Lennox G40DF-36A-045, G40DF-48B-070, G40DF-36B-090, G40DF-36C-110, G40DF-48C-110 Installation Instructions Manual

INSTALLATION

,?,>2006 Lennox Industries inc.

Dallas, Texas, USA

RETAIN THESE INSTRUCTIONS

FOR FUTURE REFERENCE

INSTRUCTIONS

G40DF(X) Series

GAsFURNACE Teohe,c ,

505,253M L Publications

08/2006
Supersedes 505,182M Litho U.S.A.

G40DF(X) Unit Dimensions ....................... 2

G40DF(X) Parts Arrangement ..................... 3

G40DF(X) Gas Furnace .......................... 4

Shipping and Packing List ........................ 4

Safety Information ............................... 4

General ........................................ 5

Combustion, Dilution, & Ventilation Air ............. 6

Downflow Installation ............................ 8

Setting Equipment ............................... 9

Filters .......................................... 10

Duct System .................................... 10

Venting ........................................ 10

Gas Piping ..................................... 18

Electrical ....................................... 19

Unit Start-Up ................................... 23

Gas Pressure Adjustment ........................ 24

High Altitude Information ......................... 25

Other Unit Adjustments .......................... 25

Service ........................................ 26

Repair Parts List ................................ 28

Ignition Control Board Diagnostic Codes ........... 28

Troubleshooting ................................. 29

G40DF(X) Start-Up & Performance Check List ...... 32

Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other ap-
pliance.

Installation and service must be
performed by a qualified installer,
service agency or the gas supplier.

08/06

IIlillillilillllllilillillllHIIIlllil

-AWARNING

WHAT TO DO IF YOU SMELL GAS:

• Do not try to light any appliance.

• Do not touch any electrical switch; do not

use any phone in your building.

• Leave the building immediately.

• Immediately call your gas supplier from a

neighbor's phone. Follow the gas supplier's
instructions.

• If you cannot reach your gas supplier, call

the fire department.

505,253M

Page1 IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

5/8 (16)

D

FLUE OUTLET 5/8

(Top) (16)

5/8 (16)

TOP VIEW

,_ A -_

9v-------- B _

ql- 5/8

(16)

!i!i!ii!i!i!i!ii!i!i!i!ii!i!i!i!ii!i!i!i!ii!i!i!i!ii!i!i!i¸I I!I!I!I!II!I!I!I!III!I!

40

(1016)

4-7/8 (124) Right

2-1/4 (57) Left -I_

9-1/4
(235)

28-1/2

(724)

-- 9-1/2 --

(495)

5/8

(16)

,,,Jl-- suoo,

(19) C Air _ (19)

FRONT VIEW

Model No.

G40DF(X)-24A-045,
G40DF-36A-045, 14-1/2 368 13-1/4 337 13 4-1/2 114

G40DFIX)-36A-070
G40DF-48B-070, 17-1/2 446 16-1/4 413 16 6 152

G40DF-36B-090
G40DF(X)-48C-090,

G40DF-36C-110, 21 533 19-1/4 502 19-1/2 7-3/4 197
G40DF-48C-110,

G40DF(X)-60C-110
G40DF-60D-135 24-1/2 622 23-1/4 591 23 9-1/2 241

A B D

in. mm in. mm in. mm

Page 2

_ 9-1/4 Supply

(489) Air

SIDE VIEW

c

in mm

33o

4o6

495

584

J

v I

3/4

(19)

Internal Flue Pipe

Assembly

Y Blower Motor

Gasket

Transformer

Integrated Ignition /]

Control Board /

Flue Box Gasket /

Flue Collector Box

/

/

Capacitor

/I

/

Blower Assembly

Door /

Interlock Switch / /

/

I /
I // Primarg ._ _/

/ Limit %1

Flame Switches i/

/

/

/

/

/

/_, Flame Rollout /

/

/

Heat Exchanger

Gasket,

'/'Combustion Air

Y

Combustion Air Inducer

Pressure Switch

Air Orifice

Manifold

Sensor _'[_ II

/

Gas

Orifices

FIGURE 1

Burner Igniter

Page 3

I
I

lgniter

racket

TheG40DF(X)gasfurnaceisshippedreadyforinstalla-
tioninthedownflowpositionfueledbynaturalgas,Acon-
versionkit(orderedseparately)isrequiredforuseinpro-
pane/LPgasapplications.

Package 1 of 1 contains

1 - Assembled G40DF(X) unit
1 - Bag assembly containing the following:

3 -Wire nuts

1 - Snap bushing
1 - Snap plug

1 - Wire tie
1 -Vent warning label

1 -Owner's manual and warranty card

The following items may be ordered separately:

1- Thermostat
1 - Propane/LP changeover kit

Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.

,WARNING

,&,CAUTION

G40DF(X) units are CSA International certified to ANSI
Z21.47 and CSA 2.3 standard.

In the USA, installation of gas furnaces must conform with
local building codes. In the absence of local codes, units

must be installed according to the current National Fuel
Gas Code (ANSI-Z223.1). The National Fuel Gas Code is
available from the following address:

American National Standards Institute, Inc.

11 West 42nd Street

New York, NY 10036

In Canada, installation must conform with current CSA
B149 Natural Gas and Propane Installation Codes, local
plumbing or waste water codes and other applicable local

codes.

Adequate clearance must be made around the air open-
ings into the vestibule area. In order to ensure proper unit
operation, combustion and ventilation air supply must be
provided according to the current National Fuel Gas Code

or CSA B149 standards.
Vent installations must be consistent with the venting

tables (in this instruction) and applicable provisions of local
building codes.

This furnace is CSA Intemational certified for installation
clearances to combustible material as listed on the unit

nameplate and in the table infigure 9. Accessibility and ser-
vice clearances must take precedence over fire protection

clearances.

NOTE - For installation on combustible floors, the furnace
shall not be installed directly on carpeting, tile, or other
combustible material other than wood flooring.

For installation in a residential garage, the furnace must
be installed so that the burner(s) and the ignition source
are located no less than 18 inches (457 mm) above the
floor. The furnace must be located or protected to avoid
physical damage by vehicles. When a furnace is installed
in a public garage, hangar, or other building that has a haz-
ardous atmosphere, the furnace must be installed accord-
ing to recommended good practice requirements and cur-

rent National Fuel Gas Code or CSA B149 standards.

NOTE - Furnace must be adjusted to obtain a temperature
rise within the range specified on the unit nameplate. Failure
to do so may cause erratic limit operation and premature heat
exchanger failure.

This G40DF(X) furnace must be installed so that its electri-
cal components are protected from water.

When this furnace is used with cooling units, it shall be
installed in parallel with, or on the upstream side of, cooling
units to avoid condensation in the heating compartment.
With a parallel flow arrangement, a damper (or other
means to control the flow of air) must adequately prevent
chilled air from entering the furnace. If the damper is manu-
ally operated, it must be equipped to prevent operation of
either the heating or the cooling unit, unless it is in the full

HEAT or COOL setting.
When installed, this furnace must be electrically grounded

according to local codes. Inaddition, in the United States,
installation must conform with the current National Elec-

tric Code, ANSI/NFPA No. 70. The National Electric Code
(ANSI/NFPA No. 70) is available from the following ad-

dress:

National Fire Protection Association

1 Battery March Park

Quincy, MA 02269

Page 4

InCanada,allelectricalwiringandgroundingfortheunit
mustbeinstalledaccordingtothecurrentregulationsofthe
CanadianElectricalCodePartI(CSAStandardC22.1)

and/orlocalcodes.

NOTE - This furnace is designed for a minimum continu-
ous return air temperature of 60°F (16°C) or intermittent

operation down to 55°F (13°C) dry bulb in cases where a
night setback thermostat is used. Return air temperature
must not exceed 85°F (29 °C) dry bulb.

NOTE - G4ODF(X) series units should not be installed as a
unit heater.

The G40DF(X) furnace may be installed in alcoves, clos-
ets, attics, basements, garages, and utility rooms in the

downflow position.
This furnace design has not been CSA International certi-

fied for installation in mobile homes, recreational vehicles,

or outdoors.
Lennox does not recommend the use of G40DF(X) units as

a construction heater during any phase of construction.
Very low return air temperatures, harmful vapors and op-
eration of the unit with clogged or misplaced filters will dam-
age the unit.

• 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, in-
put rate, temperature rise and venting) must be verified
according to these installation instructions.

NOTE - The Commonwealth of Massachusetts stipu-
lates these additional requirements:

• Gas furnaces shall be installed by a ticensedplumb-
er or gas fitter only.

• The gas cock must be "T handle" type.

• When a furnace is installed in an attic, the passage-

way to and service area surrounding the equipment

shall be floored.

These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities

having jurisdiction before installation.

, WARNING

G40DF(X) units may be used for heating of buildings or
structures under construction if the following conditions

are met:

• The vent system must be 3ermanently installed per

these installation instructions.

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

allowed.

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

• Return air temperature range between 60°F (16°C) and
80°F (27°C) must be maintained.

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

• Air filters must be replaced upon construction comple-
tion.

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

• One hundred percent (100%) outdoor air must be pro-
vided for combustion air requirements during construc-
tion. Temporary ducting may supply outdoor air to the
furnace. Do not connect duct directly to the furnace.
Size the temporary duct following these instructions in
section for Combustion, Dilution and Ventilation Air in a
confined space with air from outside.

In addition to the requirements outlined previously, the fol-
lowing general recommendations must be considered
when installing a G40DF(X) furnace:

• Place the furnace as close to the center of the air dis-
tribution system as possible. The furnace should also be

located close to the chimney or vent termination point.

• Do not install the furnace where drafts might blow direct-
ly into it. This could cause improper combustion and un-

safe operation.

• Do not block the furnace combustion air openings with
clothing, boxes, doors, etc. Air is needed for proper

combustion and safe unit operation.

• When the furnace is installed in an attic or other insu-
lated space, keep insulation away from the furnace.

Page 5

ACAUTION

In the past, there was no problem in bringing in sufficient out-
door air for combustion, Infiltration provided all the air that
was needed, In today's homes, tight construction practices
make it necessary to bring in air from outside for combus-
tion. Take into account that exhaust fans, appliance vents,
chimneys, and fireplaces force additional air that could be

used for combustion out of the house. Unless outside air is
brought into the house for combustion, negative pressure

(outside pressure is greater than inside pressure) will build
to the point that a downdraft can occur in the furnace vent
pipe or chimney. As a result, combustion gases enter the liv-
ing space creating a potentially dangerous situation.

In the absence of local codes concerning air for combus-
tion and ventilation, use the guidelines and procedures in
this section to install G40DF(X) furnaces to ensure efficient
and safe operation. You must consider combustion air
needs and requirements for exhaust vents and gas piping.
A portion of this information has been reprinted with per-

mission from the National Fuel Gas Code
(ANSl-Z223.1/NFPA 54). This reprinted material is not the

complete and official position of the ANSl on the referenced
subject, which is represented only by the standard in its en-
tirety.

In Canada, refer to the CSA B149 installation codes.

ACAUTION

All gas-fired appliances require air for the combustion pro-
cess. If sufficient combustion air is not available, the fur-
nace or other appliances will operate inefficiently and un-
safely. Enough air must be provided to meet the needs of all
fuel-burning appliances and appliances such as exhaust

fans which force air out of the house. When fireplaces, ex-
haust fans, or clothes dryers are used at the same time as
the furnace, much more air is necessary to ensure proper
combustion and to prevent a downdraft. Insufficient air
causes incomplete combustion which can result in carbon

monoxide.

In addition to providing combustion air, fresh outdoor air

dilutes contaminants in the indoor air. These contami-
nants may include bleaches, adhesives, detergents, sol-

vents and other contaminants which can corrode furnace
components.
The requirements for providing air for combustion and ven-

tilation depend largely on whether the furnace is installed in
an unconfined or a confined space.

Unconfined Space
An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the com-

bined input rating of all appliances installed in that space.
This space also includes adjacent rooms which are not
separated by a door. Though an area may appear to be un-
confined, it might be necessary to bring in outdoor air for
combustion if the structure does not provide enough air by
infiltration. If the furnace is located in a building of tight
construction with weather stripping and caulking around
the windows and doors, follow the procedures in the air

from outside section.
Confined Space

A confined space is an area with a volume less than 50 cu-
bic feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the
combined input rating of all appliances installed in that
space. This definition includes furnace closets or small
equipment rooms.

When the furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside the space contain-
ing the furnace, the return air must be handled by ducts
which are sealed to the furnace casing and which terminate

outside the space containing the furnace. This is especially
important when the furnace is mounted on a platform in a
confined space such as a closet or small equipment room.

Even a small leak around the base of the unit at the platform
or at the return air duct connection can cause a potentially
dangerous negative pressure condition. Air for combustion
and ventilation can be brought into the confined space either
from inside the building or from outside.

Page 6

EQUIPMENT IN CONFINED

CHIMNEY

VENT

FURNACE

_ WiTER

I I I I I II I I I I I I II I I I
I I

SPACE ALL AIR FROM INSIDE

HEATER

OPENINGS

(To Adjacent

Room)

I I I I

NOTE-Each opening shall have a free area of at least one square

inch (645 mm'2_')per 1,000 Btu (.29 kW) per hour of the total input rat-
ing of all equipment in the enclosure, but not less than 100 square
inches (64516 mm2).

FIGURE 2

Air from Inside

If the confined space that houses the furnace adjoins a
space categorized as unconfined, air can be brought in by
providing two permanent openings between the two
spaces. Each opening must have a minimum free area of 1

square inch (645 mm2) per 1,000 Btu (.29 kW) per hour of
total input rating of all gas-fired equipment in the confined

space, Each opening must be at least 100 square inches
(64,516 mm2), One opening shall be within 12 inches (305

mm) of the top of the enclosure and one opening within 12
inches (305 mm) of the bottom. See figure 2.

Air from Outside
If air from outside is brought in for combustion and ventila-

tion, the confined space must have two permanent open-
ings, One opening shall be within 12 inches (305 mm) of the
top of the enclosure and one opening within 12 inches (305
mm) of the bottom, These openings must communicate di-
rectly or by ducts with the outdoors or spaces (crawl or at-
tic) that freely communicate with the outdoors or indirectly
through vertical ducts. Each opening shall have a minimum
free area of 1 square inch (645 mm2) per 4,000 Btu (1,17
kW) per hour of total input rating of all equipment in the en-
closure, See figures 3 and 4. When communicating with
the outdoors through horizontal ducts, each opening shall
have a minimum free area of 1 square inch (645 mm 2) per
2,000 Btu (.56 kW) per total input rating of all equipment in
the enclosure. See figure 5.

When ducts are used, they shall be of the same cross-sec-
tional area as the free area of the openings to which they
connect. The minimum dimension of rectangular air ducts
shall be no less than 3 inches (75 mm). In calculating free
area, the blocking effect of louvers, grilles, or screens must
be considered. Ifthe design and free area d protective cov-
ering is not known for calculating the size opening required,
it may be assumed that wood louvers will have 20 to 25 per-
cent free area and metal louvers and grilles will have 60 to
75 percent free area. Louvers and grilles must be fixed in the
open position or interlocked with the equipment so that they
are opened automatically during equipment operation.

EQUIPMENT IN CONFINED SPACE

ALL AIR FROM OUTSIDE

(Inlet Air from Crawlspace and Outlet Air to Ventilated Attic)

CHIMNEY OR

GAS VENT

VENTILATION LOUVERS

(Each end of attic)

l ...... I

FURNACE AIR WATER

VENTILATION INLET

LOUVERS AIR

(For unheated crawl !

OUTLET

HEATER

q

rrmq

NOTE- The inlet and outlet air openings shall each have a free area of at least one square inch (645
mm2) per 4,000 Btu (1.17 kW) per hour of the total input rating of all equipment in the enclosure.

FIGURE 3

Page 7

EQUIPMENT IN CONFINED SPACE

ALL AIR FROM OUTSIDE

CHIMNEY

OR GAS

VENT_

FURNACE

NO TE- The inlet and outlet air openings shall each have a
free area of at least one square inch (645 mm 2)per 4,000

Btu (1.17 kW) per hour of the total input rating of all equip-
ment in the enclosure.

(All Air Through Ventilated Attic)

VENTILATION LOUVERS

(Each end of attic)

INLET AIR

(Ends 12 in.

above bottom)

HEATER

FIGURE 4

A _ EQUIPMENT IN
TT_. JJ_ CONFINED SPACE

I I "_/--/'Y _ ALLAIRFROM

OUTLET AIR

FURNACE

Installation on Noncombustible Flooring

1 - Cut floor opening keeping in mind clearances listed on

unit rating plate. Also keep in mind gas supply connec-
tions, electrical supply, flue and air intake connections

and sufficient installation and servicing clearances,
See table 1 for correct floor opening size.

2 - Flange warm air plenum and lower the plenum into the

opening.

3 - Set the unit over the plenum and seal the plenum to

the unit,

3 - Ensure that the seal is adequate,

TABLE 1

NONCOMBUSTIBLE FLOOR OPENING SIZE

Model No.

A Cabinet (14.5")

B Cabinet (17.5")
C Cabinet (21")
D Cabinet (24.5")

NOTE - Floor opening dimensions listed are 1/4 inch (6 mm) larger than
the unit opening. See figure 1.

Front to Rear
in. mm

19 - 3/4 502
19 - 3/4 502

19 - 3/4 502
19 - 3/4 502

Side to Side

in.

13 - 1/4
16 - 1/4

19 - 3/4

23- 1/4

mm

337
413

5O2
591

Installation on Combustible Flooring

1 - When unit is installed on a combustible floor, an addi-

tive base must be installed between the furnace and
the floor. The base must be ordered separately for the

following cabinet sizes:

• A cabinet 14.5" -# 11M59

• B cabinet 17.5" -# 11M60

• C cabinet 21" -# 11M61

• D cabinet 24.5" - # 11M62

See table 2 for opening size to cut in floor.

I1"-

I ii I I I I I I I I I I I T_"I

NO TE - Each air duct opening shall have a free area of at least
one square inch (645 mm 2)per 2,000 Btu (.59 kW) per hour of

the total input rating of all equipment in the enclosure. If the
equipment room is located against an outside wall and the air
openings communicate directly with the outdoors, each open-

ing shaft have a free area of at least one square inch (645 mm2)

per 4,000 Btu (1.17 kW) per hour of the total input rating of all

other equipment in the enclosure.

FIGURE 5

Downflow unit installs in three ways: on noncombustible
flooring, on combustible flooring using an additive base, or

on a reverse-flow cooling cabinet, Do not drag the unit
across the floor.

,A, CAUTION

I

TABLE 2

ADDITIVE BASE FLOOR OPENING SIZE

Model No.

A Cabinet (14.5")

B Cabinet (17.5")
C Cabinet (21")

D Cabinet (24.5")

NOTE - Floor opening dimensions listed are 1/4 inch (6 mm) larger than
unit opening. See figure 1.

Frontto Rear

in. mm
22 559
22 559
22 559
22 559

Page 8

Side to Side

in.
15 - 3/4
18 - 3/4

22 - 3/4
25 - 3/4

am
400
476
578
654

2- Afteropeningiscut,setadditivebaseintoopening.

3- Checkfiberglassstripsonadditivebasetomakesure

theyareproperlygluedandpositioned.

4- Lowersupplyairplenumintoadditivebaseuntilple-

numflangessealagainstfiberglassstrips.

NOTE - Be careful not to damage fiberglass strips.
Check for a tight seal.

5 - Set the furnace over the plenum.

6 - Ensure that the seal between the furnace and plenum

is adequate.

G40DF(X)UNIT

%

PROPERLY

SIZED FLOOR _X'xI_"

OPENING I\\_ _ ADDITIVE BASE

SUPPLY AIR PLENUM

3 - In all cases, plenum should be secured to top flanges

of furnace with sheet metal screws.

4 - In closet installations, it may be impossible to install

sheet metal screws from the outside. In this case,
make plenum with a removable front and install

screws from the inside (See figure 8).

5 - Make certain that an adequate seal is made.

n PLENUM

SECURE FROM IIJ Side View

INSIDE CABINEX_ME o EDGE

FIBERGLASS/ -

SEALING STRIP CABINET SIDE_ I

(Field Provided) PANEL --II

FIGURE 8

I

AWARNING

FIGURE 6

Installation on Cooling Cabinet

1 - Refer to reverse-flow coil installation instructions for

correctly sized opening in floor and installation of cabi-
net.

2 - When cooling cabinet is in place, set and secure the

furnace according to the instructions that are provided
with the cooling coil. Secure the furnace to the cabinet.

3 - Seal the cabinet and check for air leaks.

Return Air Opening -- Downflow Units

The following steps should be taken when installing ple-
num:

1 - Bottom edge of plenum should be flanged with a

hemmed edge (See figure 7).

2 - Fiberglass sealing strips should be used.

PLENUM SECURE FROM

CABINET

Side View

HEMMEDEDGE

FIBERGLASS SEALING

STRIP

(Field Provided)

CABINET SIDE PANEL

FIGURE 7

Install the G40DF(X) gas furnace as shipped. Do not
install the furnace horizontally.

Select a location that allows for the required clearances
that are listed on the unit nameplate. Also consider gas
supply connections, electrical supply, vent connection,
and installation and service clearances [24 inches (610
mm) at unit front]. The unit must be level.

NOTE - 1/3 hp blower motors are equipped with four flex-
ible mounting legs, and 1/2 hp blower motors are equipped

with three flexible legs and one rigid leg. The rigid leg is
equipped with a shipping bolt and a flat white plastic wash-
er (rather than the rubber mounting grommet used with a
flexible mounting leg). The bolt and washer must be re-
moved before the furnace is placed into operation. Af-
ter the bolt and washer have been removed, the rigid leg
will not touch the blower housing.

NOTE - G40DF-36C-110 units include a bracket which sta-
bilizes the blower motor during shipping. The bracket is se-

cured to the blower housing by two screws. This bracket
must be removed prior to placing the unit into opera-
tion. See figure 1.

Downflow Application
Allow for clearances to combustible materials as indi-

cated on the unit nameplate. Minimum clearances for
closet or alcove installations are shown in figure 9.

Page 9

DownflowApplication Installation Clearances

Top

Left Side

¢:::_T:T:T;

Right Side

Bottom

Type of Vent Type B1

Connector

Type C

This unit is not equipped with a filter or rack. A field-pro-
vided high-velocity filter is required for the unit to operate
properly, Table 3 lists the recommended minimum filter

sizes,
A filter must be in place any time the unit is operating,

TABLE 3

Furnace

Cabinet Size Return Air Filter Size (inches)

14-1/2" 14 X 25 X 1 (1)
17-1/2" 16 X25 X 1(1)

21" 20X25X 1(1)

24-1/2" 24 X25 X 1 (1)

Top 1 in. (25 ram)

*Front 3 in. (76 ram)

Back 0

Sides 0

Vent 1 in. (25 ram)

Floor NCtt

*Front clearance in alcove installation must be 24 in. (610 ram).

Maintain a minimum of 24 in. (610 ram) for front service access.

tLeft side requires 3 in. if a single wall vent is used on 14 -1/2 in. cab-

inets, or 2 in. if a single wall vent is used on 17 - 1/2 in. cabinets.

tiThe furnace may be installed on a combustible wood floor if an
optional additive base is installed between the furnace and the
combustible floor.

1 in. (25 ram)
3 in. (76 ram)

0

ot

6 in. (152 ram)

NCtt

FIGURE 9

-&WARNING

......

Use industry-approved standards to size and install the

supply and return air duct system. This will result in a quiet
and low-static system that has uniform air distribution.

Ensure that you have made a seal between the supply air

plenum and the furnace and between the furnace and the
return air plenum.

NOTE - Do not operate the furnace with an external static
pressure that exceeds 0.5 inches w.c. Higher external stat-

ic pressures may cause erratic limit operation.

Return Air Plenum

Return air must not be drawn from a room where this
furnace, or any other gas appliance (ie., a water heat-
er), is installed. When return air is drawn from a room, a

negative pressure is created in the room, If a gas ap-
pliance is operating in a room with negative pressure, the

flue products can be pulled back down the vent pipe and
into the room, This reverse flow of the flue gas may result

in incomplete combustion and the formation of carbon
monoxide gas. This toxic gas might then be distributed

throughout the house by the furnace duct system,

-&WARNING

A 4-inch diameter flue transition is factory-installed on all
models. Modifying or removing the flue transition will
cause the unit to operate unsafely and will void the unit

certification. The vent connector does not require insula-
tion.

The G40DF(X) series units are classified as fan-assisted
Category I furnaces when vertically vented according to
the latest edition of National Fuel Gas Code (ANSI
Z223.1/NFPA 54) in the USA and the current standards of
CSA B149 Natural Gas and Propane Installation Code in
Canada. A fan-assisted Category I furnace is an appliance
equipped with an integral mechanical means to either draw
or force combustion products through the combustion
chamber and/or heat exchanger.

NOTE - Use these instructions as a guide. They do not su-
persede local codes. This furnace must be vented accord-
ing to all local codes, these installation instructions, and the
provided venting tables (5 through 10) in these instructions.

Page 10