Page 1
INSTALLATION
E 2012 Lennox Industries Inc.
Dallas, Texas, USA
DOWNFLOW
INSTRUCTIONS
EL280DF
MERIT® SERIES GAS FURNACE
DOWNFLOW AIR DISCHARGE
506896−01
08/2012
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.
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
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.
Litho U.S.A.
AIR FLOW
Table of Contents
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EL280DF Gas Furnace 3. . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 3. . . . . . . . . . . . . . . . . . . . . . . .
Safety Information 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use of Furnace as a Construction Heater 4. . . . . . . . . . .
General 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution & Ventilation Air 5. . . . . . . . . . . . . .
Downflow Installation 8. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Equipment 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filters 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CAUTION
As with any mechanical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
Venting 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Integrated Control 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start−Up 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Adjustment 25. . . . . . . . . . . . . . . . . . . . . . . .
Proper Combustion 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Altitude 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments 27. . . . . . . . . . . . . . . . . . . . . . . . . .
Heating Sequence of Operation 28. . . . . . . . . . . . . . . . . . .
Service 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start Up and Performance Checklist 31. . . . . . . . . . . . . . .
08/12
*2P0812*
Page 1
506896−01
*P506896-01*
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Unit Dimensions − inches (mm)
A
B
AIR FLOW
9/16
(14)
FLUE OUTLET
(Top)
1−1/2 (38)
Front Panel
3−1/8
(79)
D
9/16
(14)
RETURN AIR
OPENING
B
19−7/16
(494)
9/16
(14)
TOP VIEW
27−3/4
(705)
19−7/16
(494)
9/16
(14)
9/16
(14)
ELECTRICAL INLET
33
(838)
Supply
C
Air
Model No.
EL280DF070P36A 14−1/2 368 13−3/8 340 13 330 4−3/4 121
EL280DF090P48B 17−1/2 446 16−3/8 416 16 406 6−1/4 159
EL280DF110P60C 21 533 19−7/8 504 19−1/2 495 8 203
in. mm in. mm in. mm in. mm
3/4
(19)
A B C D
5−3/8 (137) Right
2−3/16 (56) Left
6−5/8 (168) Right
7−1/8 (181) Left
(Either Side)
GAS PIPING INLET
(Either Side)
19−1/4
Supply
(489)
Air
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EL280DF Gas Furnace
The EL280DF gas furnace is shipped ready for installation
in the downflow position fueled by natural gas. A conversion kit (ordered separately) is required for use in LP/Propane gas applications.
Shipping and Packing List
Package 1 of 1 contains
1 − Assembled EL280DF 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 − LP/Propane changeover kit
1 − Combustible flooring base
1 − High altitude 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
EL280DF units are CSA International certified.
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 National Fuel
Gas Code 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 figure 13. Accessibility and
service clearances must take precedence over fire protection
clearances.
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.
NOTE − Furnace must be adjusted to obtain a temperature
rise within the range(s) specified on the unit nameplate. Failure to do so may cause erratic limit operation and may also
result in premature heat exchanger failure.
This EL280DF furnace must be installed so that its electrical components are protected from water.
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.
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 (see figure 1). 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.
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GAS UNIT
Dampers
(open during heating
operation only)
AIR HANDLER
Dampers
(open during cooling
operation only)
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 EL280DF furnace may be installed in alcoves, closets,
attics, basements, garages, and utility rooms in the downflow 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 EL280DF 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.
EL280DF 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 EL280DF 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.
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.
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WARNING
The State of California has determined that this product may contain or produce a chemical or chemicals,
in very low doses, which may cause serious illness
or death. It may also cause cancer, birth defects or reproductive harm.
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 EL280DF furnaces to ensure efficient
and safe operation. You must consider combustion air
needs and requirements for exhaust vents. 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.
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
bined 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.
3
) per 1,000 Btu (.29 kW) per hour of the com-
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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
CHIMNEY
OR GAS
VENT
FURNACE
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
).
SPACE ALL AIR FROM INSIDE
WATER
HEATER
OPENINGS
(To Adjacent
Room)
FIGURE 2
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 2.
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 3 and 4. 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 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 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.
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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 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)
FURNACE
CHIMNEY
OR GAS
VENT
CONFINED SPACE
WATER
HEATER
OUTLET AIR
INLET AIR
EQUIPMENT IN
ALL AIR FROM
OUTSIDE
WATER
HEATER
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 4
Page 7
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
per 4,000 Btu (1.17 kW) per hour of the total input rating of all
other equipment in the enclosure.
FIGURE 5
2
)
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Downflow Installation
Downflow unit installs in three ways: on non−combustible
flooring, on combustible flooring using a downflow combustible flooring base, or on a reverse−flow cooling cabinet.
Do not drag the unit across the floor.
Installation on Non−Combustible Flooring (Figure 6)
1 − Cut floor opening keeping in mind clearances listed on
unit rating plate. Also keep in mind gas supply connections, electrical supply, flue and air intake connections
and sufficient installation and servicing clearances.
See table 1 for correct floor opening size.
2 − Flange warm air plenum and lower the plenum into the
opening.
3 − Set the unit over the plenum and seal the plenum to
the unit.
4 − Ensure that the seal is adequate.
CAUTION
The furnace and downflow combustible flooring
base shall not be installed directly on carpeting, tile,
or other combustible material other than wood flooring.
EL280DF UNIT
SUPPLY AIR PLENUM
PROPERLY
SIZED FLOOR
OPENING
DOWNFLOW
COMBUSTIBLE
FLOORING BASE
EL280DF UNIT
OPENING
SUPPLY AIR
PLENUM
FIGURE 6
TABLE 1
NON−COMBUSTIBLE FLOOR OPENING SIZE
Cabinet Width
A (14.5") 19−3/4 502 13−1/4 337
B (17.5") 19−3/4 502 16−1/4 413
C (21") 19−3/4 502 19−3/4 502
NOTE − Floor opening dimensions listed are 1/4 inch (6 mm) larger than
the unit opening. See unit dimensions on page 2.
Front to Rear Side to Side
in. mm in. mm
Installation on Combustible Flooring (Figure 7)
1 − When unit is installed on a combustible floor, a down-
flow combustible flooring base must be installed between the furnace and the floor. The base must be ordered separately.
See table 2 for opening size to cut in floor.
FIGURE 7
TABLE 2
COMBUSTIBLE FLOOR OPENING SIZE
Cabinet Width
A (14.5")
B (17.5")
C (21")
Front to Rear Side to Side
in. mm in. mm
22 559 15−3/4 400
22 559 18−3/4 476
22 559 22−3/4 578
2 − After opening is cut, set combustible flooring base into
opening.
3 − Check sealing strips on combustible flooring base to
make sure they are properly glued and positioned.
4 − Lower supply air plenum into downflow combustible
flooring base until plenum flanges seal against the
strips.
NOTE − Be careful not to damage sealing strips. Check
for a tight seal.
5 − Set the furnace over the plenum.
6 − Ensure that the seal between the furnace and plenum
is adequate.
Installation on Cooling Cabinet (Figure 8)
1 − Refer to reverse−flow coil installation instructions for
correctly sized opening in floor and installation of cabinet.
NOTE − Downflow combustible flooring kit is not used
2 − When cooling cabinet is in place, set and secure the
furnace according to the instructions that are provided
with the cooling coil. Secure the furnace to the cabinet.
3 − Seal the cabinet and check for air leaks.
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Page 9
PROPERLY
SIZED FLOOR
OPENING
EL280DF UNIT
COOLING COIL
PLENUM
Setting Equipment
WARNING
Do not install the furnace on its front, back or in the
horizontal position. See figure 12. 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.
Install the EL280DF gas furnace as shipped in the downflow position only. Do not install the furnace hori-
zontally.
FIGURE 8
Return Air Opening −− Downflow Units
The following steps should be taken when installing plenum:
1 − Bottom edge of plenum should be flanged with a
hemmed edge (See figure 9).
PLENUM
SECURE FROM
OUTSIDE CABINET
Side View
HEMMED EDGE
SEALING STRIP
(Field Provided)
CABINET SIDE PANEL
FIGURE 9
2 − Sealing strip should be used.
3 − In all cases, plenum should be secured to top flanges
of furnace with sheet metal screws.
SECURE FROM IN-
SIDE CABINET
PLENUM
Side View
HEMMED EDGE
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 11. 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.
UNITS WITH 1/2 HP BLOWER MOTOR
RIGID LEG
remove shipping bolt and washer
FIBERGLASS
SEALING STRIP
(Field Provided)
CABINET SIDE
PANEL
FIGURE 10
4 − In closet installations, it may be impossible to install
sheet metal screws from the outside. In this case,
make plenum with a removable front and install
screws from the inside (See figure 10).
5 − Make certain that an adequate seal is made.
FIGURE 11
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.
Page 9
Page 10
Front
Back
FIGURE 12
Downflow Application
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or alcove installations are shown in figure 13.
Downflow 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 NC†† NC††
*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 a single wall vent pipe is used.
†Left side requires 3 in. if a single wall vent is used on 14 −1/2 in. cabinets, or 2 in. if a single wall vent is used on 17 − 1/2 in. cabinets.
††The furnace may be installed on a combustible wood floor if an
optional additive base is installed between the furnace and the
combustible floor.
Type C Type B1
Right Side
FIGURE 13
Horizontal
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.
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 3 lists recommended filter sizes.
A filter must be in place any time the unit is operating.
TABLE 3
Cabinet Width
A (14−1/2") 14 x 25 x 1 (1)
B (17−1/2") 16 x 25 x 1 (1)
C (21") 20 x 25 x 1 (1)
Return Air Filter Size (inches)
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Page 11
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.
Ensure that you have made a seal between the supply air
plenum and the furnace and between the furnace and the
return air plenum.
Return Air Plenum
Return air must not be drawn from a room where 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.
Venting
A 4−inch diameter flue transition is factory-installed on all
models. Modifying or removing the flue transition will
cause the unit to operate unsafely and will void the unit
certification. The vent connector does not require insula-
tion.
The EL280DF 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). 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.
NOTE − 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.
IMPORTANT
Once the venting system is installed, attach the Disconnected Vent" warning sticker to a visible area of
the plenum near the vent pipe. 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 CONNECTION
FLUE TRANSITION
COLLAR
FIGURE 14
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 14.
Install the first vent connector elbow at a minimum of six
inches (152 mm) from the furnace vent outlet.
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 15 and 16 for common venting.
“DISCONNECTED VENT”
WARNING
STICKER
Page 11
Page 12
Common Venting Using Tile−Lined Interior Masonry Chimney and Combined Vent Connector
MINIMUM LENGTH = AS SHORT AS PRACTICAL.
NOTE− Refer to provided venting
tables for installations.
FOR MAXIMUM LENGTH SEE NOTE TO LEFT
OTHER
APPLIANCE
FIGURE 15
Venting Using a Masonry Chimney
The following additional requirements apply when a lined
masonry chimney is used to vent this furnace.
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 16.
Common Venting Using Metal−Lined Masonry Chimney
SEALED
MAX. LENGTH
−− SEE NOTE
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.
BELOW.
MIN. LENGTH −− AS
SHORT AS PRACTICAL
FURNACE
EXTERIOR
CHIMNEY WITH
METAL
LINER
PERMANENTLY
SEALED FIREPLACE
OPENING
FIGURE 16
INTERIOR TILE−LINED
MASONRY CHIMNEY
NOTE − the chimney must be properly
sized per provided venting tables or
lined with listed metal lining system.
VENT
CONNECTOR
FURNACE
PERMANENTLY
SEALED FIREPLACE
OPENING
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 EL280DF 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.
Page 12
Page 13
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 EL280DF 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.
6 − The entire length of single wall metal vent connector
shall be readily accessible for inspection, cleaning,
and replacement.
7 − Single appliance venting configurations with zero lat-
eral lengths (tables 5 and NO TAG) are assumed to
have no elbows in the vent system. For all other vent
configurations, the vent system is assumed to have
two 90° elbows. For each additional 90° elbow or
equivalent (for example two 45° elbows equal one 90°
elbow) beyond two, the maximum capacity listed in the
venting table should be reduced by 10% (0.90 x maximum listed capacity).
8 − The common venting tables (6, 7, NO TAG, and
NO TAG) were generated using a maximum horizontal
vent connector length of 1−1/2 feet (.46 m) for each inch
(25 mm) of connector diameter as follows:
TABLE 4
Connector Diameter
inches (mm)
3 (76) 4−1/2 (1.37)
4 (102) 6 (1.83)
5 (127) 7−1/2 (2.29)
6 (152) 9 (2.74)
7 (178) 10−1/2 (3.20)
Maximum Horizontal
Connector Length feet (m)
9 − If the common vertical vent is offset, the maximum
common vent capacity listed in the common venting
tables should be reduced by 20%, the equivalent of two
90° elbows (0.80 x maximum common vent capacity).
The horizontal length of the offset shall not exceed
1-1/2 feet (.46 m) for each inch (25 mm) of common
vent diameter.
10 − The vent pipe should be as short as possible with the
least number of elbows and angles required to complete the job. Route the vent connector to the vent using the shortest possible route.
11 − A vent connector shall be supported without any dips
or sags and shall slope a minimum of 1/4 inch (6.4 mm)
per linear foot (305 mm) of connector, back toward the
appliance.
12 − Vent connectors shall be firmly attached to the furnace
flue collar by self−drilling screws or other approved
means, except vent connectors of listed type B vent
material which shall be assembled according to the
manufacturer’s instructions. Joints between sections
of single wall connector piping shall be fastened by
screws or other approved means.
13 − When the vent connector used for Category I ap-
pliances must be located in or pass through a crawlspace or other areas which may be cold, that portion of
the vent connector shall be constructed of listed
double-wall type B vent material or material having
equivalent insulation qualities.
14 − All venting pipe passing through floors, walls, and ceil-
ings must be installed with the listed clearance to combustible materials and be fire stopped according to local codes. In absence of local codes, refer to NFGC
(Z223.1).
15 − No portion of the venting system can extend into, or pass
through any circulation air duct or plenum.
16 − Vent connectors serving Category I appliances shall
not be connected to any portion of mechanical draft
systems operating under positive pressure such as
Category III or IV venting systems.
17 − If vent connectors are combined prior to entering the
common vent, the maximum common vent capacity
listed in the common venting tables must be reduced by
10%, the equivalent of one 90° elbow (0.90 x maximum
common vent capacity).
18 − The common vent diameter must always be at least as
large as the largest vent connector diameter.
Page 13
Page 14
19 − In no case, shall the vent connector be sized more than
two consecutive table size diameters over the size of
the draft hood outlet or flue collar outlet.
20 − Do not install a manual damper, barometric draft regu-
lator or flue restrictor between the furnace and the
chimney.
cated or common venting system, you must inspect the
venting system’s general condition and look for signs
of corrosion. The existing vent pipe size must conform
to these instructions and the provided venting tables. If
the existing venting system does not meet these requirements, it must be resized.
21 − When connecting this appliance to an existing dedi-
TABLE 5
Capacity of Type B Double−Wall Vents with Type B Double−Wall Connectors
Serving a Single Category I Appliance
Vent and Connector Diameter − D (inches)
Height
H
(feet)
6
8
10
15
20
30
NOTE − Single appliance venting configurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other
vent configurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for example two 45°
elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).
Lateral
L
(feet)
0 0 78 0 152 0 251 0 375
2 13 51 18 97 27 157 32 232
4 21 49 30 94 39 153 50 227
6 25 46 36 91 47 149 59 223
0 0 84 0 165 0 276 0 415
2 12 57 16 109 25 178 28 263
5 23 53 32 103 42 171 53 255
8 28 49 39 98 51 164 64 247
0 0 88 0 175 0 295 0 447
2 12 61 17 118 23 194 26 289
5 23 57 32 113 41 187 52 280
10 30 51 41 104 54 176 67 267
0 0 94 0 191 0 327 0 502
2 11 69 15 136 20 226 22 339
5 22 65 30 130 39 219 49 330
10 29 59 40 121 51 206 64 315
15 35 53 48 112 61 195 76 301
0 0 97 0 202 0 349 0 540
2 10 75 14 149 18 250 20 377
5 21 71 29 143 38 242 47 367
10 28 64 38 133 50 229 62 351
15 34 58 46 124 59 217 73 337
20 48 52 55 116 69 206 84 322
0 0 100 0 213 0 374 0 587
2 9 81 13 166 14 283 18 432
5 21 77 28 160 36 275 45 421
10 27 70 37 150 48 262 59 405
15 33 64 44 141 57 249 70 389
20 56 58 53 132 66 237 80 374
30 NA NA 73 11 3 88 214 104 346
3 Inch 4 Inch 5 Inch 6 Inch
Appliance Input Rating in Thousands of Btu Per Hour
MIN MAX MIN MAX MIN MAX MIN MAX
Page 14
Page 15
Vent
Height
H
(feet)
6
8
10
15
20
30
TABLE 6
Vent Connector Capacity
Type B Double−Wall Vents with Type B Double−Wall Connectors
Serving Two or More Category I Appliances
Connector
Rise
R
(feet)
1 22 37 35 66 46 106 58 164
2 23 41 37 75 48 121 60 183
3 24 44 38 81 49 132 62 199
1 22 40 35 72 49 114 64 176
2 23 44 36 80 51 128 66 195
3 24 47 37 87 53 139 67 210
1 22 43 34 78 49 123 65 189
2 23 47 36 86 51 136 67 206
3 24 50 37 92 52 146 69 220
1 21 50 33 89 47 142 64 220
2 22 53 35 96 49 153 66 235
3 24 55 36 102 51 163 68 248
1 21 54 33 99 46 157 62 246
2 22 57 34 105 48 167 64 259
3 23 60 35 110 50 176 66 271
1 20 62 31 113 45 181 60 288
2 21 64 33 118 47 190 62 299
3 22 66 34 123 48 198 64 309
3 Inch 4 Inch 5 Inch 6 Inch
MIN MAX MIN MAX MIN MAX MIN MAX
Vent and Connector Diameter − D (inches)
Appliance Input Rating in Thousands of Btu Per Hour
TABLE 7
Common Vent Capacity
Type B Double−Wall Vents with Type B Double−Wall Connectors
Serving Two or More Category I Appliances
Vent
Height
H
(feet)
6 92 81 140 11 6 204 161 309 248
8 101 90 155 129 224 178 339 275
10 110 97 169 141 243 194 367 299
15 125 112 195 164 283 228 427 352
20 136 123 215 183 314 255 475 394
30 152 138 244 210 361 297 547 459
FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT
4 Inch 5 Inch 6 Inch 7 Inch
Appliance Input Rating in Thousands of Btu Per Hour
Common Vent Diameter − D (inches)
Page 15
Page 16
Removal of the Furnace from Common Vent
In the event that an existing furnace is removed from a
venting system commonly run with separate gas appliances, the venting system is likely to be too large to
properly vent the remaining attached appliances.
Conduct the following test while each appliance is operating and the other appliances (which are not operating) remain connected to the common venting system. If the
venting system has been installed improperly, you must
correct the system as indicated in the general venting requirements section.
Resize the common venting system to the minimum
vent pipe size determined by using the appropriate
tables in Appendix G. (These are in the current standards of the National Fuel Gas Code ANSI Z223.1.
Gas Piping
Gas supply piping should not allow more than 0.5"W.C. drop
in pressure between gas meter and unit. Supply gas pipe
must not be smaller than unit gas connection.
WARNING
CARBON MONOXIDE POISONING HAZARD
Failure to follow the steps outlined below for each
appliance connected to the venting system being
placed into operation could result in carbon monoxide poisoning or death.
The following steps shall be followed for each appliance connected to the venting system being
placed into operation, while all other appliances
connected to the venting system are not in
operation:
1 − Seal any unused openings in the common venting sys-
tem.
2 − Inspect the venting system for proper size and horizontal
pitch. Determine that there is no blockage, restriction,
leakage, corrosion, or other deficiencies which could
cause an unsafe condition.
3 − Close all building doors and windows and all doors be-
tween the space in which the appliances remaining
connected to the common venting system are located
and other spaces of the building. Turn on clothes dryers and any appliances not connected to the common
venting system. Turn on any exhaust fans, such as
range hoods and bathroom exhausts, so they will operate at maximum speed. Do not operate a summer exhaust fan. Close fireplace dampers.
4 − Follow the lighting instructions. Turn on the appliance
that is being inspected. Adjust the thermostat so that
the appliance operates continuously.
5 − After the main burner has operated for 5 minutes, test
for leaks of flue gases at the draft hood relief opening.
Use the flame of a match or candle, or smoke from a
cigarette, cigar, or pipe.
6 − After determining that each appliance connected to the
common venting system is venting properly, (step 3)
return all doors, widows, exhaust fans, fireplace dampers, and any other gas−burning appliances to their previous mode of operation.
7 − If a venting problem is found during any of the preced-
ing tests, the common venting system must be modified to correct the problem.
CAUTION
If a flexible gas connector is required or allowed by
the authority that has jurisdiction, black iron pipe
shall be installed at the gas valve and extend outside
the furnace cabinet. The flexible connector can then
be added between the black iron pipe and the gas
supply line.
Gas Supply
1 − This unit is shipped standard for left or right side instal-
lation of gas piping. Connect the gas supply to the piping assembly.
2 − When connecting the gas supply piping, consider fac-
tors such as length of run, number of fittings, and furnace rating to avoid excessive pressure drop. Table 8
lists recommended pipe sizes for typical applications.
3 − The gas piping must not run in or through air ducts,
clothes chutes, gas vents or chimneys, dumb waiters,
or elevator shafts.
4 − The piping should be sloped 1/4 inch (6.4 mm) per 15
feet (4.57 m) upward toward the meter from the furnace. The piping must be supported at proper intervals
[every 8 to 10 feet (2.44 to 3.01 m)] with suitable hangers or straps. Install a drip leg inside vertical pipe runs
to the unit.
5 − A 1/8" N.P.T. plugged tap or pressure post is located
on the gas valve to facilitate test gauge connection.
See figure NO TAG.
6 − In some localities, codes may require the installation of
a manual main shut-off valve and union (furnished by
the installer) external to the unit. The union must be of
the ground joint type.
IMPORTANT
Compounds used on threaded joints of gas piping
must be resistant to the actions of liquified petroleum gases.
NOTE − If emergency shutoff is necessary, shut off the main
manual gas valve and disconnect main power to the furnace. The installer should properly label these devices.
Page 16
Page 17
TABLE 8
Gas Pipe Capacity − ft
Nominal
Iron Pipe
Size
inches
(mm)
1/2
(12.7)
3/4
(19.05)
1
(25.4)
1−1/4
(31.75)
1−1/2
(38.1)
2
(50.8)
2−1/2
(63.5)
3
(76.2)
NOTE − Capacity given in cubic feet (m3 ) of gas per hour and based on 0.60 specific gravity gas.
Internal
Diameter
inches
(mm)
.622
(17.799)
.824
(20.930)
1.049
(26.645)
1.380
(35.052)
1.610
(40.894)
2.067
(52.502)
2.469
(67.713)
3.068
(77.927)
10
(3.048)20(6.096)30(9.144)40(12.192)50(15.240)60(18.288)70(21.336)80(24.384)90(27.432)
172
(4.87)
360
(10.19)
678
(19.19)
1350
(38.22)
2090
(59.18)
4020
(113.83)
6400
(181.22)
11300
(319.98)
118
(3.34)
247
(7.00)
466
(13.19)
957
(27.09)
1430
(40.49)
2760
(78.15)
4400
(124.59)
7780
(220.30)
95
(2.69)
199
(5.63)
374
(10.59)
768
(22.25)
1150
(32.56)
2220
(62.86)
3530
(99.95)
6250
(176.98)
81
(2.29)
170
(4.81)
320
(9.06)
657
(18.60)
985
(27.89)
1900
(53.80)
3020
(85.51)
5350
(151.49)
3
/hr (m3/hr)
Length of Pipe − feet (m)
72
(2.03)
151
(4.28)
284
(8.04)
583
(16.50)
873
(24.72)
1680
(47.57)
2680
(75.88)
4740
(134.22)
65
(1.84)
137
(3.87)
257
(7.27)
528
(14.95)
791
(22.39)
1520
(43.04)
2480
(70.22)
4290
(121.47)
60
(1.69)
126
(3.56)
237
(6.71)
486
(13.76)
728
(20.61)
1400
(39.64)
2230
(63.14)
3950
(111.85)
56
(1.58)
117
(3.31)
220
(6.23)
452
(12.79)
677
(19.17)
1300
(36.81)
2080
(58.89)
3670
(103.92)
52
(1.47)
110
(3.11)
207
(5.86)
424
(12.00)
635
(17.98)
1220
(34.55)
1950
(55.22)
3450
(97.69)
100
(30.480)
50
(1.42)
104
(2.94)
195
(5.52)
400
(11.33)
600
(17.00)
1160
(32.844)
1840
(52.10)
3260
(92.31)
MANUAL
MAIN SHUT−OFF
VALV E
GROUND
JOINT
UNION
Left Side Piping
(Standard)
DRIP LEG
AUTOMATIC
GAS VALVE
AUTOMATIC
GAS VALVE
(with manual
shut−off valve)
FIELD
PROVIDED
AND INSTALLED
NOTE − BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET
(with manual
shut−off valve)
FIGURE 17
MANUAL
MAIN SHUT−OFF
VALV E
GROUND
JOINT
UNION
DRIP LEG
Right Side Piping
(Alternate)
Page 17
Page 18
Leak Check
After gas piping is completed, carefully check all piping
connections (factory− and field−installed) for gas leaks. Use
a leak detecting solution or other preferred means.
NOTE − If emergency shutoff is necessary, shut off the main
manual gas valve and disconnect the main power to the
furnace. The installer should properly label these devices.
CAUTION
Some soaps used for leak detection are corrosive to
certain metals. Carefully rinse piping thoroughly after leak test has been completed. Do not use
matches, candles, flame or other sources of ignition
to check for gas leaks.
INTERIOR MAKE−UP BOX INSTALLATION
(Right Side)
MAKE−UP
BOX
The furnace must be isolated from the gas supply system
by closing its individual manual shut-off valve during any
pressure testing of the gas supply system at pressures
greater than or equal to 1/2 psig (3.48 kPa, 14 inches w.c.).
IMPORTANT
When testing pressure of gas lines, gas valve must
be disconnected and isolated. See figure 18. Gas
valves can be damaged if subjected to pressures
greater than 1/2 psig (3.48 kPa, 14 inches w.c.).
MANUAL MAIN
SHUT−OFF VALVE
WILL NOT HOLD
NORMAL TEST
PRESSURE
1/8 NPT PLUG
CAP
FIGURE 18
ISOLATE
GAS VALVE
FURNACE
Electrical
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can affect electronic components. Take precautions to
neutralize electrostatic charge by
touching your hand and tools to metal
prior to handling the control.
The unit is equipped with a field make−up box on the left
hand side of the cabinet. The make−up box may be moved
to the right side of the furnace to facilitate installation. If the
make−up box is moved to the right hand side, clip the wire
ties that bundle the wires together. Secure the excess wire
to the existing harness to protect it from damage.
Cut the two wire ties to extend power wires for right side only
FIGURE 19
Refer to figure 20 for schematic wiring diagram and troubleshooting and table 9 for field wiring.
The power supply wiring must meet Class I restrictions.
Protected by either a fuse or circuit breaker, select circuit
protection and wire size according to unit nameplate.
NOTE − Unit nameplate states maximum current draw.
Maximum over−current protection allowed is 15 AMP.
Holes are on both sides of the furnace cabinet to facilitate
wiring.
Install a separate (properly sized) disconnect switch near
the furnace so that power can be turned off for servicing.
Before connecting the thermostat, check to make sure the
wires will be long enough for servicing at a later date. Make
sure that thermostat wire is long enough to facilitate future
removal of blower for service.
Complete the wiring connections to the equipment. Use
18−gauge wire or larger that is suitable for Class II rating for
thermostat connections.
Electrically ground the unit according to local codes or, in
the absence of local codes, according to the current National Electric Code (ANSI/NFPA No. 70). A green ground
wire is provided in the field make−up box.
NOTE − The EL280DF furnace contains electronic components that are polarity sensitive. Make sure that the furnace
is wired correctly and is properly grounded.
Accessory Terminals
One line voltage EAC" 1/4" spade terminal is provided on
the furnace integrated control. See figure 21 for integrated
control configuration. This terminal is energized when the
indoor blower is operating. Any accessory rated up to one
amp can be connected to this terminal with the neutral leg
Page 18
Page 19
of the circuit being connected to one of the provided neutral
terminals. If an accessory rated at greater than one amp is
connected to this terminal, it is necessary to use an external relay.
One line voltage HUM" 1/4" spade terminnal is provided on
the furnace integrated control. See figure 21 for integrated
control configuration. This terminal is energized in the
heating mode when the combustion air inducer is operating. Any humidifier rated up to one amp can be connected
to this terminal with the neutral leg of the circuit being connected to one of the provided neutral terminals. If a humidifier rated at greater than one amp is connected to this terminal, it is necessary to use an external relay relay.
One 24V "H" 1/4" spade terminal is provided on the furnace
integrated control. See figure 21 for integrated control configuration. The terminal is energized in the heating mode
when the combustion air inducer is operating and the pressure switch is closed. Any humidifier rated up to 0.5 amp
can be connected to this terminal with the ground leg of the
circuit connected to ground or the "C" terminal.
Generator Use − Voltage Requirements
The following requirements must be kept in mind when
specifying a generator for use with this equipment:
S The furnace requires 120 volts +
10% (Range: 108
volts to 132 volts).
S The furnace operates at 60 Hz +
63 Hz).
S The furnace integrated control requires both proper
polarity and proper ground. Both polarity and proper
grounding should be checked before attempting to operate the furnace on either permanent or temporary
power.
S Generator should have a wave form distortion of less
than 5% total harmonic distortion (THC).
Thermostat
Install the room thermostat according to the instructions
provided with the thermostat. See table 9 for thermostat
designations. If the furnace is being matched with a heat
pump, refer to the FM21 installation instruction or appropriate dual fuel thermostat instructions.
Indoor Blower Speeds
1 − When the thermostat is set to FAN ON," the indoor
blower will run continuously on the low heat speed
when there is no cooling or heating demand.
2 − When the EL280DF is operating in the high−fire or low−
fire heating mode, the indoor blower will run on the corresponding heating speed.
3 − When the EL280DF is operating in the low cool or the
high cool cooling mode, the indoor blower will run on
the corresponding cooling speed.
5% (Range: 57 Hz to
Page 19
Page 20
Thermostat
TABLE 9
Field Wiring Applications
DIP Switch Settings and On−Board Links (See figure 21)
W915
DIP Switch 1
Two−Stage
Cooling
W951
Heat Pumps
Wiring Connections
1 Heat / 1 Cool
NOTE − Use DIP
switch 2 to set second−stage heat ON
delay.
OFF10 minutes.
ON−15 minutes.
1 Heat / 2 Cool
NOTE − Use DIP
switch 2 to set second−stage heat ON
delay.
OFF−10 minutes.
ON−15 minutes.
ON Intact Intact
ON Cut Intact
S1
T’STAT
S1
T’STAT
CONTROL
TERM. STRIP
CONTROL
TERM. STRIP
OUTDOOR
UNIT
OUTDOOR
UNIT
Page 20
Page 21
Thermostat
TABLE 9
Field Wiring Applications (Continued)
DIP Switch Settings and On−Board Links (See figure 21)
W915
DIP Switch 1
Two−Stage
Cooling
W951
Heat Pumps
Wiring Connections
2 Heat / 2 Cool OFF Cut Intact
2 Heat / 1 Cool OFF Intact Intact
S1
T’STAT
S1
T’STAT
CONTROL
TERM. STRIP
CONTROL
TERM. STRIP
OUTDOOR
UNIT
OUTDOOR
UNIT
Page 21
Page 22
EL280DF Schematic Wiring Diagram
FIGURE 20
Page 22
Page 23
Integrated Control
DIAGNOSTIC
LEDs
DIP
SWITCHES
TWO−STAGE INTEGRATED CONTROL
1/4" QUICK CONNECT TERMINALS
SENSE = 120 VAC OUTPUT TO FLAME SENSER
NEUTRALS= 120 VAC NEUTRAL
PARK = DEAD TERMINAL FOR UNUSED BLOWER LEAD
HEAT LOW = 120 VAC OUTPUT TO CIRC BLWR −− LOW HT SPEED
ON−BOARD
LINKS
HEAT HIGH/ COOL LOW = 120 VAC OUTPUT TO CIRC BLWR −−
COOL HIGH = 120 VAC OUTPUT TO CIRC BLWR −− HIGH COOL SPEED
THERMOSTAT CONNECTIONS (TB1)
1= ERROR CODE RECALL
H= 24V HUMIDIFIER OUTPUT
L= LENNOX SYSTEM OPERATION MONITOR
HIGH HEAT AND LOW COOL SPEED
W915
W951
DIP SWITCH(ES) FUNCTION
1 −− 2 Stage T’stat Selects t/stat type (single or two−stage)
2 −− 2nd Stage Delay Second stage ON delay (single−stage t’stat)
3 & 4 −− Heat Off Delay Heating fan OFF delay
5 −− Cool Off Delay Cooling fan OFF delay
FIGURE 21
EL280DF units are equipped with a two−stage integrated
control. This control manages ignition timing and fan off
delays based on selections made using the control DIP
switches and jumpers. The control includes an internal
watchguard feature which automatically resets the ignition
control when it has been locked out. After one hour of continuous thermostat demand for heat, the watchguard will
break and remake thermostat demand to the furnace and
automatically reset the control to relight the furnace.
DIP Switch Settings
Switch 1 −− Thermostat Selection −− This unit may be used
with either a single−stage or two−stage thermostat. The
thermostat selection is made using a DIP switch which
must be properly positioned for the particular application.
The DIP switch is factory−positioned for use with a two−
stage thermostat. If a single−stage thermostat is to be used,
the DIP switch must be repositioned.
Select OFF" for two−stage heating operation con-
trolled by a two−stage heating thermostat (factory setting);
b − Select ON" for two−stage heating operation con-
trolled by a single−stage heating thermostat. This setting provides a timed delay before second−stage heat
is initiated.
DIP SWITCH FUNCTIONS
Switch 2 −− Second Stage Delay (Used with Single−
Stage Thermostat Only) −− This switch is used to deter-
mine the second stage on delay when a single−stage thermostat is being used. The switch is factory−set in the OFF
position, which provides a 10−minute delay before second−
stage heat is initiated. If the switch is toggled to the ON
position, it will provide a 15−minute delay before second−
stage heat is initiated. This switch is only activated when
the thermostat selector jumper is positioned for SINGLE−
stage thermostat use.
Switches 3 and 4 −− Heating Blower−Off Delay −− The
heating blower−on delay of 45 seconds is not adjustable.
The heating blower−off delay (time that the blower operates
after the heating demand has been satisfied) can be adjusted by moving switches 3 and 4 on the integrated control. The unit is shipped from the factory with a heating
blower−off delay of 90 seconds. The heating blower off
delay affects comfort and is adjustable to satisfy individual
applications. Adjust the blower off delay to achieve a supply air temperature between 90° and 110°F at the exact
moment that the blower is de−energized. Longer off delay
Page 23
Page 24
settings provide lower supply air temperatures; shorter settings provide higher supply air temperatures.Table 10 provides the blower off timings that will result from different
switch settings.
Heating Blower−Off Delay Switch Settings
Blower Off Delay
(Seconds)
60 Off On
90
(factory setting)
120 On Off
180 On On
Switch 5 −− Cooling Blower−Off Delay −− The cooling
blower−off delay (time that the blower operates after the
cooling demand has been satisfied) can be adjusted by
moving switch 5 on the integrated control. The switch is factory−set in the OFF position, which provides a cooling blower−off delay of 45 seconds. If the switch is toggled to the ON
position, it will provide a 2−second cooling blower−off delay
On−Board Link W951
On−board link W951 is a clippable connection between terminals R and O on the integrated control. W951 must be cut
when the furnace is installed in applications which include a
heat pump unit and a thermostat which features dual fuel
use. If the link is left intact, terminal O" will remain energized eliminating the HEAT MODE in the heat pump.
On−Board Link W915
On−board link W915 is a clippable connection between terminals Y1 and Y2 on the integrated control. W915 must be
cut if two−stage cooling will be used. If the link is not cut the
outdoor unit will operate in second−stage cooling only.
TABLE 10
Switch 3 Switch 4
Off Off
CAUTION
Before attempting to perform any service or maintenance, turn the electrical power to unit OFF at disconnect switch.
BEFORE LIGHTING smell all around the appliance area for
gas. Be sure to smell next to the floor because some gas is
heavier than air and will settle on the floor.
The gas valve on the EL280DF unit will be equipped with a
gas control switch. Use only your hand to move the switch.
Never use tools. If the switch will not turn or if the control
switch will not move by hand, do not try to repair it.
Placing the furnace into operation:
EL280DF units are equipped with an automatic ignition
system. Do not attempt to manually light burners on these
furnaces. Each time the thermostat calls for heat, the
burners will automatically light. The ignitor does not get
hot when there is no call for heat on units with an automatic
ignition system.
WARNING
If you do not follow these instructions exactly, a fire
or explosion may result causing property damage,
personal injury or death.
Unit Start−Up
FOR YOUR SAFETY READ BEFORE LIGHTING
WARNING
Do not use this furnace if any part has been underwater. A flood−damaged furnace is extremely dangerous. Attempts to use the furnace can result in
fire or explosion. Immediately call a qualified service technician to inspect the furnace and to replace
all gas controls, control system parts, and electrical
parts that have been wet or to replace the furnace,
if deemed necessary.
WARNING
If overheating occurs or if gas supply fails to shut off,
shut off the manual gas valve to the appliance before
shutting off electrical supply.
Gas Valve Operation (Figure 22)
1 − STOP! Read the safety information at the beginning of
this section.
2 − Set the thermostat to the lowest setting.
3 − Turn off all electrical power to the unit.
4 − This furnace is equipped with an ignition device which
automatically lights the burners. Do not try to light the
burners by hand.
5 − Remove the upper access panel.
6 − Move switch on gas valve to OFF. Do not force. See
figure 22.
7 − Wait five minutes to clear out any gas. If you then smell
gas, STOP! Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s instructions. If you do not smell gas go to next step.
Page 24
Page 25
INLET PRESSURE POST
GAS VALVE SHOWN IN ON POSITION
MANIFOLD
PRESSURE TAP
HIGH FIRE ADJUSTMENT
SCREW
(under cap)
FIGURE 22
8 − Move switch on gas valve to ON. Do not force. See fig-
ure 22.
9 − Replace the upper access panel.
10− Turn on all electrical power to to the unit.
11− Set the thermostat to desired setting.
NOTE − When unit is initially started, steps 1 through 11
may need to be repeated to purge air from gas line.
12− If the appliance will not operate, follow the instructions
Turning Off Gas to Unit" and call your service technician or gas supplier.
Turning Off Gas to Unit
1 − Set the thermostat to the lowest setting.
2 − Turn off all electrical power to the unit if service is to be
performed.
3 − Remove the upper access panel.
4 − Move switch on gas valve to OFF. Do not force.
5 − Replace the upper access panel.
Failure To Operate
If the unit fails to operate, check the following:
1 − Is the thermostat calling for heat?
2 − Are access panels securely in place?
3 − Is the main disconnect switch closed?
4 − Is there a blown fuse or tripped circuit breaker?
5 − Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit control to shut the unit off.
6 − Is gas turned on at the meter?
7 − Is the manual main shut-off valve open?
8 − Is the internal manual shut-off valve open?
9 − Is the unit ignition system in lock out? If the unit locks out
again, call the service technician to inspect the unit for
blockages.
10 − Is pressure switch closed? Obstructed flue will cause
unit to shut off at pressure switch. Check flue and outlet
for blockages.
11 − Are flame rollout switches tripped? If flame rollout
switches are tripped, call the service technician for in-
spection.
Gas Pressure Adjustment
Gas Flow (Approximate)
TABLE 11
GAS METER CLOCKING CHART
Seconds for One Revolution
EL280DF
Unit
−045 80 160 200 400
−070 55 11 0 136 272
−090 41 82 102 204
−110 33 66 82 164
−135 27 54 68 136
Natural−1000 btu/cu ft LP−2500 btu/cu ft
Furnace should operate at least 5 minutes before checking gas flow. Determine time in seconds for two revolutions of gas through the meter. (Two revolutions assures a
more accurate time.) Divide by two and compare to time
in table 11. If manifold pressure matches table 13 and rate
is incorrect, check gas orifices for proper size and restriction. Remove temporary gas meter if installed.
NOTE − To obtain accurate reading, shut off all other gas
appliances connected to meter.
Supply Pressure Measurement
An inlet post located on the gas valve provides access to
the supply pressure. See figure 22. Back out the 3/32 hex
screw one turn, connect a piece of 5/16 tubing and connect
to a manometer to measure supply pressure. See table 13
for supply line pressure.
Manifold Pressure
NOTE − Pressure test adapter kit (10L34) is available from
Lennox to facilitate manifold pressure measurement.
1 − Connect test gauge to manifold pressure tap (figure
22) gas valve.
2 − Ignite unit on high fire and let run for 5 minutes to allow
for steady state conditions.
3 − After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in table
13.
4 − If necessary, make adjustments. Figure 22 shows
location of high fire adjustment screw.
5 − If an adjustment is made on high fire, re−check man-
ifold pressure on low fire. Do not adjust low fire man-
ifold pressure. If low fire manifold pressure is more
than 1/2" above or below value specified in table 13,
replace valve.
NOTE − Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to remove
barbed fitting and replace threaded plug.
Natural LP
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
DIAL
Page 25
Page 26
Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking combustion. Table 12 shows acceptable combustion for ALL
EL280DF models. The maximum carbon monoxide
reading should not exceed 50 ppm
TABLE 12
Firing Rate
High Fire 6.8 − 7.4 7.5 − 9.0
Low Fire 4.2 − 5.7 5.0 − 6.0
CO2%
For Nat
CO2%
For L.P.
TABLE 13
Manifold Pressure Settings at all Altitudes
High Altitude
The manifold pressure may require adjustment and combustion air pressure switch may need replacing to ensure
proper combustion at higher altitudes. Refer to table 13 for
manifold pressure and table 14 for pressure switch change
and gas conversion kits.
IMPORTANT
For safety, shut unit off and remove manometer as
soon as an accurate reading has been obtained.
Take care to replace pressure tap plug.
Manifold
Unit
Input
070
090
110
1
This is the only permissible derate for these units.
2
Natural gas high altitude orifice kit required.
3
A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruction for the conversion
procedure.
NOTE − Units may be installed at altitudes up to 4500 ft. above sea level without modifications.
Gas
Natural 1.7 3.5 1.5 3.2 1.7 3.5 4.5 13.0
LP/propane
Natural 1.7 3.5 1.5 3.0 1.7 3.5 4.5 13.0
LP/propane
Natural 1.7 3.5 1.5 3.2 1.7 3.5 4.5 13.0
LP/propane
3
3
3
Pressure in.wg.
0−4500 ft.
Low Fire High Fire Low Fire High Fire Low Fire High Fire Min Max
4.9 10.0 4.9 10.0 4.9 10.0 11.0 13.0
4.9 10.0 4.9 10.0 4.9 10.0 11.0 13.0
4.9 10.0 4.9 10.0 4.9 10.0 11.0 13.0
Manifold
Pressure in.wg.
4501−7500 ft.
1
Manifold
Pressure in.wg.
7501 − 10,000 ft.
Supply Line
2
Pressure
in. w.g.
TABLE 14
Pressure Switch and Gas Conversion Kits at all Altitudes
Unit
Input
070
090 73W36
110 73W35
High Altitude Pressure Switch Kit
0 − 4500 ft. 4501 − 7500 ft. 7501 − 10,000 ft. 7501 − 10,000 ft. 0 − 7500 ft 7501 − 10,000 ft. 0 − 7500 ft.Min
73W36
No Change No Change
High Altitude
Natural Gas Kit
73W37 77W07 77W11 77W09
LP/Propane Gas Kit
LP/Propane to
Natural Kit
NOTE − A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruction for the conversion
procedure.
Page 26
Page 27
Other Unit Adjustments
Primary and Secondary Limits
The primary limit is located on the heating compartment
vestibule panel. The secondary limits (if equipped) are located in the blower compartment, attached to the back side
of the blower. These auto reset limits are factory−set and require no adjustment.
Flame Rollout Switches
These manually reset switches are located on the burner
box.
Pressure Switch
The pressure switch is located in the heating compartment
adjacent to the combustion air inducer. The switch checks
for proper combustion air inducer operation before allowing ignition trial. The switch is factory−set and requires no
adjustment.
Temperature Rise
After the furnace has been started, and supply and return
air temperatures have been allowed to stabilize, check the
temperature rise. If necessary, adjust the blower speed to
maintain the temperature rise within the range shown on
the unit nameplate. Increase the blower speed to decrease
the temperature. Decrease the blower speed to increase
the temperature rise. Failure to adjust the temperature rise
may cause erratic limit operation.
Fan Control
The fan−on time of 30 seconds is not adjustable. The heat
fan−off delay (amount of time that the blower operates after
the heat demand has been satisfied) may be adjusted by
changing DIP switches 3 and 4. See figure 23 and table 10.
The unit is shipped with a factory fan−off delay setting of 90
seconds. The fan−off delay affects comfort and is adjustable to satisfy individual applications. Adjust the fan−off
delay to achieve a supply air temperature between 90° and
110°F at the moment that the blower is de−energized. Longer off delay settings provide lower return air temperatures;
shorter settings provide higher return air temperatures.
See figure 23.
HEAT FAN-OFF TIME IN SECONDS
60sec.
12345 12345
120sec.
12345 12345
To adjust fan−off timing, flip dip switch to desired setting.
90sec.
180sec.
FIGURE 23
Input Voltage Requirements
The circuit is designed to be operated with AC voltage. A
voltage of 12 to 33VAC is required to energize the motor.
Expected current draw will be less than 20mA.
Blower Speeds
Follow the steps below to change the blower speeds.
1 − Turn off electrical power to furnace.
2 − Remove blower access panel.
3 − Disconnect existing speed tap at integrated control
speed terminal.
NOTE − Termination of any unused motor leads must be
insulated.
4 − Place unused blower speed tap on integrated control
PARK" terminal or insulate.
5 − Refer to blower speed selection chart on unit wiring dia-
gram for desired heating or cooling speed. See Blower
performance data beginning on the next page.
6 − Connect selected speed tap at integrated control
speed terminal.
7 − Resecure blower access panel.
8 − Turn on electrical power to furnace.
9 − Recheck temperature rise.
Electronic Ignition
The integrated control has an added feature of an internal
Watchguard control. The feature serves as an automatic reset device for integrated control lockout caused by ignition
failure. This type of lockout is usually due to low gas line
pressure. After one hour of continuous thermostat demand
for heat, the Watchguard will break and remake thermostat
demand to the furnace and automatically reset the integrated control to begin the ignition sequence.
Page 27
Page 28
Heating Sequence of Operation
When there is a call for heat, the integrated control runs a
self check. The control checks for S10 primary limit, S21
secondary limit (s) and S47 rollout switch normally closed
contacts. The control also checks for S102 high heat and
S128 low heat prove switch normally open contacts. Once
self check is complete and all safety switches are operational, heat call can continue.
Two−Stage Thermostat, Two Stage Heat. Dip Switch
set at TWO".
1− SureLight control energizes combustion air inducer B6
on low heat speed. Combustion air inducer runs until
S128 low heat prove switch contacts close (switch
must close within 2 1/2 minutes or control goes into
Watchguard Pressure Switch mode. High heat prove
switch S102 may also close). A 15 second pre−purge
follows once S128 closes.
NOTE − If the low fire pressure switch does not close the
combustion air inducer will switch to high fire. After a 15
second pre−purge the high fire pressure switch will close
and the unit will begin operation on high fire. After 10 to 20
seconds of high fire operation the unit will switch to low fire.
NOTE − If the furnace is operating on continuous fan mode
(terminal R" and G" are energized), the combustion air inducer will energize on high speed, the gas valve will energize on second−stage heat and the furnace will operate on
high fire. Furnace will stay on high fire for 60 seconds then
switch to low fire.
2− SureLight control begins 20 second ignitor warm up
period.
3− Gas valve opens on first stage for a 4 second trial for
ignition. Ignitor stays energized during the trial or until
flame sensed.
4− Flame is sensed, gas valve remains on first stage heat,
ignitor de−energizes.
5− After 30 second delay, indoor blower B3 is energized
on low heat speed.
The furnace will stay in this mode until first stage demand is satisfied OR a second stage heat demand is
initiated.
6− Second stage heat demand initiated. A 30 second sec-
ond stage recognition period begins.
7− The combustion air inducer ramps up to high heat
speed.
8− S102 high heat prove switch closes and the gas valve
energizes second stage heat.
9− B3 indoor blower switches to high heat speed.
Single−Stage Thermostat, Two Stage Heat. Dip
Switch set at SINGLE"
1− SureLight control energizes combustion air inducer B6
on low heat speed. Combustion air inducer runs until
S128 low heat prove switch contacts close (switch
must close within 2 1/2 minutes or control goes into
Watchguard Pressure Switch mode. High heat prove
switch S102 may also close). A 15 second pre−purge
follows once S128 closes.
NOTE − If the low fire pressure switch does not close the
combustion air inducer will switch to high fire. After a 15
second pre−purge the high fire pressure switch will close
and the unit will begin operation on high fire. After 10 to 20
seconds of high fire operation the unit will switch to low fire.
NOTE − If the furnace is operating on continuous fan mode
(terminal R" and G" are energized), the combustion air inducer will energize on high speed, the gas valve will energize on second−stage heat and the furnace will operate on
high fire. Furnace will stay on high fire for 60 seconds then
switch to low fire.
2− SureLight control begins 20 second ignitor warm up
period.
3− Gas valve opens on first stage for a 4 second trial for
ignition. Ignitor stays energized during the trial or until
flame sensed.
4− Flame is sensed, gas valve remains on first stage heat,
ignitor de−energizes.
5− After 30 second delay, indoor blower B3 is energized
on low heat speed.
6− A 10 minute (factory set) or 15 minute (field set) second
stage heat delay period begins.
7− After the delay the combustion air inducer ramps up to
high heat speed.
8− S102 high heat prove switch closes and the gas valve
energizes second stage heat.
9− B3 indoor blower switches to high heat speed.
Page 28
Page 29
Service
WARNING
ELECTRICAL SHOCK, FIRE,
OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly could result
in dangerous operation, serious injury, death or
property damage.
Improper servicing could result in dangerous operation, serious injury, death, or property damage.
Before servicing, disconnect all electrical power to
furnace.
When servicing controls, label all wires prior to disconnecting. Take care to reconnect wires correctly.
Verify proper operation after servicing.
At the beginning of each heating season, a licensed professional technician (or equivalent) should check the system
as follows:
Blower
Check the blower wheel for debris and clean if necessary.
The blower motors are prelubricated for extended bearing
life. No further lubrication is needed.
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.
Electrical
1 − Check all wiring for loose connections.
2 − Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 120VAC +
3 − Check amp−draw on the blower motor with blower ac-
cess panel in place.
Unit Nameplate__________Actual__________
Cleaning the Burners
NOTE − Use papers or protective covering in front of the furnace during cleaning.
1 − Turn off both electrical and gas power supplies to fur-
nace.
3 − Label the wires from gas valve, rollout switches, prima-
ry limit switch and make−up box then disconnect them.
4 − Disconnect gas supply piping. Remove the four screws
securing the burner manifold assembly to the vestibule
panel and remove the assembly from the unit.
5 − Remove 4 screws securing burner box and remove
burner box.
6− To clean burners, run a vacuum cleaner with a soft brush
attachment over the face of burners. Visually inspect inside the burners and crossovers for any blockage
caused by foreign matter. Remove any blockage. Figure
24 shows burner detail.
7− Reinstall burner box, manifold assembly and burner box
cover.
8− Reconnect all wires.
9− Reconnect gas supply piping.
10− Turn on power and gas supply to unit.
11− Set thermostat and check for proper operation.
12− Check all piping connections, factory and field, for gas
leaks. Use a leak detecting solution or other preferred
means.
10%.
Filters
All EL280DF filters are installed external to the unit. Filters
should be inspected monthly. Clean or replace the filters
when necessary to ensure that the furnace operates properly. Replacement filters must be rated for high velocity airflow. Table 3 lists recommended filter sizes.
Flue And Chimney
1 − Check flue pipe, chimney and all connections for tight-
ness and to make sure there is no blockage.
2 − Check unit for proper draft.
CAUTION
Some soaps used for leak detection are corrosive to
certain metals. Carefully rinse piping thoroughly after leak test has been completed. Do not use
matches, candles, flame or other sources of ignition
to check for gas leaks.
13− If a leak is detected, shut gas and electricity off and
repair leak.
14− Repeat steps 12 and 13 until no leaks are detected.
15− Replace access panel.
Page 29
Page 30
burner box assembly
EL280DF BURNER, COMBUSTION AIR INDUCER ASSEMBLY &
HEAT EXCHANGER REMOVAL
burners
manifold and gas valve
FIGURE 24
Repair Parts List
The following repair parts are available through independent Lennox dealers. When ordering parts, include the
complete furnace model number listed on the CSA International nameplate −− Example: EL280DF110P60C.
All service must be performed by a licensed professional installer (or equivalent), service agency, or gas
supplier.
Cabinet Parts
Main access panel
Blower access panel
Top cap
Control Panel Parts
Transformer
Integrated control
Door interlock switch
Circuit breaker
retention rings
cross over
Blower Parts
Blower wheel
Blower housing
Motor
Motor mounting frame
Blower housing cutoff plate
Heating Parts
Flame Sensor
Heat exchanger assembly
Gas manifold
Combustion air inducer
Gas valve
Main burner cluster
Main burner orifices
Pressure switches
Ignitor
Primary limit control
Flame rollout switch
Secondary limit
Page 30
Page 31
Start−Up & Performance Check List
Unit Model Number_______________
UNIT SET UP
(typical)
2
2
1
GAS SUPPLY
1
Natural Gas
Piping Connections Tight
Leak Tested
Serial Number___________________
Line Voltage
5
Gas Supply Pressure
1
LP/Propane Gas
SUPPLY
AIR
upflow furnace shown
3
Filter
RETURN
RETURN
AIR
4
3
DUCT SYSTEM
AIR
SUPPLY AIR DUCT
Sealed
Insulated (if necessary)
Supply Line Pressure W.C.________
VENT / EXHAUST PIPE
2
Secure to Unit
Elbows Secured to Pipe
Roof Flashing (water tight)
Vent Pipe Supported
Page 31
Registers Open and Unobstructed
RETURN DUCT
Sealed
Filter Installed and Clean
Grilles Unobstructed
INTEGRATED CONTROL
4
DIP Switches Set (if applicable)
Appropriate Links in Place (if applicable)
5
VOLTAGE CHECK
Supply Voltage _____
Electrical Connections Tight
Page 32
UNIT OPERATION
(typical)
Combustion CO
2
Gas Manifold Pressure
1
Blower Motor Amps
3
7
2
Thermostat
SUPPLY
AIR
6
upflow furnace shown
RETURN
RETURN
AIR
AIR
Temperatures
4
Filter
Duct Static
5
HEATING MODE
GAS MANIFOLD PRESSURE W.C._____
1
2
COMBUSTION SAMPLE CO
INDOOR BLOWER AMPS______
3
TEMPERATURE RISE
4
2%______
Supply Duct Temperature ________
Return Duct Temperature _ _____
Temperature Rise = ________
TOTAL EXTERNAL STATIC (dry coil)
5
Supply External Static _______
CO PPM_______
3
4
5
6
COOLING MODE
INDOOR BLOWER AMPS______
TEMPERATURE DROP
Return Duct Temperature _________
Supply Duct Temperature
Temperature Drop = _________
TOTAL EXTERNAL STATIC (dry coil)
Supply External Static _______
Return External Static + ______
Total External Static = _______
DRAIN LINE
Leak Free
Return External Static + ______
7
Total External Static = _______
THERMOSTAT
Adjusted and Programmed
Operation Explained to Owner
Contractor’s: Name_________________________Telephone_____________Checklist Completed____________________
_ _______
Job Address_____−________________________________Technician’s Name___________________________________
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