Lennox EL280UH User Manual
INSTALLATION
E 2012 Lennox Industries Inc.
Dallas, Texas, USA
INSTRUCTIONS
EL280UH
ELITE® SERIES GAS FURNACE
UPFLOW / HORIZONTAL AIR DISCHARGE
506894−01
02/2012
Litho U.S.A.
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.
WARNING
UPFLOW
AIR FLOW
AIR FLOWAIR FLOW
HORIZONTAL LEFT HORIZONTAL RIGHT
Table of Contents
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Arrangement 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EL280UH Gas Furnace 4. . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 4. . . . . . . . . . . . . . . . . . . . . . . .
Safety Information 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use of Furnace as a Construction Heater 5. . . . . . . . . . .
General 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution & Ventilation Air 6. . . . . . . . . . . . . .
Setting Equipment 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filters 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Venting 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
Gas Piping 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Integrated Control 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start−Up 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Adjustment 33. . . . . . . . . . . . . . . . . . . . . . . .
High Altitude 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Proper Combustion 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments 35. . . . . . . . . . . . . . . . . . . . . . . . . .
Sequence of Operation 36. . . . . . . . . . . . . . . . . . . . . . . . . .
Blower Performance Data 37. . . . . . . . . . . . . . . . . . . . . . . .
Service 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Planned Service 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Integrated Control Diagnostic Codes 43. . . . . . . . . . . . . . .
Troubleshooting 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
02/12
*2P0212*
Page 1
506894−01
*P506894-01*
Unit Dimensions − inches (mm)
1
NOTE − 60C and 60D size 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
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 TTables for additional information.
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.
A
B
9/16 (14)
3
OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)
33
(838)
D
FLUE OUTLET
(Top)
3
OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)
1−1/2 (38)
Front Panel
3 (76) Right
7 (178) Left
9−1/8 (232) Right
8−5/8 (219) Left
5−3/8 (137) Right
2−3/4 (70) Left
3−1/8 (79)
TOP VIEW
3−1/4 (83)
2
FLUE OUTLET
(Either Side)
GAS PIPING INLET
(Either Side)
ELECTRICAL INLET
(Either Side)
SUPPLY AIR
OPENING
23−3/4
(603)
25
(635)
27−3/4
(705)
19−7/16
(494)
9/16
(14)
3/4
(19)
EL280UH Model No.
070P24A
070(X)P36A
090P36B
090(X)P48B
110P48C
110(X)P60C
135P60D
23
(584)
1
Side Return
Air Opening
(Either Side)
23−1/2
(597)
1
Bottom Return
Air Opening
AIR FLOW
C
1
Bottom Return
Air Opening
3/4
(19)
14−3/4
(375)
(16)
(406)
5/8
16
3−1/4
(83)
FRONT VIEW SIDE VIEW
A B C D
in. mm in. mm in. mm in. mm
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
21 533 19−7/8 504 19−1/2 495 8 203
24−1/2 622 23−3/8 546 23 584 9−3/4 248
14
(356)
1−15/16 (49)
1−1/2
(38)
Page 2
Parts Arrangement
Combustion Air
Inducer
Combustion Air
Pressure Switch
Make Up Box
Heat Exchanger
Gas Valve and Manifold
Assembly
Transformer
Integrated Control
Collector Box
Limit Switch
(under collector box)
Door Interlock
Switch
Indoor Blower and Motor Assembly
(installed in cabinet)
Indoor Blower and Motor Assembly
(removed from cabinet)
FIGURE 1
Page 3
EL280UH Gas Furnace
The EL280UH unit is shipped ready for installation in the
upflow 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 installed
in a horizontal application. The panel may also be removed in upflow 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 filter kit
Check equipment for shipping damage. If you find 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 floor and may
be difficult 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, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
Certifications
EL280UH units are CSA International certified 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 certified for installation
clearances to combustible material as listed on the unit
nameplate and in the tables in figures 8 and 12. Accessibility
and service clearances must take precedence over fire
protection clearances.
NOTE − For installation on combustible floors, the furnace
shall not be installed directly on carpeting, tile, or other
combustible material other than wood flooring.
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
floor. 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 specified 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 4
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 figure 2. With a parallel flow arrangement, a damper (or
other means to control the flow 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 figure 2.
Heating Unit Installed Parallel to Cooling Coil
Dampers
(open during heating operation only)
Gas Unit
Cooling Coil
Dampers
(open during cooling operation only)
Heating Unit Installed Upstream of Cooling Unit
Gas Unit
Cooling Coil
FIGURE 2
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 upflow or horizontal position.
This furnace design has not been CSA International
certified for installation in mobile homes, recreational
vehicles, or outdoors.
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 filters will damage the unit.
EL280UH units may be used for heating of buildings or
structures under construction, if the following conditions
are met:
D The vent system must be permanently installed per
these installation instructions.
D A room thermostat must control the furnace. The use of
fixed jumpers that will provide continuous heating is not
allowed.
D The return air duct must be provided and sealed to the
furnace.
D Return air temperature range between 60°F (16°C) and
80°F (27°C) must be maintained.
D Air filters must be installed in the system and must be
maintained during construction.
D Air filters must be replaced upon construction comple-
tion.
D The input rate and temperature rise must be set per the
furnace rating plate.
D One hundred percent (100%) outdoor air must be pro-
vided for combustion air requirements during construction. Temporary ducting may supply outdoor air to the
furnace. Do not connect duct directly to the furnace.
Size the temporary duct following these instructions in
section for Combustion, Dilution and Ventilation Air in a
confined space with air from outside.
D The furnace heat exchanger, components, duct system,
air filters and evaporator coils must be thoroughly
cleaned following final construction clean−up.
D All furnace operating conditions (including ignition, in-
put rate, temperature rise and venting) must be verified
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:
D Place the furnace as close to the center of the air dis-
tribution system as possible. The furnace should also be
located close to the chimney or vent termination point.
Page 5
D Do not install the furnace where drafts might blow direct-
ly into it. This could cause improper combustion and unsafe operation.
D Do not block the furnace combustion air openings with
clothing, boxes, doors, etc. Air is needed for proper
combustion and safe unit operation.
D When the furnace is installed in an attic or other insu-
lated space, keep insulation away from the furnace.
NOTE − The Commonwealth of Massachusetts stipulates these additional requirements:
D Gas furnaces shall be installed by a licensed plumb-
er or fitter only.
D The gas cock must be T handle" type.
D When a furnace is installed in an attic, the passage-
way to and service area surrounding the equipment
shall be floored.
WARNING
Product contains fiberglass wool.
Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
to fiberglass wool. Breathing this may cause lung
cancer. (Fiberglass wool is known to the State of California to cause cancer.)
Fiberglass wool may also cause respiratory, skin,
and eye irritation.
To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact your
supervisor.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900
Combustion, Dilution & Ventilation Air
In the past, there was no problem in bringing in sufficient outdoor air for combustion. Infiltration 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, appliance vents,
chimneys, and fireplaces 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 efficient
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 official position of the ANSI on the referenced subject, which is represented only by the standard in its entirety.
CAUTION
Do not install the furnace in a corrosive or contaminated atmosphere. Meet all combustion and ventilation air requirements, as well as all local codes.
CAUTION
Insufficient 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-fired appliances require air for the combustion process. If sufficient combustion air is not available, the furnace or other appliances will operate inefficiently 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 fireplaces, 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. Insufficient 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 installed in
an unconfined or a confined space.
Page 6
Unconfined Space
An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.42 m
3
) 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 unconfined, it might be necessary to bring in outdoor air for
combustion if the structure does not provide enough air by
infiltration. 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.
Confined Space
A confined space is an area with a volume less than 50 cubic feet (1.42 m
3
) per 1,000 Btu (.29 kW) per hour of the
combined input rating of all appliances installed in that
space. This definition 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
confined space such as a closet or small equipment room.
Even a small leak around the base of the unit at the platform
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 confined space either
from inside the building or from outside.
EQUIPMENT IN CONFINED
SPACE ALL AIR FROM INSIDE
CHIMNEY
OR GAS
VENT
WATER
FURNACE
HEATER
Air from Inside
If the confined space that houses the furnace adjoins a
space categorized as unconfined, 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 mm
2
) per 1,000 Btu (.29 kW) per hour of
total input rating of all gas−fired equipment in the confined
space. Each opening must be at least 100 square inches
(64516 mm
2
). 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 figure 3.
Air from Outside
If air from outside is brought in for combustion and ventilation, the confined 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 mm
2
) per 4,000 Btu (1.17
kW) per hour of total input rating of all equipment in the enclosure. See figures 4 and 5. When communicating with
the outdoors through horizontal ducts, each opening shall
have a minimum free area of 1 square inch (645 mm
2
) per
2,000 Btu (.56 kW) per total input rating of all equipment in
the enclosure. See figure 6.
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 protective 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 fixed in the
open position or interlocked with the equipment so that they
are opened automatically during equipment operation.
OPENINGS
(To Adjacent
Room)
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
) per 1,000 Btu (.29 kW) per hour of the total input rat-
2
).
FIGURE 3
Page 7
CHIMNEY OR
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)
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 4
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
FURNACE
CHIMNEY
OR GAS
VENT
WATER
HEATER
EQUIPMENT IN
CONFINED SPACE
ALL AIR FROM
OUTSIDE
OUTLET AIR
INLET AIR
NOTE−The inlet and outlet air openings shall each 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 equipment in the enclosure.
FIGURE 5
Page 8
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 communicate directly with the outdoors, each opening 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.
FIGURE 6
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 upflow 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 1/2 hp blower motors are equipped with
three flexible legs and one rigid leg. See figure 7. The rigid
leg is equipped with a shipping bolt and a flat white plastic
washer (rather than the rubber mounting grommet used
with a flexible mounting leg). The bolt and washer must
be removed before the furnace is placed into operation. After the bolt and washer have been removed, the rig-
id leg will not touch the blower housing.
EL280UH090P48B and
EL280UH110P48C with 1/2 HP
BLOWER MOTOR
RIGID LEG
remove shipping bolt and washer
FIGURE 7
Upflow Applications
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or alcove installations are shown in figure 8.
Upflow Application Installation Clearances
Top
Left Side
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.
** 4−1/2 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
in. cabinets, or 2inches if a single wall vent pipe is used on 17−1/2
in. cabinets.
Type C Type B1
Right Side
FIGURE 8
Page 9
Return Air −− Upflow Applications
Return air can be brought in through the bottom or either
side of the furnace installed in an upflow 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.
Single Side Return Air
(with transition and filter)
20” X 25” X 1”
(508mm X 635mm X 25mm)
Cleanable Filter
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 filter. (Required to maintain proper air velocity.) See figure 9.
2 − Single side return air with optional return airbase. See fig-
ure 10.
3 − Bottom return air.
4 − Return air from both sides.
5 − Bottom and one side return air.
Refer to Engineering Handbook for additional information.
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
IAQ CABINET,
A SINGLE
RETURN AIR
PLENUM
MUST
COVER BOTH
UNIT AND
RETURN
AIR BASE
OPENINGS
3−1/4
(83)
7−1/4
(184)
AIR FLOW
FIGURE 9
1
23 (584)
Overall
(Maximum)
1
Unit side return air
Opening
5−5/8
(143)
SIDE RETURN
AIR OPENINGS
(Either Side)
Transition
1
2
Return Air
Plenum
Minimum
11 (279)
Maximum
14 (356)
1
22−7/16
(570)
Overall
(Maximum)
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.
OPTIONAL
RETURN AIR BASE
SIDE VIEW
23
(584)
26−7/8
(683)
3/4
(19)
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.
FIGURE 10
Page 10
Removing the Bottom Panel
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 figure 11.
Removing the Bottom Panel
Horizontal Applications
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 figure 12.
This furnace may be installed in either an attic or a crawlspace. Either suspend the furnace from roof rafters or
floor joists, as shown in figure 13, or install the furnace on a
platform, as shown in figure 14.
Typical Horizontal Application
Unit Suspended in Attic or Crawlspace
Bracket
Metal Strap
Screw
Bottom Cap
Bottom Panel
FIGURE 11
Horizontal Application
Installation Clearances
Left
End
Vent Connector
Type
Top 0 0
*Front 2−1/4 in. (57 mm)** 2−1/4 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.
** 4−1/2 in. if singlewall 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
Bottom Cap
3/16 inch
Air Flow
FIGURE 13
NOTE − Heavy−gauge perforated sheet metal straps may
be used to suspend the unit from roof rafters or ceiling
joists. 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 furnace
installed in a horizontal application. The furnace is
equipped with a removable bottom panel to facilitate
installation. See figure 11.
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.
Page 11
Horizontal Application
Unit Installed on Platform
Line contact is permissible but not preferred
See the unit nameplate for
clearances.
GAS
ENTRY
SERVICE PLATFORM
VENT
PIPE
FIGURE 14
WARNING
Improper installation of the furnace can result in personal injury or death. Combustion and flue 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 fireplace 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 filter or rack. A field−provided high−velocity filter is required for the unit to operate
properly. Table 1 lists recommended filter sizes.
A filter must be in place any time the unit is operating.
TABLE 1
Furnace
Cabinet Width
A − 14−1/2" 16 X 25 X 1 (1) 14 X 25 X 1 (1)
B − 17−1/2" 16 X 25 X 1 (1) 16 X 25 X 1 (1)
C − 21" 16 X 25 X 1 (1) 20 X 25 X 1 (1)
D − 24−1/2" 16 X 25 X 1 (2) 24 X 25 X 1 (1)
Side Return Bottom Return
Filter Size
Duct System
Use industry-approved standards (such as those published by Air Conditioning Contractors of America or American Society of Heating, Refrigerating and Air Conditioning
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 inspection
(either by smoke or reflected 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 fireplace) 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 flue products can
be pulled back down the vent pipe and into the room. This
reverse flow of the flue 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 upflow 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 fiberglass sealing strips, caulking, or equivalent sealing method between the plenum and the furnace
cabinet to ensure a tight seal. If a filter is installed, size the
return air duct to fit the filter frame.
Page 12
Venting
A 4−inch diameter flue transition is factory-installed on the
combustion air inducer outlet of all models. Figure 16
shows the combustion air inducer as shipped from the
factory.
Mounting Screws Location
Mounting Screws
FIGURE 15
UPFlow Position
If necessary reposition the combustion air inducer, pressure switch and or make up box as needed per the following steps and see figures 17 through 22.
1 − Remove the four mounting screws which secure the
combustion air inducer / pressure switch assembly to
the orifice plate. See figure 15. Lift and rotate the assembly 90 degrees clockwise or counter clockwise to
either the 3 o’clock position or to 9 o’clock position and
re−secure with four screws. Gasket should be left in
place.
2 − Use tin snips to cut preferred opening on the cabinet
for repositioning the flue outlet. Use the cut out piece
as a cover plate to patch unused opening on cabinet.
UPFLOW POSITION
Left Side Vent Discharge
Cover Plate Collector Box
Pressure
Switch
Vent Pipe
Make−Up
Box
UPFLOW POSITION
Top Vent Discharge
Vent Pipe
Pressure
Switch
Make−Up
Box
Flue
Transition
AIR
FLOW
Collector Box
FIGURE 16
IMPORTANT
The unit will not vent properly with the flue transition
pointed down in the 6 o’clock position.
The combustion air inducer may be rotated clockwise or counterclockwise by 90° to allow for top or
side vent discharge in all applications. When the unit
is installed, the flue transition must be in the 9
o’clock, 12 o’clock or 3 o’clock position.
Flue
Transition
AIR
S Gas supply piping must be brought into the unit from the right
side in order to accommodate the flue pipe.
S Remove make−up box assembly (2 screws) and cut wire tie to
free make−up box wires. Re−install make−up box on other side
of cabinet.
S Re−secure make−up box wires, either pulling excess wires
through the blower compartment and securing with supplied
wire tie, or coil excess wire and secure to the gas manifold.
FIGURE 17
UPFLOW POSITION
Right Side Vent Discharge
Cover Plate
Pressure
Switch
Collector
Box
Make−Up
Box
FLOW
AIR
S Pressure switch tubing may be too long. Cut to
fit , then re−attach to barbed fitting on pressure
switch. Tubing must not be allowed to sag.
Flue Transition
Vent Pipe
FIGURE 18
FLOW
Page 13
Horizontal Position
HORIZONTAL LEFT POSITION
Top Vent Discharge
Vent Pipe
Flue
Transition
Cover Plate
Make−Up Box
S Disconnect pressure switch hose from barbed fitting on the pres-
sure switch assembly. Remove pressure switch assembly (1
screw) and cut wire tie to free pressure switch wires. Re−install
pressure switch on the other side of orifice plate and re−connect
pressure switch hose.
S Re−secure pressure switch wires by either pulling excess wires
through the blower compartment and securing with supplied wire
tie or coil excess wire and secure to the gas manifold.
Pressure Switch
AIR
FLOW
Collector Box
FIGURE 19
HORIZONTAL LEFT POSITION
Side Vent Discharge
HORIZONTAL RIGHT POSITION
Top Vent Discharge
Vent Pipe
Flue Transition
AIR
FLOW
S Gas supply piping must be brought into the unit from the bottom
in order to accommodate the flue pipe.
S Remove make−up box assembly (2 screws) and cut wire tie to
free make−up box wires. Re−install make−up box on other side
of cabinet.
S Re−secure make−up box wires by either pulling excess wires
through the blower compartment and securing with supplied
wire tie, or coil excess wire and secure to the gas manifold.
Pressure Switch
Cover Plate
Collector Box
Make−Up Box
FIGURE 21
Pressure Switch
AIR
FLOW
Flue Transition
Make−Up Box
S Disconnect pressure switch hose from barbed fitting on the
pressure switch assembly. Remove pressure switch assembly
(1 screw) and cut wire tie to free pressure switch wires. Re−
install pressure switch on the other side of orifice plate and re−
connect pressure switch hose.
S Re−secure pressure switch wires by either pulling excess wires
through the blower compartment and securing with supplied
wire tie, or coil excess wire and secure to the gas manifold.
Collector Box
FIGURE 20
HORIZONTAL RIGHT POSITION
Side Vent Discharge
Pressure Switch
AIR
FLOW
make up box
FIGURE 22
Flue
Transition
Collector Box
Page 14
The EL280UH series units are classified as fan−assisted
Category I furnaces when vertically vented according to
the latest edition of National Fuel Gas Code (NFPA 54 /
ANSI Z223.1) in the USA. A fan−assisted Category I furnace is an appliance equipped with an integral mechanical
means to either draw or force combustion products through
the combustion chamber and/or heat exchanger. The
EL280UH is not approved for use with horizontal venting.
NOT E − Use these instructions as a guide. They do not supersede local codes. This furnace must be vented according to all local codes these installation instructions, and the
provided venting tables in these instructions
The venting tables in this manual were extracted from the
National Fuel Gas Code (NFPA 54 / ANSI Z223.1) and are
provided as a guide for proper vent installation. Proper application, termination, construction and location of vents
must conform to local codes having jurisdiction. In the absence of local codes, the NFGC serves as the defining document.
Refer to the tables and the venting information contained in
these instructions to properly size and install the venting
system.
Use self−drilling sheet metal screws or a mechanical fastener to firmly secure the vent pipe to the round collar of the
flue transition. If self−drilling screws are used to attach the
vent pipe, it is recommended that three be used. Drive one
self−drilling screw through the front and one through each
side of the vent pipe and collar. See figure 23.
Install the first vent connector elbow at a minimum of six
inches (152 mm) from the furnace vent outlet. See figure
23.
Venting Using a Masonry Chimney
The following additional requirements apply when a lined
masonry chimney is used to vent this furnace.
Masonry chimneys used to vent Category I central furnaces must be either tile-lined or lined with a listed metal
lining system or dedicated gas vent. Unlined masonry
chimneys are prohibited. See figures 24 and 25 for common venting.
A chimney with one or more sides exposed to the outside of
the structure is considered to be an exterior chimney.
An exterior masonry chimney that is not tile−lined must be
lined with B1 vent or a listed insulated flexible metal vent.
An exterior tile−lined chimney that is sealed and capped
may be lined with a listed uninsulated flexible metal vent.
If the existing chimney will not accommodate a listed metal
liner, either the chimney must be rebuilt to accommodate
one of these liners or an alternate approved venting method must be found.
Insulation for the flexible vent pipe must be an encapsulated fiberglass sleeve recommended by the flexible vent
pipe manufacturer. See figure 24.
IMPORTANT
Once the venting system is installed, attach the Disconnected Vent" warning sticker to a visible area of
the plenum near the vent pipe. See figure 23. The
warning sticker is provided in the bag assembly. Order kit 66W04 for additional stickers.
WARNING
Asphyxiation hazard. The exhaust vent for this furnace must be securely connected to the furnace flue
transition at all times.
VENT PIPE
(min. 6" length)
FLUE TRANSITION
COLLAR
VENT CONNECTION UPFLOW AND HORIZONTAL POSITION
“DISCONNECTED VENT”
WARNING
STICKER
OPTIONAL SIDE
VENTING
(min. 6" length)
“DISCONNECTED VENT”
WARNING
STICKER
VENT PIPE
(min. 6" length)
FIGURE 23
Page 15
FLUE
TRANSITION
COLLAR
Common Venting Using Metal−Lined Masonry Chimney
SEALED
MAX. LENGTH
−− SEE NOTE 1
5 ft. (1.5 m)
minimum
VENT CONNECTOR
4 in. (102 mm)
minimum
OTHER
APPLIANCE
NOTE 1 − Refer to the provided venting tables for installations. Refer
to the capacity requirements shown in the provided venting tables.
BELOW.
MIN. LENGTH −− AS
SHORT AS PRACTICAL
FURNACE
EXTERIOR
CHIMNEY WITH
METAL
LINER
PERMANENTLY
SEALED FIREPLACE
OPENING
FIGURE 24
DO NOT insulate the space between the liner and the
chimney wall with puffed mica or any other loose granular insulating material.
IMPORTANT
SINGLE appliance venting of a fan-assisted furnace
into a tile-lined masonry chimney (interior or outside
wall) is PROHIBITED. The chimney must first be lined
with either type B1 vent or an insulated single wall
flexible vent lining system which has been sized according to the provided venting tables and the vent
pipe manufacturer’s instructions.
A fan−assisted furnace may be commonly vented into an
existing lined masonry chimney if the following conditions
are met:
S The chimney is currently serving at least one drafthood−
equipped appliance;
S The vent connectors and chimney are sized according
to the provided venting tables.
If type B1 double-wall vent is used inside a chimney, no other appliance can be vented into the chimney. The outer wall
of type B1 vent pipe must not be exposed to flue products.
A type B1 vent or masonry chimney liner shall terminate
above the roof surface with a listed cap or a listed roof assembly according to the terms of their respective listings
and the vent manufacturer’s instructions.
When inspection reveals that an existing chimney is not
safe for the intended purpose, it shall be rebuilt to conform
to nationally recognized standards, lined or relined with
suitable materials, or replaced with a gas vent or chimney
suitable for venting EL280UH series units. The chimney
passageway must be checked periodically to ensure that it
is clear and free of obstructions.
Do not install a manual damper, barometric draft regulator,
or flue restrictor between the furnace and the chimney.
Never connect a Category I appliance to a chimney that is
servicing a solid−fuel appliance. If a fireplace chimney flue
is used to vent this appliance, the fireplace opening must
be permanently sealed.
A type B or listed chimney lining system that passes
through an unused masonry chimney flue is not considered
to be exposed to the outdoors.
General Venting Requirements
Vent all EL280UH furnaces according to these instructions:
1 − Vent diameter recommendations and maximum allow-
able piping runs are found in the provided venting
tables.
2 − In no case should the vent or vent connector diameter
be less than the diameter specified in the provided
venting tables.
3 − The minimum vent capacity determined by the sizing
tables must be less than the low fire input rating and the
maximum vent capacity must be greater than the high
fire input rating.
4 − Single appliance vents − If the vertical vent or tile-lined
chimney has a larger diameter or flow area than the
vent connector, use the vertical vent diameter to determine the minimum vent capacity and the vent
connector diameter to determine the maximum vent
capacity. The flow area of the vertical vent, however,
shall not exceed 7 times the flow area of the listed appliance categorized vent area, drafthood outlet area or
flue collar area unless designed according to approved
engineering methods.
5 − Multiple appliance vents − The flow area of the largest
section of vertical vent or chimney shall not exceed 7
times the smallest listed appliance categorized vent
area, drafthood outlet area or flue collar area unless designed according to approved engineering methods.
Page 16
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