International comfort products N9MSB User manual

Printed in U.S.A. 440 01 4101 03 Aug. 2012
INSTALLATION INSTRUCTIONS
Single−Stage, PSC Blower Motor
35” Tall, High Efficiency Condensing Gas Furnace
N9MSB & N9MSE (A Series)
These instructions must be read and understood completely before attempting installation.
Safety Labeling and Signal Words
DANGER, WARNING, CAUTION, and NOTE
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.
DANGER −Immediate hazards which will result in
severe personal 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 enhanced installation, reliability, or
operation.
!WARNING
Signal Words in Manuals
The signal word CAUTION is used throughout
this manual in the following manner:
!CAUTION
Signal Words on Product Labeling
Signal words are used in combination with
colors and/or pictures or product labels.
The signal word WARNING is used throughout
this manual in the following manner:
Safety−alert symbol
When you see this symbol on the unit and in
instructions or manuals, be alert to the
potential for personal injury.
TABLE OF CONTENTS
SAFETY CONSIDERATIONS 3..............................
INTRODUCTION 4.........................................
CODES AND STANDARDS 4................................
ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS 5.......
DIMENSIONS NEW 6/7/12 6................................
LOCATION 7..............................................
LOCATION RELATIVE TO COOLING EQUIPMENT 9...........
AIR FOR COMBUSTION AND VENTILATION 9................
CONDENSATE TRAP 12....................................
INSTALLATION 19..........................................
UPFLOW INSTALLATION 19.................................
DOWNFLOW INSTALLATION 20..............................
HORIZONTAL INSTALLATION 23.............................
FILTER ARRANGEMENT 24.................................
AIR DUCTS 28.............................................
GAS PIPING 28.............................................
ELECTRICAL CONNECTIONS 30.............................
J−BOX INSTALLATION 31...................................
VENTING 35...............................................
SPECIAL VENTING REQUIREMENTS
FOR INSTALLATIONS IN CANADA 35........................
DIRECT VENT / 2−PIPE SYSTEM 39..........................
VENTILATED COMBUSTION AIR 39..........................
TERMINATION REQUIREMENTS FOR THE PROVINCES OF ALBERTA
AND SASKATCHEWAN 39...................................
INSTALLING THE VENT TERMINATION 48....................
MAXIMUM EQUIVALENT VENT LENTH - FEET (METERS) 53....
MAXIMUM ALLOWABLE EXPOSED VENT
LENGTHS IN UNCONDITIONED SPACE 56...................
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 .
INSTALLER: Affix these instructions on or adjacent to the
furnace.
CONSUMER: Retain these instructions for future
reference.
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, Washington, 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.

Specifications are subject to change without notice.
2440 01 4101 03
Required Notice for Massachusetts Installations
Important
The Commonwealth of Massachusetts requires compliance with regulation 248 CMR as follows:
5.08: Modifications to NFPA−54, Chapter 10
2) Revise 10.8.3 by adding the following additional requirements:
(a) For all side wall horizontally vented gas fueled equipment installed in every dwelling, building or structure used in whole or in part for residential
purposes, including those owned or operated by the Commonwealth and where the side wall exhaust vent termination is less than seven (7) feet
above finished grade in the area of the venting, including but not limited to decks and porches, the following requirements shall be satisfied:
1. INSTALLATION OF CARBON MONOXIDE DETECTORS. At the time of installation of the side wall horizontal vented gas fueled equipment, the
installing plumber or gasfitter shall observe that a hard wired carbon monoxide detector with an alarm and battery back−up is installed on the floor
level where the gas equipment is to be installed. in addition, the installing plumber or gasfitter shall observe that a battery operated or hard wired
carbon monoxide detector with an alarm is installed on each additional level of the dwelling, building or structure served by the side wall
horizontal vented gas fueled equipment. It shall be the responsibility of the property owner to secure the services of qualified license professionals
for the installation of hard wired carbon monoxide detectors.
a. In the event that the side wall horizontally vented gas fueled equipment is installed in a crawl space or an attic, the hard wired carbon
monoxide detector with alarm and battery back−up may be installed on the next adjacent floor level.
b. In the event that the requirements of this subdivision can not be met at the time of completion of installation, the owner shall have a period of
thirty (30) days to comply with the above requirement; provided, however, that during said thirty (30) day period, a battery operated carbon
monoxide detector with an alarm shall be installed.
2. APPROVED CARBON MONOXIDE DETECTORS. Each carbon monoxide detector as required in accordance with the above provisions shall
comply with NFPA 720 and be ANSI/UL 2034 listed and IAS certified.
3. SIGNAGE. A metal or plastic identification plate shall be permanently mounted to the exterior of the building at a minimum height of eight (8) feet
above grade directly in line with the exhaust vent terminal for the horizontally vented gas fueled heating appliance or equipment. The sign shall
read, in print size no less than one−half (1/2) inch in size, “GAS VENT DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS”.
4. INSPECTION. The state of local gas inspector of the side wall horizontally vented gas fueled equipment shall not approve the installation unless,
upon inspection, the inspector observes carbon monoxide detectors and signage installed in accordance with the provisions of 248 CMR
5.08(2)(a) 1 through 4.
(b) EXEMPTIONS: The following equipment is exempt from 248 CMR 5.08(2)(a) 1 through 4:
1. The equipment listed in Chapter 10 entitled “Equipment Not Required To Be Vented” in the most current edition of NFPA 54 as adopted by the
Board; and
2. Product Approved side wall horizontally vented gas fueled equipment installed in a room or structure separate from the dwelling, building or
structure used in whole or in part for residential purposes.
(c) MANUFACTURER REQUIREMENTS −GAS EQUIPMENT VENTING SYSTEM PROVIDED. When the manufacturer of Product Approved side wall
horizontally vented gas equipment provides a venting system design or venting system components with the equipment, the instructions provided by
the manufacturer for installation of the equipment and the venting system shall include:
1. Detailed instructions for the installation of the venting system design or the venting system components; and
2. A complete parts list for the venting system design or venting system.
(d) MANUFACTURER REQUIREMENTS −GAS EQUIPMENT VENTING SYSTEM NOT PROVIDED. When the manufacturer of a Product Approved side
wall horizontally vented gas fueled equipment does not provide the parts for venting the flue gases, but identifies “special venting systems”, the
following requirements shall be satisfied by the manufacturer:
1. The referenced “special venting system” instructions shall be included with the appliance or equipment installation instructions; and
2. The “special venting systems” shall be Product Approved by the Board, and the instructions for that system shall include a parts list and detailed
installation instructions.
(e) A copy of all installation instructions for all Product Approved side wall horizontally vented gas fueled equipment, all venting instructions, all parts lists
for venting instructions, and/or all venting design instructions shall remain with the appliance or equipment at the completion of the installation.
For questions regarding these requirements, please contact the Commonwealth of Massachusetts Board of State Examiners of Plumbers and Gas
Fitters, 239 Causeway Street, Boston, MA 02114. 617−727−9952

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
440 01 4101 03 3
Specifications subject to change without notice.
Safety Considerations
!WARNING
FIRE, EXPLOSION, ELECTRICAL SHOCK, AND
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in dangerous
operation, 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
FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, or property damage.
Solvent cements and primers are combustible. Keep
away from heat, sparks and open flame. Use only in
well−ventilated areas. Avoid breathing in vapor or
allowing contact with skin or eyes.
!CAUTION
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.
Improper installation, adjustment, alteration, service,
maintenance, or use can cause 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 installer or agency must use only factory−authorized
and listed kits or accessories when modifying this product.
Refer to the individual instructions packaged with the kits or
accessories when installing.
Installing and servicing heating equipment can be hazardous
due to gas and electrical components. Only trained and
qualified personnel should install, repair, or service
heating equipment. Untrained personnel can perform basic
maintenance functions such as cleaning and replacing air
filters. All other operations must be performed by trained
service personnel. When working on heating equipment,
observe precautions in literature, on tags, and on labels
attached to or shipped with furnace and other safety
precautions that may apply.
These instructions cover minimum requirements and conform
to existing national standards and safety codes. In some
instances, these instructions exceed certain local codes and
ordinances, especially those that may not have kept up with
changing residential construction practices. We require these
instructions as a minimum for a safe installation.
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 included in literature and attached to the unit.
!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.
This is the safety−alert symbol . When you see this symbol
on the furnace 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 a
hazard which could result in personal injury or death.
CAUTION is used to identify hazards which may result in minor
personal injury or product and property damage. NOTE and
NOTICE are 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
instructions.
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
which has an external static pressure within the
allowable 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
garage must be installed as specified in the warning box
in the “Location” section. (See Figure 4)
9. The furnace may be used for construction heat provided
that the furnace installation and operation complies with
the first CAUTION in the LOCATION section on page 7
of these instructions.
10. These Multipoise Gas−Fired Furnaces are CSA
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

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
4440 01 4101 03
Specifications subject to change without notice.
accessory gas conversion kit is required to convert
furnace for use with propane gas.
11. See Table 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.
Table 1 Minimum Clearances to
Combustible Materials for All Units
POSITION CLEARANCE
In(mm)
REAR 0
FRONT (Combustion air openings in
furnace and in structure) 1 (25)
Recommended for service *24 (610)
All Sides of Supply Plenum *1 (25)
Sides 0
Vent 0
Top of Furnace 1 (25)
* Consult local building codes
13. These furnaces SHALL NOT be installed directly on
carpeting, combustible 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 manufacturer’s Coil Assembly or when
Coil Box is used. See Table 1 for clearance to
combustible construction information.
Introduction
The 4−way multipoise Category IV condensing furnace is CSA
design−certified as a direct vent (2−pipe) or non−direct vent
(1−pipe) furnace. (See Figure 3) The furnace is
factory−shipped for use with natural gas. The furnace can be
converted in the field for use with propane gas when a
factory−supplied conversion kit is used. Refer to the furnace
rating plate for conversion kit information.
These furnaces are not approved for installation in recreational
vehicles or outdoors. Single-stage furnaces (40k through
120k) are approved for installation in manufactured
housing/mobile homes with manufacturer approved accessory.
The conversion kit is required for use with both natural and
propane gas. The furnace must also be installed on a
factory−supplied accessory combustible floor base or
evaporator coil casing.
This furnace is designed for minimum continuous return−air
temperature of 60°F (15°C) db or intermittent operation down to
55°F (15°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 1)
The furnace should be sized to provide 100 percent of the
design heating load requirement plus any margin that occurs
because of furnace model size capacity increments. Heating
load estimates can be made using approved methods available
from Air Conditioning Contractors of America (Manual J);
American Society of Heating, Refrigerating, and
Air−Conditioning Engineers; or other approved engineering
methods. Excessive oversizing of the furnace could cause the
furnace and/or vent to fail prematurely.
For accessory installation details, refer to the applicable
instruction literature.
NOTE: Remove all shipping materials, parts assemblies and
literature before operating the furnace.
Figure 1 Freeze Protection and Return Air
Temperature
32°F/0°C MINIMUM INSTALLED
AMBIENT OR FREEZE
PROTECTION REQUIRED
SUPPLY AIR MAX 80°F/27°C
MIN 60°F/16°C
A10490
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 and Canada, follow all codes and
standards for the following:
Safety
US: 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
A manufactured (Mobile) home installation must
conform with the Manufactured Home Construction
and Safety Standard, Title 24 CFR, Part 3280, or
when this standard is not applicable, the Standard for
Manufactured Home Installation (Manufactured Home
Sites, Communities, and Set-Ups),ANSI/NCS A225.1,
and/or CAN/CSA-Z240, MH Series Mobile Homes
CANADA: National Standard of Canada, Natural Gas
and Propane Installation Code (NSCNGPIC)
CAN/CSA B149.1−2010
General Installation
US: NFGC and the NFPA 90B. For copies, contact the
National Fire Protection Association Inc.,
Batterymarch Park, Quincy, MA 02269; or for only the
NFGC contact the American Gas Association, 400 N.
Capitol, N.W., Washington DC 20001.
CANADA: NSCNGPIC. For a copy, contact Standard
Sales, CSA International, 178 Rexdale Boulevard,
Etobicoke (Toronto), Ontario, M9W 1R3, Canada.

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
440 01 4101 03 5
Specifications subject to change without notice.
Combustion and Ventilation Air
US: Section 9.3 of the NFPA54/ANSI Z223.1−2009,
Air for Combustion and Ventilation
CANADA: Part 8 of the CAN/CSA B149.1−2010,
Venting Systems and Air Supply for Appliances
Duct Systems
US and CANADA: Air Conditioning Contractors
Association (ACCA) Manual D, Sheet Metal and Air
Conditioning Contractors National Association
(SMACNA), or American Society of Heating,
Refrigeration, and Air Conditioning Engineers (ASHRAE)
2005 Fundamentals Handbook Chapter 35.
Acoustical Lining and Fibrous Glass
Duct
US and CANADA: current edition of SMACNA, NFPA
90B as tested by UL Standard 181 for Class I Rigid Air
Ducts
Gas Piping and Gas Pipe Pressure
Testing
U.S.A.: NFPA 54/ANSI Z223.1−2009, NFGC; Chapters
5, 6, 7, and 8 and national plumbing codes.
CANADA: CAN/CSA−B149.1−2010, Parts 4, 5, 6 and
9.
In the state of Massachusetts:
This product must be installed by a licensed plumber or
gas fitter.
When flexible connectors are used, the maximum
length shall not exceed 36−in. (914 mm).
When lever type gas shutoffs are used they shall be
T−handle type.
The use of copper tubing for gas piping is not
approved by the state of Massachusetts.
Electrical Connections
U.S.A.: National Electrical Code (NEC) ANSI/NFPA
70−2011
CANADA: Canadian Electrical Code CSA C22.1
Electrostatic Discharge (ESD)
Precautions Procedure
!CAUTION
FURNACE RELIABILITY HAZARD
Failure to follow this caution may result in unit component
damage.
Electrostatic discharge can affect electronic
components. Take precautions 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.
1. Disconnect all power to the furnace. Multiple
disconnects 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 satisfactorily
discharged.
3. After touching the chassis, you may proceed to service
the control or connecting wires as long as you do nothing
to recharge your body with static electricity (for example;
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,
unpainted metal surface of the furnace again before
touching control or wires.
5. Use this procedure for installed and uninstalled
(ungrounded) furnaces.
6. Before removing a new control from its container,
discharge 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
furnace. Put all used and new controls into containers
before touching ungrounded objects.
7. An ESD service kit (available from commercial sources)
may also be used to prevent ESD damage.
Accessories
See Specification Sheets for a list of accessories for this
product.
Table 2 Loose Parts Bag Contents
(shipped in blower compartment)
QUANTITY DESCRIPTION −See NOTE
(Provided in Loose Parts Bag)
1Outlet Choke Plate (used with 40k BTUH
furnaces, only)
1Air Intake Pipe Flange
1Vent Pipe Flange
2Pipe Flange Gaskets
10 Sharp Tip Screws (Vent and Inlet Flanges)
1Vent Pipe Coupling
2Vent Pipe Coupling Clamps
1Pressure Switch Tube
1Rubber Drain Elbow
4Drain Elbow Clamps
11/2”CPVC to 3/4” PVC Pipe Adapter
1Gas Line Grommet
1Gas Line Knockout Plug
1Junction Box Cover
1Junction Box Base
1Green Ground Screw
3Blunt Tip Screws (Junction Box)
1Thermostat Wire Grommet
Provided separately in furnace
1Drain Extension Tube −“Z” Pipe
NOTE: Only used on 40K BTUH furnaces from 0 to 2000 ft. (0
to 610m) above sea level for total equivalent vent lengths under
10 ft.

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
6440 01 4101 03
Specifications subject to change without notice.
Figure 2 Dimensions
SD5060−4 Rev F
N9MSB
FURNACE SIZE
A B C D SHIP WT.
LB (KG)
CABINET
WIDTH OUTLET WIDTH BOTTOM INLET WIDTH AIR INTAKE
0401410 14−3/16 (361) 12−1/2 (319) 12−9/16 (322) 7−1/8 (181) 123 (55)
0601410 14−3/16 (361) 12−1/2 (319) 12−9/16 (322) 7−1/8 (181) 127 (57)
0601714 17−1/2 (445) 15−7/8 (403) 16 (406) 8−3/4 (222) 144 (65)
0801716 17−1/2 (445) 15−7/8 (403) 16 (406) 8−3/4 (222) 154 (69)
0802120 21 (533) 19−3/8 (492) 19−1/2 (495) 10−1/2 (267) 162 (73)
1002114 21 (533) 19−3/8 (492) 19−1/2 (495) 10−1/2 (267) 169 (76)
1002120 21 (533) 19−3/8 (492) 19−1/2 (495) 10−1/2 (267) 169 (76)
1202420 24−1/2 (622) 22−7/8 (581) 23 (584) 12−1/4 (311) 186 (84)
N9MSE
FURNACE SIZE
A B C D SHIP WT.
LB (KG)
CABINET
WIDTH OUTLET WIDTH BOTTOM INLET WIDTH AIR INTAKE
0401410 14−3/16 (361) 12−1/2 (319) 12−9/16 (322) 7−1/8 (181) 123 (55)
0601410 14−3/16 (361) 12−1/2 (319) 12−9/16 (322) 7−1/8 (181) 127 (57)
0601714 17−1/2 (445) 15−7/8 (403) 16 (406) 8−3/4 (222) 144 (65)
0801716 17−1/2 (445) 15−7/8 (403) 16 (406) 8−3/4 (222) 154 (69)
0802120 21 (533) 19−3/8 (492) 19−1/2 (495) 10−1/2 (267) 162 (73)
1002114 21 (533) 19−3/8 (492) 19−1/2 (495) 10−1/2 (267) 169 (76)
1002120 21 (533) 19−3/8 (492) 19−1/2 (495) 10−1/2 (267) 169 (76)
1202420 24−1/2 (622) 22−7/8 (581) 23 (584) 12−1/4 (311) 186 (84)
1402420 24−1/2 (622) 22−7/8 (581) 23 (584) 12−1/4 (311) 190 (86)

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
440 01 4101 03 7
Specifications subject to change without notice.
Location
!CAUTION
PERSONAL INJURY AND/OR PROPERTY DAMAGE
HAZARD
Improper use or installation of this furnace may result in
premature furnace component failure. 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.
General
These furnaces are shipped with materials to assist in proper
furnace installation. These materials are shipped in the main
blower compartment.
See Table 2 for loose parts bag contents.
This furnace must:
•be installed so the electrical components are protected
from water.
•not be installed directly on any combustible material other
than wood flooring (refer to SAFETY
CONSIDERATIONS).
•be located close to the chimney or vent and attached to an
air distribution system. Refer to Air Ducts section.
•be provided ample space for servicing and cleaning.
Always comply with minimum fire protection clearances
shown in Table 1 or on the furnace clearance to
combustible construction label.
!WARNING
CARBON MONOXIDE POISONING / COMPONENT
DAMAGE HAZARD
Failure to follow this warning could result in personal in-
jury 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, clean-
ing solvents, salts, air fresheners, and other household
products. Do not install furnace in a corrosive or contam-
inated atmosphere. Make sure all combustion and circu-
lating air requirements are met, in addition to all local
codes and ordinances.
The following types of furnace installations may require
OUTDOOR AIR for combustion due to chemical 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.

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
8440 01 4101 03
Specifications subject to change without notice.
Figure 3 Multipoise Orientations
THE BLOWER IS LOCATED
TO THE RIGHT OF THE
BURNER SECTION, AND
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.
L12F010
!WARNING
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 or CAN/CSA
B149.1−2010. (See Figure 4)
Figure 4 Installation in a Garage
A93044
!WARNING
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 re-
turn−air ducts to the back of the furnace. (See Figure 5)
Figure 5 Prohibit Installations
BACK POSITIONED
DOWNWARD
AIR
RETURN
CUT IN
BACK
BACK POSITIONED
UPWARD
L12F011

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
440 01 4101 03 9
Specifications subject to change without notice.
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
Introduction
Direct Vent (2−pipe) Applications
When the furnace is installed as a direct vent (2-pipe) furnace,
no special provisions for air for combustion are required.
However, other gas appliances installed in the space with the
furnace may require outside air for combustion. Follow the
guidelines below to insure that other gas appliances have
sufficient air for combustion.
Non−Direct Vent (1−pipe) Applications
When the furnace is installed as a non-direct vent (1-pipe)
furnace, it will be necessary to insure there is adequate air for
combustion. Other gas appliances installed with the furnace
may also require air for combustion and ventilation in addition
to the amount of combustion air and ventilation air required for
the furnace. Follow the guidelines below to insure that the
furnace and other gas appliances have sufficient air for
combustion.
Ventilated Combustion Air Applications
When the furnace is installed using the ventilated combustion
air option, the attic or crawlspace must freely communicate with
the outdoor to provide sufficient air for combustion. The
combustion air pipe cannot be terminated in attics or
crawlspaces that use ventilation fans designed to operate
during the heating season. If ventilation fans are present in
these areas, the combustion air pipe must terminate outdoors
as a Direct Vent/ 2-Pipe system.
All air for combustion is piped directly to the furnace from a
space that is well ventilated with outdoor air (such as an attic,
crawlspace, or equipment closet) and the space is well isolated
from the living space or garage. In addition, other gas
appliances installed in the space with the furnace may require
outside air for combustion. Follow the guidelines below to
insure that the roof or crawlspace walls have sufficient free
area to provide sufficient air for combustion and ventilation for
the furnaces. The guidelines below can be used to insure that
other gas appliances have sufficient air for combustion.
Provisions for adequate combustion, ventilation, and dilution air
must be provided in accordance with:
•U.S. Installations: Section 9.3 of the NFPA 54/ANSI
Z223.1−2009 , Air for Combustion and Ventilation and
applicable provisions of the local building codes.
•Canadian Installations: Part 8 of
CAN/CSA−B149.1−2010, Venting Systems and Air
Supply for Appliances and all authorities having
jurisdiction.
!CAUTION
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.
!WARNING
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 the Carbon Monoxide Poisoning
Hazard warning in the venting section of these
instructions to determine if an adequate amount of
make−up air is available.
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 cubic feet per 1,000 Btuh (4.8 cubic
meters per kW) input rating for all gas appliances installed in
the space.
•Spaces having less than 50 cubic feet per 1,000 Btuh (4.8
cubic meters per kW) require the OUTDOOR
COMBUSTION AIR METHOD.
•Spaces having at least 50 cubic feet per 1,000 Btuh (4.8
cubic meters per kW) 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
combustion, ventilation, and dilution of flue gases using
permanent horizontal or vertical duct(s) or opening(s)
directly communicating with the outdoors or spaces that
freely communicate with the outdoors.
2. Figure 6 illustrates how to provide TWO OUTDOOR
OPENINGS, one inlet and one outlet combustion and
ventilation air openings 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 6 and Table 3.
c. TWO HORIZONTAL DUCTS require 1 square inch
(25.4 square mm) of free area per 2,000 Btuh (1,100
mm2/kW) of combined input for all gas appliances in
the space per Figure 6 and Table 3.
d. TWO OPENINGS OR VERTICAL DUCTS require 1
square inch (25.4 square mm)of free area per 4,000
Btuh (550 mm2/kW) for combined input of all gas
appliances in the space per Figure 6 and Table 3.

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
10 440 01 4101 03
Specifications subject to change without notice.
3. ONE OUTDOOR OPENING requires:
a. 1 sq. in. (25.4 square mm)of free area per 3,000 Btuh
(734 mm2/kW) for combined input of all gas
appliances in the space per Table 3 and
b. Not less than the sum of the areas of all vent
connectors 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 combustion air is permitted for combustion, ventilation,
and dilution, if the Standard or Known-Air-Infiltration Rate
Method is used.
!WARNING
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal
injury or death.
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.
Figure 6 Air for Combustion, Ventilation,
and Dilution for Outdoors
*Minimum dimensions of 3‐in. (76mm)
NOTE: Use any of the following combinations of openings:
A & B, C & D, D & E, F & G
L12F012
The Standard Method:
1. The space has no less volume than 50 cubic feet per
1,000 Btuh (4.8 cubic meters per kW) of the maximum
input ratings for all gas appliances 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 4 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.
Table 4 −Minimum Space Volumes were determined by
using the following equations from the National Fuel Gas Code
ANSI Z223.1/NFPA 54−2009, 9.3.2.2:
1. For other than fan-assisted appliances, such as a
draft hood-equipped water heater
A04002
2. For fan-assisted appliances such as this furnace:
A04003
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 closable doors between rooms.
b. Combining spaces on same floor level. Each opening
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 7)
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 appliances.
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.

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
440 01 4101 03 11
Specifications subject to change without notice.
Figure 7 Air for Combustion, Ventilation,
and Dilution from Indoors
* Minimum opening size is 100 sq in. (64516 sq. mm) with
minimum dimensions of 3‐in. (76mm)
Minimum of 3‐in. (76mm) when type‐B1 vent is used.
L12F013
3. In spaces that use the Indoor Combustion Air Method,
infiltration should be adequate to provide air for
combustion, permanent ventilation and dilution of flue
gases. However, in buildings with unusually tight
construction, additional air MUST be provided using
the methods described in the Outdoor Combustion Air
Method section.
4. Unusually tight construction is defined as Construction
with:
a. Walls and ceilings exposed to the outdoors have a
continuous, sealed vapor barrier. Openings are
gasketed or sealed and
b. Doors and openable windows are weatherstripped
and
c. Other openings are caulked or sealed. These include
joints around window and door frames, between sole
plates and floors, between wall-ceiling 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
Combustion Air Method below and,
2. Outdoor openings shall be located as required in the
Outdoor Combustion Air Method mentioned previously
and,
3. Outdoor openings shall be sized as follows:
a. Calculate the Ratio of all Indoor Space volume
divided by required volume for Indoor Combustion
Air Method.
b. Outdoor opening size reduction Factor is one 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).
Table 3 Minimum Free Area Required for Each Combustion Air Opening or Duct to Outdoors
FURNACE
INPUT
(BTUH)
TWO HORIZONTAL DUCTS
(1 SQ. IN./2,000 BTUH)
(1,100 SQ. MM/KW)
SINGLE DUCT OR OPENING
(1 SQ. IN./3,000 BTUH)
(734 SQ. MM/KW)
TWO OPENINGS OR
VERTICAL DUCTS
(1 SQ. IN./4,000 BTUH)
(550 SQ. MM/KW)
Free Area of
Opening and Duct
Sq. In (Sq. mm)
Round
Duct
In. (mm)
Dia
Free Area of Open-
ing and Duct
Sq. In (Sq. mm)
Round
Duct
In. (mm)
Dia
Free Area of Open-
ing and Duct
Sq. In (mm)
Round Duct
In. (mm)
Dia.
40,000 * 20 (12904) 5 (127) 14 (8696) 5 (127) 10 (6452) 4 (102)
60,000 30 (19355) 6 (152) 20 (13043) 5 (127) 15 (9678) 5 (127)
80,000 40 (25807) 7 (178) 27 (17391) 6 (152) 20 (12904) 5 (127)
100,000 50 (32258) 8 (203) 34 (21739) 7 (178) 25 (16130) 6 (152)
120,000 60 (38709) 9 (229) 40 (26087) 7 (178) 30 (19355) 6 (152)
140,000 * 70 (45161) 10 (254) 47 (30435) 8 (203) 35 (22581) 7 (178)
* Not all families have these models.
EXAMPLE: Determining Free Area
FURNACE WATER HEATER TOTAL INPUT
100,000 + 30,000 = (130,000 divided by 4,000) = 32.5 Sq. In. for each two Vertical Ducts or Openings
60,000 + 40,000 = (100,000 divided by 3,000) = 33.3 Sq. In. for each Single Duct or Opening
80,000 + 30,000 = (110,000 divided by 2,000) = 55.0 Sq. In. for each two Horizontal Ducts

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
12 440 01 4101 03
Specifications subject to change without notice.
Table 4 Minimum Space Volumes for 100% Combustion, Ventilation and Dilution Air from Outdoors
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 40 60 80 100 120 140
Space Volume Ft3(M3)
0.60 1,050
(29.7)
1,400
(39.6)
1,750
(49.5)
1,400
(39.6)
1,500
(42.5)
2,000
(56.6)
2,500
(70.8)
3,000
(84.9)
3,500
(99.1)
0.50 1,260
(35.6)
1,680
(47.5)
2,100
(59.4)
1,680
(47.5)
1,800
(51.0)
2,400
(67.9)
3,000
(84.9)
3,600
(101.9)
4,200
(118.9)
0.40 1,575
(44.5)
2,100
(59.4)
2,625
(74.3)
2,100
(59.4)
2,250
(63.7)
3,000
(84.9)
3,750
(106.1)
4,500
(127.3)
5,250
(148.6)
0.30 2,100
(59.4)
2,800
(79.2)
3,500
(99.1)
2,800
(79.2)
3,000
(84.9)
4,000
(113.2)
5,000
(141.5)
6,000
(169.8)
7,000
(198.1)
0.20 3,150
(89.1)
4,200
(118.9)
5,250
(148.6)
4,200
(118.9)
4,500
(127.3)
6,000
(169.8)
7,500
(212.2)
9,000
(254.6)
10,500
(297.1)
0.10 6,300
(178.0)
8,400
(237.8)
10,500
(297.3)
8,400
(237.8)
9,000
(254.6)
12,000
(339.5)
15,000
(424.4)
18,000
(509.2)
21,000
(594.1)
0.00 NP NP NP NP NP NP NP NP NP
NP = Not Permitted
CONDENSATE TRAP
Condensate Trap −Upflow Orientation
When the furnace is installed in the upflow position, it is not
necessary to relocate the condensate trap or associated
tubing. Refer to Figure 8 for upflow condensate trap
information. Refer to Condensate Drain section for information
how to install the condensate drain.
Condensate Trap −Downflow
Orientation
When the furnace is installed in the downflow position, the
condensate trap will be initially located at the upper left corner
of the collector box, as received from the factory. See the top
image in Figure 9. When the furnace is installed in the
downflow orientation, the condensate trap must be relocated
for proper condensate drainage. See the bottom image in
Figure 9.
To Relocate the Condensate Trap:
Orient the furnace in the downflow position.
Figure 9 shows the condensate trap and tubing before and
after relocation. Refer to Figure 9 to begin the trap conversion.
Refer to Condensate Drain section for information how to install
the condensate drain.
Figure 8 Upflow Trap Configuration
Condensate Trap
Relief Port
Collector Box
Plugs
Pressure Switch
Port
Condensate Trap
Outlet
Condensate Trap
Relief Port
Collector Box
Plug
Vent Elbow
Vent Elbow Clamp
Vent Pipe Clamp
UPFLOW TRAP CONFIGURATION
1 & 2 Stage Units
A11307
Representative drawing only, some models may vary in appearance.

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
440 01 4101 03 13
Specifications subject to change without notice.
Figure 9 Unconverted Factory Configuration as viewed in the Downflow Orientation
A11587LA
Remove relief tube from relief
port on condensate trap.
Remove the screw
that secures the trap
to the collector box and
remove trap.
Loosen clamp on inlet
to vent elbow.
Remove pressure switch tube from
front pressure switch and discard. A
new tube is shipped in the loose parts
bag. Remove tube from relief port.
Remove middle and bottom
plugs. DO NOT DISCARD.
Representative drawing only, some models may vary in appearance.
Downflow Trap Configuration
A11587LB
Install the two plugs
previously removed
on the open ports
of the collector box.
Connect relief tube
to port on collector
box.
Rotate elbow to
desired position and
tighten clamp to
15 lb.−in.
Slide tube in stand−offs
to adjust length.
Connect the new pressure switch
tube from Loose Parts bag to
port on front pressure switch.
Route tube through inducer
stand−offs to adjust position
of the tube.
Trim excess tube.
Connect pressure switch
tube to port on collector
box.
Attach condensate trap
with screw to collector box.
Connect relief tube to
relief port on condensate
trap.
Align condensate trap
over middle and bottom
ports of collector box.
4
5
Representative drawing only, some models may vary in appearance.

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
14 440 01 4101 03
Specifications subject to change without notice.
Condensate Trap −Horizontal
Orientation
When the furnace is installed in the horizontal right position, the
condensate trap will be initially located at the bottom of the
collector box, as received from the factory. See the top image in
Figure 10. When the furnace is installed in the horizontal left
position, the condensate trap will be initially located at the top of
the collector box, as received from the factory. See the top image
in Figure 11. In both cases the trap must be repositioned on the
collector box for proper condensate drainage. See bottom images
in Figure 10 and Figure 11.
A field−supplied, accessory Horizontal Installation Kit (trap
grommet) is required for all direct−vent horizontal installations
(only). The kit contains a rubber casing grommet designed to seal
between the furnace casing and the condensate trap. (See
Figure 17)
NOTICE
The field-supplied, accessory horizontal drain trap
grommet is ONLY REQUIRED FOR DIRECT VENT
APPLICATIONS. It is NOT required for applications
using single-pipe or ventilated combustion air venting.
NOTICE
The condensate trap extends below the side of the
casing in the horizontal position. A minimum of 2-in.
(51 mm) of clearance is required between the casing
side and the furnace platform for the trap to extend out
of the casing in the horizontal position. Allow at least
1/4-in. per foot (20mm per meter) of slope down and
away from the furnace in horizontal sections of drain
line.
To Relocate the Condensate Trap:
Remove the knockout in the casing for the condensate trap.
Install the grommet in the casing when required for direct−vent
horizontal applications.
Orient the furnace in the desired position.
Allow for 2 in. (51 mm) of clearance underneath the furnace for
the condensate trap and drain line.
Figure 10 shows the condensate trap and tubing before and
after relocation in the horizontal right position.
Figure 11 shows the condensate trap and tubing before and
after relocation in the horizontal left position.
Refer to the appropriate figure to begin the trap conversion.
Refer to Condensate Drain section for information how to install
the condensate drain.
Figure 10 Unconverted Factory Configuration as viewed in the Horizontal Right Orientation
A11573LA
Remove plug from
collector box.
DO NOT DISCARD.
If alternate vent position
is required, loosen clamp
on inlet of vent elbow.
Remove the screw that secures
the trap to the collector box and
remove trap.
Representative drawing only, some models may vary in appearance.

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
440 01 4101 03 15
Specifications subject to change without notice.
Horizontal Right Trap Configuration (CONTINUED)
A11573LB
Attach condensate
trap with screw to
collector box.
Slide relief tube in stand−offs
to adjust length.
Vent elbow shown in alternate
orientation. Tighten clamp on
inlet to vent elbow 15 lb.−in.
Align trap over middle and
right−hand port on collector
box.
NOTE: Remove knockout in
casing before re−installing the
condensate trap.
Representative drawing only, some models may vary in appearance.
Install plug on
open port of
collector box
Figure 11 Unconverted Factory Configuration as viewed in the Horizontal Left Orientation
A11574LA
If alternate vent position
is required, loosen clamp
on vent elbow inlet.
Remove relief tube
from port on collector
box.
Remove the screw that secures the
condensate trap to the collector box
and remove trap.
Remove relief tube from
relief port on condensate
trap.
Remove front pressure
switch tube and discard.
A new tube is shipped in
the Loose Parts bag.
Remove middle and right
plug from collector box.
DO NOT DISCARD.
5
6
Representative drawing only, some models may vary in appearance.

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
16 440 01 4101 03
Specifications subject to change without notice.
Horizontal Left Trap Configuration (CONTINUED)
A11574LB
Rotate elbow to
desired position
and torque clamp
on inlet 15 lb.−in.
Slide relief tube in
stand−offs to adjust
length.
Attach condensate
trap with screw to
collector box.
Align trap over middle
and right−hand port on
collector box.
Install two plugs previously
removed in open ports on
collector box.
Connect relief tube to port
on collector box.
Connect the new pressure switch
tube from Loose Parts bag to port
on front pressure switch.
Route pressure switch tube
underneath relief tube and
connect to port on
collector box.
Connect relief tube to relief
port on condensate trap.
9
7
8
NOTE: Remove knockout in
casing before re−installing the
condensate trap.
Representative drawing only, some models may vary in appearance.
Condensate Drain Connection
!CAUTION
FROZEN AND BURST WATER PIPE HAZARD
Failure to protect against the risk of freezing may result
in property damage.
Special precautions MUST be made if installing furnace
in an area which may drop below freezing. This can
cause improper operation or damage to equipment. If
furnace environment has the potential of freezing, the
drain trap and drain line must be protected. The use of
accessory drain trap heaters, electric heat tape and/or
RV antifreeze is recommended for these installations.
!CAUTION
PROPERY DAMAGE HAZARD
Failure to follow this caution may result in burst water
pipes and/or property damage.
If a condensate pump is installed, a plugged condensate
drain or a failed pump may cause the furnace to shut
down. Do not leave the home unattended during freezing
weather without turning off water supply and draining
water pipes or otherwise protecting against the risk of
frozen pipes.
DO NOT trap the drain line in any other location than at the
condensate drain trap supplied with the furnace. If possible, DO
NOT route the drain line where it may freeze. The drain line
must terminate at an inside drain to prevent freezing of the
condensate and possible property damage.
Special precautions MUST be made if installing furnace in an
area which may drop below freezing. This can cause improper
operation or damage to the equipment. If the furnace
environment has the potential of freezing, the drain trap and
drain line must be protected. A self−regulating, shielded and
waterproof heat tape rated at 3 to 6 watt per foot (10 to 20 watt
per meter) at 115 volt, 40°F (4°C) may be used to help provide
freeze protection. Wrap the drain trap and drain line with the
heat tape and secure with appropriate plastic ties. Follow the
heat tape manufacturer’s recommendations. Prime the trap
before furnace operation.
Upflow/Downflow Orientation
In the Upflow or Downflow orientation, the condensate trap is
inside the furnace casing. The condensate drain must be
routed from the trap through the furnace casing. The
condensate drain can be routed through the left or right side of
the casing. (The left or right side is as you are viewing/facing
the furnace from the front.) The furnace condensate drain can
be connected to the indoor coil condensate drain, humidifier or
auxiliary drain traps as shown in Figure 12.
NOTE: On narrower casings, it may be easier to remove the
condensate trap, connect the drain line components and
re-install the condensate trap. Read the steps thoroughly to
familiarize yourself with the required steps.
For Right Side Condensate Drain:
1. Remove the 7/8−in. knock−out from the right side of the
casing. (See Figure 13 for suggested knockout removal
technique.)
2. Remove the pre−formed rubber drain elbow and two
spring clamps from the loose parts bag.
3. Slide a spring clamp 1 in. (25 mm) down the plain end
(the end without the formed grommet) of the drain elbow.
4. From inside the casing, insert the formed grommet end
of the elbow through the 7/8−in. knockout in the casing.
5. Pull the grommet through the casing from the outside
until it is seated in the knockout
6. Attach the plain end of the drain elbow to the outlet stub
on the drain trap. Secure the drain elbow to the trap with
the spring clamp.
The remaining drain line can be constructed from field supplied
1/2−in. CPVC or 3/4−in. PVC pipe in compliance with local

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
440 01 4101 03 17
Specifications subject to change without notice.
building codes. A factory−supplied 1/2−in. CPVC to 3/4−in PVC
adapter is supplied in the loose parts bag for use as required.
7. Install the adapter or connect the 1/2−in. CPVC pipe by
sliding a spring clamp over the open end of the grommet
on the outside of the furnace casing.
8. Open the spring clamp and insert the long end of the
adapter of the 1/2−in. CPVC pipe into the outlet stub on
the drain elbow.
9. Connect additional condensate piping to a
code−approved drain, or to a condensate pump
approved for use with acidic furnace condensate and
compatible with mineral and vegetable oils, such as
canola oil.
Allow at least 1/4−in. per foot (20 mm per meter) of slope down
and away from the furnace in horizontal sections of drain line.
Figure 12 Example of Field Drain Attachment
OPEN STAND
PIPE FOR
A/C OR
HUMIDIFIER
DRAIN
TEE
TO OPEN
DRAIN
A11276
TIPS FROM CONTRACTORS: Contractors have found that
temporarily removing the inducer assembly in upflow
applications while performing the steps below, makes upflow
left−side drain connections easier.
For Left Side Condensate Drain Connection:
1. For left side condensate drainage, the drain line is routed
from the condensate trap, behind the inducer (upflow) or
gas valve (downflow) and out through the left side of the
furnace casing. A pre-formed 1/2−in. CPVC “Z” pipe is
provided with the furnace. The “Z“ pipe is long enough to
extend across the casing for drain connections.
2. Locate the “Z” pipe. Remove the pre-formed drain elbow
and four spring clamps from the loose parts bag.
3. The “Z” pipe is connected to the condensate trap and the
outside of the furnace by modifying the formed rubber
drain elbow as shown in Figure 14.
4. Remove the formed grommet from the rubber drain
elbow by cutting the elbow along the vertical line located
about 1 3/8−in. (35 mm) away from the formed grommet.
See Figure 13. DO NOT DISCARD THE FORMED
GROMMET OR THE RUBBER ELBOW. Both of these
pieces will be used.
Assemble and route the drain line to the opposite side of the
furnace as detailed below:
5. Remove the knock−out from the left side of the casing.
(See Figure 13 for suggested knockout removal
technique.)
6. From the outside of the casing, insert the angled end of
the ”Z” pipe through drain hole in the left side of the
casing and behind the inducer or gas valve. Allow the ”Z”
pipe to temporarily rest on the blower shelf (upflow) or
burner box (downflow). (NOTE: When the inducer
housing has been removed to ease installation in upflow
applications, this step is not needed.)
7. After inserting the “Z” pipe through the casing, slide a
spring clamp over each end of the “Z” pipe.
8. From inside the casing, insert the short end of the formed
grommet cut from the rubber drain elbow through the
7/8−in. drain knockout in the casing.
9. Pull the grommet through the casing from the outside
until it is seated in the knockout.
10. Align the ”Z” pipe with the long end of the grommet inside
the furnace and insert slightly. The angled end of the
tube at the other side of the casing should be facing the
front of the furnace.
11. Slide a spring clamp over the end of the remaining
rubber drain elbow.
12. Attach the drain elbow to the angled end of ”Z” pipe and
the drain trap outlet stub. Adjust the length of ”Z” pipe
inserted into the grommet at the opposite side of the
furnace as necessary for proper fit and positioning. In
both upflow and downflow orientations, the ”Z” pipe
should NOT be resting on any sheet metal parts.
13. Secure the rubber elbow to the drain trap and the ”Z”
pipe with spring clamps.
14. Secure the grommet to the ”Z” pipe with the spring clamp
The remaining drain line can be constructed from field
supplied 1/2−in. CPVC or 3/4−in. PVC pipe, in
compliance with local building codes. A factory−supplied
1/2−in. CPVC to 3/4−in. PVC adapter is supplied in the
loose parts bag for use as required.
15. Install the adapter or connect the 1/2−in. CPVC pipe by
sliding a spring clamp over the open end of the grommet
on the outside the furnace casing.
16. Open the spring clamp and insert the long end of the
adapter or the 1/2−in. CPVC pipe into the outlet stub on
the drain elbow.
17. Connect additional condensate piping to a
code−approved drain, or to a condensate pump
approved for use with acidic furnace condensate and
compatible with mineral and vegetable oils, such as
canola oil.
Allow at least 1/4-in. per foot (20 mm per meter) of slope down
and away from the furnace in horizontal sections of drain line.
NOTICE
The field-supplied, accessory horizontal drain trap
grommet is ONLY REQUIRED FOR DIRECT VENT
APPLICATIONS. It is NOT required for applications
using single-pipe or ventilated combustion air venting.
TIPS FROM CONTRACTORS: When installing the furnace
horizontally, use the entire drain elbow (that is, do NOT cut as
shown in Figure 14) to connect the trap to the drain line. This
helps to prevent bumps and shocks to the drain line from
damaging the furnace drain trap. Avoid misalignment of the
drain pipe which may cause kinks in the elbow.
Horizontal Orientation
1. The condensate trap outlet extends 2−in. (51 mm) below
the furnace casing. Leave enough clearance between
the furnace and the furnace platform for the trap.

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
18 440 01 4101 03
Specifications subject to change without notice.
2. To allow for servicing the trap, the condensate drain
elbow in the loose parts bag can be used to make a
coupler to allow for future service of the condensate trap
and drain line.
3. Remove the knockout for the condensate trap in the side
of the casing.
4. Install the drain trap grommet in the casing, if required for
direct−vent applications. If necessary, remove the trap,
install the grommet and re−install the trap.
5. Remove the pre−formed rubber drain elbow and two
spring clamps from the loose parts bag.
6. Connect the full or modified elbow and/or grommet to the
outlet of the condensate trap with one spring clamp.
Avoid misalignment of the drain pipe which may cause
kinks in the elbow or grommet.
7. The remaining drain line can be constructed from field
supplied 1/2−in. CPVC or 3/4−in. PVC pipe, in
compliance with local building codes. A factory−supplied
1/2−in. CPVC to 3/4−in. PVC adapter is supplied in the
loose parts bag for use as required.
8. Install the adapter or connect the 1/2−in. CPVC pipe by
sliding a spring clamp over the open end of the elbow or
grommet on the outside the furnace casing.
9. Open the spring clamp and insert the long end of the
adapter or the 1/2−in. CPVC pipe into the outlet stub on
the drain elbow.
10. Connect additional condensate piping to a
code−approved drain, or to a condensate pump
approved for use with acidic furnace condensate and
compatible with mineral and vegetable oils, such as
canola oil.
Allow at least 1/4-in. per foot (20 mm per meter) of slope down
and away from the furnace in horizontal sections of drain line.
Figure 13 Knockout Removal
L12F019
!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.
Figure 14 Modify Rubber Drain Elbow
Cut line for left side condensate drain.
Do not discard parts after cutting.
1−3/8 in
(35 mm)
L11F089
Figure 15 Drain Trap Connection and Routing
s
TRAP, DRAIN ELBOW WITH DISCHARGE PIPE
Attach elbow to condensate trap
Cut formed end off
condensate drain
elbow
Connect short end
of “Z” pipe to modified
drain elbow
Factory supplied 1/2−in. CPVC to
3/4−in. PVC adapter
LEFT SIDE DRAIN ROUTED BEHIND INDUCER
Formed end of grommet
Open spring clamp. Insert
1/2−in. to 3/4−in. CPVC to
PVC adapter or 1/2−in.
CPVC pipe
Modified drain elbow connect to
condensate trap and “Z” pipe
Formed end of
grommet
NOTE: Remove Inducer Housing for easier access, if desired.
L12F015

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
440 01 4101 03 19
Specifications subject to change without notice.
Figure 16 Formed Rubber Drain Grommet
L12F022
INSTALL CLAMPS ON DRAIN ELBOW
ATTACH DRAIN ELBOW TO CONDENSATE
DRAIN TRAP
PULL DRAIN STUB
THROUGH CASING
OPEN SPRING CLAMP
INSERT FACTORY−SUPPLIED 1/2−IN. CPVC
TO 3/4−IN. PVC ADAPTER OR 1/2−IN. CPVC PIPE
*CLAMP MAY BE LOCATED ON OUTSIDE OF DRAIN ELBOW
Figure 17 Horizontal Drain Trap Grommet
Remove knockout.
Install grommet before
relocating condensate
trap.
A11348
INSTALLATION
NOTICE
This furnace is certified to leak 2% or less of nominal air con-
ditioning CFM delivered when pressurized to 1-inch water
column (250 Pa) with all present air inlets (including bottom
closure in upflow and horizontal applications), air outlets, and
plumbing and electrical ports sealed.
UPFLOW INSTALLATION
NOTE: The furnace must be pitched as shown in Figure 18 for
proper condensate drainage.
Figure 18 Furnace Pitch Requirements
LEVEL 0-IN. (0 MM) TO
1/2-IN. (13 MM) MAX
UPFLOW OR
DOWNFLOW HORIZONTAL
MIN 1/4-IN. (6 MM) TO
1/2-IN. (13 MM) MAX
A11237
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.
Connect supply−air duct to flanges on furnace supply−air
outlet. Bend flange upward to 90with wide duct pliers. (See
Figure 22) 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
supply−side accessories MUST be connected to duct external
to furnace main casing.
Return Air Connections
!WARNING
FIRE HAZARD
A failure to follow this warning could cause personal
injury, death and/or property damage.
Never connect return−air ducts to the back of the
furnace. Follow instructions below.
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. Bypass humidifier may be attached into unused return
air side of the furnace casing. (See Figure 27, Figure 28 and
Figure 29)
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 four (4) screws holding
bottom plate. (See Figure 19)
2. Remove bottom plate.
3. Remove bottom closure panel.
4. Reinstall bottom plate and screws.

INSTALLATION INSTRUCTIONS Gas Furnace: N9MSB, N9MSE
20 440 01 4101 03
Specifications subject to change without notice.
Figure 19 Removing Bottom Closure Panel
L11F004
BOTTOM
PLATE
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. (See Figure 27,
Figure 28 and Figure 29)
Leveling Legs (If Desired)
In upflow position with side return inlet(s), leveling legs may be
used. (See Figure 20) Install field−supplied, 5/16 x 1−1/2−in. (8
x 38 mm) (max) corrosion−resistant machine bolts, washers
and nuts.
Figure 20 Leveling Legs
A89014
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 Step 1 in Bottom Return Air Inlet section.
To install leveling legs:
1. Position furnace on its back. Locate and drill a hole in
each bottom corner of furnace.
2. For each leg, install nut on bolt and then install bolt with
nut in hole. (Install flat washer if desired.)
3. Install another nut on other side of furnace base. (Install
flat washer if desired.)
4. Adjust outside nut to provide desired height, and tighten
inside nut to secure arrangement.
5. Reinstall bottom closure panel if removed.
DOWNFLOW INSTALLATION
NOTE: The furnace must be pitched as shown in Figure 18 for
proper condensate drainage.
Supply Air Connections
NOTE: For downflow applications, this furnace is approved for
use on combustible flooring when any one of the following two
accessories are used (see specification sheets for list of
approved accessories):
•Special Base −NAHA01101SB
•Cased Coil Assembly −EAM4X, END4X, ENW4X
1. Determine application being installed from Table 5.
2. Construct hole in floor per Table 5 and Figure 21.
3. Construct plenum to dimensions specified in Table 5
and Figure 21.
4. Install as shown in Figure 23. If Coil Assembly Part is
used, install as shown in Figure 24 .
Figure 21 Floor and Plenum Opening
Dimensions
A96283
NOTE: It is recommended that the perforated supply−air duct
flanges be completely 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 22)
!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.
Connect supply−air duct to supply−air outlet on furnace. Bend
flange inward past 90with wide duct pliers (See Table 1
Figure 22) 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 factory−approved accessory