Lennox EL280UH070P24A, EL280UH070P36A, EL280UH070XP36A, EL280UH110P48C, EL280UH110XP60C Installation Instructions Manual
...
© 2017 Lennox Industries Inc.
OFF
ON
C
C
HI
I
I
LO
HI
UPFLOW
HORIZONTAL LEFT HORIZONTAL RIGHT
AIR FLOW
AIR FLOWAIR FLOW
Dallas, Texas USA
INSTALLATION
INSTRUCTIONS
EL280UH
ELITE ® SERIES GAS FURNACE
UPFL0W / HORIZONTAL AIR DISCHARGE
507333-01
11/2017
Supersedes 05/2016
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
This is a safety alert symbol and should never be
ignored. When you see this symbol on labels or in manuals, be alert to the potential for personal injury or death
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.
Contents
Unit Dimensions .............................................................2
EL280UH Gas Furnace ..................................................3
Shipping and Packing List ..............................................3
Safety Information ..........................................................3
Use of Furnace as Construction Heater .........................4
General ........................................................................... 4
Combustion, Dilution & Ventilation Air ............................5
Setting Equipment .........................................................8
Filters ............................................................................ 11
Duct System .................................................................12
Venting..........................................................................13
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 or
equivalent, service agency, or the gas supplier.
Gas Piping .................................................................... 21
Electrical ....................................................................... 23
Integrated Control ......................................................... 28
Unit Start Up ................................................................. 29
Gas Pressure Adjustment ............................................. 30
Proper Combustion.......................................................31
High Altitude .................................................................31
Other Unit Adjustments................................................. 32
Sequence of Operation.................................................32
Service..........................................................................34
Repair Parts List ........................................................... 36
Start-Up & Performance Checl List ..............................37
Page 1
Unit Dimensions - inches (mm)
AIR FLOW
23
(584)
(19)
3/4
(19)
1
Bottom Return
Air Opening
GAS PIPING INLET
(Either Side)
Side Return
Air Opening
(Either Side)
1
Bottom Return
Air Opening
FLUE OUTLET
(Top)
ELECTRICAL INLET
(Either Side)
SUPPLY AIR
OPENING
FRONT VIEW SIDE VIEW
TOP VIEW
A
B
9/16 (14)
C
D
3/4
27-3/4
(705)
19-7/16
(494)
23-1/2
(597)
1-1/2
(38)
9-1/8 (232) Right
8-5/8 (219) Left
5-3/8 (137) Right
2-3/16 (56) Left
33
(838)
3-1/8 (79)
1-15/16 (49)
14
(356)
9/16
(14)
3 (76) Right
7 (178) Left
2
FLUE OUTLET
(Either Side)
3
OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)
16
(406)
14-3/4
(375)
3
OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)
2
Flue outlet may be horizontal but furnace must be
vented vertically
3
Optional External Side Return Air Filter Kit is not for use
with the optional Return Air Base.
1
NOTE - 60C and 60D size units that require second stage
air volumes over 1800 cfm (850 L/s) must have one
of the following:
1. Single side return air with transition, to accommodate
20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air
filter. Required to maintain proper air velocity.
2. Single side return air with optional Return Air Base
3. Bottom return air.
4. Return air from both sides.
5. Bottom and
one side return air.
See Blower Performance Ta bles for additional information.
3-1/4 (83)
5/8
(16)
1
3-1/4
(83)
23-3/4
(603)
25
(635)
1-1/2 (38)
Front Panel
EL280UH Model
070P24A
070(X)P36A
090P36A
090(X)P48B
110P48C
110(X)P60C
14-1/2 368 13-3/8 340 13 330 4-3/4 121
17-1/2 446 16-3/8 416 16 406 6-1/4 159
A B C D
in mm in mm in mm in mm
21 533 19-7/8 504 19-1/2 495 8 203
135P60D 24-1/2 622 23-3/8 546 23 584 9-3/4 248
Page 2
EL280UH Gas Furnace
The EL280UH unit is shipped ready for installation in the
upow or horizontal right position (for horizontal left position the combustion air pressure switch must be moved).
The furnace is shipped with the bottom panel in place.
The bottom panel must be removed if the unit is to be in-
stalled in a horizontal application. The panel may also be
removed in upow applications.
Shipping and Packing List
Package 1 of 1 contains
1 - Assembled EL280UH unit
1 - Bag assembly containing the following:
2 - Screws
1 - Snap bushing
1 - Snap plug
1 - Wire tie
1 -Vent warning label
1 - Owner’s manual and warranty card
The following items may be ordered separately:
1 - Thermostat
1 - Suspension kit (for horizontal installations)
1 - Propane/LP changeover kit
1 - Return air base
1 - High altitude kit
1 - Side lter kit
Check equipment for shipping damage. If you nd any
damage, immediately contact the last carrier.
Safety Information
DANGER
Danger of explosion.
There are circumstances in which odorant used with LP/
propane gas can lose its scent. In case of a leak, LP/
propane gas will settle close to the oor and may be
difcult to smell. An LP/propane leak detector should be
installed in all LP applications.
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 installer (or
equivalent), service agency or the gas supplier.
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.
Certications
EL280UH units are CSA International certied to ANSI
Z21.47.
In the USA, installation of gas furnaces must conform with
local building codes. In the absence of local codes, units
must be installed according to the current National Fuel
Gas Code (ANSI-Z223.1). The National Fuel Gas Code is
available from the following address:
American National Standards Institute, Inc.
11 West 42nd Street
New York, NY 10036
Clearances
Adequate clearance must be made around the air openings into the vestibule area. In order to ensure proper unit
operation, combustion and ventilation air supply must
be provided according to the current National Fuel Gas
Code. Vent installations must be consistent with the venting tables (in this instruction) and applicable provisions of
local building codes.
This furnace is CSA International certied for installation
clearances to combustible material as listed on the unit
nameplate and in the tables in gures 7 and 11. Accessibility and service clearances must take precedence over
re protection clearances.
NOTE - For installation on combustible oors, the furnace
shall not be installed directly on carpeting, tile, or other
combustible material other than wood ooring.
Installed Locations
For installation in a residential garage, the furnace must
be installed so that the burner(s) and the ignition source
are located no less than 18 inches (457 mm) above the
oor. The furnace must be located or protected to avoid
physical damage by vehicles. When a furnace is installed
in a public garage, hangar, or other building that has a
hazardous atmosphere, the furnace must be installed according to recommended good practice requirements and
current National Fuel Gas Code.
Temperature Rise
NOTE - Furnace must be adjusted to obtain a temperature rise within the range specied on the unit nameplate.
Failure to do so may cause erratic limit operation and may
result in premature heat exchanger failure.
This EL280UH furnace must be installed so that its electrical components are protected from water.
Page 3
Installed in Combination with a Cooling Coil
When this furnace is used with cooling units, it shall be installed in parallel with, or on the upstream side of, cooling
units to avoid condensation in the heating compartment.
See gure 1. With a parallel ow arrangement, a damper
(or other means to control the ow of air) must adequately
prevent chilled air from entering the furnace. If the damper
is manually operated, it must be equipped to prevent operation of either the heating or the cooling unit, unless it is
in the full HEAT or COOL setting. See gure 1.
Heating Unit Installed Parallell to Air Handler Unit
Dampers
(open during heating operation only)
Gas Unit
Air Handler Unit
Dampers
(open during cooling operation only)
Use of Furnace as Construction Heater
Lennox does not recommend the use of EL280UH units
as a construction heater during any phase of construction. Very low return air temperatures, harmful vapors and
operation of the unit with clogged or misplaced lters will
damage the unit.
EL280UH units may be used for heating of buildings or
structures under construction, if the following conditions
are met:
• The vent system must be permanently installed per
these installation instructions.
• A room thermostat must control the furnace. The
use of xed jumpers that will provide continuous
heating is not allowed.
• The return air duct must be provided and sealed
to the furnace.
• Return air temperature range between 60°F (16°C)
and 80°F (27°C) must be maintained.
• Air lters must be installed in the system and must
be maintained during construction.
Heating Unit Installed Upstream of Cooling Unit
Gas Unit
Evaporator
FIGURE 1
When installed, this furnace must be electrically grounded
according to local codes. In addition, in the United States,
installation must conform with the current National Electric Code, ANSI/NFPA No. 70. The National Electric Code
(ANSI/NFPA No. 70) is available from the following address:
National Fire Protection Association
1 Battery March Park
Quincy, MA 02269
NOTE - This furnace is designed for a minimum continuous return air temperature of 60°F (16°C) or an intermittent
operation down to 55°F (13°C) dry bulb for cases where a
night setback thermostat is used. Return air temperature
must not exceed 85°F (29°C) dry bulb.
The EL280UH furnace may be installed in alcoves, closets, attics, basements, garages, crawl spaces and utility
rooms in the upow or horizontal position.
This furnace design has not been CSA International
certied for installation in mobile homes, recreational
vehicles, or outdoors.
• Air lters must be replaced upon construction com-
pletion.
• The input rate and temperature rise must be set
per the furnace rating plate.
• One hundred percent (100%) outdoor air must be
provided for combustion air requirements during
construction. Temporary ducting may supply outdoor air to the furnace. Do not connect duct direct-
ly to the furnace. Size the temporary duct following
these instructions in section for Combustion, Dilu-
tion and Ventilation Air in a conned space with air
from outside.
• The furnace heat exchanger, components, duct
system, air lters and evaporator coils must be
thoroughly cleaned following nal construction
clean-up.
• All furnace operating conditions (including ignition,
input rate, temperature rise and venting) must be
veried according to these installation instructions.
General
These instructions are intended as a general guide and
do not supersede local codes in any way. Consult authorities having jurisdiction before installation.
In addition to the requirements outlined previously, the
following general recommendations must be considered
when installing a EL280UH furnace
• Place the furnace as close to the center of the air
distribution system as possible. The furnace should
also be located close to the chimney or vent termination point.
Page 4
• Do not install the furnace where drafts might blow
directly into it. This could cause improper combustion and unsafe operation.
• Do not block the furnace combustion air openings
with clothing, boxes, doors, etc. Air is needed for
proper combustion and safe unit operation.
• When the furnace is installed in an attic or other
insulated space, keep insulation away from the furnace.
• Please consult the manufacturer of your evaporator
coil for their recommendations on distance required
between the heat exchanger and their drain pan.
Adequate space must be provided between the
drain pan and the furnace heat exchanger.
NOTE - The Commonwealth of Massachusetts stipulates these additional requirements:
• Gas furnaces shall be installed by a licensed
plumber or tter only.
• The gas cock must be “T handle” type.
• When a furnace is installed in an attic, the pas-
sageway to and service area surrounding the
equipment shall be oored.
WARNING
This product contains a chemical known to the State
of California to cause cancer, birth defects, or other
reproductive harm.
Combustion, Dilution & Ventilation Air
In the past, there was no problem in bringing in sufcient
outdoor air for combustion. Inltration provided all the air
that was needed. In today’s homes, tight construction
practices make it necessary to bring in air from outside for
combustion. Take into account that exhaust fans, appli-
ance vents, chimneys, and replaces force additional air
that could be used for combustion out of the house. Unless outside air is brought into the house for combustion,
negative pressure (outside pressure is greater than inside
pressure) will build to the point that a downdraft can occur in the furnace vent pipe or chimney. As a result, combustion gases enter the living space creating a potentially
dangerous situation.
In the absence of local codes concerning air for combustion and ventilation, use the guidelines and procedures in
this section to install EL280UH furnaces to ensure efcient and safe operation. You must consider combustion
air needs and requirements for exhaust vents and gas
piping. A portion of this information has been reprinted
with permission from the National Fuel Gas Code (ANSI-Z223.1). This reprinted material is not the complete
and ofcial position of the ANSI on the referenced subject,
which is represented only by the standard in its entirety.
CAUTION
Insufcient combustion air can cause headaches,
nausea, dizziness or asphyxiation. It will also cause
excess water in the heat exchanger resulting in rusting
and premature heat exchanger failure. Excessive
exposure to contaminated combustion air will result
in safety and performance related problems. Avoid
exposure to the following substances in the combustion
air supply:
Permanent wave solutions
Chlorinated waxes and cleaners
Chlorine base swimming pool chemicals
Water softening chemicals
De-icing salts or chemicals
Carbon tetrachloride
Halogen type refrigerants
Cleaning solvents (such as perchloroethylene)
Printing inks, paint removers, varnishes, etc.
Hydrochloric acid
Cements and glues
Antistatic fabric softeners for clothes dryers
Masonry acid washing materials
All gas-red appliances require air for the combustion
process. If sufcient combustion air is not available, the
furnace or other appliances will operate inefciently and
unsafely. Enough air must be provided to meet the needs
of all fuel-burning appliances and appliances such as exhaust fans which force air out of the house. When replaces, exhaust fans, or clothes dryers are used at the
same time as the furnace, much more air is necessary
to ensure proper combustion and to prevent a downdraft.
Insufcient air causes incomplete combustion which can
result in carbon monoxide.
In addition to providing combustion air, fresh outdoor air
dilutes contaminants in the indoor air. These contaminants
may include bleaches, adhesives, detergents, solvents
and other contaminants which can corrode furnace components.
The requirements for providing air for combustion and
ventilation depend largely on whether the furnace is in-
stalled in an unconned or a conned space.
Unconned Space
An unconned space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the combined input rating of all appliances installed in that space.
This space also includes adjacent rooms which are not
separated by a door. Though an area may appear to be
un conned, it might be necessary to bring in outdoor air
for combustion if the structure does not provide enough air
by inltration. If the furnace is located in a building of tight
construction with weather stripping and caulking around
the windows and doors, follow the procedures in the air
from outside section.
Page 5
Conned Space
Air from Inside
A conned space is an area with a volume less than 50
cubic feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of
the combined input rating of all appliances installed in that
space. This denition includes furnace closets or small
equipment rooms.
When the furnace is installed so that supply ducts carry
air circulated by the furnace to areas outside the space
containing the furnace, the return air must be handled by
ducts which are sealed to the furnace casing and which
terminate outside the space containing the furnace. This
is especially important when the furnace is mounted on
a platform in a conned space such as a closet or small
equipment room.
Even a small leak around the base of the unit at the plat-
form or at the return air duct connection can cause a potentially dangerous negative pressure condition. Air for
combustion and ventilation can be brought into the con-
ned space either from inside the building or from outside
.
EQUIPMENT IN CONFINED
CHIMNEY
OR GAS
VENT
FURNACE
AIR FLOW
NOTE - Each opening shall have a free area of at least one square
inch (645 mm
ing of all equipment in the enclosure, but not less than 100 square
inches (64516 mm
2
2
).
SPACE ALL AIR FROM INSIDE
WATER
HEATER
OPENINGS
(To Adjacent
Room)
If the conned space that houses the furnace adjoins a
space categorized as unconned, air can be brought in by
providing two permanent openings between the two spaces. Each opening must have a minimum free area of 1
square inch (645 mm2) per 1,000 Btu (.29 kW) per hour of
total input rating of all gas-red equipment in the conned
space. Each opening must be at least 100 square inches
(64516 mm2). One opening shall be within 12 inches (305
mm) of the top of the enclosure and one opening within 12
inches (305 mm) of the bottom. See gure 2.
Air from Outside
If air from outside is brought in for combustion and ventilation, the conned space must have two permanent openings. One opening shall be within 12 inches (305 mm) of
the top of the enclosure and one opening within 12 inches
(305 mm) of the bottom. These openings must communicate directly or by ducts with the outdoors or spaces (crawl
or attic) that freely communicate with the outdoors or indirectly through vertical ducts. Each opening shall have a
minimum free area of 1 square inch (645 mm2) per 4,000
Btu (1.17 kW) per hour of total input rating of all equipment
in the enclosure. See gures 3 and 4. When communicating with the outdoors through horizontal ducts, each
opening shall have a minimum free area of 1 square inch
(645 mm2) per 2,000 Btu (.56 kW) per total input rating of
all equipment in the enclosure. See gure 5.
When ducts are used, they shall be of the same cross-sectional area as the free area of the openings to which they
connect. The minimum dimension of rectangular air ducts
shall be no less than 3 inches (75 mm). In calculating free
area, the blocking effect of louvers, grilles, or screens
must be considered. If the design and free area of protec-
tive covering is not known for calculating the size opening
required, it may be assumed that wood louvers will have
20 to 25 percent free area and metal louvers and grilles
will have 60 to 75 percent free area. Louvers and grilles
must be xed in the open position or interlocked with the
equipment so that they are opened automatically during
equipment operation.
FIGURE 2
Page 6
CHIMNEY OR
EQUIPMENT IN
CONFINED SPACE
ALL AIR FROM
OUTSIDE
OUTLET AIR
INLET AIR
WATER
HEATER
CHIMNEY
OR GAS
VENT
NOTE - Each air duct opening shall have a free area of at least
one square inch (645 mm
2
) per 2,000 Btu (.59 kW) per hour of
the total input rating of all equipment in the enclosure. If the
equipment room is located against an outside wall and the air
openings
ing shall have a free area of at least one square inch (645 mm
2
)
per 4,000 Btu (1.17 kW) per hour of the total input rating of all
other equipment in the enclosure.
FURNACE
AIR FLOW
GAS VENT
FURNACE
(Inlet Air from Crawlspace and Outlet Air to Ventilated Attic)
VENTILATION LOUVERS
(Each end of attic)
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
OUTLET
AIR
WATER
HEATER
CHIMNEY
OR GAS
VENT
FURNACE
VENTILATION
LOUVERS
(For unheated crawl space)
AIR FLOW
NOTE-The inlet and outlet air openings shall each have a free area of at least one square inch (645
2
mm
) per 4,000 Btu (1.17 kW) per hour of the total input rating of all equipment in the enclosure.
INLET
AIR
FIGURE 3
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
(All Air Through Ventilated Attic)
VENTILATION LOUVERS
(Each end of attic)
OUTLET
AIR
INLET AIR
(Ends 12 in.
above bottom)
WATER
HEATER
AIR FLOW
NOTE-The inlet and outlet air openings shall each have a
free area of at least one square inch (645 mm
ment in the enclosure.
FIGURE 4
2
) per 4,000
FIGURE 5
Page 7
Setting Equipment
WARNING
Do not install the furnace on its front or its back. Do not
connect the return air ducts to the back of the furnace.
Doing so will adversely affect the operation of the safety
control devices, which could result in personal injury or
death.
The EL280UH gas furnace can be installed as shipped in
either the upow position or the horizontal position. Select a location that allows for the required clearances that
are listed on the unit nameplate. Also consider gas supply
connections, electrical supply, vent connection, and installation and service clearances [24 inches (610 mm) at unit
front]. The unit must be level.
NOTE - Units with 1/3HP and 1/2HP blower motors are
equipped with three exible legs and one shipping leg. See
gure 6. In some units with 1/3HP blower motor, the shipping leg is exible with rubber mounting grommets similar
to the other three mounting legs and require no modication. The rest of the units with 1/3HP and 1/2HP blower
motors (these blower motor housings will be tagged) have
a rigid shipping leg equipped with a shipping bolt and at
white plastic washer. The bolt and washer must be re-
moved before the furnace is placed into operation. After the bolt and washer have been removed, the rigid leg
will not touch the blower housing.
Blower motor with three exible legs and one
rigid shipping leg. Blower motor housings
will be tagged for shipping bolt removal
RIGID LEG
(Remove shipping bolt
and washer)
Upow Applications
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or
alcove installations are shown in gure 7.
Upflow Application Installation Clearances
Top
Left Side
AIR FLOW
Bottom
Type of Vent
Connector
Top 1 in. (25 mm) 1 in. (25 mm)
*Front 2-1/4 in. (57 mm)** 2-1/4 in. (57 mm)
Back 0 0
Sides 0† 0
Vent 6 in. (152 mm) 1 in. (25 mm)
Floor 0‡ 0‡
*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
** 3-1/4 in. if single wall vent pipe is used.
‡For installation on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other
than wood flooring.
†Left side requires 3 inches if a single wall vent is used on 14-1/2
inch
nets.
Type C Type B1
Right Side
FIGURE 6
FIGURE 7
Page 8
Return Air -- Upow Applications
Return air can be brought in through the bottom or either
side of the furnace installed in an upow application. If the
furnace is installed on a platform with bottom return, make
an airtight seal between the bottom of the furnace and the
platform to ensure that the furnace operates properly and
safely. The furnace is equipped with a removable bottom
panel to facilitate installation.
Markings are provided on both sides of the furnace cabinet for installations that require side return air. Cut the
furnace cabinet at the maximum dimensions shown on
page 2.
NOTE - 60C and 60D units that require air volumes
over 1800 cfm (850 L/s) must have one of the following:
1 - Single side return air with transition to accommodate
20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air
lter. (Required to maintain proper air velocity.) See
gure 8.
2 - 2 - Single side return air with optional return
airbase. See gure 9.
3 - 3 - Bottom return air.
4 - 4 - Return air from both sides.
5 - 5 - Bottom and one side return air.
Refer to Engineering Handbook for additional information.
Single Side Return Air
(with transition and filter)
20” X 25” X 1”
(508mm X635mm X 25mm)
Cleanable Filter
Return Air
Plenum
AIR FLOW
Transition
FIGURE 8
Optional Return Air Base
(Upflow Applications Only -- For use with A, B, C and D cabinets)
FURNACE
FRONT
IF BASE
IS USED
WITHOUT
INDOOR AIR
AIR FLOW
14−1/2” (368) A Width (65W75)
17−1/2” (446) B Width (50W98)
21”− (533) C Width (50W99)
24−1/2”− (622) D Width (51W00)
NOTE- Optional Side Return Air Filter Kits are not for use with Optional Return Air Base.
1
Both the unit return air opening and the base return air opening must be covered by a single plenum or IAQ cabinet.
Minimum unit side return air opening dimensions for units requiring 1800 cfm or more of air (W x H): 23 x 11 in. (584 x 279 mm).
The opening can be cut as needed to accommodate plenum or IAQ cabinet while maintaining dimensions shown.
Side return air openings must be cut in the field. There are cutting guides stenciled on the cabinet for the side return air
opening. The size of the opening must not extend beyond the markings on the furnace cabinet.
2
To minimize pressure drop, the largest opening height possible (up to 14 inches) is preferred.
OPTIONAL
RETURN AIR BASE
IAQ CABINET,
A SINGLE
RETURN AIR
PLENUM
MUST
COVER BOTH
UNIT AND
RETURN
AIR BASE
OPENINGS
3−1/4
(83)
7−1/4
(184)
1
23 (584)
Overall
(Maximum)
1
Unit side return air
Opening
5−5/8
(143)
SIDE RETURN
AIR OPENINGS
(Either Side)
26−7/8
(683)
SIDE VIEW
23
(584)
1
Minimum
11 (279)
2
Maximum
14 (356)
1
22−7/16
(570)
Overall
(Maximum)
3/4
(19)
FIGURE 9
Page 9
Removing the Bottom Panel
Removing the Bottom Panel
Hori
zontal Application
Horizontal Applications
Remove the two screws that secure the bottom cap to the
furnace. Pivot the bottom cap down to release the bottom
panel. Once the bottom panel has been removed, reinstall
the bottom cap. See gure 10.
Screw
Bottom Cap
The EL280UH furnace can be installed in horizontal applications. Order horizontal suspension kit (51W10) from
Lennox, or use equivalent suspension method. Allow for
clearances to combustible materials as indicated on the
unit nameplate. Minimum clearances for closet or alcove
installations are shown in gure 11.
This furnace may be installed in either an attic or a crawlspace. Either suspend the furnace from roof rafters or
oor joists, as shown in gure 12, or install the furnace on
a platform, as shown in gure 13.
Typical Horizontal Application
Unit Suspended in Attic or Crawlspace
Bracket
Metal Strap
Bottom Cap
3/16 inch
Air Flow
Bottom Panel
FIGURE 10
Installation Clearances
Left
End
Vent Connector
Type
Top 0 0
*Front 2-1/4 in. (57 mm)** 2-14 in. (57 mm)
Back 0 0
Ends 2 in. (51 mm) 2 in. (51 mm)
Vent 6 in. (152 mm) 1 in. (25 mm)
Floor 0‡ 0‡
*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
** 3-1/4 in. if single wall vent pipe is used.
‡For installations on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other
than wood flooring.
Top
Right
AIR FLOW
End
Bottom
Type C Type B1
FIGURE 12
NOTE - Heavy-gauge perforated sheet metal straps may
be used to suspend the unit from roof rafters or ceiling
oists. When straps are used to suspend the unit in this
way, support must be provided for both the ends. The
straps must not interfere with the plenum or exhaust piping installation. Cooling coils and supply and return air
plenums must be supported separately.
NOTE - When the furnace is installed on a platform in a
crawlspace, it must be elevated enough to avoid water
damage and to allow the evaporator coil to drain
. Return Air -- Horizontal Applications
Return air must be brought in through the end of a fur-
nace installed in a horizontal application. The furnace is
equipped with a removable bottom panel to facilitate in-
stallation. See gure 10.
CAUTION
If this unit is being installed in a space serviced by an
exhaust fan, power exhaust fan, or other device which
may create a negative pressure in the space, take care
when sizing the inlet air opening. The inlet air opening
must be sized to accommodate the maximum volume
of exhausted air as well as the maximum volume of
combustion air required for all gas appliances serviced
by this space.
FIGURE 11
Page 10
Horizontal Application
Unit Installed on Platform
Line contact is permissible
See the unit nameplate for
clearances.
GAS
ENTRY
SERVICE PLATFORM
VENT
PIPE
FIGURE 13
WARNING
Improper installation of the furnace can result in personal
injury or death. Combustion and ue products must
never be allowed to enter the return air system or the
living space. Use screws and joint tape to seal the return
air system to the furnace.
In platform installations with bottom return air, the furnace
should be sealed airtight to the return air plenum. A
door must never be used as a portion of the return air
duct system. The base must provide a stable support
and an airtight seal to the furnace. Allow absolutely no
sagging, cracks, gaps, etc. The return and supply air
duct systems must never be connected to or from other
heating devices such as a replace or stove, etc. Fire,
explosion, carbon monoxide poisoning, personal injury
and/or property damage could result.
WARNING
The blower access panel must be securely in place when
the blower and burners are operating. Gas fumes, which
could contain carbon monoxide, can be drawn into living
space resulting in personal injury or death.
Filters
This unit is not equipped with a lter or rack. A eld-provided high-velocity lter is required for the unit to operate
properly. Table 1 lists recommended lter sizes.
A lter must be in place any time the unit is operating.
IMPORTANT
If a highefciency lter is being installed as part of this
system to ensure better indoor air quality, the lter must
be properly sized. Highefciency lters have a higher
static pressure drop than standardefciency glass/foam
lters. If the pressure drop is too great, system capacity
and performance may be reduced. The pressure drop
may also cause the limit to trip more frequently during
the winter and the indoor coil to freeze in the summer,
resulting in an increase in the number of service calls.
Before using any lter with this system, check the
specications provided by the lter manufacturer against
the data given in the appropriate Lennox Product
Specications bulletin. Additional information is provided
in Service and Application Note ACC002 (August 2000).
TABLE 1
Furnace Cabinet
Width
14-1/2” 16 X 25 X 1 (1) 14 X 25 X 1 (1)
17-1/2” 16 X 25 X 1 (1) 16 X 25 X 1 (1)
21” 16 X 25 X 1 (1) 20 X 25 X 1 (1)
24-1/2” 16 X 25 X 1 (2) 24 X 25 X 1 (1)
Side Return Bottom Return
Filter Size
Page 11
Duct
Use industry-approved standards (such as those published by Air Conditioning Contractors of America or American Society of Heating, Refrigerating and Air Condition-
ing Engineers) to size and install the supply and return
air duct system. This will result in a quiet and low-static
system that has uniform air distribution.
NOTE - Do not operate the furnace in the heating mode
with an external static pressure that exceeds 0.5 inches
w.c. Higher external static pressures may cause erratic
limit operation.
Supply Air Plenum
If the furnace is installed without a cooling coil, a removable access panel must be installed in the supply air duct.
The access panel should be large enough to permit in-
spection (either by smoke or reected light) of the heat
exchanger for leaks after the furnace is installed. The
furnace access panel must always be in place when the
furnace is operating and it must not allow leaks into the
supply air duct system.
Return Air Plenum
NOTE - Return air must not be drawn from a roomwhere
this furnace, or any other gas-fueled appliance (i.e., water
heater), or carbon monoxide producing device (i.e., wood
replace) is installed.
When return air is drawn from a room, a negative pressure
is created in the room. If a gas appliance is operating in
a room with negative pressure, the ue products can be
pulled back down the vent pipe and into the room. This
reverse ow of the ue gas may result in incomplete combustion and the formation of carbon monoxide gas. This
toxic gas might then be distributed throughout the house
by the furnace duct system.
In upow applications, the return air can be brought in
through the bottom or either side of the furnace. If a furnace with bottom return air is installed on a platform, make
an airtight seal between the bottom of the furnace and
the platform to ensure that the unit operates properly and
safely. Use berglass sealing strips, caulking, or equivalent sealing method between the plenum and the furnace
cabinet to ensure a tight seal. If a lter is installed, size the
return air duct to t the lter frame.
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