INSTALLATION INSTRUCTIONS
A80DF & 80G1DF
Warm Air Gas Furnace
Downflow Air Discharge
This manual must be left with the homeowner for future reference.
This is a safety alert symbol and should never be ignored. When you see this symbol on labels or in
manuals, be alert to the potential for personal injury or death.
CAUTION
As with any mechanical equipment, personal injury can
result from contact with sharp sheet metal edges. Be
careful when you handle this equipment.
WARNING
Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal injury
or loss of life. Installation and service must be performed
by a licensed professional installer (or equivalent), service
agency or the gas supplier.
TABLE OF CONTENTS
Unit Dimensions ............................................................ 2
A80DF & 80G1DF Parts Arrangement .......................... 3
A80DF & 80G1DF Gas Furnace ................................... 4
Shipping and Packing List ............................................ 4
Safety Information ......................................................... 4
Use of Furnace as a Construction Heater .................... 5
General ......................................................................... 6
Combustion, Dilution, Ventilation Air ............................. 6
Setting Equipment ........................................................ 9
Filters .......................................................................... 12
Duct System ................................................................ 12
Venting ........................................................................ 12
Gas Piping .................................................................. 21
*506528-01*
Electrical ..................................................................... 22
Unit Start-Up ............................................................... 27
Heating Sequence of Operation ................................. 28
Gas Pressure Adjustment ........................................... 28
Control Settings .......................................................... 28
High Altitude ................................................................ 29
Other Unit Adjustments ............................................... 29
Service ........................................................................ 31
Planned Service .......................................................... 34
Control Diagnostic Codes ........................................... 34
Troubleshooting .......................................................... 34
Repair Parts List ......................................................... 35
Manufactured By
Allied Air Enterprises, Inc.
A Lennox International, Inc. Company
215 Metropolitan Drive
West Columbia, SC 29170
506528-01 Page 1 of 37Issue 1035
A80DF & 80G1DF Unit Dimensions - inches (mm)
FRONT VIEW
Model
A801DF/80G1DF
045-08
045-12
070-08
070-12
090-12
090-16
110-12
110-16
110-20
135-20
in.
14-1/2
17-1/2
21
24-1/2
SIDE VIEW
A
mm
368
446
533
622
13-3/8
16-3/8
19-7/8
23-3/8
B
in.
mm
340
416
504
546
19-1/2
C
in.
13
16
23
mm
330
406
495
584
in.
4-3/4
6-1/4
9-3/4
D
mm
121
159
8
203
248
506528-01Page 2 of 37 Issue 1035
BLOWER ASSEMBLY
CONTROL BOX
FLUE CHASE
A80DF & 80G1DF
Expanded View
INTERNAL FLUE
PIPE ASSEMBLY
BURNER BOX ASSEMBLY
CABINET
HEAT EXCHANGER
COMBUSTION AIR INDUCER
GAS VALVE
ACCESS PANEL
506528-01 Page 3 of 37Issue 1035
Figure 1
A80DF & 80G1DF Gas Furnace
The A80DF & 80G1DF gas furnace is shipped ready for
installation in the downflow position.
The furnace is equipped for installation in natural gas
applications. A conversion kit (ordered separately) is required
for use in propane/LP gas applications.
This unit can be installed as either a Direct Vent or a
Non-Direct Vent gas central furnace
NOTE: In Direct Vent installations, combustion air is taken
from outdoors and flue gases are discharged outdoors. In
Non-Direct Vent installations, combustion air is taken from
indoors and flue gases are discharged outdoors.
Shipping and Packing List
1 - Assembled Gas Furnace
1 - Bag assembly containing the following:
2 - Screws
3 - Wire nuts
1 - Snap bushing
1 - Snap Plug
1 - Wire tie
1 - Vent warning label
1 - Owner’s manual and warranty card
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
Please refer to the technical specification sheets for available
accessories.
Safety Information
CAUTION
As with any mechanical equipment, personal injury can
result from contact with sharp sheet metal edges. Be
careful when you handle this equipment.
Certifications
These units are CSA International certified to ANSI Z21.47.
In the USA, installation of gas furnaces must conform with
local building codes. In the absence of local codes, units
must be installed according to the current National Fuel Gas
Code (ANSI-Z223.1). The National Fuel Gas Code is
available from the following address: American National
Standards Institute, Inc., 11 West 42nd Street, New York,
NY 10036.
Clearances
Adequate clearance must be made around the air openings
into the vestibule area. In order to ensure proper unit
operation, combustion and ventilation air supply must be
provided according to the current National Fuel Gas Code.
Vent installations must be consistent with the venting tables
(in this instruction) and applicable provisions of local building
codes.
This furnace is CSA International certified for installation
clearances to combustible material as listed on the unit
nameplate and in the tables in figures 8 and 10. Accessibility
and service clearances must take precedence over fire
protection clearances.
DANGER
DANGER OF EXPLOSION!
There are circumstances in which odorant used with LP/
Propane gas can lose its scent. In case of a leak, LP/
Propane gas will settle close to the floor and may be difficult
to smell. An LP/Propane leak detector should be installed
in all LP applications.
WARNING
Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal injury
or loss of life. Installation and service must be performed
by a licensed professional installer (or equivalent), service
agency or the gas supplier.
NOTE: For installation on combustible floors, the furnace
shall not be installed directly on carpeting, tile, or other
combustible material other than wood flooring.
Installed Locations
For installation in a residential garage, the furnace must be
installed so that the burner(s) and the ignition source are
located no less than 18 inches (457 mm) above the floor.
The furnace must be located or protected to avoid physical
damage by vehicles. When a furnace is installed in a public
garage, hangar, or other building that has a hazardous
atmosphere, the furnace must be installed according to
recommended good practice requirements and current
National Fuel Gas Code.
506528-01Page 4 of 37 Issue 1035
Temperature Rise
NOTE: Furnace must be adjusted to obtain a temperature
rise within the range specified on the unit nameplate. Failure
to do so may cause erratic limit operation and may result in
premature heat exchanger failure.
This furnace may be installed in alcoves, closets, attics,
basements, garages, and utility rooms in the upflow or
horizontal position.
This furnace design has not been certified for installation in
mobile homes, recreational vehicles, or outdoors.
This furnace must be installed so that its electrical
components are protected from water.
Installed in Combination with a Cooling Coil
When this furnace is used with cooling units, it shall be
installed in parallel with, or on the upstream side of, cooling
units to avoid condensation in the heating compartment. See
Figure 2. With a parallel flow arrangement, a damper (or
other means to control the flow of air) must adequately
prevent chilled air from entering the furnace. If the damper
is manually operated, it must be equipped to prevent
operation of either the heating or the cooling unit, unless it
is in the full HEAT or COOL setting. See Figure 2.
Heating Unit Installed Parallel to Air Handler Unit
Use of Furnace as a Construction Heater
These units are not recommended for construction heating
during any phase of construction. Very low return air
temperature, harmful vapors and operation of the unit with
clogged or misplaced filters will damage the unit.
These units may be used for heating of buildings or structures
under construction, if the following conditions are met:
• The vent system must be permanently installed per these
installation instructions.
• A room thermostat must control the furnace. The use
of fixed jumpers that will provide continuous heating is
not allowed.
• The return air duct must be provided and sealed to the
furnace.
• Return air temperature range between 60°F (16°C) and
80°F (27°C) must be maintained.
• Air filters must be installed in the system and must be
maintained during construction.
• Air filters must be replaced upon construction
completion.
Figure 2
When installed, this furnace must be electrically grounded
according to local codes. In addition, in the United States,
installation must conform with the current National Electric
Code, ANSI/NFPA No. 70. The National Electric Code (ANSI/
NFPA No. 70) is available from the following address:
National Fire Protection Association
1 Battery March Park
Quincy, MA 02269
NOTE: This furnace is designed for a minimum continuous
return air temperature of 60° F (16°C) or an intermittent
operation down to 55° F (13°C) dry bulb for cases where a
night setback thermostat is used. Return air temperature
must not exceed 85° F (29°C) dry bulb.
• The input rate and temperature rise must be set per the
furnace rating plate.
• One hundred percent (100%) outdoor air must be
provided for combustion air requirements during
construction. Temporary ducting may supply outdoor
air to the furnace. Do not connect duct 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.
• The furnace heat exchanger, components, duct system,
air filters and evaporator coils must be thoroughly
cleaned following final construction clean-up.
• All furnace operating conditions (including ignition, input
rate, temperature rise and venting) must be verified
according to these installation instructions.
506528-01 Page 5 of 37Issue 1035
General
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
In addition to the requirements outlined previously, the
following general recommendations must be considered
when installing one of these furnaces:
• Place the furnace as close to the center of the air
distribution system as possible. The furnace should also
be located close to the chimney or vent termination point.
• Do not install the furnace where drafts might blow directly
into it. This could cause improper combustion.
• Do not block the furnace combustion air openings with
clothing, boxes, doors, etc. Air is needed for proper
combustion and safe unit operation.
• When the furnace is installed in an attic or other insulated
space, keep insulation away from the furnace.
Combustion, Dilution & Ventilation Air
In the past, there was no problem in bringing in sufficient
outdoor air for combustion. Infiltration provided all the air
that was needed. In today’s homes, tight construction
practices make it necessary to bring in air from outside for
combustion. Take into account that exhaust fans, appliance
vents, chimneys, and fireplaces force additional air that could
be used for combustion out of the house. Unless outside
air is brought into the house for combustion, negative
pressure (outside pressure is greater than inside pressure)
will build to the point that a downdraft can occur in the furnace
vent pipe or chimney. As a result, combustion gases enter
the living space creating a potentially dangerous situation.
In the absence of local codes concerning air for combustion
and ventilation, use the guidelines and procedures in this
section to install this furnaces to ensure efficient and safe
operation. You must consider combustion air needs and
requirements for exhaust vents and gas piping.
NOTE: The Commonwealth of Massachusetts stipulates
these additional requirements:
• Gas furnaces shall be installed by a licensed plumber
or fitter only.
• The gas cock must be “T handle” type.
• When a furnace is installed in an attic, the passageway
to and service area surrounding the equipment shall be
floored.
WARNING
Product Contains Fiberglass Wool.
Disturbing the insulation in this product during
installation, maintenance, or repair will expose you to
fiberglass wool. Breathing this may cause lung cancer.
(Fiberglass wool is known to the State of California to
cause cancer.)
Fiberglass wool may also cause respiratory, skin, and
eye irritation.
To reduce exposure to this substance or for further
information, consult material safety data sheets available
from address shown below, or contact your supervisor.
Allied Air Enterprises, Inc.
215 Metropolitan Drive
West Columbia, SC 29170
A portion of this information has been reprinted with
permission from the National Fuel Gas Code (ANSI-Z223.1).
This reprinted material is not the complete and official
position of the ANSI on the referenced subject, which is
represented only by the standard in its entirety.
WARNING
Insufficient combustion air can cause headaches,
nausea, dizziness or asphyxiation. It will also cause
excess water in the heat exchanger resulting in rusting
and premature heat exchanger failure. Excessive
exposure to contaminated combustion air will result in
safety and performance related problems. Avoid
exposure to the following substances in the combustion
air supply:
Permanent wave solutions
Chlorinated waxes and cleaners
Chlorine base swimming pool chemicals
Water softening chemicals
De-icing salts or chemicals
Carbon tetrachloride
Halogen type refrigerants
Cleaning solvents (such as perchloroethylene)
Printing inks, paint removers, varnishes, etc.
Hydrochloric acid
Antistatic fabric softeners for clothes dryers
Masonry acid washing materials
506528-01Page 6 of 37 Issue 1035
All gas fired appliances require air for the combustion
process. If sufficient combustion air is not available, the
furnace or other appliances will operate inefficiently and
unsafely. Enough air must be provided to meet the needs
of all fuelburning appliances and appliances such as exhaust
fans which force air out of the house. When fireplaces,
exhaust fans, or clothes dryers are used at the same time
as the furnace, much more air is necessary to ensure proper
combustion and to prevent a downdraft. Insufficient air
causes incomplete combustion which can result in carbon
monoxide.
In addition to providing combustion air, fresh outdoor air
dilutes contaminants in the indoor air. These contaminants
may include bleaches, adhesives, detergents, solvents and
other contaminants which can corrode furnace components.
Equipment in Confined Space - All Air From Inside
The requirements for providing air for combustion and
ventilation depend largely on whether the furnace is installed
in an unconfined or a confined space.
Unconfined Space
An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the
combined input rating of all appliances installed in that space.
This space also includes adjacent rooms which are not
separated by a door. Though an area may appear to be
unconfined, it might be necessary to bring in outdoor air for
combustion if the structure does not provide enough air by
infiltration. If the furnace is located in a building of tight
construction with weather stripping and caulking around the
windows and doors, follow the procedures in the air from
outside section.
Confined Space
A confined space is an area with a volume less than 50
cubic feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the
combined input rating of all appliances installed in that space.
This definition includes furnace closets or small equipment
rooms.
When the furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside the space
containing the furnace, the return air must be handled by
ducts which are sealed to the furnace casing and which
terminate outside the space containing the furnace. This is
especially important when the furnace is mounted on a
platform in a confined space such as a closet or small
equipment room. Even a small leak around the base of the
unit at the platform or at the return air duct connection can
cause a potentially dangerous negative pressure condition.
Air for combustion and ventilation can be brought into the
confined space either from inside the building or from outside.
NOTE: Each opening shall have a free area of at least one square
inch per 1,000 Btu (645 mm² per .29 kW) per hour of the total input
rating of all equipment in the enclosure, but not less than 100 square
inches (64546 mm²).
Figure 3
Air from Inside
If the confined space that houses the furnace adjoins a space
categorized as unconfined, air can be brought in by providing
two permanent openings between the two spaces. Each
opening must have a minimum free area of 1 square inch
(645 mm2) per 1,000 Btu (.29 kW) per hour of total input
rating of all gas fired equipment in the confined space. Each
opening must be at least 100 square inches (64516 mm2).
One opening shall be within 12 inches (305 mm) of the top
of the enclosure and one opening within 12 inches (305 mm)
of the bottom. See Figure 3.
Air from Outside
If air from outside is brought in for combustion and ventilation,
the confined space must have two permanent openings. One
opening shall be within 12 inches (305 mm) of the top of the
enclosure and one opening within 12 inches (305 mm) of
the bottom. These openings must communicate directly or
by ducts with the outdoors or spaces (crawl or attic) that
freely communicate with the outdoors or indirectly through
vertical ducts. Each opening shall have a minimum free
area of 1 square inch (645 mm2) per 4,000 Btu (1.17 kW)
per hour of total input rating of all equipment in the enclosure.
See Figures 4 and 5. When communicating with the
outdoors through horizontal ducts, each opening shall have
a minimum free area of 1 square inch (645 mm2) per 2,000
Btu (.56 kW) per total input rating of all equipment in the
enclosure. See Figure 6.
506528-01 Page 7 of 37Issue 1035
When ducts are used, they shall be of the same cross
sectional area as the free area of the openings to which
they connect. The minimum dimension of rectangular air
ducts shall be no less than 3 inches (75 mm). In calculating
free area, the blocking effect of louvers, grilles, or screens
must be considered. If the design and free area of protective
covering is not known for calculating the size opening
required, it may be assumed that wood louvers will have
20 to 25 percent free area and metal louvers and grilles will
have 60 to 75 percent free area. Louvers and grilles must
be fixed in the open position or interlocked with the
equipment so that they are opened automatically during
equipment operation.
EQUIPMENT IN CONFINED SPACE - ALL AIR FROM OUTSIDE
(Inlet Air from Crawlspace &
Outlet Air to Ventilated Attic)
EQUIPMENT IN CONFINED SPACE
(ALL AIR FROM OUTSIDE)
NOTE: Each air duct opening shall have a free area of at least one
square inch per 2,000 Btu (645 mm² per .59 kW) per hour of the
total input rating of all equipment in the enclosure. If the equipment
room is located against an outside wall and the air openings
communicate directly with the outdoors, each opening shall have a
free area of at least 1 square inch per 4,000 Btu (645 mm² per 1.17
kW) per hour of the total input rating of all other equipment in the
enclosure.
NOTE: The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645 mm² per 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
(All Air through Ventilated Attic)
Figure 6
NOTE: The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645 mm² per 1.17 kW) per
hour of the total input rating of all equipment in the enclosure.
Figure 5
506528-01Page 8 of 37 Issue 1035
Setting Equipment
WARNING
Do not install the furnace on its front or its back. Do not
connect the return air ducts to the back of the furnace.
Doing so will adversely affect the operation of the safety
control devices, which could result in personal injury or
death.
The gas furnace can be installed as shipped in either the
upflow position or the horizontal position.
Select a location that allows for the required clearances
that are listed on the unit nameplate. Also consider gas
supply connections, electrical supply, vent connection, and
installation and service clearances [24 inches (610 mm) at
unit front]. The unit must be level.
NOTE: Units with 1/2 hp blower motors are equipped with
three flexible legs and one rigid leg. See Figure 7. The
rigid leg is equipped with a shipping bolt and a flat white
plastic washer (rather than the rubber mounting grommet
used with a flexible mounting leg). The bolt and washer
must be removed before the furnace is placed into
operation. After the bolt and washer have been removed,
the rigid leg will not touch the blower housing.
Downflow Applications
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or
alcove installations are shown in Figure 8.
Downflow Application Installation Clearances
Figure 7
Units with 1/2 HP
Blower Motor.
* Front clearance In alcove Installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
‡ For installation on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other than
wood flooring.
† Left side requires 3 inches if a single wall vent is used on 14-1/2
inch cabinets.
Figure 8
Return Air
Return air must be brought in through the top of the furnace
installed in an downflow application.
506528-01 Page 9 of 37Issue 1035
Figure 9
WARNING
Improper installation of the furnace can result in personal
injury or death. Combustion and flue products must
never be allowed to enter the return air system or air in
the living space. Use sheet metal screws and joint tape
to seal return air system to furnace.
In platform installations with furnace return, the furnace
should be sealed airtight to the return air plenum. A
door must never be used as a portion of the return air
duct system. The base must provide a stable support
and an airtight seal to the furnace. Allow absolutely no
sagging, cracks, gaps, etc.
For no reason should return and supply air duct systems
ever be connected to or from other heating devices such
as a fireplace or stove, etc. Fire, explosion, carbon
monoxide poisoning, personal injury and/or property
damage could result.
Installation on Non-Combustible Flooring (Figure 11)
1. Cut floor opening keeping in mind clearances listed on
unit rating plate. Also keep in mind gas supply
connections, electrical supply, flue and air intake
connections and sufficient installation and servicing
clearances. See Table 1 for correct floor opening size.
2. Flange warm air plenum and lower the plenum into the
opening.
3. Set the unit over the plenum and seal the plenum to the
unit.
4. Ensure that the seal is adequate.
NON-COMBUSTIBLE FLOOR OPENING SIZE
NOTE: Floor opening dimensions listed are 1/4 inch (6 mm) larger
than the unit opening. See dimension drawing on page 2.
Table 1
Installation Clearances
* Front
Back
Sides
Vent
Floor
* Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
† Allow proper clearances to accommodate condensate trap and vent
pipe installation.
‡ The furnace may be installed on a combustible wood floor if an
optional additive base is installed between the furnace and the
combustivle floor.
0
0
0†
0
NC‡
Figure 11
Installation on Combustible Flooring (Figure 12)
1. When unit is installed on a combustible floor, a downflow
combustible flooring base must be installed between the
furnace and the floor. The base must be ordered
separately. See Table 2 for opening size to cut in floor.
CAUTION
The furnace and combustible flooring base shall not be
installed directly on carpeting, tile, or other combustible
material other than wood flooring.
Figure 10
506528-01Page 10 of 37 Issue 1035
COMBUSTIBLE FLOORING BASE OPENING SIZE
Table 2
Figure 12
2. After opening is cut, set the combustible flooring base
into opening.
3. Check fiberglass strips on the combustible flooring base
to make sure they are properly glued and positioned.
4. Lower supply air plenum into the combustible flooring
base until plenum flanges seal against fiberglass strips.
er opening is
NOTE: Be careful not to damage fiberglass strips. Check
for a tight seal.
Figure 13
Return Air Opening - Downflow Units
Return air may be brought in only through the top opening
of a furnace installed in the downflow position. The following
steps should be taken when installing plenum:
1. Bottom edge of plenum should be flanged with a
hemmed edge (See Figure 14 or 15).
2. Sealing strips should be used to ensure an airtight seal
between the cabinet and the plenum.
3. In all cases, plenum should be secured to top of furnace
using sheet metal screws.
4. Make certain that an adequate seal is made.
5. Set the furnace over the plenum.
6. Ensure that the seal between the furnace and plenum
is adequate.
Installation on Cooling Coil Cabinet (Figure 13)
NOTE: Downflow combustible flooring kit is not used.
1. Refer to reverse flow coil installation instructions for
correctly sized opening in floor and installation of cabinet.
2. When cooling cabinet is in place, set and secure the
furnace according to the instructions that are provided
with the cooling coil. Secure the furnace to the cabinet.
3. Seal the cabinet and check for air leaks.
506528-01 Page 11 of 37Issue 1035
Figure 14
Figure 15
Filters
This unit is not equipped with a filter or rack. A field provided
high velocity filter is required for the unit to operate properly.
Venting
A 4 inch diameter flue transition is factory installed on the
combustion air inducer outlet of all models.
A filter must be in place any time the unit is operating.
Duct System
Use industry approved standards (such as those published
by Air Conditioning Contractors of America or American
Society of Heating, Refrigerating and Air Conditioning
Engineers) to size and install the supply and return air duct
system. This will result in a quiet and low static system that
has uniform air distribution.
NOTE: Do not operate the furnace in the heating mode
with an external static pressure that exceeds 0.8 inches w.c.
Higher external static pressures may cause erratic limit
operation.
Supply Air Plenum
If the furnace is installed without a cooling coil, a removable
access panel must be installed in the supply air duct. The
access panel should be large enough to permit inspection
(either by smoke or reflected light) of the heat exchanger
for leaks after the furnace is installed. The furnace access
panel must always be in place when the furnace is operating
and it must not allow leaks into the supply air duct system.
Return Air Plenum
IMPORTANT
The unit will not vent properly with the flue transition pointed
down in the 6 o’clock position.
The combustion air inducer may be rotated clockwise or
counterclockwise by 90° to allow for top or side vent
discharge in all applications. When the unit is installed,
the flue transition must be in the 9 o’clock, 12 o’clock or 6
o’clock position.
These series units are classified as fan assisted Category I
furnaces when vertically vented according to the latest edition
of National Fuel Gas Code (NFPA 54 / ANSI Z223.1) in the
USA. A fan assisted Category I furnace is an appliance
equipped with an integral mechanical means to either draw
or force combustion products through the combustion
chamber and/or heat exchanger. This unit is not approved
for use with horizontal venting.
NOTE: Use these instructions as a guide. They do not
supersede local codes. This furnace must be vented
according to all local codes these installation instructions,
and the provided venting tables in these instructions.
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 device (i.e., wood
fireplace) is installed.
When return air is drawn from a room, a negative pressure
is created in the room. If a gas appliance is operating in a
room with negative pressure, the flue products can be pulled
back down the vent pipe and into the room. This reverse
flow of the flue gas may result in incomplete combustion
and the formation of carbon monoxide gas. This toxic gas
might then be distributed throughout the house by the furnace
duct system.
The venting tables in this manual were extracted from the
National Fuel Gas Code (NFPA 54 / ANSI Z223.1) and are
provided as a guide for proper vent installation. Proper
application, termination, construction and location of vents
must conform to local codes having jurisdiction. In the
absence of local codes, the NFGC serves as the defining
document.
Refer to the tables and the venting information contained in
these instructions to properly size and install the venting
system.
IMPORTANT
Once the venting system is installed, attach the
“Disconnected Vent” warning sticker to a visible area of
the plenum near the vent pipe. See Figure 15. The
warning sticker is provided in the bag assembly. Order
kit 66W04 for additional stickers.
506528-01Page 12 of 37 Issue 1035
WARNING
Asphyxiation hazard. The exhaust vent for this furnace
must be securely connected to the furnace flue transitiion
at all times.
If the existing chimney will not accommodate a listed metal
liner, either the chimney must be rebuilt to accommodate
one of these liners or an alternate approved venting method
must be found.
Insulation for the flexible vent pipe must be an encapsulated
fiberglass sleeve recommended by the flexible vent pipe
manufacturer.
Vent Connection
Figure 15
Use self drilling sheet metal screws or a mechanical fastener
to firmly secure the vent pipe to the round collar of the flue
transition. If self drilling screws are used to attach the vent
pipe, it is recommended that three be used. Drive one self
drilling screw through the front and one through each side
of the vent pipe and collar. See Figure 15.
Common Venting Using Metal Lined
Masonry Chimney
NOTE 1: Refer to the provided venting tables for installations.
Refer to the capacity requirements shown in the provided venting
tables.
Figure 16
Install the first vent connector elbow at a minimum of six
inches (152 mm) from the furnace vent outlet. See Figure
15.
Venting Using a Masonry Chimney
The following additional requirements apply when a lined
masonry chimney is used to vent this furnace.
Masonry chimneys used to vent Category I central furnaces
must be either tile lined or lined with a listed metal lining
system or dedicated gas vent. Unlined masonry chimneys
are prohibited. See Figures 16 and 17 for common venting.
A chimney with one or more sides exposed to the outside of
the structure is considered to be an exterior chimney.
An exterior masonry chimney that is not tile lined must be
lined with B 1 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.
506528-01 Page 13 of 37Issue 1035
Common Venting Using Tile Lined Interior Masonry Chimney and Combined Vent Connector
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.
Figure 17
DO NOT insulate the space between the liner and the
chimney wall with puffed mica or any other loose granular
insulating material.
IMPORTANT
SINGLE appliance venting of a fan assisted furnace into
a tile lined masonry chimney (interior or outside wall) is
prohibited. The chimney must first be lined with either
type B1 vent or an insulated single wall flexible vent
lining system which has been sized according to the
provided venting tables and the vent pipe manufacturer’s
instructions.
A fan assisted furnace may be commonly vented into an
existing lined masonry chimney if the following conditions
are met:
· The chimney is currently serving at least one drafthood
equipped appliance.
· The vent connectors and chimney are sized according
to the provided venting tables.
If type B1 double wall vent is used inside a chimney, no
other appliance can be vented into the chimney. The outer
wall of type B1 vent pipe must not be exposed to flue
products. A type B1 vent or masonry chimney liner shall
terminate above the roof surface with a listed cap or a listed
roof assembly according to the terms of their respective
listings and the vent manufacturer’s instructions.
When inspection reveals that an existing chimney is not safe
for the intended purpose, it shall be rebuilt to conform to
nationally recognized standards, lined or relined with suitable
materials, or replaced with a gas vent or chimney suitable
for venting. The chimney passageway must be checked
periodically to ensure that it is clear and free of obstructions.
Do not install a manual damper, barometric draft regulator,
or flue restrictor between the furnace and the chimney.
Never connect a Category I appliance to a chimney that is
servicing a solid fuel appliance. If a fireplace chimney flue
is used to vent this appliance, the fireplace opening must be
permanently sealed.
A type B or listed chimney lining system that passes through
an unused masonry chimney flue is not considered to be
exposed to the outdoors.
General Venting Requirements
Vent all furnaces according to these instructions:
1. Vent diameter recommendations and maximum
allowable piping runs are found in the provided venting
tables.
2. In no case should the vent or vent connector diameter
be less than the diameter specified in the provided
venting tables.
3. The minimum vent capacity determined by the sizing
tables must be less than the low fire input rating and the
maximum vent capacity must be greater than the high
fire input rating.
4 . Single appliance vents - If the vertical vent or tile lined
chimney has a larger diameter or flow area than the
vent connector, use the vertical vent diameter to
determine the minimum vent capacity and the vent
connector diameter to determine the maximum vent
capacity. The flow area of the vertical vent, however,
shall not exceed 7 times the flow area of the listed
appliance categorized vent area, drafthood outlet area
or flue collar area unless designed according to
approved engineering methods.
5. Multiple appliance vents - The flow area of the largest
section of vertical vent or chimney shall not exceed 7
times the smallest listed appliance categorized vent
area, drafthood outlet area or flue collar area unless
designed according to approved engineering methods.
506528-01Page 14 of 37 Issue 1035
6. The entire length of single wall metal vent connector
shall be readily accessible for inspection, cleaning, and
replacement.
7. Single appliance venting configurations with zero lateral
lengths (Tables 3 and 4) are assumed to have no elbows
in the vent system. For all other vent configurations,
the vent system is assumed to have two 90° elbows.
For each additional 90° elbow or equivalent (for example
two 45° elbows equal one 90° elbow) beyond two, the
maximum capacity listed in the venting table should be
reduced by 10% (0.90 x maximum listed capacity).
8. The common venting Tables (5, 6, 7, and 8) were
generated using a maximum horizontal vent connector
length of 1-1/2 feet (.46 m) for each inch (25 mm) of
connector diameter as follows:
Table 2
9. If the common vertical vent is offset, the maximum
common vent capacity listed in the common venting
tables should be reduced by 20%, the equivalent of two
90° elbows (0.80 x maximum common vent capacity).
The horizontal length of the offset shall not exceed
1-1/2 feet (.46 m) for each inch (25 mm) of common
vent diameter.
10. The vent pipe should be as short as possible with the
least number of elbows and angles required to complete
the job. Route the vent connector to the vent using the
shortest possible route.
11. A vent connector shall be supported without any dips or
sags and shall slope a minimum of 1/4 inch (6.4 mm)
per linear foot (305 mm) of connector, back toward the
appliance.
12. Vent connectors shall be firmly attached to the fumace
flue collar by self drilling screws or other approved
means,except vent connectors of listed type B1 vent
material which shall be assembled according to the
manufacturer’s instructions. Joints between sections
of single wall connector piping shall be fastened by
screws or other approved means.
13. When the vent connector used for Category I appliances
must be located in or pass through a crawl space, attic
or other areas which may be cold, that portion of the
vent connector shall be constructed of listed doublewall
type B1 vent material or material having equivalent
insulation qualities.
14. All venting pipe passing through floors, walls, and
ceilings must be installed with the listed clearance to
combustible materials and be fire stopped according to
local codes. In absence of local codes, refer to NFGC
(2223.1 ).
15. No portion of the venting system can extend into, or
pass through any circulation air duct or plenum.
16. Vent connectors serving Category I appliances shall not
be connected to any portion of mechanical draft systems
operating under positive pressure such as Category III
or IV venting systems.
17. If vent connectors are combined prior to entering the
common vent, the maximum common vent capacity
listed in the common venting tables must be reduced by
10%, the equivalent of one 90° elbow (0.90 x maximum
common vent capacity).
18. The common vent diameter must always be at least as
large as the largest vent connector diameter.
19. In no case, shall the vent connector be sized more than
two consecutive table size diameters over the size of
the draft hood outlet or flue collar outlet.
20. Do not install a manual damper, barometric draft
regulator or flue restrictor between the furnace and the
chimney.
21. When connecting this appliance to an existing dedicated
or common venting system, you must inspect the venting
system’s general condition and look for signs of
corrosion. The existing vent pipe size must conform to
these instructions and the provided venting tables. If
the existing venting system does not meet these
requirements, it must be resized.
506528-01 Page 15 of 37Issue 1035
Capacity of Type B Double Wall Vents with Type B Double Wall Connectors
Serving a Single Category I Appliance
NOTE: Single appliance venting configureations with zero lateral lengths are assumed to have no elbows in the vent system. For all other vent
configurations, the vent system is assumed to have two 90 ° elbows. For each additional 90° elbow or equivalent (for example two 45° elbows equal
one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).
Table 3
506528-01Page 16 of 37 Issue 1035
Capacity of Type B Double Wall Vents with Single Wall Metal Connectors
Serving a Single Category I Appliance
NOTE: Single appliance venting configureations with zero lateral lengths are assumed to have no elbows in the vent system. For all other vent
configurations, the vent system is assumed to have two 90 ° elbows. For each additional 90° elbow or equivalent (for example two 45° elbows equal
one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).
506528-01 Page 17 of 37Issue 1035
Table 4
Vent Connector Capacity
Type B Double Wall Vents with Type B Double Wall Connectors
Serving Two or More Category I Appliances
Table 5
Common Vent Capacity
Type B Double Wall Vents with Type B Double Wall Connectors
Serving Two or More Category I Appliances
Table 6
506528-01Page 18 of 37 Issue 1035
Vent Connector Capacity
Type B Double Wall Vents with Single Wall Metal Connectors
Serving Two or More Category I Appliances
NOTE: Single appliance venting configureations with zero lateral lengths are assumed to have no elbows in the vent system. For all other vent
configurations, the vent system is assumed to have two 90 ° elbows. For each additional 90° elbow or equivalent (for example two 45° elbows equal
one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).
Table 7
Common Vent Capacity
Type B Double Wall Vents with Single Wall Metal Connectors
Serving Two or more Category I Appliances
Table 8
506528-01 Page 19 of 37Issue 1035
Removal of the Furnace from Common Vent
In the event that an existing furnace is removed from a
venting system commonly run with separate gas appliances,
the venting system is likely to be too large to properly vent
the remaining attached appliances.
Conduct the following test while each appliance is operating
and the other appliances (which are not operating) remain
connected to the common venting system. If the venting
system has been installed improperly, you must correct the
system as indicated in the general venting requirements
section.
WARNING
CARBON MONOXIDE POISONING HAZARD
Failure to follow the steps outlined below for each
appliance connected to the venting system being placed
into operation could result in carbon monoxide poisoning
or death.
3. Close all building doors and windows and all doors
between the space in which the appliances remaining
connected to the common venting system are located
and other spaces of the building. Turn on clothes dryers
and any appliances not connected to the common
venting system. Turn on any exhaust fans, such as
range hoods and bathroom exhausts, so they will
operate at maximum speed. Do not operate a summer
exhaust fan. Close fireplace dampers.
4. Follow the lighting instructions. Turn on the appliance
that is being inspected. Adjust the thermostat so that
the appliance operates continuously.
5. After the burners 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.
6. After determining that each appliance connected to the
common venting system is venting properly, (step 3)
return all doors, widows, exhaust fans, fireplace
dampers, and any other gas burning appliances to their
previous mode of operation.
7. If a venting problem is found during any of the preceding
tests, the common venting system must be modified to
correct the problem.
The following steps shall be followed for each appliance
connected to the venting system being placed into operation,
while all other appliances connected to the venting system
are not in operation:
1. Seal any unused openings in the common venting
system.
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.
Resize the common venting system to the minimum vent
pipe size determined by using the appropriate tables in
Appendix G. (These are in the current standards of the
National Fuel Gas Code ANSI 2223.1.
506528-01Page 20 of 37 Issue 1035
Gas Piping
CAUTION
If a flexible gas connector is required or allowed by the
authority that has jurisdiction, black iron pipe shall be
installed at the gas valve and extend outside the furnace
cabinet. The flexible connector can then be added
between the black iron pipe and the gas supply line.
Gas Supply
1. This unit is shipped standard for left or right side
installation of gas piping (or top entry in horizontal
applications). Connect the gas supply to the piping
assembly.
2. When connecting the gas supply piping, consider factors
such as length of run, number of fittings, and furnace
rating to avoid excessive pressure drop. Table 9 lists
recommended pipe sizes for typical applications.
3. The gas piping must not run in or through air ducts,
clothes chutes, gas vents or chimneys, dumb waiters,
or elevator shafts.
4. The piping should be sloped 1/4 inch (6.4 mm) per 15
feet (4.57 m) upward toward the meter from the furnace.
The piping must be supported at proper intervals [every
8 to 10 feet (2.44 to 3.01 m)] with suitable hangers or
straps. Install a drip leg in vertical pipe runs to the unit.
5. A 1/8" N.P.T. plugged tap or pressure post is located on
the gas valve to facilitate test gauge connection. See
Figure 26.
6. In some localities, codes may require the installation of
a manual main shut off valve and union (furnished by
the installer) external to the unit. The union must be of
the ground joint type.
IMPORTANT
Compounds used on threaded joints of gas piping must
be resistant to the actions of liquified petroleum gases.
NOTE: If emergency shutoff is necessary, shut off the main
manual gas valve and disconnect main power to the furnace.
The installer should properly label these devices.
Gas Pipe Capacity - ft³/hr (m³/hr)
Note: Capacity given in cubic feet (m³) of gas per hour and based on 06.0 specific gravity gas.
Table 9
506528-01 Page 21 of 37Issue 1035
NOTE: BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET
Figure 18
Leak Check
After gas piping is completed, carefully check all piping
connections (factory and field installed) for gas leaks. Use
a leak detecting solution or other preferred means.
NOTE: If emergency shutoff is necessary, shut off the main
manual gas valve and disconnect the main power to the
furnace. The installer should properly label these devices.
CAUTION
Some soaps used for leak detection are corrosive to
certain metals. Carefully rinse piping thoroughly after
leak test has been completed. Do not use matches,
candles, flame or other sources of ignition to check for
gas leaks.
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 less than or equal to 1/2 psig (3.48
kPa, 14 inches w.c.).
IMPORTANT
When testing pressure of gas lines, gas valve must be
disconnected and isolated. See Figure 19. Gas valves
can be damaged if subjected to pressures greater than
1/2 psig (3.48 kPa, 14 inches w.c.).
Electrical
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can affect electronic
components. Take precautions during furnace
installation and service to protect the furnace’s electronic
controls. Precautions will help to avoid control exposure
to electrostatic discharge by putting the furnace, the
control and the technician at the same electrostatic
potential. Neutralize electrostatic charge by touching
hand and all tools on an unpainted unit surface, such
as the gas valve or blower deck, before performing any
service procedure.
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.
Figure 19
506528-01Page 22 of 37 Issue 1035
INTERIOR MAKE-UP BOX INSTALLATION
Before connecting the thermostat, check to make sure the
wires will be long enough for servicing at a later date. Make
sure that thermostat wire is long enough to facilitate future
removal of blower for service.
Complete the wiring connections to the equipment. Use the
provided unit wiring diagram and the field wiring diagram
shown in Figure 24. Use 18 gauge wire or larger that is
suitable for Class II rating for thermostat connections.
Electrically ground the unit according to local codes or, in
the absence of local codes, according to the current National
Electric Code (ANSI/NFPA No. 70). A green ground wire is
provided in the field make-up box.
Figure 20
INTERIOR MAKE-UP BOX INSTALLATION
Figure 21
Refer to Figure 23 for schematic wiring diagram and
troubleshooting and Figure 24 for field wiring.
NOTE: This furnace contains electronic components that
are polarity sensitive. Make sure that the furnace is wired
correctly and is properly grounded.
Accessory Terminals
One line voltage “EAC” 1/4" spade terminal is provided on
the furnace integrated control. See Figure 25 for integrated
control configuration. This terminal is energized when the
indoor blower is operating. Any accessory rated up to one
amp can be connected to this terminal with the neutral leg
of the circuit being connected to one of the provided neutral
terminals. If an accessory rated at greater than one amp is
connected to this terminal, it is necessary to use an external
relay.
One line voltage “HUM” 1/4" spade terminal is provided on
the furnace integrated control. See Figure 25 for integrated
control configuration. This terminal is energized in the
heating mode when the combustion air inducer is operating.
Any humidifier rated up to one amp can be connected to
this terminal with the neutral leg of the circuit being connected
to one of the provided neutral terminals. If a humidifier rated
at greater than one amp is connected to this terminal, it is
necessary to use an external relay relay.
The power supply wiring must meet Class I restrictions.
Protected by either a fuse or circuit breaker, select circuit
protection and wire size according to unit nameplate.
NOTE: Unit nameplate states maximum current draw.
Maximum over current protection allowed is 15 AMP.
Holes are on both sides of the furnace cabinet to facilitate
wiring.
Install a separate (properly sized) disconnect switch near
the furnace so that power can be turned off for servicing.
506528-01 Page 23 of 37Issue 1035
Generator Use - Voltage Requirements
The following requirements must be kept in mind when
specifying a generator for use with this equipment:
• The furnace requires 120 volts ± 10% (Range: 108 volts
to 132 volts).
• 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% RHO.
Thermostat
Install the room thermostat according to the instructions
provided with the thermostat. See Figure 22 for thermostat
designations. If the furnace is being matched with a heat
pump, refer to the FM21 installation instruction or appropriate
dual fuel thermostat instructions.
Condensing Unit Thermostat Designations
(Refer to Specific Thermostat and Outdoor Unit.)
* Note: “R” Required on some outdoor units.
Figure 22
Indoor Blower Speeds
1. When the thermostat is set to “FAN ON,” the indoor
blower will run continuously on the heating speed when
there is no cooling or heating demand.
2. When the unit is running in the heating mode, the indoor
blower will run on the heating speed.
3. When there is a cooling demand, the indoor blower will
run on the cooling speed.
506528-01Page 24 of 37 Issue 1035
Wiring Diagram
506528-01 Page 25 of 37Issue 1035
Figure 23
Typical Field Wiuring Diagram
Figure 24
Integrated Control
(Automatic Hot Surface Ignition System)
Figure 25
506528-01Page 26 of 37 Issue 1035
Unit Start-UP
FOR YOUR SAFETY READ BEFORE LIGHTING UNIT.
WARNING
Do not use this furnace if any part have been underwater.
Immediately call a licensed professional service
technician (or equivalent) to inspect the furnace and to
replace any part of the control system and any gas
control which has been underwater.
WARNING
6. Move switch on gas valve to OFF. Do not force. See
Figure 26.
7. Wait five minutes to clear out any gas. If you then smell
gas, STOP! Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s instructions.
If you do not smell gas go to next step.
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
Before attempting to perform any service or
maintenance, turn the electrical power to unit OFF at
disconnect switch.
BEFORE LIGHTING smell all around the appliance area for
gas. Be sure to smell next to the floor because some gas is
heavier than air and will settle on the floor.
The gas valve on this unit will be equipped with a gas control
switch. Use only your hand to move the switch. Never use
tools. If the switch will not turn or if the control switch will not
move by hand, do not try to repair it.
Placing the Furnace into Operation:
These units are equipped with an automatic ignition system.
Do not attempt to manually light burners on these furnaces.
Each time the thermostat calls for heat, the burners will
automatically light. The ignitor does not get hot when there
is no call for heat on units with an automatic ignition system.
WARNING
If you do not follow these instructions exactly, a fire or
explosion may result causing property damage, personal
injury or death.
Gas Valve Operation (Figure 26)
1. STOP! Read the safety information at the beginning of
this section.
2. Set the thermostat to the lowest setting.
3. Turn off all electrical power to the unit.
4. This furnace is equipped with an ignition device which
automatically lights the burners. Do not try to light the
burners by hand.
5. Remove the upper access panel.
506528-01 Page 27 of 37Issue 1035
Gas Valve Shown in “ON” Position
Figure 26
8. Move switch on gas valve to ON. Do not force. See
Figure 26.
9. Replace the upper access panel.
10. Turn on all electrical power to to the unit.
11. Set the thermostat to desired setting.
NOTE: When unit is initially started, steps 1 through 11
may need to be repeated to purge air from gas line.
12. If the appliance will not operate, follow the instructions
“Turning Off Gas to Unit” and call your service technician
or gas supplier.
Turning Off Gas to Unit
1. Set the thermostat to the lowest setting.
2. Turn OFF all electrical power to the unit if service is to
be performed.
3. Remove the upper access panel.
4. Move switch on gas valve to OFF. Do not force.
5. Replace the upper access panel.
Failure To Operate
If the unit fails to operate, check the following:
1. Is the thermostat calling for heat?
2. Are access panels securely in place?
3. Is the main disconnect switch closed?
4. Is there a blown fuse or tripped circuit breaker?
5. Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit control to shut the unit off.
6. Is gas turned on at the meter?
7. Is the manual main shut-off valve open?
8. Is the internal manual shut-off valve open?
9. Is the unit ignition system in lock out? If the unit locks
out again, call the service technician to inspect the unit
for blockages.
10. Is pressure switch closed? Obstructed flue will cause
unit to shut off at pressure switch. Check flue and outlet
for blockages.
11. Are flame rollout switches tripped? If flame rollout
switches are tripped, call the service technician for
inspection.
Heating Sequence Of Operation (Figure 27)
1. When thermostat calls for heat, combustion air blower
starts.
2. Combustion air pressure switch proves blower operation.
Switch is factory set and requires no adjustment.
3. After a 15 second prepurge, the hot surface ignitor
energizes.
4. After a 20 second ignitor warm-up period, the gas valve
solenoid opens. A 4 second trial for ignition period
begins.
5. Gas is ignited, flame sensor proves the flame, and the
combustion process continues.
6. If flame is not detected after first ignition trial, the ignition
control will repeat steps 3 and 4 four more times before
locking out the gas valve. The ignition control will then
automatically repeat steps 1 through 6 after 60 minutes.
7. To interrupt the 60 minute, move thermostat from “Heat”
to “OFF” then back to “Heat.” Heating sequence then
restarts at step 1.
Gas Pressure Adjustment
Gas Flow (Approximate)
NOTE: To obtain accurate reading, shut off all other gas
appliances connected to meter.
Supply Pressure Measurement
A threaded plug on the inlet side of the gas valve provides
access to the supply pressure tap. Remove the threaded
plug, install a field provided barbed fitting and connect a
manometer to measure supply pressure. See Table 12 for
proper line pressure. Replace the threaded plug after
measurements have been taken.
Manifold Pressure Measurement
1. Remove the threaded plug from the outlet side of the
gas valve and install a field provided barbed fitting.
Connect to a manometer to measure manifold pressure.
2. Start unit and allow 5 minutes for unit to reach steady
state.
3. While waiting for the unit to stabilize, observe the flame.
Flame should be stable and should not lift from burner.
Natural gas should burn blue.
4. After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in Table
12.
NOTE: Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to remove
barbed fitting and replace threaded plug.
Table 10
Furnace should operate at least 5 minutes before checking
gas flow. Determine time in seconds for two revolutions of
gas through the meter. (Two revolutions assures a more
accurate time.) Divide by two and compare to time in Table
10 above. If manifold pressure matches Table 12 and rate
is incorrect, check gas orifices for proper size and restriction.
Remove temporary gas meter if installed.
INTEGRATED IGNITION CONTROL
Proper Combustion
Furnace should operate a minimum 15 minutes with correct
manifold pressure and gas flow rate before checking
combustion. Take combustion sample beyond the flue out
let and compare to the tables below. The maximum carbon
monoxide reading should not exceed 50 ppm.
Table 11
Blower on time will be 45 seconds after gas valve is energized. Blower off time will depend on “OFF TIME” Setting.
Figure 27
506528-01Page 28 of 37 Issue 1035
High Altitude
The manifold pressure may require adjustment to ensure
proper combustion at higher altitudes. Refer to Table 12 for
manifold pressure and pressure switch change.
For Safety, shut unit off and remove manometer as soon
IMPORTANT
as an accurate reading has been obtained. Take care
to replace pressure tap plub.
Manifold Pressure Settings and Pressure Switch
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.
NOTE: For Altitudes of 7501' - 10,000' call Lennox Technical Support Product Applications.
Other Unit Adjustments
Primary and Secondary Limits
The primary limit is located on the heating compartment
vestibule panel. The secondary limits (if equipped) are
located in the blower compartment, attached to the back
side of the blower. These auto reset limits are factory set
and require no adjustment.
Flame Rollout Switches
This manually reset switches are located on the top of the
burner box.
Pressure Switch
The pressure switch is located in the heating compartment
adjacent to the combustion air inducer. The switch checks
for proper combustion air inducer operation before allowing
ignition trial. The switch is factory set and requires no
adjustment.
Temperature Rise
After the furnace has been started, and supply and return
air temperatures have been allowed to stabilize, check the
temperature rise. If necessary, adjust the blower speed to
maintain the temperature rise within the range shown on
the unit nameplate. Increase the blower speed to decrease
the temperature. Decrease the blower speed to increase
the temperature rise. Failure to adjust the temperature rise
may cause erratic limit operation.
Table 12
Fan Control
The fan on time of 45 seconds is not adjustable. The heat
fan off delay (amount of time that the blower operates after
the heat demand has been satisfied) may be adjusted by
changing the jumper position across the five pins on the
integrated control. The unit is shipped with a factory fan off
delay setting of 90 seconds. The fan off delay affects comfort
and is adjustable to satisfy individual applications. Adjust
the fan off delay to achieve a supply air temperature between
90° and 110° F at the moment that the blower is deenergized.
Longer off delay settings provide lower return air
temperatures; shorter settings provide higher return air
temperatures. See Figure 28.
HEAT FAN OFF TIME IN SECONDS
506528-01 Page 29 of 37Issue 1035
Figure 28
Thermostat Heat Anticipation
Set the heat anticipator setting (if adjustable) according to
the amp draw listed on the wiring diagram that is attached
to the unit.
NOTE: Do not secure the electrical conduit directly to the
air ducts or structure.
Electrical
1. Check all wiring for loose connections.
2. Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 120VAC ± 10%.
3.Check amp-draw on the blower motor with inner blower
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.
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
diagram for desired heating or cooling speed. See
Blower performance data beginning on the next page.
6. Connect selected speed tap at integrated control speed
terminal.
7. Resecure blower access panel.
8. Turn on electrical power to furnace.
9. Recheck temperature rise.
Electronic Ignition
The integrated control has an added feature of an internal
control. The feature serves as an automatic reset device
for integrated control lockout caused by ignition failure. This
type of lockout is usually due to low gas line pressure. After
one hour of continuous thermostat demand for heat, the
control will break and remake thermostat demand to the
furnace and automatically reset the integrated control to
begin the ignition sequence.
506528-01Page 30 of 37 Issue 1035
Service
WARNING
WARNING
ELECTRICAL SHOCK, FIRE,
OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly could result in
dangerous operation, serious injury, death or property
damage.
Improper servicing could result in dangerous operation,
serious injury, death, or property damage. Before
servicing, disconnect all electrical power to furnace.
When servicing controls, label all wires prior to
disconnecting. Take care to reconnect wires correctly.
Verify proper operation after servicing.
At the beginning of each heating season, a qualified
technician should check the system as follows:
Blower
Check the blower wheel for debris and clean if necessary.
The blower motors are prelubricated for extended bearing
life. No further lubrication is needed.
The blower access panel must be securely in place when
the blower and burners are operating. Gas fumes, which
could contain carbon monoxide, can be drawn into living
space resulting in personal injury or death.
Filters
Filters are installed external to the unit. Filters should be
inspected monthly. Clean or replace the filters when
necessary to ensure that the furnace operates properly.
Replacement filters must be rated for high velocity airflow.
Flue And Chimney
1. Check flue pipe, chimney and all connections for
tightness and to make sure there is no blockage.
2. Check unit for proper draft.
Electrical
1. Check all wiring for loose connections.
2. Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 120VAC.± 10%.
3. Check amp draw on the blower motor with inner blower
panel in place.
Unit Nameplate___________Actual_______________
506528-01 Page 31 of 37Issue 1035
Cleaning the Heat Exchanger and Burners
NOTE: Use papers or protective covering in front of the
furnace during cleaning.
1. Turn off both electrical and gas power supplies to
furnace.
2. Remove flue pipe and top cap (some applications top
cap can remain) from the unit.
3. Label the wires from gas valve, rollout switches, primary
limit switch and make-up box then disconnect them.
4. Remove the screws that secure the combustion air
inducer/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.
BURNER, COMBUSTION AIR INDUCER ASSEMBLY & HEAT EXCHANGER REMOVAL
5. Remove the collector box located behind the combustion
air inducer. Be careful with the collector box gasket. If
the gasket is damaged, it must be replaced to prevent
leakage.
6. Disconnect gas supply piping. Remove the screw
securing the burner box cover and remove cover.
Remove the four screws securing the burner manifold
assembly to the vestibule panel and remove the
assembly from the unit.
7. Remove screws securing burner box and remove burner
box.
8. NOX units only - Remove screw securing NOX insert.
Remove NOX insert. See Figure 30.
Figure 29
506528-01Page 32 of 37 Issue 1035
9. Remove screws from both sides, top and bottom of
vestibule panel.
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. See
Figure 31.
11. Backwash using steam. Begin from the burner opening
on each clam. Steam must not exceed 275° F.
12. To clean burners, run a vacuum cleaner with a soft brush
attachment over the face of burners. Visually inspect
inside the burners and crossovers for any blockage
caused by foreign matter. Remove any blockage. Figure
29 shows burner detail.
13. To clean the combustion air inducer visually inspect and
using a wire brush clean where necessary. Use
compressed air to clean off debris and any rust.
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.
Remove 5 Screws If Necessary
(either side of cabinet)
NOx INSERTS
Figure 30
Figure 31
18. Reconnect all wires.
19. Reconnect top cap and vent pipe to combustion air
inducer 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 after
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.
25. Repeat steps 24 and 26 until no leaks are detected.
26. Replace access panel.
506528-01 Page 33 of 37Issue 1035
Planned Service
The following items should be checked during an annual
inspection. Power to the unit must be shut off for the service
technician’s safety.
Fresh air grilles and louvers (on the unit and in the room
where the furnace is installed) - Must be open and
unobstructed to provide combustion air.
Burners - Must be inspected for rust, dirt, or signs of water.
Vent pipe - Must be inspected for signs of water, damaged
or sagging pipe, or disconnected joints.
Unit appearance - Must be inspected for rust, dirt, signs of
water, burnt or damaged wires, or components.
Blower access panel - Must be properly in place and provide
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.
Operating performance - Unit must be observed during
operation to monitor proper performance of the unit and the
vent system.
FAILURE CODES
Combustion gases - Flue products must be analyzed and
compared to the unit specifications.
Problems detected during the inspection may make it
necessary to temporarily shut down the furnace until the
items can be repaired or replaced.
Instruct the homeowners to pay attention to their
furnace. Situations can arise between annual furnace
inspections 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.
506528-01Page 34 of 37 Issue 1035
Repair Parts List
The following repair parts are available through independent Allied Air dealers. When ordering parts, include the complete
furnace model number listed on the CSA International nameplate — Example: A801DF045JP24A-01. All service must be
performed by a licensed professional installer (or equivalent), service agency, or gas supplier.
Cabinet Parts
Upper access panel
Blower panel
Top cap
Control Panel
Parts Transformer
Integrated control
Door interlock switch
Circuit breaker
Blower Parts
Blower wheel
Blower housing
Motor
Motor mounting frame
Motor capacitor
Blower housing cutoff plate
Heating Parts
Flame sensor
Heat exchanger assembly
Gas manifold
Combustion air inducer
Gas valve
Main burner cluster
Main burner orifices
Pressure switch
Ignitor
Primary limit control
Flame rollout switch
Secondary limit
506528-01 Page 35 of 37Issue 1035
Start-Up & Performance Check List
UNIT SET UP
506528-01Page 36 of 37 Issue 1035
UNIT OPERATION
506528-01 Page 37 of 37Issue 1035
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