International comfort products N8MSN User manual

Portions of the text and tables are reprinted from NFPA 54 /ANSI Z223.1−2009©, with permission of National Fire Protection Association, Quincy, MA 02269 and American Gas Association, Washing-
ton, DC 20001. This reprinted material is not the complete and official position of the NFPA or ANSI, on the referenced subject, which is represented only by the standard in its entirety.
Printed in U.S.A. 441 01 1402 02 May. 2012
INSTALLATION INSTRUCTIONS
80% Single Stage, PSC Motor
Category I, Gas Furnace
N8MSN, N8MSL
These instructions must be read and understood completely before attempting installation.
Safety Labeling and Signal Words
DANGER, WARNING, CAUTION, and NOTE Signal Words in Manuals
The signal words DANGER, WARNING,CAUTION,and NOTE
are used to identify levels of hazard seriousness. The signal word
DANGER is only used on product labels to signify an immediate
hazard. The signal words WARNING, CAUTION, and NOTE will
be used on product labels and throughout this manual and other
manual that may apply to the product.
The signal word WARNING is used throughout this manual in the
following manner:
The signal word CAUTION is used throughout this manual in the
following manner:
!WARNING
DANGER −Immediate hazards which will result in severe person-
al injury or death.
WARNING −Hazards or unsafe practices which could result in
severe personal injury or death.
CAUTION −Hazards or unsafe practices which may result in
minor personal injury or product or property damage.
NOTE −Used to highlight suggestions which will result in en-
hanced installation, reliability, or operation.
!CAUTION
Signal Words on Product Labeling
Signal words are used in combination with colors and/or pictures
or product labels.
Safety−alert symbol
When you see this symbol on the unit and in instructions or manu-
als, be alert to the potential for personal injury.
TABLE OF CONTENTS
DIMENSIONS 3...............................................
SAFETY CONSIDERATIONS 3..................................
INTRODUCTION 4............................................
CODES AND STANDARDS 5...................................
SAFETY 5................................................
GENERAL INSTALLATION 5................................
COMBUSTION AND VENTILATION AIR 5.....................
DUCT SYSTEMS 5........................................
ACOUSTICAL LINING AND FIBROUS GLASS DUCT 5.........
GAS PIPING AND GAS PIPE PRESSURE TESTING 5..........
ELECTRICAL CONNECTIONS 5............................
VENTING 5..............................................
ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS 5...........
LOCATION 6.................................................
AIR FOR COMBUSTION AND VENTILATION 7....................
INSTALLATION 10..............................................
UPFLOW INSTALLATION 10.................................
DOWNFLOW INSTALLATION 11.............................
FILTER ARRANGEMENT 12.................................
AIR DUCTS 13.............................................
AIR DELIVERY −CFM 14....................................
ELECTRICAL CONNECTIONS 20............................
115−V WIRING 20..........................................
J−BOX RELOCATION 20....................................
ELECTRICAL CONNECTION TO J−BOX 20....................
ELECTRICAL DATA 21......................................
24−V WIRING 22...........................................
ACCESSORIES 22.........................................
VENTING 23..................................................
GENERAL VENTING REQUIREMENTS 23.....................
MASONRY CHIMNEY REQUIREMENTS 24....................
APPLIANCE APPLICATION REQUIREMENTS 26...............
ADDITIONAL VENTING REQUIREMENTS 26..................
SIDEWALL VENTING 27....................................
START−UP, ADJUSTMENT, AND SAFETY CHECK 30...............
GENERAL 30..............................................
START−UP PROCEDURES 30...............................
ADJUSTMENTS 31.........................................
SPEED SELECTION 32.....................................
CHECK SAFETY CONTROLS 33.............................
CHECKLIST 34............................................
ORIFICE SIZE AND MANIFOLD PRESSURE 35................
SERVICE AND MAINTENANCE PROCEDURES 39.................
CARE AND MAINTENANCE 39...................................
SEQUENCE OF OPERATION 43.................................
WIRING DIAGRAM 44..........................................
TROUBLESHOOTING GUIDE 45.................................
Use of the AHRI Certified TM Mark indicates
a manufacturer’s participation in the program.
For verification of certification for individual
products, go to www.ahridirectory.org .
!WARNING
PERSONAL INJURY, AND/OR PROPERTY
DAMAGE HAZARD
Failure to carefully read and follow this warning could
result in equipment malfunction, property damage,
personal injury and/or death.
Installation or repairs made by unqualified persons
could result in equipment malfunction, property
damage, personal injury and/or death.
The information contained in this manual is intended for
use by a qualified service technician familiar with safety
procedures and equipped with proper tools and test
instruments.
Installation must conform with local building codes and
with the Natural Fuel Gas Code (NFCG) NFPA
54/ANSI Z223.1, and National standards of Canada
CAN/CSA−B149.1 and .2 Natural Gas and Propane
Installation Codes.
INSTALLER: Affix these instructions on or adjacent to the furnace.
CONSUMER: Retain these instructions for future reference.

2441 01 1402 02
Figure 1 - Dimensional Drawing
NOTES:
1. Two additional 7/8-in. (22 mm) diameter holes are located in the top plate.
2. Minimum return-air openings at furnace, based on metal duct. If flex duct is used, see flex duct manufacturer's recommendations for equivalent diameters.
a. For 800 CFM-16-in. (406 mm) round or 14 1/2 x 12-in. (368 x 305 mm) rectangle.
b. For 1200 CFM-20-in. (508 mm) round or 14 1/2 x 19 1/2-in. (368 x 495 mm) rectangle.
c. For 1600 CFM-22-in. (559 mm) round or 14 1/2 x 22 1/16-in. (368 x 560mm) rectangle.
d. For airflow requirements above 1800 CFM, see Air Delivery table in Product Data literature for specific use of single side inlets. The use of both side inlets, a
combination of 1 side and the bottom, or the bottom only will ensure adequate return air openings for airflow requirements above 1800 CFM.

3
441 01 1402 02
Table 1—Dimensions −In. (mm)
FURNACE SIZE
N8MSN & N8MSL
A B C D
CABINET WIDTH
IN (mm)
OUTLET
WIDTH
IN (mm)
TOP AND
BOTTOM
FLUE COLLAR
IN (mm)
BOTTOM
WIDTH
IN (mm)
VENT
CONNECTION
SIZE*
IN (mm)
SHIP WT
LB (KG)
0451408 14−3/16 (360) 12−9/16 (319) 9−5/16 (237) 12−11/16 (322) 4 (102) 104 (47)
0451412 14−3/16 (360) 12−9/16 (319) 9−5/16 (237) 12−11/16 (322) 4 (102) 107 (49)
0701408 14−3/16 (360) 12−9/16 (319) 9−5/16 (237) 12−11/16 (322) 4 (102) 111 (50)
0701412 14−3/16 (360) 12−9/16 (319) 9−5/16 (237) 12−11/16 (322) 4 (102) 115 (52)
0701716 17−1/2 (445) 15−7/8 (403) 11−9/16 (294) 16 (406) 4 (102) 126 (57)
0901714 17−1/2 (445) 15−7/8 (403) 11−9/16 (294) 16 (406) 4 (102) 127 (58)
0902116 21 (533) 19−3/8 (492) 13−5/16 (338) 19−1/2 (495) 4 (102) 140 (64)
0902120 21 (533) 19−3/8 (492) 13−5/16 (338) 19−1/2 (495) 4 (102) 146 (66)
1101712 17−1/2 (445) 15−7/8 (403) 11−9/16 (294) 16 (406) 4 (102) 135 (61)
1102116 21 (533) 19−3/8 (492) 13−5/16 (338) 19−1/2 (495) 4 (102) 146 (66)
1102122 21 (533) 19−3/8 (492) 13−5/16 (338) 19−1/2 (495) 4 (102) 152 (69)
1352116 21 (533) 19−3/8 (492) 13−5/16 (338) 19−1/2 (495) 4 (102)* 149 (68)
1352422 24−1/2 (622) 22−7/8 (581) 15−1/16 (383) 23 (584) 4 (102)* 163 (74)
1552420 24−1/2 (622) 22−7/8 (581) 15−1/16 (383) 23 (584) 4 (102)* 170 (77)
*135 and 155 size furnaces require a 5 or 6-in. (127 or 152 mm) vent. Use a vent adapter between furnace and vent stack. See Installation Instructions for complete
installation requirements.
SAFETY CONSIDERATIONS
FIRE, EXPLOSION, ELECTRICAL SHOCK, AND
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal
injury, death, or property damage.
Improper installation, adjustment, alteration, service,
maintenance, or use can cause carbon monoxide
poisoning, explosion, fire, electrical shock, or other
conditions which may cause personal injury or
property damage. Consult a qualified service agency,
local gas supplier, or your distributor or branch for
information or assistance. The qualified service
agency must use only factory−authorized and listed
kits or accessories when modifying this product.
!WARNING
FURNACE RELIABILITY HAZARD
Failure to follow this caution may result in unit
component damage.
Application of this furnace should be indoors with
special attention given to vent sizing and material,
gas input rate, air temperature rise, unit leveling, and
unit sizing.
CAUTION
!
CUT HAZARD
Failure to follow this caution may result in personal
injury.
Sheet metal parts may have sharp edges or burrs.
Use care and wear appropriate protective clothing,
safety glasses and gloves when handling parts, and
servicing furnaces.
CAUTION
!
Improper installation, adjustment, alteration, service,
maintenance, or use can cause explosion, fire, electrical
shock, or other conditions which may cause death, personal
injury, or property damage. Consult a qualified installer,
service agency, or your distributor or branch for information or
assistance. The qualified installer or agency must use
factory−authorized kits or accessories when modifying this
product. Refer to the individual instructions packaged with
the kits or accessories when installing.
Follow all safety codes. Wear safety glasses, protective
clothing, and work gloves. Have a fire extinguisher available.
Read these instructions thoroughly and follow all warnings or
cautions include in literature and attached to the unit. Consult
local building codes, the current editions of the National Fuel
Gas Code (NFGC) NFPA 54/ANSI Z223.1 and the National
Electrical Code (NEC) NFPA 70.
Recognize safety information. This is the safety−alert symbol
. When you see this symbol on the unit and in instructions
or manuals, be alert to the potential for personal injury.
Understand the signal words DANGER, WARNING, and
CAUTION. These words are used with the safety−alert
symbol. DANGER identifies the most serious hazards which
will result in severe personal injury or death. WARNING
signifies hazards which could result in personal injury or
death. CAUTION is used to identify unsafe practices which
may result in minor personal injury or product and property
damage. NOTE is used to highlight suggestions which will
result in enhanced installation, reliability, or operation.
1. Use only with type of gas approved for this furnace.
Refer to the furnace rating plate.
2. Install this furnace only in a location and position as
specified in the “Location” section of these instructions.
3. Provide adequate combustion and ventilation air to the
furnace space as specified in “Air for Combustion and
Ventilation” section.
4. Combustion products must be discharged outdoors.
Connect this furnace to an approved vent system only,
as specified in the “Venting” section of these instruc-
tions.
5. Never test for gas leaks with an open flame. Use a
commercially available soap solution made specifically
for the detection of leaks to check all connections, as
specified in the “Gas Piping” section.
6. Always install furnace to operate within the furnace’s
intended temperature−rise range with a duct system

4441 01 1402 02
which has an external static pressure within the allow-
able range, as specified in the “Start−Up, Adjustments,
and Safety Check” section. See furnace rating plate.
7. When a furnace is installed so that supply ducts carry
air circulated by the furnace to areas outside the space
containing the furnace, the return air shall also be
handled by duct(s) sealed to the furnace casing and
terminating outside the space containing the furnace.
See “Air Ducts” section.
8. A gas−fired furnace for installation in a residential gar-
age must be installed as specified in the warning box in
the “Location” section.
9. The furnace may be used for construction heat
provided that the furnace installation and operation
complies with the first CAUTION in the LOCATION sec-
tion of these instructions.
10. These Multipoise Gas−Fired Furnaces are CSA
(formerly A.G.A. and C.G.A.) design−certified for use
with natural and propane gases (see furnace rating
plate) and for installation in alcoves, attics, basements,
closets, utility rooms, crawlspaces, and garages. The
furnace is factory−shipped for use with natural gas. A
CSA (A.G.A. and C.G.A.) listed accessory gas conver-
sion kit is required to convert furnace for use with pro-
pane gas.
11. See Figure 1 for required clearances to combustible
construction.
12. Maintain a 1−in. (25 mm) clearance from combustible
materials to supply air ductwork for a distance of 36 in.
(914 mm) horizontally from the furnace. See NFPA 90B
or local code for further requirements.
13. These furnaces SHALL NOT be installed directly on
carpeting, tile, or any other combustible material other
than wood flooring. In downflow installations, factory
accessory floor base MUST be used when installed on
combustible materials and wood flooring. Special base
is not required when this furnace is installed on manu-
facturer’s coil model numbers END4X, ENW4X or
when coil casing model number NAEA is used. See
Figure 1 for clearance to combustible construction in-
formation.
INTRODUCTION
N8MSN & N8MSL 4−way multipoise Category I fan−assisted
furnace is CSA design−certified. A Category I fan−assisted
furnace is an appliance equipped with an integral mechanical
means to either draw or force products of combustion through
the combustion chamber and/or heat exchanger. The furnace
is factory−shipped for use with natural gas. This furnace is
not approved for installation in mobile homes, recreational
vehicles, or outdoors.
This furnace is designed for minimum continuous return−air
temperature of 60F (16C) db or intermittent operation down
to 55F (13C) db such as when used with a night setback
thermostat. Return−air temperature must not exceed 80F
(27C) db. Failure to follow these return−air temperature limits
may affect reliability of heat exchangers, motors, and
controls. (See Figure 3)
Figure 2 - Clearances to Combustibles

5
441 01 1402 02
Figure 3 - Return Air Temperature
A06745
80F/27C
60F/16C
For accessory installation details, refer to the applicable
instruction literature.
NOTE: Remove all shipping brackets and materials before
operating the furnace.
CODES AND STANDARDS
Follow all national and local codes and standards in
addition to these instructions. The installation must comply
with regulations of the serving gas supplier, local building,
heating, plumbing, and other codes. In absence of local
codes, the installation must comply with the national codes
listed below and all authorities having jurisdiction. In the
United States , follow all codes and standards for the
following:
Step 1 —Safety
National Fuel Gas Code (NFGC) NFPA
54−2009/ANSI Z223.1−2009 and the Installation
Standards, Warm Air Heating and Air Conditioning
Systems ANSI/NFPA 90B
Step 2 —General Installation
Current edition of the NFGC and the NFPA 90B. For
copies, contact the National Fire Protection Associ-
ation Inc., Batterymarch Park, Quincy, MA 02269;
(www.NFPA.org) or for only the NFGC, contact the
American Gas Association, 400 N. Capitol Street,
N.W., Washington, DC 20001 (www.AGA.org).
Step 3 —Combustion and Ventilation Air
Section 9.3 of the NFGC, NFPA 54 / ANSI
Z223.1−2009 Air for Combustion and Ventilation
Step 4 —Duct Systems
Air Conditioning Contractors Association (ACCA)
Manual D, Sheet Metal and Air Conditioning Con-
tractors National Association (SMACNA), or Americ-
an Society of Heating, Refrigeration, and Air Condi-
tioning Engineers (ASHRAE) 2001 Fundamentals
Handbook Chapter 34 or 2000 HVAC Systems and
Equipment Handbook Chapters 9 and 16.
Step 5 —Acoustical Lining and Fibrous Glass
Duct
Current edition of SMACNA and NFPA 90B as
tested by UL Standard 181 for Class I Rigid Air
Ducts
Step 6 —Gas Piping and Gas Pipe Pressure
Testing
NFGC; NFPA 54 / ANSI Z223.1−2009 chapters 5, 6,
7 and 8 and National Plumbing Codes
Step 7 —Electrical Connections
National Electrical Code (NEC) ANSI/NFPA
70−2008
Step 8 —Venting
NFGC NFPA 54 / ANSI Z223.1−2009; chapters 12
and 13
ELECTROSTATIC DISCHARGE (ESD)
PRECAUTIONS PROCEDURE
FURNACE RELIABILITY HAZARD
Failure to follow this caution may result in furnace
component damage.
Electrostatic discharge can affect electronic components.
Follow the Electrostatic Discharge Precautions
Procedure listed below during furnace installation and
servicing to protect the furnace electronic control.
Precautions will prevent electrostatic discharges from
personnel and hand tools which are held during the
procedure. These precautions will help to avoid exposing
the control to electrostatic discharge by putting the
furnace, the control, and the person at the same
electrostatic potential.
CAUTION
!
1. Disconnect all power to the furnace. Multiple discon-
nects may be required. DO NOT TOUCH THE
CONTROL OR ANY WIRE CONNECTED TO THE
CONTROL PRIOR TO DISCHARGING YOUR BODY’S
ELECTROSTATIC CHARGE TO GROUND.
2. Firmly touch the clean, unpainted, metal surface of the
furnace chassis which is close to the control. Tools
held in a person’s hand during grounding will be satis-
factorily discharged.
3. After touching the chassis, you may proceed to service
the control or connecting wires as long as you do noth-
ing to recharge your body with static electricity (for ex-
ample; DO NOT move or shuffle your feet, do not touch
ungrounded objects, etc.).
4. If you touch ungrounded objects (and recharge your
body with static electricity), firmly touch a clean, un-
painted metal surface of the furnace again before
touching control or wires.
5. Use this procedure for installed and uninstalled (un-
grounded) furnaces.
6. Before removing a new control from its container, dis-
charge your body’s electrostatic charge to ground to
protect the control from damage. If the control is to be
installed in a furnace, follow items 1 through 4 before
bringing the control or yourself in contact with the fur-
nace. Put all used and new controls into containers be-
fore touching ungrounded objects.
7. An ESD service kit (available from commercial
sources) may also be used to prevent ESD damage.

6441 01 1402 02
LOCATION
CARBON MONOXIDE POISONING AND UNIT
DAMAGE HAZARD
Failure to follow this warning could result in personal
injury or death, and unit component damage.
Corrosive or contaminated air may cause failure of parts
containing flue gas, which could leak into the living
space. Air for combustion must not be contaminated by
halogen compounds, which include fluoride, chloride,
bromide, and iodide. These elements can corrode heat
exchangers and shorten furnace life. Air contaminants
are found in aerosol sprays, detergents, bleaches,
cleaning solvents, salts, air fresheners, and other
household products. Do not install furnace in a corrosive
or contaminated atmosphere. Make sure all combustion
and circulating air requirements are met, in addition to
all local codes and ordinances.
!WARNING
GENERAL
This multipoise furnace is shipped in packaged configuration.
Some assembly and modifications are required when used in
any of the four applications shown in Figure 4.
This furnace must:
be installed so the electrical components are protec-
ted from water.
not be installed directly on any combustible material
other than wood flooring for upflow applications.
Downflow installations require use of a factory−ap-
proved floor base, coil model numbers END4X,
ENW4X or coil casing model number NAEA when
installed on combustible materials or wood flooring.
(Refer to SAFETY CONSIDERATIONS).
be located as close to the chimney or vent and at-
tached to an air distribution system. Refer to Air
Ducts section.
Figure 4 - Multipoise Orientations
THE BLOWER IS LOCATED
TO THE RIGHT OF THE
BURNER SECTION, AND
AIR CONDITIONED AIR IS
DISCHARGED TO THE LEFT.
THE BLOWER IS
LOCATED BELOW THE
BURNER SECTION, AND
CONDITIONED AIR IS
DISCHARGED UPWARD.
THE BLOWER IS
LOCATED ABOVE THE
BURNER SECTION, AND
CONDITIONED AIR IS
DISCHARGED DOWNWARD
THE BLOWER IS
LOCATED TO THE LEFT
OF THE BURNER SECTION,
AND CONDITIONED AIR IS
DISCHARGED TO THE RIGHT.
A02097
be provided ample space for servicing and cleaning.
Always comply with minimum fire protection clear-
ances shown on the furnace clearance to combust-
ible label.
The following types of furnace installations may re-
quire OUTDOOR AIR for combustion due to chemic-
al exposures:
Commercial buildings
Buildings with indoor pools
Laundry rooms
Hobby or craft rooms, and
Chemical storage areas
If air is exposed to the following substances, it should not be
used for combustion air, and outdoor air may be required for
combustion:
Permanent wave solutions
Chlorinated waxes and cleaners
Chlorine based swimming pool chemicals
Water softening chemicals
De−icing salts or chemicals
Carbon tetrachloride
Halogen type refrigerants
Cleaning solvents (such as perchloroethylene)
Printing inks, paint removers, varnishes, etc.
Hydrochloric acid
Cements and glues
Antistatic fabric softeners for clothes dryers
Masonry acid washing materials
All fuel−burning equipment must be supplied with air for fuel
combustion. Sufficient air must be provided to avoid negative
pressure in the equipment room or space. A positive seal
must be made between the furnace cabinet and the
return−air duct to prevent pulling air from the burner area and
from draft safeguard opening.

7
441 01 1402 02
FIRE, INJURY OR DEATH HAZARD
Failure to follow this warning could result in personal
injury, death and/or property damage.
When the furnace is installed in a residential garage,
the burners and ignition sources must be located at
least 18 in. (457 mm) above the floor. The furnace
must be located or protected to avoid damage by
vehicles. When the furnace is installed in a public
garage, airplane hangar, or other building having a
hazardous atmosphere, the furnace must be installed
in accordance with the NFPA 54/ANSI Z223.1−2009 .
(See Figure 5)
!WARNING
PERSONAL INJURY AND/OR PROPERTY
DAMAGE HAZARD
Failure to follow this caution may result in furnace
component damage.
This gas furnace may be used for heating buildings
under construction provided that:
−The furnace is permanently installed with all
electrical wiring, piping, venting and ducting installed
according to these installation instructions. A return
air duct is provided, sealed to the furnace casing, and
terminated outside the space containing the furnace.
This prevents a negative pressure condition as
created by the circulating air blower, causing a flame
rollout and/or drawing combustion products into the
structure.
−The furnace is controlled by a thermostat. It may not
be hot wired to provide heat continuously to the
structure without thermostatic control.
−Clean outside air is provided for combustion. This is
to minimize the corrosive effects of adhesives,
sealers and other construction materials. It also
prevents the entrainment of drywall dust into
combustion air, which can cause fouling and plugging
of furnace components.
−The temperature of the return air to the furnace is
maintained between 55F (13C) and 80F (27C),
with no evening setback or shutdown. The use of the
furnace while the structure is under construction is
deemed to be intermittent operation per our
installation instructions.
−The air temperature rise is within the rated rise
range on the furnace rating plate, and the gas input
rate has been set to the nameplate value.
−The filters used to clean the circulating air during the
construction process must be either changed or
thoroughly cleaned prior to occupancy.
−The furnace, ductwork and filters are cleaned as
necessary to remove drywall dust and construction
debris from all HVAC system components after
construction is completed.
−Verify proper furnace operating conditions including
ignition, gas input rate, air temperature rise, and
venting according to these installation instructions.
CAUTION
!
Figure 5 - Installation in a Garage
18−IN. (457.2 mm)
MINIMUM TO BURNERS
A93044
FIRE HAZARD
Failure to follow this warning could result in personal
injury, death and/or property damage.
Do not install the furnace on its back or hang furnace
with control compartment facing downward. Safety
control operation will be adversely affected. Never
connect return−air ducts to the back of the furnace.
(See Figure 6)
!WARNING
Figure 6 - Prohibit Installation on Back
A02054
LOCATION RELATIVE TO COOLING EQUIPMENT
The cooling coil must be installed parallel with, or on the
downstream side of the unit to avoid condensation in the heat
exchangers. When installed parallel with the furnace,
dampers or other flow control must prevent chilled air from
entering the furnace. If the dampers are manually operated,
they must be equipped with means to prevent operation of
either unit unless the damper is in the full−heat or full−cool
position.
AIR FOR COMBUSTION AND
VENTILATION
Provisions for adequate combustion, ventilation, and dilution
air must be provided in accordance with:
Section 9.3 of the NFPA 54 / ANSI Z223.1−2009, Air
for Combustion and Ventilation, and applicable pro-
visions of the local building codes.

8441 01 1402 02
FURNACE CORROSION HAZARD
Failure to follow this caution may result in furnace
damage.
Air for combustion must not be contaminated by
halogen compounds, which include fluoride, chloride,
bromide, and iodide. These elements can corrode
heat exchangers and shorten furnace life. Air
contaminants are found in aerosol sprays,
detergents, bleaches, cleaning solvents, salts, air
fresheners, and other household products.
CAUTION
!
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal
injury or death.
The operation of exhaust fans, kitchen ventilation
fans, clothes dryers, attic exhaust fans or fireplaces
could create a NEGATIVE PRESSURE CONDITION
at the furnace. Make−up air MUST be provided for the
ventilation devices, in addition to that required by the
furnace. Refer to Carbon Monoxide Poisoning Hazard
warning in venting section of these instructions to
determine if an adequate amount of make−up air is
available.
!WARNING
The requirements for combustion and ventilation air depend
upon whether or not the furnace is located in a space having
a volume of at least 50 cu/ft. per 1,000 Btuh input rating for all
gas appliances installed in the space.
Spaces having less than 50 cu/ft. per 1,000 Btuh
require the OUTDOOR COMBUSTION AIR
METHOD.
Spaces having at least 50 cu/ft. per 1,000 Btuh may
use the INDOOR COMBUSTION AIR, STANDARD
or KNOWN AIR INFILTRATION METHOD.
Outdoor Combustion Air Method
1. Provide the space with sufficient air for proper combus-
tion, ventilation, and dilution of flue gases using per-
manent horizontal or vertical duct(s) or opening(s) dir-
ectly communicating with the outdoors or spaces that
freely communicate with the outdoors.
2. Figure 7 illustrates how to provide TWO OUTDOOR
OPENINGS, one inlet and one outlet combustion and
ventilation air opening, to the outdoors.
a. One opening MUST commence within 12 in. (300
mm) of the ceiling and the second opening MUST
commence within 12 in. (300 mm) of the floor.
b. Size openings and ducts per Figure 7 and Table 2.
c. TWO HORIZONTAL DUCTS require 1 sq./in. of free
area per 2,000 Btuh (1,100 mm2/kW) of combined
input for all gas appliances in the space per
Figure 7 and Table 2.
d. TWO OPENINGS OR VERTICAL DUCTS require 1
sq./in. of free area per 4,000 Btuh (550 mm2/kW)
for combined input of all gas appliances in the
space per Figure 7 and Table 2.
3. ONE OUTDOOR OPENING requires:
a. 1 square inch of free area per 3,000 Btuh (734
mm2/kW) for combined input of all gas appliances
in the space per Table 2 and
b. Not less than the sum of the areas of all vent con-
nectors in the space.
The opening shall commence within 12 in. (300 mm) of the
ceiling. Appliances in the space shall have clearances of at
least 1 in. (25 mm) from the sides and back and 6 in. (150
mm) from the front. The opening shall directly communicate
with the outdoors or shall communicate through a vertical or
horizontal duct to the outdoors or spaces (crawl or attic) that
freely communicate with the outdoors.
Indoor Combustion Air NFPA & AGA
Standard and Known−Air−Infiltration Rate Methods
Indoor air is permitted for combustion, ventilation, and
dilution, if the Standard or Known−Air−Infiltration Method
is used.
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in death
and/or personal injury.
Many homes require air to be supplied from outdoors
for furnace combustion, ventilation, and dilution of flue
gases. The furnace combustion air supply must be
provided in accordance with this instruction manual.
!WARNING
Table 2—Minimum Free Area Required for Each Combustion Air Opening of Duct to Outdoors
FURNACE
INPUT
(BTUH)
TWO HORIZONTAL DUCTS SINGLE DUCT OR OPENING TWO OPENINGS OR VERTICAL
DUCTS
(1 SQ. IN./2,000 BTUH)
(1,100 SQ. MM/KW)
(1 SQ. IN./3,000 BTUH)
(734 SQ. MM/KW)
(1 SQ. IN./4,000 BTUH)
(550 SQ. MM/KW)
Free Area of
Opening and Duct
Sq. In. (Sq. mm)
Round Duct
Dia.
In. (mm)
Free Area of
Opening and Duct
Sq. In. (Sq. mm)
Round Duct
Dia.
In. (mm)
Free Area of
Opening and Duct
Sq. In. (Sq. mm)
Round Duct
Dia.
In. (mm)
44,000 22 (14194) 6 (152) 14.7 (9484) 5 (127) 11 (7096) 4 (102)
66,000 33 (21290) 7 (178) 22.0 (14193) 6 (152) 16.5 (10645) 5 (127)
88,000 44 (28387) 8 (203) 29.3 (18903) 7 (178) 22 (14193) 6 (152)
110,000 55 (35484) 9 (229) 36.7 (23677) 7 (178) 27.5 (17742) 6 (152)
132,000 66 (42580) 10 (254) 44 .0 (28387) 8 (203) 33 (21290) 7 (178)
154,000 77 (49677) 10 (254) 51.3 (33096) 9 (229) 38.5 (24839) 8 (203)
EXAMPLES: Determining Free Area
FURNACE WATER HEATER TOTAL INPUT
110,000 + 30,000 = (140,000 divided by 4,000) = 35.0 Sq. In. for each two Vertical Ducts or Openings
66,000 + 40,000 = (106,000 divided by 3,000) = 35.3 Sq. In. for a Single Duct or Opening
88,000 + 30,000 = (118,000 divided by 2,000) =59.0 Sq. In. for each of two Horizontal Ducts

9
441 01 1402 02
Table 3—Minimum Space Volumes for 100% Combustion, Ventilation, and Dilution from Indoors
OTHER THAN FAN‐ASSISTED TOTAL
(1,000'S BTUH GAS INPUT RATE)
FAN‐ASSISTED TOTAL
(1,000'S BTUH GAS INPUT RATE)
ACH 30 40 50 44 66 88 110 132 154
Space Volume Ft3(M3)
0.60 1,050
(29.7)
1,400
(39.6)
1,750
(49.5)
1,100
(31.1)
1,650
(46.7)
2,200
(62.2)
2,750
(77.8)
3,300
(93.4)
3,850
(109.0)
0.50 1,260
(35.6)
1,680
(47.5)
2,100
(59.4)
1,320
(37.3)
1,980
(56.0)
2,640
(74.7)
3,300
(93.4)
3,960
(112.1)
4,620
(130.8)
0.40 1,575
(44.5)
2,100
(59.4)
2,625
(74.3)
1,650
(46.7)
2,475
(70.0)
3,300
(93.4)
4,125
(116.8)
4,950
(140.1)
5,775
(163.5)
0.30 2,100
(59.4)
2,800
(79.2)
3,500
(99.1)
2,200
(62.2)
3,300
(93.4)
4,400
(124.5)
5,500
(155.7)
6,600
(186.8)
7,700
(218.0)
0.20 3,150
(89.1)
4,200
(118.9)
5,250
(148.6)
3,300
(93.4)
4,950
(140.1)
6,600
(186.8)
8,250
(233.6)
9,900
(280.3)
11,550
(327.0)
0.10 6,300
(178.3)
8,400
(237.8)
10,500
(297.3)
6,600
(186.8)
9,900
(280.3)
13,200
(373.7)
16,500
(467.2)
19,800
(560.6)
23,100
(654.1)
0.00 NP NP NP NP NP NP NP NP NP
NP = Not Permitted
Figure 7 - Air for Combustion, Ventilation, and Dilution
for Outdoors
1 SQ IN.
PER
4000
BTUH*
DUCTS
TO
OUTDOORS
1 SQ IN.
PER 4000
BTUH*
CIRCULATING
AIR DUCTS
VENT
THROUGH
ROOF
D
B
A
C
E
1 SQ IN.
PER 4000
BTUH*
DUCT
TO
OUTDOORS
CIRCULATING AIR DUCTS
1 SQ IN.
PER 2000
BTUH*
1 SQ IN.
PER 2000
BTUH*
DUCTS
TO
OUTDOORS
12″MAX
12″MAX
12″MAX
12″
MAX
12″
MAX
OUTDOORS
1 SQ IN.
PER
4000
BTUH*
F
G
CLEARANCE IN FRONT
OF COMBUSTION AIR
OPENINGS SHALL BE
AT LEAST 3 IN.
(305mm)
(305mm)
(305mm)
(305mm)
(305mm)
(76mm)
*Minimum dimensions of 3-in. (76 mm).
NOTE: Use any of the following combinations of openings:
A & B C & D D & E F & G
A03174
The Standard Method:
1. The space has no less volume than 50 cu/ft. per 1,000
Btuh of the maximum input ratings for all gas appli-
ances installed in the space and
2. The air infiltration rate is not known to be less than 0.40
air changes per hour (ACH).
The Known Air Infiltration Rate Method shall be used, if the
infiltration rate is known to be:
1. Less than 0.40 ACH and
2. Equal to or greater than 0.10 ACH
Infiltration rates greater than 0.60 ACH shall not be used. The
minimum required volume of the space varies with the
number of ACH and shall be determined per Table 3 or
Equations 1 and 2. Determine the minimum required volume
for each appliance in the space and add the volumes
together to get the total minimum required volume for the
space.
Figure 8 - Air for Combustion, Ventilation, and Dilution
from Indoors
CIRCULATING AIR
DUCTS
6" MIN
(FRONT)Ü
CIRCULATING AIR DUCTS
VENT THROUGH ROOF
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
12" MAX
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
12" MAX
UNCONFINED
SPACE
INTERIOR
HEATED
SPACE
CLEARANCE IN FRONT OF COMBUSTION AIR
OPENINGS SHALL BE AT LEAST 3 IN.
(305mm)
(152mm)
(305mm)
* Minimum opening size is 100 sq in. (64516 sq. mm)with minimum dimensions of
3 in. (76 mm)
† Minimum of 3 in. (76 mm) when type‐B1 vent is used.
A03175
Table 3−Minimum Space Volumes were determined by
using the following equations from the National Fuel Gas
Code ANSI Z223.1−2009/NFPA 54−2009, 9.3.2.2:
1. For other than fan−assisted appliances, such as a
draft hood−equipped water heater:
Volume
Other
=21ft
3
ACH
I
other
1000 Btu/hr
A04002
2. For fan−assisted appliances such as this furnace:
Volume
Fan
=15ft
3
ACH
I
fan
1000 Btu/hr
A04003

10 441 01 1402 02
If:
Iother = combined input of all other than fan−assisted
appliances in Btuh/hr
Ifan = combined input of all fan−assisted appliances in
Btuh/hr ACH = air changes per hour (ACH shall not exceed
0.60.) The following requirements apply to the Standard
Method and to the Known Air Infiltration Rate Method.
1. Adjoining rooms can be considered part of a space if:
a. There are no closeable doors between rooms.
b. Combining spaces on same floor level. Each open-
ing shall have free area of at least 1 in.2/1,000 Btuh
(2,000 mm2/kW) of the total input rating of all gas
appliances in the space, but not less than 100 in.2
(0.06 m2). One opening shall commence within 12
in. (300 mm) of the ceiling and the second opening
shall commence within 12 in. (300 mm) of the floor.
The minimum dimension of air openings shall be at
least 3 in. (80 mm). (See Figure 8)
c. Combining space on different floor levels. The
volumes of spaces on different floor levels shall be
considered as communicating spaces if connected
by one or more permanent openings in doors or
floors having free area of at least 2 in.2/1,000 Btuh
(4,400 mm2/kW) of total input rating of all gas appli-
ances.
2. An attic or crawlspace may be considered a space that
freely communicates with the outdoors provided there
are adequate permanent ventilation openings directly
to outdoors having free area of at least 1−in.2/4,000
Btuh of total input rating for all gas appliances in the
space.
3. In spaces that use the Indoor Combustion Air Method,
infiltration should be adequate to provide air for com-
bustion, permanent ventilation and dilution of flue
gases. However, in buildings with unusually tight con-
struction, additional air MUST be provided using the
methods described in the Outdoor Combustion Air
Method section.
Unusually tight construction is defined as Construction with:
a. Walls and ceilings exposed to the outdoors have a
continuous, sealed vapor barrier. Openings are gas-
keted or sealed and
b. Doors and openable windows are weatherstripped
and
c. Other openings are caulked or sealed. These in-
clude joints around window and door frames,
between sole plates and floors, between wall−ceil-
ing joints, between wall panels, at penetrations for
plumbing, electrical and gas lines, etc.
Combination of Indoor and Outdoor Air
1. Indoor openings shall comply with the Indoor Com-
bustion Air Method below and,
2. Outdoor openings shall be located as required in the
Outdoor Combustion Air Method mentioned previ-
ously and,
3. Outdoor openings shall be sized as follows:
a. Calculate the Ratio of all Indoor Space volume di-
vided by required volume for Indoor Combustion
Air Method below.
b. Outdoor opening size reduction Factor is 1 minus
the Ratio in a. above.
c. Minimum size of Outdoor openings shall be the size
required in Outdoor Combustion Air Method
above multiplied by reduction Factor in b. above.
The minimum dimension of air openings shall be
not less than 3 in. (80 mm).
INSTALLATION
UPFLOW INSTALLATION
Bottom Return Air Inlet
These furnaces are shipped with bottom closure panel
installed in bottom return−air opening. Remove and discard
this panel when bottom return air is used. To remove bottom
closure panel, perform the following:
1. Tilt or raise furnace and remove 2 screws holding bot-
tom filler panel. (See Figure 9.)
Figure 9 - Removing Bottom Closure Panel
BOTTOM
FILLER PANEL
BOTTOM
CLOSURE
PANEL
2. Rotate bottom filler panel downward to release holding
tabs.
3. Remove bottom closure panel.
4. Reinstall bottom filler panel and screws.
Side Return Air Inlet
These furnaces are shipped with bottom closure panel
installed in bottom return−air opening. This panel MUST be in
place when only side return air is used.
NOTE: Side return−air openings can be used in UPFLOW
and most HORIZONTAL configurations. Do not use side
return−air openings in DOWNFLOW configuration.
In upflow position with side return inlet(s), leveling legs may
be used. (See Figure 10) Install field−supplied, 5/16 x 1−1/2
in. (8 x 38 mm) (max) corrosion−resistant machine bolts,
washers and nuts.
NOTE: Bottom closure must be used when leveling legs are
used. It may be necessary to remove and reinstall bottom
closure panel to install leveling legs. To remove bottom
closure panel, see Item 1. in Bottom Return Air Inlet section.

11
441 01 1402 02
Figure 10 - Leveling Legs
1
3
/ 4 ″
1
3
/ 4 ″
1
3/
4 ″
1
3/
4 ″
5/
16 ″
5
/ 16 ″
5/
16 ″
5/
16 ″
(44mm)
(8mm)
(44mm)
(8mm)
(8mm)
(8mm)
(44mm)
(44mm)
A89014
Leveling Legs (If Desired)
To install leveling legs:
1. Position furnace on its back. Locate and drill a hole in
each bottom corner of furnace. (See Figure 10)
2. For each leg, install nut on bolt and then install bolt and
nut in hole. (Install flat washer if desired.)
3. Install another nut on other side of furnace base. (In-
stall flat washer if desired.)
4. Adjust outside nut to provide desired height, and tight-
en inside nut to secure arrangement.
5. Reinstall bottom closure panel if removed.
DOWNFLOW INSTALLATION
NOTE: For downflow applications, this furnace is approved
for use on combustible flooring when any one of the following
3 accessories are used:
Downflow combustible floor subbase
Coil model number END4X or ENW4X
Coil casing model number NAEA
1. Determine application being installed from Table 4.
2. Construct hole in floor per Table 4 and Figure 11.
3. Construct plenum to dimensions specified in Table 4
and Figure 11.
4. If downflow subbase is used, install as shown in
Figure 12. If coil model numbers END4X, ENW4X or
coil casing model number NAEA is used, install as
shown in Figure 13.
Figure 11 - Floor and Plenum Opening Dimensions
C
A
B D
A96283
NOTE: It is recommended that the perforated supply−air duct
flanges be completely folded over or removed from furnace
when installing the furnace on a factory−supplied cased coil
or coil box. To remove the supply−air duct flange, use wide
duct pliers or hand seamers to bend flange back and forth
until it breaks off. Be careful of sharp edges. (See Figure 14)
Figure 12 - Furnace, Plenum, and Subbase Installed on
a Combustible Floor
DOWNFLOW
SUBBASE
SHEET METAL
PLENUM
FLOOR
OPENING
FURNACE
(OR COIL CASING
WHEN USED)
COMBUSTIBLE
FLOORING
A96285

12 441 01 1402 02
Figure 13 - Furnace, Plenum, and Coil or Coil Casing
Installed on a Combustible Floor
APPROVED
COIL ASSEMBLY
OR
COIL BOX
FURNACE
SHEET METAL
PLENUM
FLOOR
OPENING
COMBUSTIBLE
FLOORING
A08556
Bottom Return Air Inlet
These furnaces are shipped with bottom closure panel
installed in bottom return−air opening. Remove and discard
this panel when bottom return air is used. To remove bottom
closure panel, perform the following:
1. Tilt or raise furnace and remove 2 screws holding bot-
tom filler panel. (See Figure 9)
2. Rotate bottom filler panel downward to release holding
tabs.
3. Remove bottom closure panel.
4. Reinstall bottom filler panel and screws.
HORIZONTAL INSTALLATION
FIRE, EXPLOSION, AND CARBON MONOXIDE
POISONING HAZARD
Failure to follow this warning could result in personal
injury, death, or property damage.
Do not install the furnace on its back or hang furnace
with control compartment facing downward. Safety
control operation will be adversely affected. Never
connect return−air ducts to the back of the furnace.
!WARNING
The furnace can be installed horizontally in an attic or crawl
space on either the left−hand (LH) or right−hand (RH) side.
The furnace can be hung from floor joists, rafters or trusses or
installed on a non−combustible platform, blocks, bricks or
pad.
Suspended Furnace Support
The furnace may be supported under each end with threaded
rod, angle iron or metal plumber’s strap as shown. (See
Figure 15 and Figure 16) Secure angle iron to bottom of
furnace as shown. Heavy−gauge sheet metal straps
(plumber’s straps) may be used to suspend the furnace from
each bottom corner. To prevent screws from pulling out, use 2
#8 x 3/4−in. (19 mm) screws into the side and 2 #8 x 3/4−in.
(19 mm) screws in the bottom of the furnace casing for each
strap. (See Figure 15 and Figure 16)
If the screws are attached to ONLY the furnace sides and not
the bottom, the straps must be vertical against the furnace
sides and not pull away from the furnace sides, so that the
strap attachment screws are not in tension (are loaded in
shear) for reliable support.
Platform Furnace Support
Construct working platform at location where all required
furnace clearances are met. (See Figure 2 and Figure 17) For
furnaces with 1−in. (25 mm) clearance requirement on side,
set furnace on non−combustible blocks, bricks or angle iron.
For crawl space installations, if the furnace is not suspended
from the floor joists, the ground underneath furnace must be
level and the furnace set on blocks or bricks.
Roll−Out Protection
Provide a minimum 17−3/4 in. x 22 in. (451 x 559 mm) piece
of sheet metal for flame roll−out protection in front of burner
area for furnaces closer than 12 inches (305 mm) above the
combustible deck or suspended furnaces closer than 12
inches (305 mm) to joists. The sheet metal MUST extend
underneath the furnace casing by 1 in. (25 mm) with the door
removed.
The bottom closure panel on furnaces of widths 17−1/2 in.
(445 mm) and larger may be used for flame roll−out
protection when bottom of furnace is used for return air
connection. See Figure 17 for proper orientation of roll−out
shield.
Bottom Return Air Inlet
These furnaces are shipped with bottom closure panel
installed in bottom return−air opening. Remove and discard
this panel when bottom return air is used. To remove bottom
closure panel, perform the following:
1. Tilt or raise furnace and remove 2 screws holding bot-
tom filler panel. (See Figure 9)
2. Rotate bottom filler panel downward to release holding
tabs.
3. Remove bottom closure panel.
4. Reinstall bottom filler panel and screws.
Side Return Air Inlet
These furnaces are shipped with bottom closure panel
installed in bottom return−air opening. This panel MUST be in
place when side return air inlet(s) is used without a bottom
return air inlet.
Not all horizontal furnaces are approved for side return air
connections. (See Figure 20)
FILTER ARRANGEMENT
CARBON MONOXIDE AND POISONING HAZARD
Failure to follow this warning could result in personal
injury, death and/or property damage.
Never operate a furnace without a filter or with filter
access door removed.
!WARNING
There are no provisions for an internal filter rack in these
furnaces.
A field−supplied accessory external filter rack is required.
This furnace requires 1 in. (25 mm) external filter rack.
Refer to the instructions supplied with external filter rack for
assembly and installation options.

13
441 01 1402 02
Table 4—Opening Dimensions −In. (mm)
FURNACE
CASING
WIDTH
APPLICATION PLENUM OPENING FLOOR OPENING
A B C D
14–3/16
(360)
Upflow Applications on Combustible or Noncombustible Flooring
(subbase not required)
12−11/16
(322)
21−5/8
(549)
13−5/16
(338)
22−1/4
(565)
Downflow Applications on Noncombustible Flooring
(subbase not required)
12−9/16
(319)
19
(483)
13−3/16
(335)
19−5/8
(498)
Downflow Applications on Combustible Flooring
(subbase required)
11−13/16
(284)
19
(483)
13−7/16
(341)
20−5/8
(600)
Downflow Applications on Combustible Flooring with Coil END4X,
ENW4X or Coil Casing NAEA (subbase not required)
12−5/16
(319)
19
(483)
13−5/16
(338)
20
(508)
17–1/2
(445)
Upflow Applications on Combustible or Noncombustible Flooring
(subbase not required)
16
(406)
21−5/8
(549)
16−5/8
(422)
22−1/4
(565)
Downflow Applications on Noncombustible Flooring
(subbase not required)
15−7/8
(403)
19
(483)
16−1/2
(419)
19−5/8
(498)
Downflow Applications on Combustible Flooring
(subbase required)
15−1/8
(384)
19
(483)
16−3/4
(425)
20−5/8
(600)
Downflow Applications on Combustible Flooring with Coil END4X,
ENW4X or Coil Casing NAEA (subbase not required)
15−1/2
(394)
19
(483)
16−1/2
(419)
20
(508)
21
(533)
Upflow Applications on Combustible or Noncombustible Flooring
(subbase not required)
19−1/2
(495)
21−5/8
(549)
20−1/8
(511)
22−1/4
(565)
Downflow Applications on Noncombustible Flooring
(subbase not required)
19−3/8
(492)
19
(483)
20
(508)
19−5/8
(498)
Downflow Applications on Combustible Flooring
(subbase required)
18−5/8
(473)
19
(483)
20−1/4
(514)
20−5/8
(600)
Downflow Applications on Combustible Flooring with Coil END4X,
ENW4X or Coil Casing NAEA (subbase not required)
19
(483)
19
(483)
20
(508)
20
(508)
24−1/2
(622)
Upflow Applications on Combustible or Noncombustible Flooring
(subbase not required)
23
(584)
21−1/8
(537)
23−5/8
(600)
22−1/4
(565)
Downflow Applications on Noncombustible Flooring
(subbase not required)
22−7/8
(581)
19
(483)
23−1/2
(597)
19−5/8
(498)
Downflow Applications on Combustible flooring
(subbase required)
22−1/8
(562)
19
(483)
23−3/4
(603)
20−5/8
(600)
Downflow Applications on Combustible Flooring with Coil END4X,
ENW4X or Coil Casing NAEA (subbase not required)
22−1/2
(572)
19
(483)
23−1/2
(597)
20
(508)
AIR DUCTS
General Requirements
The duct system should be designed and sized according to
accepted national standards such as those published by: Air
Conditioning Contractors Association (ACCA), Sheet Metal
and Air Conditioning Contractors National Association
(SMACNA) or American Society of Heating, Refrigerating and
Air Conditioning Engineers (ASHRAE) or consult The Air
Systems Design Guidelines reference tables available from
your local distributor. The duct system should be sized to
handle the required system design CFM at the design
external static pressure. The furnace airflow rates are
provided in Table 5 −AIR DELIVERY−CFM (With Filter).
When a furnace is installed so that the supply ducts carry air
circulated by the furnace to areas outside the space
containing the furnace, the return air shall also be handled by
duct(s) sealed to the furnace casing and terminating outside
the space containing the furnace.
Secure ductwork with proper fasteners for type of ductwork
used. Seal supply−and return−duct connections to furnace
with code approved tape or duct sealer.
NOTE: Flexible connections should be used between
ductwork and furnace to prevent transmission of vibration.
Ductwork passing through unconditioned space should be
insulated and sealed to enhance system performance. When
air conditioning is used, a vapor barrier is recommended.
Maintain a 1−in. (25 mm) clearance from combustible
materials to supply air ductwork for a distance of 36 in. (914
mm) horizontally from the furnace. See NFPA 90B or local
code for further requirements.
Ductwork Acoustical Treatment
NOTE: Metal duct systems that do not have a 90 degree
elbow and 10 ft. (3 M) of main duct to the first branch take−off
may require internal acoustical lining. As an alternative,
fibrous ductwork may be used if constructed and installed in
accordance with the latest edition of SMACNA construction
standard on fibrous glass ducts. Both acoustical lining and
fibrous ductwork shall comply with NFPA 90B as tested by UL
Standard 181 for Class 1 Rigid air ducts.
Supply Air Connections
For a furnace not equipped with a cooling coil, the outlet duct
shall be provided with a removable access panel. This
opening shall be accessible when the furnace is installed and
shall be of such a size that the heat exchanger can be
viewed for possible openings using light assistance or a
probe can be inserted for sampling the air stream. The cover
attachment shall prevent leaks.

14 441 01 1402 02
Table 5—Air Delivery −CFM (with Filter)*
FURNACE
SIZE
RETURN−AIR
INLET SPEED EXTERNAL STATIC PRESSURE (in. w.c.)
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0451408A
Bottom
or
Side(s)
High
Med−Low
Low
1035
865
760
995
830
720
945
790
680
895
745
635
835
690
580
770
625
520
675
545
445
565
440
345
390
250
220
195
195
195
0451412A
Bottom
or
Side(s)
High
Med−Low
Low
1440
1360
1250
1375
1300
1210
1305
1240
1160
1240
1175
1100
1160
1115
1040
1070
1040
965
975
950
885
870
850
790
730
725
670
560
575
520
0701408A
Bottom
or
Side(s)
High
Med−Low
Low
1030
835
725
1005
815
700
965
790
675
925
755
635
870
710
595
810
660
545
740
590
460
645
480
350
465
325
250
280
205
−−
0701412A
Bottom
or
Side(s)
High
Med−Low
Low
1425
1320
1200
1375
1280
1175
1320
1240
1145
1265
1205
1105
1200
1140
1050
1125
1075
990
1035
995
920
940
905
840
830
790
725
655
620
555
0701716A
Bottom
or
Side(s)
High
Med−Low
Low
1755
1550
1355
1700
1520
1340
1635
1475
1310
1505
1430
1280
1570
1375
1240
1435
1310
1190
1350
1240
1125
1260
1155
1060
1160
1070
975
1055
970
890
0901714B
Bottom
or
Side(s)
High
Med−High
Med−Low
Low
1650
1515
1385
1205
1600
1485
1360
1180
1535
1440
1320
1160
1465
1380
1260
1120
1385
1300
1195
1065
1285
1220
1120
1005
1175
1115
1025
925
1055
990
915
810
895
830
710
630
645
600
565
510
0902116A
Bottom
or
Side(s)
High
Med−Low
Low
1940
1740
1505
1880
1700
1505
1805
1650
1480
1720
1590
1440
1635
1525
1375
1540
1440
1300
1425
1335
1190
1290
1195
1045
1090
1010
890
830
820
740
0902120A
Bottom Only
High
Med−Low
Low
2405
2170
1920
2310
2110
1875
2220
2040
1835
2130
1970
1780
2025
1895
1715
1920
1785
1630
1790
1675
1535
1660
1565
1420
1530
1420
1275
1350
1260
1135
Both Sides
or
1 Side & Bottom
High
Med−Low
Low
2530
2230
1895
2450
2170
1890
2365
2110
1845
2270
2050
1815
2165
1985
1755
2065
1890
1685
1940
1780
1600
1805
1660
1480
1670
1525
1350
1505
1360
1180
1 Side Only
High
Med−Low
Low
2475
2105
1850
2395
2145
1860
2300
2070
1810
2200
2010
1770
2090
1940
1715
1985
1845
1650
1865
1735
1555
1730
1620
1445
1585
1475
1310
1425
1325
1150
1101712A
Bottom
or
Side(s)
High
Med−Low
Low
1600
1475
1315
1550
1435
1295
1490
1395
1265
1425
1335
1220
1355
1285
1155
1260
1185
1080
1135
1070
985
990
890
810
785
725
675
530
450
440
1102116A
Bottom
or
Side(s)
High
Med−Low
Low
1980
1745
1530
1915
1710
1515
1835
1650
1470
1750
1560
1400
1655
1450
1310
1495
1340
1215
1365
1205
1095
1185
1090
990
965
865
830
700
605
670
1102122A
Bottom Only
High
Med−Low
Low
2485
2135
1855
2415
2100
1840
2340
2060
1815
2255
2000
1775
2160
1930
1725
2060
1860
1675
1950
1765
1600
1840
1670
1510
1720
1555
1405
1565
1425
1290
Bottom, Sides
or
1 Side & Bottom
High
Med−Low
Low
−−
2140
1855
−−
2100
1840
2355
2050
1815
2285
1990
1775
2190
1935
1725
2090
1865
1675
1965
1760
1600
1850
1670
1510
1705
1545
1405
1535
1410
1290
1 Side Only
High
Med−Low
Low
2495
2030
−−
2440
2025
1735
2370
2000
1725
2290
1950
1695
2205
1905
1650
2120
1850
1595
2015
1750
1535
1910
1660
1455
1775
1555
1335
1625
1425
1230
1352116A
Bottom
or
Side(s)
High
Med−Low
Low
2065
1790
1480
2000
1755
1480
1930
1705
1480
1835
1640
1450
1710
1550
1380
1590
1465
1295
1420
1295
1160
1235
1145
1005
1025
945
855
835
775
670
1352422A
Bottom Only
High
Med−Low
Low
2445
2130
1860
2365
2080
1830
2280
2025
1800
2190
1960
1755
2085
1880
1705
1980
1795
1630
1850
1690
1530
1705
1550
1415
1520
1405
1280
1355
1255
1140
Bottom, Sides
or Side &
Bottom
High
Med−Low
Low
−−
2120
1860
−−
2075
1830
2355
1995
1800
2280
1970
1755
2160
1905
1725
2065
1835
1630
1930
1735
1530
1805
1645
1415
1655
1515
1280
1465
1325
1140
1 Side Only
High
Med−Low
Low
−−
2070
1860
−−
2015
1830
2215
1970
1800
2130
1935
1755
2030
1855
1725
1920
1765
1630
1795
1655
1530
1675
1550
1415
1540
1445
1280
1385
1265
1140
1552420A
Bottom Only
High
Med−Low
Low
2465
2115
1800
2430
2095
1790
2375
2055
1770
2305
2005
1735
2215
1940
1695
2110
1845
1640
2000
1820
1570
1865
1675
1465
1715
1525
1345
1530
1390
1225
Both Sides
or
1 Side & Bottom
High
Med−Low
Low
−−
2155
1800
−−
2125
1790
2375
2075
1770
2285
2015
1735
2185
1935
1695
2105
1830
1640
1995
1780
1570
1870
1635
1465
1720
1485
1345
1555
1365
1225
1 Side Only
High
Med−Low
Low
−−
2140
1800
−−
2085
1790
2260
2020
1770
2180
1950
1735
2070
1850
1695
1975
1745
1640
1865
1695
1570
1740
1545
1465
1595
1415
1345
1440
1290
1225
* A filter is required for each return-air inlet. Airflow performance included 3/4-in. (19 mm) washable filter media such as contained in factory-authorized accessory
filter rack. To determine airflow performance without this filter, assume an additional 0.1 in. w.c. available external static pressure.
-- Indicates unstable operating conditions.

15
441 01 1402 02
Figure 14 - Duct Flanges
UPFLOW DOWNFLOW HORIZONTAL
YES
NO NO
YES
YES
YES
NO
120°
MIN
YES 120°
MIN
YES
120°
MIN
90°90°
A02020
Figure 15 - Horizontal Unit Suspension
1
/4 " (6mm) THREADED ROD
4 REQ.
SECURE ANGLE
IRON TO BOTTOM
OF FURNACE WITH
3 #8 x
3/4" (19mm) SCREWS
TYPICAL FOR 2 SUPPORTS
1” (25mm) SQUARE, 1-1/4”x1-1/4”x1/8” (32x32x3mm)
ANGLE IRON OR UNI-STRUT MAY BE USED
(2) HEX NUTS, (2) WASHERS & (2) LOCK WASHERS
REQ. PER ROD
8" (203mm) MIN
FOR DOOR REMOVAL
OUTER DOOR
ASSEMBLY
A10130

16 441 01 1402 02
Figure 16 - Horizontal Suspension with Straps
METHOD 2
USE (4) #8 x 3/4 (19 mm) SHEET
METAL SCREWS FOR EACH
STRAP. THE STRAPS
SHOULD BE VERTICAL
AGAINST THE FURNACE
SIDES AND NOT PULL AWAY
FROM THE FURNACE
SIDES.
METHOD 1
FOLD ALL STRAPS UNDER
FURNACE AND SECURE WTH
(4) #8 x 3/4 (19 mm) SHEET METAL SCREWS
(2 SCREWS IN SIDE AND 2 SCREWS
IN BOTTOM).
A10131
Figure 17 - Typical Attic Installation
30-IN. (762mm)
MIN WORK AREA
6″ MIN
*
TYPE-B
VENT
17
3
/ 4 ″
22 ″
SHEET
METAL
SEDIMENT
TRAP
EQUIPMENT MANUAL
SHUT-OFF GAS VALVE
LINE CONTACT ONLY PERMISSIBLE BETWEEN
LINES FORMED BY INTERSECTIONS OF
THE TOP AND TWO SIDES OF THE FURNACE
JACKET AND BUILDING JOISTS,
STUDS, OR FRAMING.
GAS
ENTRY
17
3
/ 4 ″ (451mm) OVERALL
4
3
/ 4 ″ (121mm) UNDER DOOR
1″
(25mm) UNDER FURNACE
EXTEND OUT 12″
(305mm)
FROM FACE OF DOOR
* WHEN USED WITH
SINGLE WALL VENT
CONNECTIONS
UNION
(152mm)
(451mm)
(559mm)
A10164

17
441 01 1402 02
Figure 18 - Upflow Return Air Configurations and Restrictions
5TONS AND
GREATER *
*2000 CFM AND GREATER AT .6 ESP HI COOLING SPEED
Figure 19 - Downflow Return Air Configurations and Restrictions
5TONS AND
GREATER *
*2000 CFM AND GREATER AT .6 ESP HI COOLING SPEED
Figure 20 - Horizontal Return Air Configurations and Restrictions
5TONS AND
GREATER *
*2000 CFM AND GREATER AT .6 ESP HI COOLING SPEED

18 441 01 1402 02
Upflow and Horizontal Furnaces
Connect supply−air duct to flanges on furnace supply−air
outlet. Bend flange upward to 90with wide duct pliers. (See
Figure 14) The supply−air duct must be connected to ONLY
the furnace supply−outlet−air duct flanges or air conditioning
coil casing (when used). DO NOT cut main furnace casing
side to attach supply air duct, humidifier, or other accessories.
All accessories MUST be connected to duct external to
furnace main casing.
NOTE: For horizontal applications, the top−most flange may
be bent past 90to allow the evaporator coil to hang on the
flange temporarily while the remaining attachment and
sealing of the coil are performed.
Downflow Furnaces
Connect supply−air duct to supply−air outlet on furnace. Bend
flange inward past 90with wide duct pliers. (See Figure 14)
The supply−air duct must be connected to ONLY the furnace
supply−outlet or air conditioning coil casing (when used).
When installed on combustible material, supply−air duct must
be connected to ONLY the accessory subbase or a factory
approved air conditioning coil casing. DO NOT cut main
furnace casing to attach supply side air duct, humidifier, or
other accessories. All accessories MUST be connected to
duct external to furnace casing.
FIRE HAZARD
A failure to follow this warning could result in
personal injury, or death and/or property damage.
Never connect return−air ducts to the back of the
furnace. Follow instructions below.
!WARNING
Return Air Connections
Downflow Furnaces
The return−air duct must be connected to return−air opening
(bottom inlet) as shown in Figure 19. DO NOT cut into casing
sides (left or right). Side opening is permitted for only upflow
and most horizontal furnaces. (See Figure 19) Bypass
humidifier connections should be made at ductwork or coil
casing sides exterior to furnace.
Upflow and Horizontal Furnaces
The return−air duct must be connected to bottom, sides (left
or right), or a combination of bottom and side(s) of main
furnace casing as shown in Figure 18 and Figure 20. Bypass
humidifier may be attached into unused return air side of the
furnace casing. (See Figure 18 and Figure 20)
Not all horizontal furnaces are approved for side return air
connections. (See Figure 20)
GAS PIPING
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Never purge a gas line into a combustion chamber.
Never test for gas leaks with an open flame. Use a
commercially available soap solution made
specifically for the detection of leaks to check all
connections.
!WARNING
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Use proper length of pipe to avoid stress on gas
control manifold and a gas leak.
!WARNING
Gas piping must be installed in accordance with national and
local codes. Refer to current edition of NFGC.
Installations must be made in accordance with all authorities
having jurisdiction. If possible, the gas supply line should be a
separate line running directly from meter to furnace.
NOTE: In the state of Massachusetts:
1. Gas supply connections MUST be performed by a li-
censed plumber or gas fitter.
2. When flexible connectors are used, the maximum
length shall not exceed 36 inches (915 mm).
3. When lever handle type manual equipment shutoff
valves are used, they shall be T−handle valves.
4. The use of copper tubing for gas piping is NOT ap-
proved by the state of Massachusetts.
Refer to Table 6 for recommended gas pipe sizing. Risers
must be used to connect to furnace and to meter. Support all
gas piping with appropriate straps, hangers, etc. Use a
minimum of 1 hanger every 6 ft. (1.8 M) Joint compound (pipe
dope) should be applied sparingly and only to male threads of
joints. Pipe dope must be resistant to the action of propane
gas.
Table 6—Maximum Capacity of Pipe
NOMINAL
IRON PIPE
SIZE
IN. (MM)
INTERNAL
DIA.
IN. (MM)
LENGTH OF PIPE - FT (M)
10
(3.0)
20
(6.0)
30
(9.1)
40
(12.1)
50
(15.2)
1/2 (12.7) 0.622 (158) 175 120 97 82 73
3/4 (19.0) 0.824 (20.9) 360 250 200 170 151
1( 25.4) 1.049 (26.6) 680 465 375 320 285
1‐1/4 (31.8) 1.380 (35.0) 1400 950 770 660 580
1‐1/2 (38.1) 1.610 (40.9) 2100 1460 1180 990 900
* Cubic ft. of natural gas per hr for gas pressures of 0.5 psig (14-in. w.c.) or
less and a pressure drop of 0.5-in. w.c. (based on a 0.60 specific gravity
gas). Ref: Table 6 and ANSI Z223-2009/NFPA 54-2009.
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
If local codes allow the use of a flexible gas appliance
connector, always use a new listed connector. Do not
use a connector which has previously served another
gas appliance. Black iron pipe shall be installed at the
furnace gas control valve and extend a minimum of 2
in. (51 mm) outside the furnace.
!WARNING

19
441 01 1402 02
FURNACE OVERHEAT HAZARD
Failure to follow this caution may result in unit
component damage.
Connect gas pipe to gas valve using a backup
wrench to avoid damaging gas controls and burner
misalignment.
CAUTION
!
An accessible manual equipment shutoff valve MUST be
installed external to furnace casing and within 6 ft. (1.8 M) of
furnace. A 1/8−in. (3 mm) NPT plugged tapping, accessible
for test gauge connection, MUST be installed immediately
upstream of gas supply connection to furnace and
downstream of manual equipment shutoff valve.
NOTE: The furnace gas valve inlet pressure tap connection
is suitable to use as test gauge connection providing test
pressure DOES NOT exceed maximum 0.5 psig (14−in. w.c.)
stated on gas control valve. (See Figure 41)
Figure 21 - Burner and Manifold
2” (51mm)
Street Elbow
A08551
Figure 22 - Typical Gas Pipe Arrangement
UNION
SEDIMENT
TRAP
MANUAL
SHUTOFF
VALVE
(REQUIRED)
GAS
SUPPLY
A02035
Some installations require gas entry on right side of furnace
(as viewed in upflow.) (See Figure 21)
Install a sediment trap in riser leading to furnace as shown in
Figure 22. Connect a capped nipple into lower end of tee.
Capped nipple should extend below level of furnace gas
controls. Place a ground joint union between furnace gas
control valve and exterior manual equipment gas shutoff
valve. A 1/8−in. (3 mm) NPT plugged tapping, accessible for
test gauge connection, MUST be installed immediately
upstream of gas supply connection to furnace and
downstream of manual equipment shutoff valve.
Piping should be pressure and leak tested in accordance with
NFGC, local, and national plumbing and gas codes before
the furnace has been connected. After all connections have
been made, purge lines and check for leakage at furnace
prior to operating furnace.
If pressure exceeds 0.5 psig (14−in. w.c.), gas supply pipe
must be disconnected from furnace and capped before and
during supply pipe pressure test. If test pressure is equal to or
less than 0.5 psig (14−in. w.c.), turn off electric shutoff switch
located on furnace gas control valve and accessible manual
equipment shutoff valve before and during supply pipe
pressure test. After all connections have been made, purge
lines and check for leakage at furnace prior to operating
furnace.
Figure 23 - Relocating J−Box
FACTORY
INSTALLED
LOCATION ALTERNATE
FIELD
LOCATION
Figure 24 - Field−Supplied Electrical Box on Furnace
Casing
The gas supply pressure shall be within the maximum and
minimum inlet supply pressures marked on the rating plate
with the furnace burners ON and OFF.

20 441 01 1402 02
ELECTRICAL CONNECTIONS
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Blower access panel door switch opens 115−v power
to control. No component operation can occur. Do not
bypass or close switch with panel removed.
!WARNING
See Figure 26 for field wiring diagram showing typical field
115−v wiring. Check all factory and field electrical
connections for tightness.
ELECTRICAL SHOCK AND FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, or property damage.
The cabinet MUST have an uninterrupted or
unbroken ground according to NEC ANSI/NFPA
70−2008 or local codes to minimize personal injury if
an electrical fault should occur. This may consist of
electrical wire, conduit approved for electrical ground
or a listed, grounded power cord (where permitted
by local code) when installed in accordance with
existing electrical codes. Refer to the power cord
manufacturer’s ratings for proper wire gauge. Do not
use gas piping as an electrical ground.
!WARNING
FURNACE MAY NOT OPERATE
Failure to follow this caution may result in intermittent
furnace operation.
Furnace control must be grounded for proper
operation or else control will lock out. Control must
remain grounded through green/yellow wire routed to
gas valve and manifold bracket screw.
CAUTION
!
115−V WIRING
Verify that the voltage, frequency, and phase correspond to
that specified on unit rating plate. Also, check to be sure that
service provided by utility is sufficient to handle load imposed
by this equipment. Refer to rating plate or Table 7 for
equipment electrical specifications.
Make all electrical connections in accordance with National
Electrical Code (NEC) ANSI/NFPA 70−2008 and any local
codes or ordinances that might apply.
FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, or property damage.
Do not connect aluminum wire between disconnect
switch and furnace. Use only copper wire.
!WARNING
Use a separate, fused branch electrical circuit with a properly
sized fuse or circuit breaker for this furnace. See Table 7 for
wire size and fuse specifications. A readily accessible means
of electrical disconnect must be located within sight of the
furnace.
NOTE: Proper polarity must be maintained for 115−v wiring.
If polarity is incorrect, control LED status indicator light will
flash a status code 10 and furnace will NOT operate.
J−BOX RELOCATION
NOTE: If factory location of J−Box is acceptable, go to next
section (ELECTRICAL CONNECTION TO J−BOX).
NOTE: On 14−in. (356 mm) wide casing models, the J−Box
shall not be relocated to other side of furnace casing when
the vent pipe is routed within the casing.
1. Remove and save two screws holding J−Box. (See
Figure 23)
NOTE: The J−Box cover need not be removed from the
J−Box in order to move the J−Box. Do NOT remove green
ground screw inside J−Box. The ground screw is not
threaded into the casing flange and can be lifted out of the
clearance hole in casing while swinging the front edge of the
J−Box outboard of the casing.
2. Cut wire tie on loop in furnace wires attached to J−box.
3. Move J−Box to desired location.
4. Fasten J−Box to casing with two screws removed in
Step 1.
5. Route J−Box wires within furnace away from sharp
edges, rotating parts and hot surfaces.
ELECTRICAL CONNECTION TO J−BOX
Field−Supplied Electrical Box on Furnace J−Box Bracket See
Figure 24.
1. Remove cover from furnace J−Box.
2. Attach electrical box to furnace J−Box bracket with at
least two field−supplied screws through holes in elec-
trical box into holes in bracket. Use blunt−nose screws
that will not pierce wire insulation.
3. Route furnace power wires through holes in electrical
box and J−Box bracket, and make field−wire connec-
tions in electrical box. Use best practices (NEC in U.S.)
for wire bushings, strain relief, etc.
4. Route and secure field ground wire to green ground
screw on J−Box bracket.
5. Connect line voltage leads as shown in Figure 26.
6. Reinstall cover to J−Box. Do not pinch wires between
cover and bracket. Electrical Box on Furnace Casing
Side See Figure 24.
FIRE OR ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury, death, or property damage.
If field−supplied manual disconnect switch is to be
mounted on furnace casing side, select a location
where a drill or fastener cannot damage electrical or
gas components.
!WARNING
1. Select and remove a hole knockout in the casing
where the electrical box is to be installed.
NOTE: Check that duct on side of furnace will not interfere
with installed electrical box.
2. Remove the desired electrical box hole knockout and
position the hole in the electrical box over the hole in
the furnace casing.
3. Fasten the electrical box to casing by driving two field
supplied screws from inside electrical box into casing
steel.