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.
LEVELING
NUT
⅜”THREADED
ROD
SUSPENSION
BRACKET
FIELD-PROVIDED
ISOLATION GROMMET
WASHER
INDOOR UNIT
LEVELING
NUT
⅜”THREADED
ROD
SUSPENSION
BRACKET
SUPPLY AIR
OPENING
FRONT VIEW
When unit is
level, tighten
nut to secure
position of
suspension
bracket on
rod.
Figure 3. Suspension Hardware
Figure 4. Isolation Grommet

8
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 dimen-
sions.
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.
Figure 6. Loosen Filter Retaining Bracket
Filter
removal
tab
Figure 7. Slide Out Filter
Filter removal tab
3. Reverse these steps to reinstall the lter. Be sure
to reinstall the receiver if it was detached during the
lter removal.
Figure 8. Filter Partially Removed
Indoor Unit Model Filter Dimensions Each Section of Filter Dimensions
VOSB036, 048, 054 42-5/8 x 13-1/4 x 3/8 in.
1083 x 336 x 10 mm
14-1/8 x 13-1/4 x 3/8 in.
359 x 336 x 10 mm
VOSB072, 096 44-1/2 x 13-1/4 x 3/8 in.
1130 x 336 x 10 mm
14-3/4 x 13-1/4 x 3/8 in.
375 x 336 x 10 mm
Table 1. Filter Dimensions
Hook & Loop Strap
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.
External Static Pressure

9
Refrigerant Piping Connections
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.
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
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.
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.
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.
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.

10
Table 2. Refrigerant Piping Connections
• 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.
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.
Indoor Unit Size
(Btuh) Liquid Line Vapor Line
36,000
48,000
54,000
3/8” 5/8”
72,000
96,000 3/8” 7/8”