INSTALLATION
INSTRUCTIONS
E 2012 Lennox Industries Inc.
Dallas, Texas, USA
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
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person-
al injury or loss of life. Installation and service must
be performed by a licensed professional installer (or
equivalent), service agency or the gas supplier.
UPFLOW
AIR FLOW
CAUTION
As with any mechanical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
AIR FLOW
AIR 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
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
Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Duct System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
02/12
506894−01
Page 1
*2P0212*
*P506894-01*
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Parts Arrangement
Make Up Box
Heat Exchanger
Combustion Air
Inducer
Combustion Air
Pressure Switch
Gas Valve and Manifold
Assembly
Collector Box
Indoor Blower and Motor Assembly
(installed in cabinet)
Limit Switch
(under collector box)
Transformer
Door Interlock
Switch
Integrated Control
Indoor Blower and Motor Assembly
(removed from cabinet)
FIGURE 1
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EL280UH Gas Furnace
CAUTION
The EL280UH unit is shipped ready for installation in the
upflow or horizontal right position (for horizontal left posi-
tion 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 re-
moved in upflow applications.
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:
Shipping and Packing List
Package 1 of 1 contains
1 − Assembled EL280UH unit
1 − Bag assembly containing the following:
2 −Screws
American National Standards Institute, Inc.
11 West 42nd Street
New York, NY 10036
1 −Snap bushing
Clearances
1 −Snap plug
Adequate clearance must be made around the air open-
ings 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.
1 − Wire tie
1 −Vent warning label
1 −Owner’s manual and warranty card
The following items may be ordered separately:
1 − Thermostat
Vent installations must be consistent with the venting
tables (in this instruction) and applicable provisions of local
building codes.
1 − Suspension kit (for horizontal installations)
1 − Propane/LP changeover kit
1 − Return air base
This furnace is CSA International certified for installation
clearances to combustible material as listed on the unit
and service clearances must take precedence over fire
protection clearances.
1 − High altitude kit
1 − Side filter kit
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
NOTE − For installation on combustible floors, the furnace
shall not be installed directly on carpeting, tile, or other
combustible material other than wood flooring.
Safety Information
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 apublic garage, hangar, or other building that has a haz-
ardous atmosphere, the furnace must be installed accord-
ing to recommended good practice requirements and cur-
rent National Fuel Gas Code.
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.
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.
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person-
al injury or loss of life. Installation and service must
be performed by a licensed professional installer (or
equivalent), service agency or the gas supplier.
This EL280UH furnace must be installed so that its electri-
cal components are protected from water.
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Installed in Combination with a Cooling Coil
This furnace design has not been CSA International
certified for installation in mobile homes, recreational
vehicles, or outdoors.
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.
other means to control the flow of air) must adequately pre-
vent 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
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 op-
eration of the unit with clogged or misplaced filters will dam-
age the unit.
EL280UH units may be used for heating of buildings or
structures under construction, if the following conditions
are met:
Heating Unit Installed Parallel to Cooling Coil
D The vent system must be permanently installed per
these installation instructions.
Dampers
(open during heating operation only)
D A room thermostat must control the furnace. The use of
fixed jumpers that will provide continuous heating is not
allowed.
Gas Unit
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.
Cooling Coil
D Air filters must be installed in the system and must be
maintained during construction.
Dampers
(open during cooling operation only)
D Air filters must be replaced upon construction comple-
tion.
Heating Unit Installed Upstream of Cooling Unit
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 construc-
tion. 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.
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 Elec-
tric Code, ANSI/NFPA No. 70. The National Electric Code
(ANSI/NFPA No. 70) is available from the following ad-
dress:
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.
National Fire Protection Association
1 Battery March Park
General
Quincy, MA 02269
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
NOTE − This furnace is designed for a minimum continu-
ous return air temperature of 60°F (16°C) or an intermit-
tent operation down to 55°F (13°C) dry bulb for cases
where a night setback thermostat is used. Return air tem-
perature must not exceed 85°F (29°C) dry bulb.
In addition to the requirements outlined previously, the fol-
lowing general recommendations must be considered
when installing a EL280UH furnace:
The EL280UH furnace may be installed in alcoves, closets,
attics, basements, garages, crawl spaces and utility rooms
in the upflow or horizontal position.
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.
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D Do not install the furnace where drafts might blow direct-
ly into it. This could cause improper combustion and un-
safe operation.
A portion of this information has been reprinted with per-
mission from the National Fuel Gas Code (ANSI-Z223.1).
This reprinted material is not the complete and official posi-
tion of the ANSI on the referenced subject, which is repre-
sented only by the standard in its entirety.
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.
CAUTION
Do not install the furnace in a corrosive or contami-
nated atmosphere. Meet all combustion and ventila-
tion air requirements, as well as all local codes.
NOTE − The Commonwealth of Massachusetts stipu-
lates 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.
CAUTION
Insufficient combustion air can cause headaches,
nausea, dizziness or asphyxiation. It will also cause
excess water in the heat exchanger resulting in rust-
ing 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 combus-
tion air supply:
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 Cal-
ifornia to cause cancer.)
Permanent wave solutions
Chlorinated waxes and cleaners
Chlorine base swimming pool chemicals
Water softening chemicals
De-icing salts or chemicals
Fiberglass wool may also cause respiratory, skin,
and eye irritation.
Carbon tetrachloride
Halogen type refrigerants
To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact your
supervisor.
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
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900
All gas-fired appliances require air for the combustion pro-
cess. If sufficient combustion air is not available, the fur-
nace or other appliances will operate inefficiently and un-
safely. 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, ex-
haust 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.
Combustion, Dilution & Ventilation Air
In the past, there was no problem in bringing in sufficient out-
door 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 combus-
tion. 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 liv-
ing space creating a potentially dangerous situation.
In addition to providing combustion air, fresh outdoor air
dilutes contaminants in the indoor air. These contami-
nants may include bleaches, adhesives, detergents, sol-
vents and other contaminants which can corrode furnace
components.
In the absence of local codes concerning air for combus-
tion 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.
The requirements for providing air for combustion and ven-
tilation depend largely on whether the furnace is installed in
an unconfined or a confined space.
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Unconfined Space
Air from Inside
An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
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
3
feet (1.42 m ) per 1,000 Btu (.29 kW) per hour of the com-
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 un-
confined, 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.
2
square inch (645 mm ) 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
2
(64516 mm ). One opening shall be within 12 inches (305
mm) of the top of the enclosure and one opening within 12
Air from Outside
If air from outside is brought in for combustion and ventila-
tion, the confined space must have two permanent open-
ings. 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 di-
rectly or by ducts with the outdoors or spaces (crawl or at-
tic) that freely communicate with the outdoors or indirectly
through vertical ducts. Each opening shall have a minimum
Confined Space
A confined space is an area with a volume less than 50 cu-
3
bic feet (1.42 m ) 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 contain-
ing 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.
2
free area of 1 square inch (645 mm ) per 4,000 Btu (1.17
kW) per hour of total input rating of all equipment in the en-
the outdoors through horizontal ducts, each opening shall
2
have a minimum free area of 1 square inch (645 mm ) 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−sec-
tional 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 cov-
ering is not known for calculating the size opening required,
it may be assumed that wood louvers will have 20 to 25 per-
cent 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.
EQUIPMENT IN CONFINED
SPACE ALL AIR FROM INSIDE
CHIMNEY
OR GAS
VENT
WATER
HEATER
FURNACE
OPENINGS
(To Adjacent
Room)
NOTE − Each opening shall have a free area of at least one square
2
inch (645 mm ) per 1,000 Btu (.29 kW) per hour of the total input rat-
ing of all equipment in the enclosure, but not less than 100 square
2
inches (64516 mm ).
FIGURE 3
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EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
(Inlet Air from Crawlspace and Outlet Air to Ventilated Attic)
CHIMNEY OR
GAS VENT
VENTILATION LOUVERS
(Each end of attic)
OUTLET
AIR
WATER
HEATER
FURNACE
INLET
AIR
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.
FIGURE 4
EQUIPMENT IN
CONFINED SPACE
ALL AIR FROM
OUTSIDE
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
(All Air Through Ventilated Attic)
CHIMNEY
OR GAS
VENT
CHIMNEY
OR GAS
VENT
WATER
HEATER
VENTILATION LOUVERS
(Each end of attic)
OUTLET AIR
OUTLET
AIR
FURNACE
FURNACE
INLET AIR
(Ends 12 in.
above bottom)
INLET AIR
WATER
HEATER
NOTE − Each air duct opening shall have a free area of at least one
2
square inch (645 mm ) per 2,000 Btu (.59 kW) per hour of the total
NOTE−The inlet and outlet air openings shall each have a
2
input rating of all equipment in the enclosure. If the equipment room
is located against an outside wall and the air openings communi-
cate 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.
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 equip-
ment in the enclosure.
2
FIGURE 5
FIGURE 6
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Upflow Applications
Setting Equipment
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or al-
WARNING
Do not install the furnace on its front or its back. Do
not connect the return air ducts to the back of the fur-
nace. Doing so will adversely affect the operation of
the safety control devices, which could result in per-
sonal injury or death.
Upflow Application Installation Clearances
Top
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.
Left Side
Right Side
NOTE − Units with 1/2 hp blower motors are equipped with
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 opera-
tion. After the bolt and washer have been removed, the rig-
id leg will not touch the blower housing.
Bottom
Type C
Type of Vent
Connector
Type B1
Top
*Front
Back
Sides
Vent
1 in. (25 mm)
1 in. (25 mm)
2−1/4 in. (57 mm)**
2−1/4 in. (57 mm)
0
0
0†
6 in. (152 mm)
0‡
0
1 in. (25 mm)
0‡
EL280UH090P48B and
EL280UH110P48C with 1/2 HP
BLOWER MOTOR
Floor
*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.
RIGID LEG
remove shipping bolt and washer
†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.
FIGURE 8
FIGURE 7
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Return Air −− Upflow Applications
Single Side Return Air
(with transition and filter)
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.
20” X 25” X 1”
(508mm X 635mm X 25mm)
Cleanable Filter
Markings are provided on both sides of the furnace cabinet
for installations that require side return air. Cut the furnace
cabinet at the maximum dimensions shown on page 2.
NOTE −60C and 60D units that require air volumes over 1800
cfm (850 L/s) must have one of the following:
Return Air
Plenum
1 − Single side return air with transition to accommodate 20
x 25 x 1 in. (508 x 635 x 25 mm) cleanable air filter. (Re-
quired to maintain proper air velocity.) See figure 9.
AIR FLOW
2 − Single side return air with optional return airbase. See fig-
Transition
3 − Bottom return air.
4 − Return air from both sides.
5 − Bottom and one side return air.
Refer to Engineering Handbook for additional information.
FIGURE 9
Optional Return Air Base
(Upflow Applications Only −− For use with A, B, C and D cabinets)
FURNACE
FRONT
1 23 (584)
IF BASE
3−1/4
(83)
IS USED
WITHOUT
IAQ CABINET,
A SINGLE
RETURN AIR
PLENUM
Overall
1 Minimum
11 (279)
(Maximum)
INDOOR AIR
2
1 22−7/16
(570)
Maximum
1 Unit side return air
Opening
14 (356)
Overall
MUST
AIR FLOW
(Maximum)
COVER BOTH
UNIT AND
RETURN
AIR BASE
OPENINGS
SIDE RETURN
5−5/8
(143)
7−1/4
(184)
AIR OPENINGS
(Either Side)
23
3/4
(19)
OPTIONAL
RETURN AIR BASE
14−1/2” (368) A Width (65W75)
17−1/2” (446) B Width (50W98)
21”− (533) C Width (50W99)
(584)
26−7/8
(683)
SIDE VIEW
24−1/2”− (622) D Width (51W00)
NOTE− Optional Side Return Air Filter Kits are not for use with Optional Return Air Base.
1
Both the unit return air opening and the base return air opening must be covered by a single plenum or IAQ cabinet.
Minimum unit side return air opening dimensions for units requiring 1800 cfm or more of air (W x H): 23 x 11 in. (584 x 279 mm).
The opening can be cut as needed to accommodate plenum or IAQ cabinet while maintaining dimensions shown.
Side return air openings must be cut in the field. There are cutting guides stenciled on the cabinet for the side return air
opening. The size of the opening must not extend beyond the markings on the furnace cabinet.
2
To minimize pressure drop, the largest opening height possible (up to 14 inches) is preferred.
FIGURE 10
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Removing the Bottom Panel
Horizontal Applications
Remove the two screws that secure the bottom cap to the
furnace. Pivot the bottom cap down to release the bottom
panel. Once the bottom panel has been removed, reinstall
The EL280UH furnace can be installed in horizontal ap-
plications. 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 al-
cove installations are shown in figure 12.
Removing the Bottom Panel
This furnace may be installed in either an attic or a crawl-
space. Either suspend the furnace from roof rafters or
Typical Horizontal Application
Unit Suspended in Attic or Crawlspace
Bracket
Metal Strap
Bottom Cap
3/16 inch
Screw
Air Flow
Bottom Cap
FIGURE 13
Bottom Panel
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 pip-
ing installation. Cooling coils and supply and return air
plenums must be supported separately.
FIGURE 11
Horizontal Application
Installation Clearances
Top
Left
End
Right
End
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.
Bottom
Type C
Return Air −− Horizontal Applications
Vent Connector
Type
Type B1
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
Top
*Front
Back
Ends
Vent
0
2−1/4 in. (57 mm)**
0
0
2−1/4 in. (57 mm)
0
2 in. (51 mm)
6 in. (152 mm)
0‡
2 in. (51 mm)
1 in. (25 mm)
0‡
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 in-
let 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.
Floor
*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.
FIGURE 12
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TABLE 1
Horizontal Application
Unit Installed on Platform
Filter Size
Furnace
Cabinet Width
Line contact is permissible but not preferred
See the unit nameplate for
Side Return
Bottom Return
clearances.
A − 14−1/2"
B − 17−1/2"
C − 21"
16 X 25 X 1 (1)
16 X 25 X 1 (1)
16 X 25 X 1 (1)
16 X 25 X 1 (2)
14 X 25 X 1 (1)
16 X 25 X 1 (1)
20 X 25 X 1 (1)
24 X 25 X 1 (1)
D − 24−1/2"
GAS
ENTRY
VENT
PIPE
Duct System
Use industry-approved standards (such as those pub-
lished by Air Conditioning Contractors of America or Ameri-
can 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.
SERVICE PLATFORM
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 lim-
it operation.
FIGURE 14
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 operat-
ing and it must not allow leaks into the supply air duct sys-
tem.
WARNING
Improper installation of the furnace can result in per-
sonal 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 ple-
num. 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. Al-
low 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 proper-
ty damage could result.
Return Air Plenum
NOTE − 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 de-
vice (i.e., wood fireplace) is installed.
When return air is drawn from a room, a negative pres-
sure is created in the room. If agas 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 com-
bustion and the formation of carbon monoxide gas. This
toxic gas might then be distributed throughout the house
by the furnace duct system.
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 inju-
ry or death.
In upflow applications, the return air can be brought in
through the bottom or either side of the furnace. If a fur-
nace 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 equiva-
lent 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.
Filters
This unit is not equipped with a filter or rack. A field−pro-
vided high−velocity filter is required for the unit to operate
A filter must be in place any time the unit is operating.
Page 12
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If necessary reposition the combustion air inducer, pres-
sure switch and or make up box as needed per the follow-
ing steps and see figures 17 through 22.
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.
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 as-
sembly 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.
Mounting Screws Location
Mounting Screws
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
Make−Up
Box
Vent Pipe
FIGURE 15
UPFlow Position
Flue
Transition
UPFLOW POSITION
Top Vent Discharge
FLOW
AIR
Vent Pipe
S
S
Gas supply piping must be brought into the unit from the right
side in order to accommodate the flue pipe.
Flue
Transition
Collector Box
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.
Pressure
Switch
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.
Make−Up
Box
FIGURE 17
UPFLOW POSITION
Right Side Vent Discharge
Cover Plate
Flue Transition
Pressure
Switch
Vent Pipe
Collector
Box
FLOW
AIR
FIGURE 16
Make−Up
Box
IMPORTANT
The unit will not vent properly with the flue transition
pointed down in the 6 o’clock position.
FLOW
AIR
The combustion air inducer may be rotated clock-
wise 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.
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.
FIGURE 18
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Horizontal Position
HORIZONTAL RIGHT POSITION
Top Vent Discharge
Vent Pipe
HORIZONTAL LEFT POSITION
Top Vent Discharge
Vent Pipe
Pressure Switch
Pressure Switch
Flue Transition
Cover Plate
Flue
Transition
AIR
AIR
FLOW
FLOW
Collector Box
Cover Plate
Collector Box
Make−Up Box
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
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 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.
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.
FIGURE 19
FIGURE 21
HORIZONTAL LEFT POSITION
Side Vent Discharge
Pressure Switch
HORIZONTAL RIGHT POSITION
Side Vent Discharge
Pressure Switch
AIR
FLOW
AIR
Flue Transition
FLOW
Flue
Transition
Collector Box
Make−Up Box
S
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.
Collector Box
make up box
FIGURE 22
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.
FIGURE 20
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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 fur-
nace 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.
Masonry chimneys used to vent Category I central fur-
naces must be either tile-lined or lined with a listed metal
lining system or dedicated gas vent. Unlined masonry
mon 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.
NOTE − Use these instructions as a guide. They do not su-
persede local codes. This furnace must be vented accord-
ing to all local codes these installation instructions, and the
provided venting tables in these instructions
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 meth-
od must be found.
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 ap-
plication, termination, construction and location of vents
must conform to local codes having jurisdiction. In the ab-
sence of local codes, the NFGC serves as the defining doc-
ument.
Insulation for the flexible vent pipe must be an encapsu-
lated fiberglass sleeve recommended by the flexible vent
pipe manufacturer. See figure 24.
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 ꢀDis-
connected Vent" warning sticker to a visible area of
warning sticker is provided in the bag assembly. Or-
der kit 66W04 for additional stickers.
Use self−drilling sheet metal screws or a mechanical fas-
tener 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
WARNING
Asphyxiation hazard. The exhaust vent for this fur-
nace must be securely connected to the furnace flue
transition at all times.
Venting Using a Masonry Chimney
The following additional requirements apply when a lined
masonry chimney is used to vent this furnace.
VENT CONNECTION UPFLOW AND HORIZONTAL POSITION
“DISCONNECTED VENT”
WARNING
STICKER
OPTIONAL SIDE
VENTING
(min. 6" length)
VENT PIPE
(min. 6" length)
“DISCONNECTED VENT”
WARNING
STICKER
FLUE TRANSITION
COLLAR
FLUE
TRANSITION
COLLAR
VENT PIPE
(min. 6" length)
FIGURE 23
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A type B1 vent or masonry chimney liner shall terminate
above the roof surface with a listed cap or a listed roof as-
sembly according to the terms of their respective listings
and the vent manufacturer’s instructions.
Common Venting Using Metal−Lined Masonry Chimney
SEALED
MAX. LENGTH
−− SEE NOTE 1
BELOW.
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.
5 ft. (1.5 m)
minimum
MIN. LENGTH −− AS
SHORT AS PRACTICAL
EXTERIOR
CHIMNEY WITH
METAL
LINER
VENT CONNECTOR
4 in. (102 mm)
minimum
Do not install a manual damper, barometric draft regulator,
or flue restrictor between the furnace and the chimney.
FURNACE
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.
OTHER
APPLIANCE
PERMANENTLY
SEALED FIREPLACE
OPENING
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.
NOTE 1 − Refer to the provided venting tables for installations. Refer
to the capacity requirements shown in the provided venting tables.
General Venting Requirements
FIGURE 24
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.
DO NOT insulate the space between the liner and the
chimney wall with puffed mica or any other loose gran-
ular insulating material.
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.
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 ac-
cording to the provided venting tables and the vent
pipe manufacturer’s instructions.
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 de-
termine 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 ap-
pliance categorized vent area, drafthood outlet area or
flue collar area unless designed according to approved
engineering methods.
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
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 de-
signed according to approved engineering methods.
to the provided venting tables.
If type B1 double-wall vent is used inside a chimney, no oth-
er appliance can be vented into the chimney. The outer wall
of type B1 vent pipe must not be exposed to flue products.
Page 16
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Common Venting Using Tile−Lined Interior Masonry Chimney and Combined Vent Connector
MINIMUM LENGTH = AS SHORT AS PRACTICAL.
FOR MAXIMUM LENGTH SEE NOTE TO LEFT
INTERIOR TILE−LINED
MASONRY CHIMNEY
NOTE− Refer to provided venting
tables for installations.
NOTE − the chimney must be properly
sized per provided venting tables or
lined with listed metal lining system.
VENT
CONNECTOR
OTHER
APPLIANCE
PERMANENTLY
SEALED FIREPLACE
OPENING
FURNACE
FIGURE 25
6 − The entire length of single wall metal vent connector
shall be readily accessible for inspection, cleaning,
and replacement.
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 com-
plete the job. Route the vent connector to the vent us-
ing the shortest possible route.
7 − Single appliance venting configurations with zero lat-
eral lengths (tables 3 and 4) are assumed to have no
elbows in the vent system. For all other vent configura-
tions, the vent system is assumed to have two 90° el-
bows. 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 ca-
pacity).
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.
erated 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 2
13 − When the vent connector used for Category I ap-
pliances must be located in or pass through a crawl-
space, attic or other areas which may be cold, that por-
tion of the vent connector shall be constructed of listed
double-wall type B vent material or material having
equivalent insulation qualities.
Maximum Horizontal
Connector Length feet (m)
Connector Diameter
inches (mm)
3 (76)
4 (102)
5 (127)
6 (152)
7 (178)
4−1/2 (1.37)
6 (1.83)
7−1/2 (2.29)
9 (2.74)
14 − All venting pipe passing through floors, walls, and ceil-
ings must be installed with the listed clearance to com-
bustible materials and be fire stopped according to lo-
cal codes. In absence of local codes, refer to NFGC
(Z223.1).
10−1/2 (3.20)
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
15 − No portion of the venting system can extend into, or pass
through any circulation air duct or plenum.
Page 17
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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.
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.
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).
21 − When connecting this appliance to an existing dedi-
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 re-
quirements, it must be resized.
18 − The common vent diameter must always be at least as
large as the largest vent connector diameter.
19 − In no case, shall the vent connector be sized more than
TABLE 3
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)
Lateral
L
(feet)
3 Inch
4 Inch
5 Inch
6 Inch
Appliance Input Rating in Thousands of Btu Per Hour
MIN
0
MAX
78
51
49
46
84
57
53
49
88
61
57
51
94
69
65
59
53
97
75
71
64
58
52
100
81
77
70
64
58
NA
MIN
0
MAX
152
97
MIN
0
MAX
251
157
153
149
276
178
171
164
295
194
187
176
327
226
219
206
195
349
250
242
229
217
206
374
283
275
262
249
237
214
MIN
0
MAX
375
232
227
223
415
263
255
247
447
289
280
267
502
339
330
315
301
540
377
367
351
337
322
587
432
421
405
389
374
346
0
2
13
21
25
0
18
30
36
0
27
39
47
0
32
50
59
0
6
8
4
94
6
91
0
165
109
103
98
2
12
23
28
0
16
32
39
0
25
42
51
0
28
53
64
0
5
8
0
175
118
113
104
191
136
130
121
112
202
149
143
133
124
116
213
166
160
150
141
132
113
2
12
23
30
0
17
32
41
0
23
41
54
0
26
52
67
0
10
5
10
0
2
11
22
29
35
0
15
30
40
48
0
20
39
51
61
0
22
49
64
76
0
5
15
10
15
0
2
10
21
28
34
48
0
14
29
38
46
55
0
18
38
50
59
69
0
20
47
62
73
84
0
5
20
10
15
20
0
2
9
13
28
37
44
53
73
14
36
48
57
66
88
18
45
59
70
80
104
5
21
27
33
56
NA
10
15
20
30
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 maxi-
mum listed capacity).
Page 18
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TABLE 4
Capacity of Type B Double−Wall Vents with Single−Wall Metal Connectors
Serving a Single Category I Appliance
Vent and Connector Diameter − D (inches)
Height
H
(feet)
Lateral
L
(feet)
3 Inch
4 Inch
5 Inch
6 Inch
Appliance Input Rating in Thousands of Btu Per Hour
MIN
38
MAX
77
MIN
59
60
74
83
58
59
77
90
57
59
76
97
56
57
75
95
NA
54
56
73
93
NA
NA
53
55
72
91
115
NA
NA
MAX
151
96
MIN
85
MAX
249
156
152
147
273
176
168
161
293
193
185
171
325
225
216
201
186
346
248
239
223
208
192
372
281
271
255
239
223
NA
MIN
126
123
146
163
123
121
151
175
120
119
148
188
116
115
144
182
220
114
113
141
177
216
254
110
109
136
171
208
246
NA
MAX
373
231
225
220
412
261
252
243
444
287
277
261
499
337
326
308
290
537
375
363
344
325
306
584
429
417
397
377
357
NA
0
2
39
51
85
6
8
4
NA
NA
37
NA
NA
83
92
102
114
83
6
89
0
164
108
102
95
2
39
56
83
5
NA
NA
37
NA
NA
87
107
122
82
8
0
174
117
111
100
190
136
128
116
NA
2
39
61
82
10
5
52
56
105
132
80
10
0
NA
36
NA
93
2
38
69
80
5
51
63
102
128
158
78
15
10
15
0
NA
NA
35
NA
NA
96
200
148
140
129
NA
2
37
74
78
5
50
68
100
125
155
186
76
20
10
15
20
0
NA
NA
NA
34
NA
NA
NA
99
NA
211
164
157
144
131
NA
2
37
80
76
5
49
74
98
10
15
20
30
NA
NA
NA
NA
NA
NA
NA
NA
122
151
181
NA
30
NA
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 maxi-
mum listed capacity).
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TABLE 5
Vent Connector Capacity
Type B Double−Wall Vents with Type B Double−Wall Connectors
Serving Two or More Category I Appliances
Vent and Connector Diameter − D (inches)
Vent
Height
H
Connector
Rise
3 Inch
4 Inch
5 Inch
6 Inch
R
(feet)
Appliance Input Rating in Thousands of Btu Per Hour
(feet)
MIN
22
23
24
22
23
24
22
23
24
21
22
24
21
22
23
20
21
22
MAX
37
41
44
40
44
47
43
47
50
50
53
55
54
57
60
62
64
66
MIN
35
37
38
35
36
37
34
36
37
33
35
36
33
34
35
31
33
34
MAX
66
MIN
46
48
49
49
51
53
49
51
52
47
49
51
46
48
50
45
47
48
MAX
106
121
132
114
128
139
123
136
146
142
153
163
157
167
176
181
190
198
MIN
58
60
62
64
66
67
65
67
69
64
66
68
62
64
66
60
62
64
MAX
164
183
199
176
195
210
189
206
220
220
235
248
246
259
271
288
299
309
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
75
6
81
72
80
8
87
78
86
10
15
20
30
92
89
96
102
99
105
110
113
118
123
TABLE 6
Common Vent Capacity
Type B Double−Wall Vents with Type B Double−Wall Connectors
Serving Two or More Category I Appliances
Common Vent Diameter − D (inches)
Vent
Height
H
4 Inch
5 Inch
6 Inch
7 Inch
Appliance Input Rating in Thousands of Btu Per Hour
(feet)
FAN + FAN
92
FAN + NAT
FAN + FAN
140
FAN + NAT
116
FAN + FAN
204
FAN + NAT
161
FAN + FAN
309
FAN + NAT
248
6
81
90
8
101
155
129
224
178
339
275
10
15
20
30
110
97
169
141
243
194
367
299
125
112
123
138
195
164
283
228
427
352
136
215
183
314
255
475
394
152
244
210
361
297
547
459
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TABLE 7
Vent Connector Capacity
Type B Double−Wall Vents with Single−Wall Metal Connectors
Serving Two or More Category I Appliances
Vent and Connector Diameter − D (inches)
Height
H
(feet)
Lateral
L
(feet)
3 Inch
4 Inch
5 Inch
6 Inch
Appliance Input Rating in Thousands of Btu Per Hour
MIN
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
49
MAX
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
56
MIN
NA
NA
NA
NA
NA
NA
NA
84
MAX
NA
NA
NA
NA
NA
NA
NA
85
MIN
NA
MAX
NA
MIN
NA
MAX
NA
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
NA
NA
168
175
NA
182
198
NA
6
121
NA
131
NA
125
130
119
124
129
116
121
127
115
120
125
112
117
122
126
138
121
134
144
138
150
160
152
163
172
175
185
193
184
191
182
189
197
177
185
193
175
182
190
169
177
185
193
208
186
203
217
214
230
243
238
252
264
278
290
300
8
10
15
20
30
89
91
79
87
83
94
87
100
97
78
52
59
82
103
107
110
115
119
55
62
87
47
60
77
51
62
81
54
64
85
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 maxi-
mum listed capacity).
TABLE 8
Common Vent Capacity
Type B Double−Wall Vents with Single−Wall Metal Connectors
Serving Two or More Category I Appliances
Common Vent Diameter − D (inches)
Vent
4 Inch
5 Inch
6 Inch
7 Inch
Height
H
(feet)
Appliance Input Rating in Thousands of Btu Per Hour
FAN + FAN
FAN + NAT
FAN + FAN
NA
FAN + NAT
113
FAN + FAN
200
FAN + NAT
158
FAN + FAN
FAN + NAT
244
6
NA
NA
78
87
304
331
357
416
463
533
8
NA
126
218
173
269
10
15
20
30
NA
94
163
137
237
189
292
121
131
145
108
118
132
189
159
275
221
343
208
177
305
247
383
236
202
350
286
446
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Removal of the Furnace from Common Vent
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 dry-
ers 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 oper-
ate at maximum speed. Do not operate a summer ex-
haust fan. Close fireplace dampers.
In the event that an existing furnace is removed from a
venting system commonly run with separate gas ap-
pliances, the venting system is likely to be too large to
properly vent the remaining attached appliances.
Conduct the following test while each appliance is operat-
ing and the other appliances (which are not operating) re-
main 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 re-
quirements section.
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 burner have operated for 5 minutes, test for
leaks of flue gases at the draft hood relief opening. Use
the flame of a match or candle.
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 mon-
oxide poisoning or death.
The following steps shall be followed for each ap-
pliance connected to the venting system being
placed into operation, while all other appliances
connected to the venting system are not in
operation:
6 − After determining that each appliance connected to the
common venting system is venting properly, (step 3)
return all doors, widows, exhaust fans, fireplace damp-
ers, and any other gas−burning appliances to their pre-
vious mode of operation.
7 − If a venting problem is found during any of the preced-
ing tests, the common venting system must be modi-
fied to correct the problem.
1 − Seal any unused openings in the common venting sys-
tem.
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 stan-
dards of the National Fuel Gas Code ANSI Z223.1.
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.
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4 − The piping should be sloped 1/4 inch (6.4 mm) per 15
feet (4.57 m) upward toward the meter from the fur-
nace. The piping must be supported at proper intervals
[every 8 to 10 feet (2.44 to 3.01 m)] with suitable hang-
ers or straps. Install a drip leg in vertical pipe runs to the
unit.
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.
CAUTION
5 − A 1/8" N.P.T. plugged tap or pressure post is located
on the gas valve to facilitate test gauge connection.
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.
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.
Gas Supply
1 − This unit is shipped standard for left or right side instal-
lation of gas piping (or top entry in horizontal applica-
tions). 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 fur-
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.
IMPORTANT
Compounds used on threaded joints of gas piping
must be resistant to the actions of liquified petro-
leum gases.
NOTE − If emergency shutoff is necessary, shut off the main
manual gas valve and disconnect main power to the fur-
nace. The installer should properly label these devices.
TABLE 9
3
3
Gas Pipe Capacity − ft /hr (m /hr)
Nominal
Iron Pipe
Size
inches
(mm)
Length of Pipe − feet (m)
Internal
Diameter
inches
(mm)
10
(3.048)
20
(6.096)
30
(9.144)
40
50
60
70
80
90
100
(12.192) (15.240) (18.288) (21.336) (24.384) (27.432) (30.480)
1/2
(12.7)
.622
(17.799)
172
(4.87)
118
(3.34)
95
(2.69)
81
(2.29)
72
(2.03)
65
(1.84)
60
(1.69)
56
(1.58)
52
(1.47)
50
(1.42)
3/4
(19.05)
.824
(20.930)
360
(10.19)
247
(7.00)
199
(5.63)
170
(4.81)
151
(4.28)
137
(3.87)
126
(3.56)
117
(3.31)
110
(3.11)
104
(2.94)
1
(25.4)
1.049
(26.645)
678
(19.19)
466
(13.19)
374
(10.59)
320
(9.06)
284
(8.04)
257
(7.27)
237
(6.71)
220
(6.23)
207
(5.86)
195
(5.52)
1−1/4
(31.75)
1.380
(35.052)
1350
(38.22)
957
(27.09)
768
(22.25)
657
(18.60)
583
(16.50)
528
(14.95)
486
(13.76)
452
(12.79)
424
(12.00)
400
(11.33)
1−1/2
(38.1)
1.610
(40.894)
2090
(59.18)
1430
(40.49)
1150
(32.56)
985
(27.89)
873
(24.72)
791
(22.39)
728
(20.61)
677
(19.17)
635
(17.98)
600
(17.00)
2
(50.8)
2.067
(52.502)
4020
(113.83)
2760
(78.15)
2220
(62.86)
1900
(53.80)
1680
(47.57)
1520
(43.04)
1400
(39.64)
1300
(36.81)
1220
(34.55)
1160
(32.844)
2−1/2
(63.5)
2.469
(67.713)
6400 4400
(181.22) (124.59)
3530
(99.95)
3020
(85.51)
2680
(75.88)
2480
(70.22)
2230
(63.14)
2080
(58.89)
1950
(55.22)
1840
(52.10)
3
(76.2)
3.068
(77.927)
11300 7780
6250
5350
4740
4290
3950
3670
(319.98) (220.30) (176.98) (151.49) (134.22) (121.47) (111.85) (103.92)
3450
(97.69)
3260
(92.31)
3
NOTE − Capacity given in cubic feet (m ) of gas per hour and based on 0.60 specific gravity gas.
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Left Side Piping
(Standard)
MANUAL
MAIN SHUT−OFF
VALVE
AUTOMATIC
GAS VALVE
MANUAL
MAIN SHUT−OFF
VALVE
(With 1/8 in. NPT
Plugged Tap Shown)
(With 1/8 in. NPT
Plugged Tap
Shown)
GROUND
JOINT
UNION
AUTOMATIC
GAS VALVE
GROUND
JOINT
UNION
DRIP LEG
Right Side Piping
(Alternate)
FIELD
PROVIDED
AND INSTALLED
DRIP LEG
NOTE − BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET
FIGURE 26
Horizontal Applications
Possible Gas Piping Configurations
MANUAL
MAIN SHUT−OFF
VALVE
MANUAL
MAIN SHUT−OFF
VALVE
Horizontal Application
Left−Side Air Discharge
GROUND
JOINT
UNION
GROUND
JOINT
UNION
DRIP LEG
DRIP LEG
MANUAL
MAIN SHUT−OFF
VALVE
GROUND
JOINT
UNION
FIELD
PROVIDED
AND INSTALLED
Horizontal Application
Right−Side Air Discharge
NOTE − BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET
DRIP LEG
FIGURE 27
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Leak Check
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 side, clip the wire ties
that bundle the wires together. The excess wire must be
pulled into the blower compartment. Secure the excess
wire to the existing harness to protect it from damage.
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.
INTERIOR MAKE−UP BOX INSTALLATION
Right Side
CAUTION
Some soaps used for leak detection are corrosive to
certain metals. Carefully rinse piping thoroughly af-
ter leak test has been completed. Do not use
matches, candles, flame or other sources of ignition
to check for gas leaks.
BOX
The furnace must be isolated by closing its individual
manual shut-off valve and disconnecting from from the gas
supply system the during any pressure testing of the gas
supply system at pressures greater than 1/2 psig (3.48
kPa, 14 inches w.c.).
FIGURE 29
IMPORTANT
INTERIOR MAKE−UP BOX INSTALLATION
When testing pressure of gas lines, gas valve must
valves can be damaged if subjected to pressures
greater than 1/2 psig (3.48 kPa, 14 inches w.c.).
Left side
BOX
MANUAL MAIN
ISOLATE
SHUT−OFF VALVE
WILL NOT HOLD
NORMAL TEST
PRESSURE
GAS VALVE
FURNACE
1/8 NPT PLUG
CAP
FIGURE 28
FIGURE 30
Electrical
bleshooting and table 10 and figure 32 for field wiring.
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
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.
CAUTION
Maximum over−current protection allowed is 15 AMP.
Electrostatic discharge can affect elec-
tronic components. Take precautions to
neutralize electrostatic charge by
touching your hand and tools to metal
prior to handling the control.
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.
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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.
Generator Use − Voltage Requirements
The following requirements must be kept in mind when
specifying a generator for use with this equipment:
S
S
S
The furnace requires 120 volts + 10% (Range: 108
volts to 132 volts).
Complete the wiring connections to the equipment. Use the
provided unit wiring diagram and the field wiring diagram
able 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 Na-
tional Electric Code (ANSI/NFPA No. 70). A green ground
wire is provided in the field make−up box.
The furnace operates at 60 Hz + 5% (Range: 57 Hz to
63 Hz).
The furnace integrated control requires both polarity
and proper ground. Both polarity and proper grounding
should be checked before attempting to operate the
furnace on either permanent or temporary power.
Generator should have a wave form distortion of less
than 5% total harmonic distortion (THD).
S
NOTE − The EL280UH furnace contains electronic compo-
nents that are polarity sensitive. Make sure that the furnace
is wired correctly and is properly grounded.
Thermostat
Install the room thermostat according to the instructions
designations. If the furnace is being matched with a heat
pump, refer to the FM21 installation instruction or appropri-
ate dual fuel thermostat instructions.
Accessory Terminals
One line voltage ꢀEAC" 1/4" spade terminal is provided on
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
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 exter-
nal relay.
Indoor Blower Speeds
1 − When the thermostat is set to ꢀFAN ON," the indoor
blower will run continuously on the low speed when
there is no cooling or heating demand.
2 − When the EL280UH is operating in the high−fire or low−
fire heating mode, the indoor blower will run on the cor-
responding heating speed.
One line voltage ꢀHUM" 1/4" spade terminal is provided on
the furnace integrated control. See figure 33 for integrated
control configuration. This terminal is energized in the
heating mode when the combustion air inducer is operat-
ing. Any humidifier rated up to one amp can be connected
to this terminal with the neutral leg of the circuit being con-
nected to one of the provided neutral terminals. If a humidi-
fier rated at greater than one amp is connected to this termi-
nal, it is necessary to use an external relay relay.
3 − When the EL280UH is operating in the low cool or the
high cool cooling mode, the indoor blower will run on
the corresponding cooling speed.
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TABLE 10
Field Wiring Applications
W915
Two−Stage
Cooling
Thermostat
Wiring Connections
W951
Heat Pumps
DIP Switch 1
1 Heat / 1 Cool
ON
Intact
Intact
S1
T’STAT
CONTROL
TERM. STRIP
OUTDOOR
UNIT
NOTE − Use DIP
switch 2 to set sec-
ond−stage heat ON
delay.
OFF10 minutes.
ON−15 minutes.
1 Heat / 2 Cool
ON
Cut
Intact
S1
T’STAT
CONTROL
TERM. STRIP
OUTDOOR
UNIT
NOTE − Use DIP
switch 2 to set sec-
ond−stage heat ON
delay.
OFF−10 minutes.
ON−15 minutes.
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TABLE 10
Field Wiring Applications (Continued)
W915
Thermostat
Wiring Connections
Two−Stage
Cooling
W951
Heat Pumps
DIP Switch 1
2 Heat / 2 Cool
OFF
Cut
Intact
S1
T’STAT
CONTROL
TERM. STRIP
OUTDOOR
UNIT
2 Heat / 1 Cool
OFF
Intact
Intact
S1
T’STAT
CONTROL
TERM. STRIP
OUTDOOR
UNIT
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EL280UH SCHEMATIC WIRING DIAGRAM
070P24A
BLACK
YELLOWRED
BROWN
070P36A
090P36B
090P48B
110P48C
BLACK YELLOW RED BROWN
BLACK
BLACK
BLACK
RED
BROWN
YELLOW
YELLOW RED BROWN
BROWN
RED
BLACK
YELLOW
G
110P60C BROWN
135P60D
070XP36A
090XP48B
110XP60C BROWN
RED
YELLOW
BROWNYELLOW RED BLACK
BLACK YELLOW RED
BROWN
BLACK
YELLOW
YELLOW
BROWN
RED
RED BLACK
.50 AMP
.43 AMP WHITE RODGERS VALVE
JUMPER W915 FROM Y1 TO Y2, LABELED ”2 STAGE
COMPR”, IS FACTORY INSTALLED AT A92 CONTROL
BOARD. LEAVE IN FOR ONE STAGE COOL
THERMOSTAT, CUT JUMPER FOR TWO STAGE COOL
THERMOSTAT.
1
2
3
4
5
6
7
8
9
10
11
12
FACTORY DEFAULT IS FOR A 2 STAGE THERMOSTAT
9
8
TERMINAL #1 IS USED FOR ERROR CODE RECALL ONLY.
SEE INSTALLATION INSTRUCTIONS FOR DETAILS.
24V POWER IS PROVIDED FOR OPTIONAL
HUMIDIFIER DURING HEAT DEMAND
8
9
K6
K8
K9
K4
K1
K10
K11
BURNER
ASSY GND
120V
EAC
FIGURE 31
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TYPICAL EL280UH FIELD WIRING DIAGRAM
FIGURE 32
TWO−STAGE INTEGRATED CONTROL
1/4" QUICK CONNECT TERMINALS
SENSE = 120 VAC OUTPUT TO FLAME SENSOR
NEUTRALS= 120 VAC NEUTRAL
PARK = DEAD TERMINAL FOR UNUSED BLOWER LEAD
HEAT LOW = 120 VAC OUTPUT TO CIRC BLWR −− LOW HT SPEED
HEAT HIGH/ COOL LOW = 120 VAC OUTPUT TO CIRC BLWR −−
HIGH HEAT AND LOW COOL SPEED
COOL HIGH = 120 VAC OUTPUT TO CIRC BLWR −− HIGH COOL SPEED
DIAGNOSTIC
LEDs
THERMOSTAT CONNECTIONS (TB1)
DIP
SWITCHES
ON−BOARD
LINKS
1= ERROR CODE RECALL
H= 24V HUMIDIFIER OUTPUT
L= LENNOX SYSTEM OPERATION MONITOR
DIP SWITCH FUNCTIONS
W915
W951
DIP SWITCH(ES)
FUNCTION
1 −− 2 Stage T’stat
2 −− 2nd Stage Delay
3 & 4 −− Heat Off Delay
5 −− Cool Off Delay
Selects t/stat type (single or two−stage)
Second stage ON delay (single−stage t’stat)
Heating fan OFF delay
Cooling fan OFF delay
FIGURE 33
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justed by moving switches 3 and 4 on the integrated con-
trol. 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 sup-
ply air temperature between 90° and 110°F at the exact
moment that the blower is de−energized. Longer off delay
settings provide lower supply air temperatures; shorter set-
vides the blower off timings that will result from different
switch settings.
Integrated Control
EL280UH 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. The control includes an internal watchguard fea-
ture which automatically resets the integrated control when
it has been locked out. After one hour of continuous ther-
mostat demand for heat, the watchguard will break and re-
make thermostat demand to the furnace and automatically
reset the control to relight the furnace.
DIP Switch Settings
TABLE 11
Heating Blower−Off Delay 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.
Blower Off Delay
(Seconds)
60
Switch 3
Switch 4
Off
On
90
(factorysetting)
Off
Off
120
180
On
On
Off
On
a − Select ꢀOFF" for two−stage heating operation con-
trolled by a two−stage heating thermostat (factory set-
ting);
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 fac-
tory−set in the OFF position, which provides a cooling blow-
er−off delay of 45 seconds. If the switch is toggled to the ON
position, it will provide a 2−second cooling blower−off delay
b − Select ꢀON" for two−stage heating operation con-
trolled by a single−stage heating thermostat. This set-
ting provides a timed delay before second−stage heat
is initiated.
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 ther-
mostat 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.
On−Board Link W951 Heat Pump (R to O)
On−board link W951 is a clippable connection between ter-
minals 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 ener-
gized eliminating the HEAT MODE in the heat pump.
On−Board Link W915 2 Stage Compr (Y1 to Y2)
On−board link W915 is a clippable connection between ter-
minals 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 and
the indoor blower will operate on high cool speed only.
Switches 3 and 4 −− Heating Blower−Off Delay −− The
heating blower−on delay of 30 seconds is not adjustable.
The heating blower−off delay (time that the blower operates
after the heating demand has been satisfied) can be ad-
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4 − This furnace is equipped with an ignition device which
automatically lights the burners. Do not try to light the
burners by hand.
Unit Start−Up
FOR YOUR SAFETY READ BEFORE LIGHTING
5 − Remove the upper access panel.
6 − Move switch on gas valve to OFF. Do not force. See
WARNING
Do not use this furnace if any part has been under-
water. A flood−damaged furnace is extremely dan-
gerous. Attempts to use the furnace can result in
fire or explosion. Immediately call a qualified ser-
vice 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.
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 instruc-
tions. If you do not smell gas go to next step.
HIGH FIRE ADJUSTMENT
SCREW
(under cap)
MANIFOLD
PRESSURE POST
INLET PRESSURE POST
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.
CAUTION
GAS VALVE SHOWN IN ON POSITION
Before attempting to perform any service or mainte-
nance, turn the electrical power to unit OFF at dis-
connect switch.
FIGURE 34
8 − Move switch on gas valve to ON. Do not force. See fig-
9 − Replace the upper access panel.
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.
10− Turn on all electrical power to to the unit.
11− Set the thermostat to desired setting.
The gas valve on the EL280UH 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.
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 techni-
cian or gas supplier.
Placing the furnace into operation:
EL280UH 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.
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
WARNING
If the unit fails to operate, check the following:
1 − Is the thermostat calling for heat?
If you do not follow these instructions exactly, a fire
or explosion may result causing property damage,
personal injury or death.
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?
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.
7 − Is the manual main shut-off valve open?
8 − Is the internal manual shut-off valve open?
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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.
the 3/32 hex screw one turn, connect a piece of 5/16" tubing
and connect to a manometer to measure manifold pres-
sure.
10 − Is pressure switch closed? Obstructed flue will cause
unit to shut off at pressure switch. Check flue and outlet
for blockages.
NOTE − Pressure test adapter kit (10L34) is available from
Lennox to facilitate manifold pressure measurement.
11 − Are flame rollout switches tripped? If flame rollout
switches are tripped, call the service technician for in-
spection.
1 − Connect test gauge to manifold pressure post (figure
2 − Ignite unit on high fire and let run for 5 minutes to allow
for steady state conditions.
Gas Pressure Adjustment
Gas Flow (Approximate)
3 − After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in table
TABLE 12
GAS METER CLOCKING CHART
Seconds for One Revolution
location of high fire adjustment screw.
Natural
LP
EL280UH
Unit
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 14,
replace valve.
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
DIAL
−045
−070
−090
−110
−135
80
160
110
82
200
136
102
82
400
272
204
164
136
55
41
NOTE − Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Turn the supply and
manifold 3/32" hex screw one revolution back into the gas
valve.
33
66
27
54
68
Natural−1000 btu/cu ft
LP−2500 btu/cu ft
Proper Combustion
Furnace should operate at least 5 minutes before check-
ing gas flow. Determine time in seconds for two revolu-
tions of gas through the meter. (Two revolutions assures a
more accurate time.) Divide by two and compare to time
and rate is incorrect, check gas orifices for proper size and
restriction. Remove temporary gas meter if installed.
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking com-
EL280UH models. The maximum carbon monoxide
reading should not exceed 50 ppm
TABLE 13
Firing Rate
High Fire
Low Fire
CO %
2
CO %
For L.P.
For Nat
2
NOTE − To obtain accurate reading, shut off all other gas
appliances connected to meter.
6.8 − 7.4
4.2 − 5.7
7.5 − 9.0
5.0 − 6.0
Supply Pressure Measurement
An inlet post located on the gas valve provides access to
screw one turn, connect a piece of 5/16" tubing and con-
nect to a manometer to measure supply pressure. See
High Altitude
The manifold pressure may require adjustment and com-
bustion air pressure switch may need replacing to ensure
and gas conversion kits.
Manifold Pressure
A manifold pressure post located on the gas valve provides
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TABLE 14
Manifold Pressure Settings at all Altitudes
Manifold
Pressure in.wg.
0−4500 ft.
Manifold
Pressure in.wg.
4501−7500 ft.
Manifold
Pressure in.wg.
7501 − 10,000 ft.
Supply Line
Pressure
in. w.g.
Unit
Input
1
2
Gas
Low Fire
High Fire
Low Fire
High Fire
Low Fire High Fire
Min
4.5
Max
13.0
13.0
13.0
13.0
13.0
13.0
13.0
13.0
Natural
LP/propane3
Natural
1.7
4.9
1.7
4.9
1.7
4.9
1.7
4.9
3.5
10.0
3.5
1.6
4.9
1.5
4.9
1.5
4.9
1.5
4.9
3.4
10.0
3.2
1.7
4.9
1.7
4.9
1.7
4.9
1.7
4.9
3.5
10.0
3.5
070
090
110
135
11.0
4.5
LP/propane3
Natural
10.0
3.5
10.0
3.2
10.0
3.5
11.0
4.5
LP/propane3
Natural
10.0
3.5
10.0
2.8
10.0
3.5
11.0
4.5
LP/propane3
10.0
10.0
10.0
11.0
1
2
3
This is the only permissible derate for these units.
Natural gas high altitude orifice kit required.
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.
TABLE 15
Pressure Switch and Gas Conversion Kits at all Altitudes
High Altitude
Natural Gas Kit
LP/Propane to
Natural Kit
High Altitude Pressure Switch Kit
LP/Propane Gas Kit
Unit
Input
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
070
090
110
135
91W53
73W35
73W35
73W35
73W34
91W53
No Change
91W53
73W37
77W07
77W11
77W09
73W33
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.
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Other Unit Adjustments
HEAT FAN-OFF TIME IN SECONDS
60sec.
90sec.
Primary and Secondary Limits
The primary limit is located on the heating compartment
vestibule panel. The secondary limits (if equipped) are lo-
cated in the blower compartment, attached to the back side
of the blower. These auto reset limits are factory−set and re-
quire no adjustment.
1
2
3
4
5
1
2
3
4
5
120sec.
180sec.
Flame Rollout Switches
This manually reset switches are located on the baffle plate
in the burner assembly.
1
2
3
4
5
1
2
3
4
5
Pressure Switch
To adjust fan−off timing, flip dip switch to desired setting.
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 allow-
ing ignition trial. The switch is factory−set and requires no
adjustment.
FIGURE 35
Electrical
1 − Check all wiring for loose connections.
2 − Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 120VAC + 10%.
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.
3 − Check amp−draw on the blower motor with inner blow-
er panel in place.
Unit Nameplate__________Actual__________
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.
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
The unit is shipped with a factory fan−off delay setting of 90
seconds. The fan−off delay affects comfort and is adjust-
able 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. Lon-
ger off delay settings provide lower return air temperatures;
shorter settings provide higher return air temperatures.
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.
Thermostat Heat Anticipation
8 − Turn on electrical power to furnace.
9 − Recheck temperature rise.
Set the heat anticipator setting (if adjustable) according to
the amp draw listed on the wiring diagram that is attached
to the unit.
Electronic Ignition
The integrated control has an added feature of an internal
Watchguard control. The feature serves as an automatic re-
set 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 inte-
grated control to begin the ignition sequence.
NOTE − Do not secure the electrical conduit directly to the
air ducts or structure.
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Single−Stage Thermostat, Two Stage Heat. Dip
Switch set at ꢀSINGLE"
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 opera-
tional, heat call can continue.
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.
Two−Stage Thermostat, Two Stage Heat. Dip Switch
set at ꢀTWO".
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.
®
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 furnace is operating on continuous fan mode
(terminal ꢀR" and ꢀG" are energized), the combustion air in-
ducer will energize on high speed, the gas valve will ener-
gize 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.
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.
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.
NOTE − If the furnace is operating on continuous fan mode
(terminal ꢀR" and ꢀG" are energized), the combustion air in-
ducer will energize on high speed, the gas valve will ener-
gize 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.
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.
2− SureLight control begins 20 second ignitor warm up
period.
6− A 10 minute (factory set) or 15 minute (field set) second
stage heat delay period begins.
3− Gas valve opens on first stage for a 4 second trial for
ignition. Ignitor stays energized during the trial or until
flame sensed.
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.
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.
9− B3 indoor blower switches to high heat speed.
The furnace will stay in this mode until first stage de-
mand 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.
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BLOWER DATA
EL280UH070P24A PERFORMANCE (Less Filter)
EL280UH090P48B PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High Medium Low
Watts
Air Volume / Watts at Various Blower Speeds
External
Medium-
High
Medium-
Low
Static
Pressure
in. w.g.
High
Low
cfm
Watts
cfm
Watts
cfm
cfm Watts cfm Watts cfm Watts cfm Watts
2030 804 1780 719 1525 613 1280 518
1910 740 1740 666 1535 580 1305 493
1840 698 1705 643 1500 551 1305 474
1770 664 1635 594 1460 517 1280 445
1665 625 1560 567 1410 483 1225 420
1585 595 1470 523 1330 451 1190 391
1470 561 1365 483 1260 421 1115 368
1355 514 1230 433 1155 392 1020 338
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
1135
1115
1085
1045
1015
965
439
429
410
389
374
358
335
315
990
975
955
925
885
835
780
700
369
358
348
335
321
307
289
268
845
820
790
775
735
700
635
560
299
289
279
270
260
248
232
214
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
890
810
NOTES - All air data is measured external to unit without filter
(not furnished - field provided)
NOTES - All air data is measured external to unit without filter
(not furnished - field provided)
EL280UH070P36A PERFORMANCE (Less Filter)
EL280UH110P48C PERFORMANCE (Less Filter)
Air Volume / Watts at Various Blower Speeds
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
External
Medium-
High
Medium-
Low
Medium-
High
Medium-
Low
Static
Pressure
in. w.g.
High
Low
High
Low
cfm Watts cfm Watts cfm Watts cfm Watts
1620 658 1365 568 1115 468 945 374
1580 621 1355 535 1135 442 960 362
1520 595 1335 513 1130 423 955 350
1480 562 1300 478 1100 403 945 335
1400 520 1270 450 1080 382 925 320
1340 490 1205 420 1035 358 880 301
1245 458 1125 393 975 333 835 282
1160 434 1045 364 915 310 775 262
cfm Watts cfm Watts cfm Watts cfm Watts
2125 919 1820 747 1555 648 1300 540
2080 862 1790 705 1540 619 1335 516
2015 807 1745 652 1545 587 1335 498
1940 748 1695 629 1505 552 1320 470
1850 716 1635 581 1470 523 1295 449
1775 679 1575 560 1395 484 1235 417
1680 637 1470 508 1320 450 1170 387
1560 592 1350 469 1205 404 1050 345
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
NOTES - All air data is measured external to unit without filter
(not furnished - field provided)
NOTES - All air data is measured external to unit without filter
(not furnished - field provided)
EL280UH090P36B PERFORMANCE (Less Filter)
Air Volume / Watts at Various Blower Speeds
External
Medium-
High
Medium-
Low
Static
Pressure
in. w.g.
High
Low
cfm Watts cfm Watts cfm Watts cfm Watts
1760 730 1435 576 1185 452 970 378
1725 683 1420 547 1170 440 975 368
1685 656 1410 525 1170 420 980 356
1630 625 1370 501 1150 400 955 340
1535 569 1315 469 1125 391 925 326
1470 533 1275 440 1085 367 910 309
1365 490 1185 407 1020 344 840 290
1255 466 1105 380 935 314 785 266
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
NOTES - All air data is measured external to unit without filter
(not furnished - field provided)
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BLOWER DATA
EL280UH110P60C PERFORMANCE (Less Filter)
Air Volume / Watts at Different Blower Speeds
Bottom Return Air, Side Return Air with Optional Return Single Side Return Air − Air volumes in bold require field
Air Base, Return Air from Both Sides or Return Air from fabricated transition to accommodate 20 x 25 x 1 in. air filter
External
Static
Pressure
in. w.g.
Bottom and One Side.
in order to maintain proper air velocity.
High
Medium-High Medium-Low
Low
High Medium-High Medium-Low
Low
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
2520 1359 2250 1034 1860 841 1455 654 2605 1454 2160 1060 1740 848 1430 651
2465 1329 2230 1018 1870 823 1480 647 2505 1401 2150 1018 1785 838 1450 649
2385 1307 2180 981 1885 809 1540 646 2435 1349 2115 991 1795 818 1485 638
2295 1256 2105 942 1865 778 1570 638 2350 1308 2070 965 1805 801 1480 631
2200 1214 2055 909 1845 762 1570 619 2260 1274 2010 929 1785 775 1480 621
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
2130 1186 1985 882 1795 741 1550 604 2175 1228 1955 901 1755 752 1490
611
2015 1150 1890 848 1720 711 1505 580 2085 1186 1850 853 1710 722 1460 594
1905 1105 1810 815 1675 687 1470 565 1965 1147 1785 818 1640 689 1425 567
NOTES - All air data is measured external to unit without filter (not furnished - field provided)
EL280UH135P60D PERFORMANCE (Less Filter)
Air Volume / Watts at Different Blower Speeds
Bottom Return Air, Side Return Air with Optional Return Single Side Return Air − Air volumes in bold require field
Air Base, Return Air from Both Sides or Return Air from fabricated transition to accommodate 20 x 25 x 1 in. air filter
External
Static
Pressure
in. w.g.
Bottom and One Side.
in order to maintain proper air velocity.
High
Medium-High Medium-Low
Low
High Medium-High Medium-Low
Low
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
2750 1441 2220 1056 1725 825 1395 625 2725 1463 2180 1075 1715 827 1320 624
2720 1392 2235 1029 1785 810 1445 618 2640 1400 2180 1051 1720 819 1380 626
2605 1362 2220 1002 1820 800 1460 623 2575 1374 2165 1005 1790 803 1420 622
2495 1312 2185 968 1845 779 1485 616 2495 1343 2145 988 1775 791 1450 617
2420 1275 2135 939 1825 767 1505 605 2405 1292 2105 948 1780 777 1470 610
2335 1234 2080 909 1825 753 1495 593 2305 1257 2045 914 1775 753 1480 593
2220 1190 1995 864 1760 716 1475 576 2215 1214 1970 884 1740 727 1455 583
2120 1157 1890 835 1680 686 1435 558 2110 1170 1890 851 1675 699 1430 565
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
NOTES - All air data is measured external to unit without filter (not furnished - field provided)
Page 38
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Service
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 inju-
ry or death.
WARNING
ELECTRICAL SHOCK, FIRE,
OR EXPLOSION HAZARD.
Filters
Failure to follow safety warnings exactly could result
in dangerous operation, serious injury, death or
property damage.
Improper servicing could result in dangerous opera-
tion, serious injury, death, or property damage.
Before servicing, disconnect all electrical power to
furnace.
All EL280UH 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 prop-
erly. Replacement filters must be rated for high velocity air-
Flue And Chimney
When servicing controls, label all wires prior to dis-
connecting. Take care to reconnect wires correctly.
Verify proper operation after servicing.
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.
Electrical
At the beginning of each heating season, a qualified techni-
cian should check the system as follows:
1 − Check all wiring for loose connections.
2 − Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 120VAC + 10%.
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.
3 − Check amp−draw on the blower motor with inner blow-
er panel in place.
Unit Nameplate__________Actual__________
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Cleaning the Heat Exchanger and Burners
NOTE − Use papers or protective covering in front of the fur-
nace during cleaning.
5 − Remove the collector box located behind the combus-
tion air inducer. Be careful with the collector box gas-
ket. If the gasket is damaged, it must be replaced to
prevent leakage.
1 − Turn off both electrical and gas power supplies to fur-
nace.
2 − Remove flue pipe and top cap (some applications top
cap can remain) from the unit.
6 − Disconnect gas supply piping. Remove the screw se-
curing the burner box cover and remove cover. Re-
move the four screws securing the burner manifold as-
sembly to the vestibule panel and remove the
assembly from the unit.
3 − Label the wires from gas valve, rollout switches, prima-
ry limit switch and make−up box then disconnect them.
4 − Remove the screws that secure the combustion air in-
ducer/pressure switch assembly to the collector box.
Carefully remove the combustion air inducer to avoid
damaging blower gasket. If gasket is damaged, it must
be replaced to prevent leakage.
7 − Remove screws securing burner box and remove
burner box.
8 − NOX units only − Remove screw securing NOX insert.
EL280UH BURNER, COMBUSTION AIR INDUCER ASSEMBLY &
HEAT EXCHANGER REMOVAL
gasket
pressure switch
flue transition
Ignitor
collector box
orifice plate
Heat Exchanger
Rollout Switches
(location)
combustion air inducer
Sensor
Retention Rings
Cross Over
Manifold And Gas Valve
FIGURE 36
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9 − Remove screws from both sides, top and bottom of
vestibule panel.
Remove 5 screws if necessary
(either side of cabinet)
10 −Remove heat exchanger. It may be necessary to
spread cabinet side to allow more room. If so, remove
five screws from the left side or right side of cabinet.
11 − Backwash using steam. Begin from the burner opening
on each clam. Steam must not exceed 275°F.
1
2
12 −To clean burners, run a vacuum cleaner with a soft brush
attachment over the face of burners. Visually inspect in-
side the burners and crossovers for any blockage
caused by foreign matter. Remove any blockage. Figure
36 shows burner detail.
3
4
13 −To clean the combustion air inducer visually inspect and
using a wire brush clean where necessary. Use com-
pressed air to clean off debris and any rust.
5
14 −Reinstall heat exchanger in vestibule. (Replace the
five screws in the cabinet from step 10 if removed).
15 −NOx units only − Replace NOx inserts.
16 −Reinstall collector box and combustion air assembly.
Reinstall all screws to the collector box and combustion
air inducer. Failure to replace all screws may cause
leaks. Inspect gaskets for any damage and replace if
necessary.
17 −Reinstall burner box, manifold assembly and burner box
cover.
FIGURE 38
18 −Reconnect all wires.
EL280UH NOx INSERTS
19 −Reconnect top cap and vent pipe to combustion air in-
ducer outlet.
20 −Reconnect gas supply piping.
21 −Turn on power and gas supply to unit.
22 −Set thermostat and check for proper operation.
23 −Check all piping connections, factory and field, for gas
leaks. Use a leak detecting solution or other preferred
means.
CAUTION
Some soaps used for leak detection are corrosive to
certain metals. Carefully rinse piping thoroughly af-
ter leak test has been completed. Do not use
matches, candles, flame or other sources of ignition
to check for gas leaks.
24 −If a leak is detected, shut gas and electricity off and
repair leak.
NOx Insert
25 −Repeat steps 24 and 26 until no leaks are detected.
26 −Replace access panel.
FIGURE 37
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Planned Service
The following items should be checked during an annual inspection. Power to the unit must be shut off for the service techni-
cian’s safety.
Fresh air grilles and louvers (on the unit and in the room
where the furnace is installed) − Must be open and unob-
structed to provide combustion air.
Operating performance − Unit must be observed during
operation to monitor proper performance of the unit and the
vent system.
Combustion gases − Flue products must be analyzed and
Burners − Must be inspected for rust, dirt, or signs of water.
compared to the unit specifications.
Vent pipe − Must be inspected for signs of water, damaged
Problems detected during the inspection may make it nec-
essary to temporarily shut down the furnace until the items
can be repaired or replaced.
or sagging pipe, or disconnected joints.
Unit appearance − Must be inspected for rust, dirt, signs
of water, burnt or damaged wires, or components.
Instruct the homeowners to pay attention to their
furnace. Situations can arise between annual furnace in-
spections that may result in unsafe operation. For instance,
items innocently stored next to the furnace may obstruct
the combustion air supply. This could cause incomplete
combustion and the production of carbon monoxide gas.
Blower access panel − Must be properly in place and pro-
vide a seal between the return air and the room where the
furnace is installed.
Return air duct − Must be properly attached and provide
an air seal to the unit.
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: EL280UH070P24A−01. All service must be
performed by a licensed professional installer (or equivalent), service agency, or gas supplier.
Cabinet Parts
Main access panel
Heating Parts
Flame sensor
Blower panel
Top cap
Heat exchanger assembly
Gas manifold
Control Panel Parts
Transformer
Combustion air inducer
Gas valve
Integrated control
Door interlock switch
Circuit breaker
Blower Parts
Main burner cluster
Main burner orifices
Pressure switch
Ignitor
Primary limit control
Flame rollout switch (s)
Secondary limit
Blower wheel
Blower housing
Motor
Motor mounting frame
Motor capacitor
Blower housing cutoff plate
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Integrated Control Diagnostic Codes
FLASH CODE
(X + Y)
STATUS / ERROR DESCRIPTION
FLASH CODE DESCRIPTIONS
Pulse
A 1/4 second flash followed by four seconds of off time.
Heartbeat
Constant 1/2 second bright and 1/2 second dim cycles.
LED flashes X times at 2Hz, remains off for two seconds, flashes Y times at 2Hz, remains off for four
seconds, then repeats.
X + Y
Pulse
Power on − Standby.
Heartbeat
Normal operation − signaled when heating demand initiated at thermostat.
FLAME CODES
1 + 2
1 + 3
Low flame current −− run mode.
Flame sensed out of sequence −− flame still present.
PRESSURE SWITCH CODES
2 + 3
2 + 4
2 + 5
2 + 6
2 + 7
Low pressure switch failed open.
Low pressure switch failed closed.
High pressure switch failed open.
High pressure switch failed closed.
Low pressure switch opened during ignition trial or heating demand.
LIMIT CODE
3 + 1
Limit switch open.
WATCHGUARD CODES
4 + 1
4 + 2
4 + 3
4 + 5
4 + 6
4 + 7
4 + 8
Watchguard −− Exceeded maximum number of retries.
Watchguard −− Exceeded maximum number of retries or last retry was due to pressure switch opening.
Watchguard −− Exceeded maximum number of retries or last retry was due to flame failure.
Watchguard −− Limit remained open longer than three minutes.
Watchguard −− Flame sensed out of sequence; flame signal gone.
Ignitor circuit fault −− Failed ignitor or triggering circuitry.
Low line voltage.
HARD LOCKOUT CODES
5 + 1
5 + 2
5 + 3
5 + 4
5 + 6
Hard lockout −− Rollout circuit open or previously opened.
Control failed self check, internal error (control will restart if error recovers).
No Earth ground (control will restart if error recovers).
Reversed line voltage polarity (control will restart if the error recovers).
Low secondary (24VAC) voltage.
Error Code Storage
5 − After final error code is indicated, STATUS LED will
flash to indicate normal operation.
The ignition control stores the last ten error codes in
memory. The codes are retained in case of power loss.
Clearing Error Codes
Error Code Review
1 − Short R (2) to (1). Within 1/2 second, the STATUS LED
will stay lit continuously to indicate that the short was
sensed.
1 − Short R (2) to (1). Within 1/2 second, the STATUS LED
will stay lit continuously to indicate that the short was
sensed.
2 − Continue to hold the short between R (2) to (1). After 5
seconds, STATUS LED will go from being continuously
lit to off.
2 − Continue to hold the short between R (2) to (1). After 5
seconds, STATUS LED will go from being continuously
lit to off. This indicates that error code review is pend-
ing.
3 − Continue to hold the short between R (2) to (1) beyond
ten seconds after STATUS LED has turned off. STA-
TUS LED will turn on, indicating that error codes have
been cleared.
3 − Remove R (2) to (1) short within ten seconds of STA-
TUS LED turning off. This activates error code review.
4 − Last ten error codes will be flashed on the STATUS
LED.
4 − Remove R (2) to (1) short. STATUS LED will flash to in-
dicate normal operation.
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Troubleshooting: Heating Sequence of Operation
HEATING SEQUENCE OF OPERATION
NORMAL AND ABNORMAL HEATING MODE
POWER ON
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF. (RESET CONTROL BY
TURNING MAIN POWER OFF.)
NO
NO
CONTROL SELF−CHECK OKAY?
POLARITY REVERSED.
STATUS ERROR CODE 5 + 4.
POLARITY OKAY?
YES
NO
IS THERE A
PROPER GROUND?
SIGNAL HOLDS UNTIL UNIT IS PROPERLY GROUNDED.
STATUS ERROR CODE 5 + 3.
YES
A
NORMAL OPERATION:
STATUS LED −− PULSE
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER ON. HAS PRIMARY OR
SECONDARY LIMIT RESET WITHIN 3 MINUTES?
YES
STATUS ERROR CODE 3 + 1.
B
THERMOSTAT CALLS FOR HEAT:
STATUS LED −− HEARTBEAT
NO
NO
NO
60−MINUTE LIMIT WATCHGUARD MODE.
GAS VALVE OFF, COMBUSTION AIR INDUCER
OFF, INDOOR BLOWER OFF WITH DELAY.
STATUS ERROR CODE 4 + 5.
YES
PRIMARY AND SECONDARY LIMIT
SWITCHES CLOSED?
YES
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER ON.
STATUS ERROR CODE 5 + 1.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS
RESET AND MAIN POWER IS INTERRUPTED OR
T’STAT IS CYCLED OFF/ON FOR 3 SEC. MINIMUM.
NO
ROLLOUT SWITCH CLOSED?
NO
YES
YES
FIRST (LOW) STAGE PRESSURE SWITCH
CONTACTS OPEN?
NO
YES
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF. CONTROL REMAINS UNTIL
PRESSURE SWITCH IS DETECTED OPEN.
STATUS ERROR CODE 2 + 4
SECOND (HIGH) STAGE PRESSURE SWITCH
CONTACTS OPEN?
NO
YES
GAS VALVE OFF.
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF.
TWO−STAGE OR SINGLE−STAGE THERMOSTAT
CALL FOR HEAT
CONTROL WILL NOT ATTEMPT SECOND−STAGE
OPERATION DURING THIS HEAT DEMAND.
FIRST−STAGE OPERATION WILL BE ATTEMPTED.
STATUS ERROR CODE 2 + 6.
COMBUSTION AIR INDUCER ON LOW SPEED.
STATUS LED −− HEARTBEAT
1
CONTINUED ON NEXT PAGE
If the furnace is operating on continuous fan mode (terminals ꢀ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 60 seconds then switch to low fire.
1
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Troubleshooting: Heating Sequence of Operation (Continued)
HEATING SEQUENCE OF OPERATION
CONTINUED
THERMOSTAT CALLS FOR HEAT
STATUS LED − HEARTBEAT.
(Refer to box A on previous page)
GAS VALVE OFF. COMBUSTION AIR INDUCER
OFF. INDOOR BLOWER OFF. UNIT WILL RETRY
AFTER 5−MINUTE WAIT PERIOD.
FIRST−STAGE (LOW FIRE) PRESSURE
SWITCH CLOSED WITHIN 2.0 MINUTES?
1
NO
STATUS ERROR CODE 2 + 3.
YES
15−SECOND COMBUSTION AIR INDUCER
LOW AND HIGH
COMBUSTION AIR INDUCER
PRESSURE SWITCH
NO
PRE−PURGE INITIATED BY CLOSED FIRST−STAGE
PRESSURE SWITCH (or 15 SECOND
INTER−PURGE PERIOD.)
ENERGIZED ON HIGH SPEED
CLOSED WITHIN 30
SECONDS
YES
1
STATUS LED −− HEARTBEAT.
IGNITOR WARM−UP (20 SECONDS)
STATUS LED −− HEARTBEAT.
YES
COMBUSTION AIR INDUCER OFF, IGNITOR OFF.
SIGNAL HOLDS UNTIL IGNITOR IS REPLACED
OR RECONNECTED.
NO
IS IGNITOR INTACT AND CONNECTED?
STATUS ERROR CODE 4 + 7.
YES
2
AT END OF IGNITOR 20 SECOND WARM UP
PERIOD, 4−SECOND TRIAL FOR IGNITION.
GAS VALVE OPENS, IGNITOR ENERGIZED DURING
4−SECOND TRIAL UNTIL FLAME SENSED.
YES
IS VOLTAGE ABOVE 90 VOLTS?
NO
YES
COMBUSTION AIR INDUCER OFF, IGNITOR OFF.
SIGNAL HOLDS UNTIL VOLTAGE RISES ABOVE 95
VOLTS. STATUS ERROR CODE 4 + 8.
4−SECOND FLAME STABILIZATION PERIOD.
NO
FLAME RECTIFICATION CURRENT CHECK
CAN FLAME BE PROVEN WITHIN 4
SECONDS AFTER GAS VALVE OPENS?
(u0.20 microamps)
GAS VALVE OFF. COMBUSTION AIR
INDUCER ON. INDOOR BLOWER OFF.
STATUS LED −− HEARTBEAT.
HAS CONTROL FAILED TO SENSE
FLAME FOR FIVE CONSECUTIVE TRIES
DURING A SINGLE HEAT DEMAND?
NO
YES
WATCHGUARD MODE. GAS VALVE OFF,
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF.
YES
STATUS ERROR CODE 4 + 1.
IS 60−MINUTE RESET PERIOD COMPLETE?
YES
NO
FLAME PRESENT?
HAS CONTROL RESET IGNITION SEQUENCE
FOUR (4) TIMES?
WATCHGUARD MODE.
NO
YES
STATUS ERROR CODE 4 + 3.
CONTINUED ON NEXT PAGE
If the furnace is operating on continuous fan mode (terminals ꢀ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 60 seconds then switch to low fire.
1
If combustion air inducer is operating on high speed and gas valve is energized on second−
stage heat, 20 seconds after flame is sensed furnace will switch to low fire.
2
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Troubleshooting: Heating Sequence of Operation (Continued)
HEATING SEQUENCE OF OPERATION
CONTINUED
THERMOSTAT CALLS FOR HEAT.
STATUS LED −− HEARTBEAT.
SEE BOX A.
FLAME SIGNAL ABOVE
(u1.40 microamps)
NO
LOW FLAME SIGNAL
(Does not affect control operation)
STATUS ERROR CODE 1 + 2.
YES
YES
SINGLE−STAGE THERMOSTAT MODE
(DIP SWITCH SET AT ꢀSINGLE")
TWO STAGE THERMOSTAT MODE
(DIP SWITCH SET AT ꢀTWO")
YES
YES
START SECOND−STAGE RECOGNITION
ON DELAY (10 OR 15 MINUTES).
STATUS LED −− HEARTBEAT
45−SECOND INDOOR BLOWER ON DELAY BEGINS.
STATUS LED −− HEARTBEAT.
YES
NO
YES
NO
PRIMARY & SECONDARY LIMIT SWITCHES
CLOSED?
ROLLOUT SWITCHES CLOSED?
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER ON.
YES
STATUS ERROR CODE 5 + 1. SEQUENCE HOLDS
UNTIL ROLLOUT SWITCH IS RESET AND MAIN
POWER IS INTERRUPTED OR THERMOSTAT
IS CYCLED OFF/ON FOR 3 SECOND MINIMUM.
YES
FIRST−STAGE (LOW FIRE)
PRESSURE SWITCH CLOSED?
NO
YES
NO
GAS VALVE OFF, COMBUSTION AIR INDUCER OFF,
INDOOR BLOWER ON.
STATUS ERROR CODE 3 + 1.
FIRST−STAGE HEAT DEMAND SATISFIED?
YES
YES
YES
HAS PRIMARY OR SECONDARY LIMIT
SWITCH CLOSED WITHIN 3 MINUTES?
(Indoor blower on low speed during 3−minute period)
GAS VALVE OFF, COMBUSTION AIR INDUCER
OFF FOLLOWING POST PURGE.
INDOOR BLOWER OFF WITH DELAY
STATUS LED −− PULSE
NO
LIMIT SWITCH WATCHGUARD MODE.
GAS VALVE OFF, COMBUSTION AIR INDUCER OFF,
INDOOR BLOWER OFF WITH DELAY.
SECOND−STAGE HEAT DEMAND.
SECOND−STAGE HEAT DEMAND REQUIRED?
STATUS ERROR CODE 4 + 5
IS 60−MINUTE RESET PERIOD COMPLETE?
YES
SECOND STAGE PRESSURE SWITCH CLOSED?
ABNORMAL FLASH CODE.
NOTE − IF SECOND−STAGE PRESSURE SWITCH
WAS ORIGINALLY FOUND CLOSED,
ABNORMAL CODE WILL FLASH.
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER OFF AFTER DELAY.
STATUS ERROR CODE 2 + 3. CONTROL RESTARTS
IGNITION SEQUENCE IF PRESSURE SWITCH
CLOSES WITHIN 2−1/2 MINUTES.
YES
NO
YES
NO
SECOND−STAGE PRESSURE SWITCH CLOSED
AT BEGINNING OF HEAT DEMAND?
STATUS ERROR CODE 2 + 6.
SECOND−STAGE 30−SECOND DELAY ON BEGINS.
STATUS LED −− HEARTBEAT.
YES
SECOND STAGE HEAT DEMAND
STATUS LED −− HEARTBEAT.
SECOND−STAGE COMBUSTION AIR INDUCER
ON. SECOND−STAGE GAS VALVE ON. HIGH
HEAT INDOOR BLOWER SPEED ON.
STATUS LED −− HEARTBEAT.
NO
RETURNS TO FIRST−STAGE HEAT MODE WHICH
CONTINUES UNTIL SECOND−STAGE PRESSURE
SWITCH CAN BE PROVEN or HEAT DEMAND IS
SATISFIED. FIVE (5) MINUTE WAIT PERIOD
INITIATED BEFORE RETRY. WERE 5 ATTEMPTS
MADE FOR SECOND−STAGE HEAT?
YES
SECOND−STAGE PRESSURE SWITCH CLOSED
IN LESS THAN TEN (10) SECONDS?
STATUS LED −− HEARTBEAT
NO
YES
CONTINUES FIRST−STAGE HEATING DEMAND.
WILL NOT REATTEMPT SECOND−STAGE
HEATING DEMAND.
YES
CONTINUED ON NEXT PAGE
STATUS ERROR CODE 2 + 5.
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Troubleshooting: Heating Sequence of Operation (Continued)
HEATING SEQUENCE OF OPERATION
CONTINUED
SEE BOX A
NORMAL OPERATION.
SEE BOX B
THERMOSTAT CALLS FOR HEAT.
RETURN TO FIRST−STAGE HEAT MODE.
FIRST−STAGE CONTINUES UNTIL SECOND−
STAGE PRESSURE SWITCH CAN BE PROVEN
or HEAT DEMAND IS SATISFIED. A FIVE (5)
MINUTE WAIT PERIOD IS INITIATED BEFORE
RETRY. WERE 5 ATTEMPTS MADE FOR
SECOND−STAGE HEAT?
SECOND−STAGE (HIGH FIRE) HEAT
PRESSURE SWITCH CLOSED?
YES
NO
YES
NO
HEAT DEMAND SATISFIED?
STATUS LED −− HEARTBEAT.
SEE BOX C
FIRST−STAGE HEAT DEMAND SATISFIED?
YES
YES
SINGLE−STAGE THERMOSTAT MODE
(DIP SWITCH SET AT ꢀSINGLE")
TWO STAGE THERMOSTAT MODE?
(DIP SWITCH SET AT ꢀTWO")
YES
YES
SECOND STAGE HEAT
DEMAND SATISFIED?
STATUS LED −− HEARTBEAT.
FIRST AND SECOND STAGE HEAT
DEMAND SATISFIED SIMULTANEOUSLY.
STATUS LED −− HEARTBEAT.
GAS VALVE OFF, COMBUSTION AIR
INDUCER OFF AFTER 5−SECOND
LOW SPEED POST PURGE PERIOD,
INDOOR BLOWER OFF DELAY
INITIATED ON LOW HEAT SPEED.
STATUS LED −− HEARTBEAT.
NO
YES
YES
GAS VALVE, COMBUSTION AIR INDUCER
AND INDOOR BLOWER RETURN TO FIRST−
STAGE OPERATION.
STATUS LED −− HEARTBEAT.
FIRST STAGE HEAT DEMAND SATISFIED?
YES
GAS VALVE OFF. COMBUSTION AIR INDUCER
OFF AFTER 5−SECOND LOW SPEED POST−
PURGE PERIOD. INDOOR BLOWER OFF.
DELAY INITIATED ON LOW HEAT SPEED.
STATUS LED −− PULSE.
DEMAND FOR HEAT SATISFIED.
POWER ON STAND BY.
STATUS LED −− PULSE.
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Troubleshooting: Cooling Sequence of Operation
COOLING SEQUENCE OF OPERATION
POWER ON
SIGNAL POLARITY REVERSED.
CONTROL WILL CONTINUE TO CALL FOR COOLING
IN THIS CONDITION.
YES
IS POLARITY REVERSED?
STATUS ERROR CODE 5 + 4.
NO
SIGNAL IMPROPER GROUND AT LED.
CONTROL WILL CONTINUE TO CALL FOR COOLING
IN THIS CONDITION.
NO
IS THERE
PROPER GROUND?
STATUS ERROR CODE 5 + 3.
YES
THERMOSTAT CALLS FOR FIRST−STAGE COOL.
COMPRESSOR AND CONDENSER FAN
ENERGIZED.
INDOOR BLOWER ENERGIZED ON FIRST STAGE
COOL SPEED AFTER 2 SECOND DELAY.
YES
COMPRESSOR AND CONDENSER FAN DE−ENERGIZED.
INDOOR BLOWER DE−ENEGIZED.
FIRST−STAGE DEMAND FOR COOL SATISFIED?
NO
THERMOSTAT CALLS FOR SECOND−STAGE COOL.
INDOOR BLOWER RAMPS UP TO SECOND−STAGE COOL SPEED.
SECOND−STAGE DEMAND FOR COOL SATISFIED?
YES
UNIT RETURNS TO FIRST STAGE COOL
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Troubleshooting: Continuous Fan Sequence of Operation
CONTINUOUS LOW SPEED FAN SEQUENCE OF OPERATION
MANUAL FAN SELECTION MADE AT THERMOSTAT.
AFTER 2 SECOND DELAY, INDOOR BLOWER IS
ENERGIZED ON CONTINUOUS FAN SPEED.
YES
YES
THERMOSTAT CALLS FOR FIRST STAGE COOL.
YES
THERMOSTAT CALLS FOR FIRST−STAGE HEAT.
YES
INDOOR BLOWER RAMPS TO FIRST STAGE
COOLING SPEED AFTER A 2−SECOND DELAY.
AFTER 45−SECOND DELAY, INDOOR BLOWER
SWITCHES TO LOW HEAT SPEED.
FIRST−STAGE COOL DEMAND SATISFIED?
FIRST−STAGE HEAT DEMAND SATISFIED.
NO
YES
YES
NO
SECOND STAGE COOL DEMAND
THERMOSTAT CALLS FOR SECOND−STAGE HEAT.
YES
INDOOR BLOWER RAMPS TO SECOND
STAGE COOL SPEED
INDOOR BLOWER SWITCHES TO HIGH HEAT SPEED
AFTER 30−SECOND RECOGNITION PERIOD.
YES
SECOND STAGE COOL DEMAND SATISFIED?
YES
SECOND−STAGE HEAT DEMAND SATISFIED.
YES
INDOOR BLOWER RAMPS DOWN TO FIRST STAGE
COOL SPEED.
INDOOR BLOWER RAMPS DOWN TO LOW
HEAT SPEED.
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Start−Up & Performance Check List
UNIT SET UP
(typical)
Unit Model Number_______________
Serial Number___________________
2
SUPPLY
AIR
Line Voltage
5
2
upflow furnace shown
1
3
Gas Supply Pressure
Filter
1
RETURN
AIR
4
3
DUCT SYSTEM
GAS SUPPLY
Natural Gas
1
SUPPLY AIR DUCT
Sealed
LP/Propane Gas
Piping Connections Tight
Leak Tested
Insulated (if necessary)
Registers Open and Unobstructed
Supply Line Pressure ꢀ W.C.________
RETURN DUCT
Sealed
VENT / EXHAUST PIPE
2
Secure to Unit
Filter Installed and Clean
Grilles Unobstructed
Elbows Secured to Pipe
Roof Flashing (water tight)
Vent Pipe Supported
INTEGRATED CONTROL
4
DIP Switches Set (if applicable)
Appropriate Links in Place (if applicable)
5
VOLTAGE CHECK
Supply Voltage _____
Electrical Connections Tight
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UNIT OPERATION
(typical)
Combustion CO
2
2
SUPPLY
AIR
7
Thermostat
Gas Manifold Pressure
Temperatures
6
1
upflow furnace shown
4
Filter
Blower Motor Amps
Duct Static
3
RETURN
AIR
5
COOLING MODE
HEATING MODE
INDOOR BLOWER AMPS______
3
4
GAS MANIFOLD PRESSURE ꢀW.C._____
1
2
TEMPERATURE DROP
COMBUSTION SAMPLE CO % CO PPM_______
2 ______
Return Duct Temperature _________
_
Supply Duct Temperature _______
Temperature Drop = _________
INDOOR BLOWER AMPS______
TEMPERATURE RISE
3
4
TOTAL EXTERNAL STATIC (dry coil)
Supply External Static _______
5
Supply Duct Temperature ________
_
Return External Static + ______
Total External Static = _______
Return Duct Temperature _____
Temperature Rise = ________
DRAIN LINE
Leak Free
6
7
TOTAL EXTERNAL STATIC (dry coil)
Supply External Static _______
Return External Static + ______
Total External Static = _______
5
THERMOSTAT
Adjusted and Programmed
Operation Explained to Owner
Contractor’s: Name_________________________Telephone_____________Checklist Completed____________________
Job Address_____−________________________________Technician’s Name___________________________________
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