Lennox B050A3B, B075A4B, B075A3B, B100A5B, B125A5B Installation/servicing Instructions And Users Information Manual

AFFIX LABEL HERE

INSTALLATION / SERVICING INSTRUCTIONS

AND USER’S INFORMATION MANUAL

HORIZONTAL GAS-FIRED NON-CONDENSING FURNACE

Save these instructions for future reference.

WARNING

Improper installation, adjustment, alteration, service, or maintenance can cause injury or property damage.
Refer to this manual. For assistance or additional information, consult a qualified installer, service agency,
or the gas supplier.

WARNING

Do not store combustible materials, including gasoline
and other flammable vapors and liquids, near the
furnace, vent pipe, or warm air ducts. The homeowner
should be cautioned that the furnace area must not be
used as a broom closet or for any other storage
purposes. Such uses may result in actions that could
cause property damage, personal injury, or death.

WARNING

This furnace is not approved for installation in a mobile
home. Do not install this furnace in a mobile home.
Installation in a mobile home could result in actions that
could cause property damage, personal injury, or death.

TABLE OF CONTENTS

SECTION 1: INSTALLATION AND

SERVICING INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . 1 - 28

Important Safety Information . . . . . . . . . . . . . . . . . . 2

Specification and Installation . . . . . . .. . . . . . . . . . . 3

Start-up and Operation . . . . . . . . . . . . . . . . . . . . . . 17

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Sequence of Operation & Diagnostics . . . . . . . . . . . 23

Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

SECTION 2: USER’S INFORMATION MANUAL . . . . . . . . 29 - 36

Important Safety Information . . . . . . . . . . . . . . . . . 30

Operating Your Furnace . . . . . . . . . . . . .. . . . . . . . .30

Maintenance of Your Furnace . . . . .. . . . . . . . . . . . .32

Repair Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Owner Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Manufactured By

Allied Air Enterprises Inc.

A Lennox International Inc. Company

215 Metropolitan Drive

West Columbia, SC 29170

*P506307-01*

(P) 506307-01

IMPORTANT

The installation of the furnace, wiring, warm air ducts, venting, etc. must conform to the requirements of the National Fire
Protection Association; the National Fuel Gas Code, ANSI Z223.1/NFPA No. 54 (latest edition) and the National Electrical
Code, ANSI/NFPA No. 70 (latest edition) in the United States; CSA B149.1 (latest edition) Natural Gas and Propane
Installation Codes and the Canadian Electrical Code Part 1, CSA 22.1 (latest edition) in Canada; and any state or
provincial laws, local ordinances (including plumbing or wastewater codes), or local gas utility requirements. Local
authorities having jurisdiction should be consulted before installation is made. Such applicable regulations or requirements
take precedence over the general instructions in this manual.

506307-01 Page 1 of 36Issue 1207

IMPORTANT SAFETY INFORMATION

The following is a list of safety rules and precautions that
must be followed when installing this furnace.

1. Use only with the 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 on page 7 of these
instructions.

3. Provide adequate combustion and ventilation air to
the furnace space as specified in the Air for
Combustion and Ventilation section beginning on
page 8 of these instructions.

4. Combustion products must be discharged outdoors.
Connect this furnace to an approved vent system
only, as specified in Venting beginning on page 10
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 Gas Connection
Section beginning on page 14 of these instructions.

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 Temperature Rise on page 3 of
these instructions. See furnace rating plate.

7. 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. See Ducting beginning on page 9 of
these instructions.

8. A gas-fired furnace for installation in a residential
garage must be installed as specified in the Location
section on page 7 of these instructions.

9. The furnace is permitted to be used for temporary
heating of buildings or structures under construction
as specified in the Location section on page 7 of
these instructions.

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". When
lever-type gas shutoffs are used, they shall be T­handle type.

Page 2 of 36 506307-01Issue 1207

506307-01 Page 3 of 36Issue 1207

FURNACE BLOWER SPECIFICATIONS AND AIR FLOW DATA

NOTES:

1. Air flow values in cubic feet per minute (CFM), rounded to nearest five (5) CFM.

2. Data taken without filters in place or A/C evaporator in place.

WARNING

When operating the furnace in the heating mode, the static pressure and the temperature rise (supply air temperature
minus return air temperature) must be within those limits specified on the rating label. Failure to follow this warning could
lead to severe furnace damage.

WARNING

Turn OFF all gas and electrical power to furnace before performing any maintenance or service on unit. (Unless specific
test requires gas and electrical supplies.) Failure to take this precaution may result in personal injury due to electrical shock
or uncontrolled gas leakage.

Page 4 of 36 506307-01Issue 1207

FURNACE WIRING SPECIFICATIONS

506307-01 Page 5 of 36Issue 1207

WARNING

The furnace cabinet must have an uninterrupted or unbroken electrical ground to minimize personal injury if an electrical
fault should occur. The unit must also be electrically grounded in accordance with local codes, or in the absence of local
codes, with the latest edition of the (U.S.)
Canadian Electrical Code, if an external electrical source is utilized. DO NOT use gas piping as an electrical ground.

National Electrical Code ANSI/NFPA No. 70 or CSA Standard C22.1: Part 1

INTRODUCTION

This furnace is design certified by CSA International as a Category I furnace using air from inside the structure for
combustion. The combustion system is fan-assisted which means it is equipped with an integral mechanical means to draw
products of combustion through the heat exchanger.

It is shipped as a packaged unit, complete with burners and controls, and requires a line voltage (115V) connection to the
junction box, a thermostat hook-up as per the wiring diagram and a gas line connection, ducting and flue piping. This furnace

can be installed in either horizontal right or horizontal left airflow positions. The design of this furnace is NOT CSA
Certified for installation in recreation vehicles, in manufactured (mobil) homes, outdoors or as a construction heater.

This furnace has been designed to interface with split system cooling equipment (approved by a nationally recognized
testing laboratory) so as to provide “year round air conditioning”. The blower has been sized for both heating and cooling and
the furnace controls include a cooling fan relay.

The furnace installation must conform with local building codes or in the absence of local codes, with the latest edition of
the (U.S.) National Fuel Gas Code ANSI Z223.1 (NFPA-54) or Canadian Natural Gas and Propane Installation Codes CSA
B149.1.

For complete information on installation standards consult the (U.S.) National Fuel Gas Code, obtainable from the National
Fire Protection Association, Inc., Batterymarch Park, Quincy, MA 02269 or the American Gas Association, 1515 Wilson
Boulevard, Arlington, VA 22209 or the Canadian installation codes obtainable from Canadian Standards Association, 178
Rexdale Boulevard, Etobicoke, Ontario, Canada M9W 1R3.

This furnace is designed from minimum continuous return-air temperature of 60°F dB or intermittent operation down to
55°F dB such as when used with a night setback thermostat. Return-air must not exceed a maximum continuous temperature
of 85°F dB.

The furnace may be used for heating of buildings or structures under construction, if the following conditions are met:

• The vent system must be permanently installed per these instructions.

• A room thermostat must control the furnace. The use of fixed jumpers that will provide continuous heating is not allowed.

• The return air duct must be provided and sealed to the furnace.

• Return air temperature range between 60°F and 80°F must be maintained.

• Air filters must be installed in the system and must be maintained during construction.

• Air filters must be replaced upon construction completion.

• The input rate and temperature rise must be set per the furnace rating plate.

• One hundred percent (100%) outdoor air must be provided for combustion air requirements during construction. Temporary

ducting may supply outdoor air to the furnace. Do not connect combustion air duct directly to the furnace. Size the

temporary duct following these instructions in the section “Air for Combustion & Ventilation” for air in a confinced space

with air from outside.

• The furnace heat exchanger, components, duct system, air filters and evaporator coils must be thoroughly cleaned

following final construction clean-up.

• All furnace operating conditions (including ignition, input rate, temperature rise and venting) must be verified according to

these installation instructions.

These instructions are written for individual residential installation only. For multi-unit installation, please contact
manufacturer for recommendations.

Page 6 of 36 506307-01Issue 1207

LOCATION / PLACEMENT

Site Selection: This furnace may be located in an attic, closet, basement, crawl space, alcove or suspended from the ceiling

of a utility room or basement. Select a location that will meet all requirements for safety, clearances, ventilation
and combustion air, ductwork design, gas piping, electrical wiring and venting.

Clearances: The following minimum clearances, or greater, must be provided between the furnace and adjacent

construction.

If the furnace is to be installed in a crawl space, consult

WARNING

Failure to comply with all of the clearances will create a
fire hazard.

The furnace should also be located as near to the center
of the air distribution system as possible, and should be
installed level.

This furnace may be installed on mon-combustible
flooring or on wood flooring, however, it must not be installed
directly on carpeting, tile or any other combustible material.

Line contact is only permissible bewteen lines formed
by the intersection of the furnace top, the front and back
sides, and building joists, studs or framing (See Figure 1).

HORIZONTAL LINE CONTACT

local codes. (Use of a concrete pad 1” to 2” thick is
recommended.)

If the furnace is to be suspended from the ceiling, it will
be necessary to use steel pipe straps around each end of
the furnace. These straps should be attached to the furnace
with sheet metal screws and to the rafters with bolts. The
furnace may also be suspended by using an angle iron frame
bolted to the rafters. (See Table on page 3 for size and
weight of furnace.) Care must be taken to allow for service
access.

If a furnace is to be installed in a residential garage, it
must be installed so the burners and the ignition source are
located not less than 18” above the floor and the furnace
must be located or protected to avoid physical damage by
vehicles.

Figure 1

Furnace must not lean back. It must be level or tilt

up to 2° to the front. (See Figure 1.)

A clearance of at lease 30” should be provided at the
front of the unit for servicing. For attic installations, the
passageway and servicing area adjacent to the furnace
should be floored.

506307-01 Page 7 of 36Issue 1207

WARNING

Do not place combustible material on the furnace jacket.
Failure to comply with this warning will create a fire hazard.

WARNING

This furnace is not watertight and is not designed for
outdoor installation. This furnace shall be installed in such
a manner as to protect the electrical components from
water. Outdoor installation would lead to a hazrdous
electrical condition and to premature furnace failure.

AIR FOR COMBUSTION AND VENTILATION

Contaminated Combustion Air and Fuels:

Allowing exposure to substances containing chlorine or

fluoride could harm the furnace and void warranty.
Substances to avoid include, but are not limited to:

• 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 fabiric softeners for clothes dryers

• Masonry acid washing materials

• Unrefined Gases

WARNING

Contaminated combustion air may cause premature failure
of the heat exchanger that may lead to a hazardous
condition and/or bodily harm, or loss of life.

For purposes of this instruction the following definitions

apply:

Confined Space: A space whose volume is less than

50 cubic feet per 1000 Btu/hr of the
aggregate input rating of all
appliances installed in that space.

Unconfined Space: A space whose volume is not less

than 50 cubic feet per 1000 Btu/hr
of the aggregate input rating of all
appliances installed in that space.
Rooms communicating directly
with the space in which the
applicances are installed, through
openings not furnished with doors,
are considered a part of the
unconfined space.

If the installation area meets the definition of “Unconfined
Space” and does not have additional air requirements as
described, the furnace may be installed without making
special provisions for combustion and ventilation air.

CAUTION

Whenever this furnace is installed in an area along with
one or more gas appliances, the total Btu/hr input of all
appliances must be included when determining the free
area requirements for combustion and ventilation air
openings.

Adequate Ventilation and Combustion Air:

This section is provided to give guidelines for the
introduction of air for ventilation and combustion air. The
total quantity of air provided to the installation area must
equal the requirements of all gas appliances in the area.

Adequate facilities for providing air for combustion and
ventilation must be provided in accordance with the latest
edition of the National Fuel Gas Code ANSI Z223.1/NFPA54
or CSA B149.1 Natural Gas and Propane Installation Codes,
or applicable provisions of the local building codes.

The furnace shall be installed in a location in which the
facilities for ventilation permits satisfactory combustion of
gas, proper venting and maintenance of ambient
temperature at safe limits under normal conditions of use.
The furnace shall be located so as not to interfere with proper
circulation of air.

In addition to air needed for combustion, ventilation in
the form of process air must be provided as required for:
cooling of eqipment or material, controlling dew point,
heating, drying, oxidation or dilution, safety exhaust and odor
control. Air must be supplied for ventilation, including all air
required for comfort and proper working conditions for
personnel.

WARNING

Do not block the combustion or ventilation air openings in
the furnace. Any blockage will result in improper
combustion and may result in a fire hazard or unsafe
condition.

If ventilation and/or combustion air must be supplied to
the “Confined Space” from outside the building structure,
two permanent openings to the outdoors must be created.
Each opening must have a free area of not less than one
square inch per 4000 Btu per hour of total input of all
applicances within the “Confined Space”, (See Figures 2
and 3). Neither openings can be blocked at any time.

Page 8 of 36 506307-01Issue 1207

CONFINED SPACE / OUTDOOR AIR FROM ATTIC

FURNACE

VENTILATION LOUVERS
1 SQ. IN. / 4000 BTUH

OF TOTAL INPUT

F0000309

VENTILATION LOUVERS
1 SQ. IN. / 4000 BTUH
OF TOTAL INPUT

F0000310

CONFINED SPACE / OUTDOOR AIR FROM

ATTIC & CRAWL SPACE

For an attic installation it is important to keep insulation
12” or more away from any furnace openings. Some types
of insulating materials may be combustible.

The proper sizing of warm air ducts is necessary to insure satisfactory heating operation. Ductwork should be in accordance
with the latest editions of (U.S.)
Systems) or Canadian equivalent.

Ductwork Recommendation:

The supply ductwork should be attached to the flanged
opening provided at the discharge end of the furnace. See
page 3 Furnace Specifications for the dimensions of this
opening.

Undersized return air vents will adversely affect the
airflow capability of the furnace and could cause
overheating of the heat exchanger. The following

recommendations should be followed when installing the
ductwork:

1. Install locking-type dampers in all branches of the

individual ducts to balance out the system. Dampers
should be adjusted to impose the proper static at the outlet
of the furnace.

2. Noncombustible flexible duct connectors are

recommended to connect both the supply and return ducts
to the furnace.

3. In cases where the return air grille is located close to the

blower inlet, there should be at least one 90° air turn
between blower and return grille. Further reduction in
sound can be accomplished by installing acoustical air
turning vanes and/or lining the inside of the duct with
acoustical material.

Figure 2

CAUTION

NFPA-90A (Air Conditioning Systems) and NFPA-90B (Warm Air Heating and Air Conditioning

Figure 3

WARNING

Furnaces installed with combustion air drawn from a
heated space which includes exhaust fans, fireplaces,
or other devices that may produce a negative pressure
should be considered confined space installations.

DUCTING

4. It is recommended that the supply duct be provided with
a removable access panel. This opening shall be
accessible when the furnace is installed and shall be 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 access panel shall be
designed so as to prevent leaks when locked in position.
If an air conditioning coil is installed, the access panel to
the coil can be used for this purpose.

WARNING

When supply ducts carry air circulated by the furnace to
areas outside the spaces containing the furnace, the
return air shall also be handled by a duct sealed to the
furnace casing and terminating outside the space
containing the furance. Incorrect ductwork termination
and sealing will create a hazardous condition that could
lead to bodily harm.

506307-01 Page 9 of 36Issue 1207

CAUTION

BTU
INPUT

FILTER
SIZE

50,000

75,000

100,000

125,000

13 X 23

13 X 23

16 1/2 X 26

20 X 23

Air openings, intake and outlet pipes, return air grilles and
warm air registers must not be obstructed.

Filters:

Air filters must be used in every installation.

Minimum filter size and suggested filter material are
shown in Table 2. If different type filter is used, it must be an
equivalent high airflow capacity.

Filter Size Selection

Table 2

If the washable permanent filters are used with this unit they
should be cleaned periodically to prevent nuisance tripping
of the high limit switch and failure to provide adequate filter
media can cause equipment malfunction, uneven room
temperature and excessive fuel usage.

When installing the furnace with cooling equipment for
year round operation, the following recommendations must
be followed for series or parallel air flow:

1. In series flow applications, the coil is mounted after the

furnace in an enclosure in the supply air stream. The
furnace blower is used for both heating and cooling airflow.

2. In parallel flow installation, dampers must be provided to

direct air over the furnace heat exchanger when heat is
desired and over the cooling when cooling is desired.

IMPORTANT: The dampers should be adequate to
prevent cooled air from entering the furance, and if manually
operated, must be equipped with means to prevent operation
of either the cooling unit or furnace unless the damper is in
the full cool or full heat position.

WARNING

The coil MUST be installed on the air discharge side of
the furnace. Under no circumstances should the air flow
be such that cooled, conditioned air can pass over the
furnace heat exchanger. This will cause condensation
in the heat exchanger and possible failure of the heat
exchanger that could lead to a fire hazard and/or
hazardous conditions that may lead to bodily harm. Heat
exchanger failure due to improper installation will not be
covered by warranty.

VENTING

Venting for the furnace must be to the outside and in
accordance with local codes or requirements of the local
utility. In the absence of local codes, venting must conform
to the applicable sections of the latest edition of the (U.S.)
National Fuel Gas Code ANSI Z223.1/NFPA 54. and/or CSA
B149.1 Natural Gas and Propane Installation Codes, and
the vent manufacturers instructions.

This furnace is CSA International apporved as a
Category I forced air appliance and can not be vented into
a vent system with any Category II, III or IV appliance. It
must be vented vertically, or nearly vertically, unless installed
with a listed mechancial venter in accordance with horizontal
venting instructions. It must not be connected to any portion
of a mechanical draft system operating under positive
pressure.

The vent system must be securely fastened to the
furnace flue collar with two (2) field supplied, corrosion
resitant, sheet metal screws located at least 120 degrees
apart and midway up the collar (see Figure 4).

Page 10 of 36 506307-01Issue 1207

VENT SYSTEM CONNECTION

Figure 4

Pre-Installation Vent System Inspection:

Before this furnace is installed, it is highly recommended

that any existing vent system be completely inspected.

For a chimney or “B” vent, this should include the

following:

1. Inspection for any deterioration in the chimney or “B” vent.
If deterioration is discovered, the chimney must be
repaired or the “B” vent must be replaced.

2. Inspection to ascertain that the vent system is clear and
free of obstructions. Any blockage must be cleared before
installing this furnace.

3. Cleaning the chimney or “B” vent if previously used for
venting a solid fuel burning appliance or fireplace.

4. Confirming that all unused chimney or “B” vent connections
are properly sealed.

5. Verification that the chimney is properly lined and sized
per the applicable codes.

Masonry Chimney:

This furnace can be common vented into an existing

tile lined masonry chimney provided:

1. The chimney is currently serving at least one drafthood
equipped appliance.

2. The vent connectors and chimney are sized in accordance
with the applicable sections of the (U.S.) National Fuel
Gas Code ANSI Z223.1/NFPA54, and/or CSA B149.1
Natural Gas and Propane Installation Codes.

This furnace must

NOT be vented ALONE into an
existing masonry chimney (either title lined or unlined) unless
the chimney is also lined with either a type “B” vent system
or a listed single wall, metal lining system. Both of these
systems must be sized in accordance with the applicable
sections of the (U.S.) National Fuel Gas Code ANSI Z223.1/
NFPA 54, and/or CSA B149.1 Natural Gas and Propane
Installation Codes.

Before venting this furnace into a chimney, check the
chimney for deterioration and repair if necessary. This
furnace must not be vented into a chimney serving a separate
appliance designed to burn solid fuel. Type II “B” vent
connectors must be used on all installations and it must be
sized per the applicable sections of the (U.S.) National Fuel
Gas Code ANSI Z223.1/NFPA 54, and/or CSA B149.1
Natural Gas and Propane Installation Codes.

Horizontal Venting:

This furnace is design certified by CSA International for
horizontal venting through an outside wall by use of one of
the following auxiliary draft inducer kits:

AUXILIARY DRAFT INDUCERS

Table 3

See Figure 5 on page 12 for information on where the
sidewall vent terminal can and cannot terminate.

For Massachusetts Installations: The installation must
comply with Massachusetts 248 CMR 5.08 Modifications to
sections of NFPA-54, Chapter 10. (See pages 26 and 27)

General Venting Requirements:

This furnace may be common vented only with other
Category I appliances. Common venting is allowed as
permitted by national and/or local codes. Refer to the
applicable sections of the (U.S.) National Fuel Gas Code
ANSI Z223.1/NFPA 54, and/or CSA B149.1 Natural Gas and
Propane Installation Codes for proper sizing and set up.

The vent must be terminated with a listed vent cap or
roof assembly. This venting must be installed in accordance
with the vent manufacturer’s instructions and be in
accordance with all local codes and/or national codes.

The following requirements are provided for a proper
venting system:

1. Be sure that the chimney flue is clear of any dirt or debris.

2. Be sure that the chimney is not servicing an open fireplace.

Type “B” Vent:

The furnace is also approved for use with a “B” vent
that terminates through the roof. Refer to the applicable
sections of the (U.S.) National Fuel Gas Code ANSI Z223.1/
NFPA 54, and/or CSA B149.1 Natural Gas and Propane
Installation Codes for proper sizing and set-up of this furnace
with “B” vent for a dedicated vent system or a common
vented system.

506307-01 Page 11 of 36Issue 1207