Lennox G24M SERIES User manual

Page 1

2000 Lennox Industries Inc.
Dallas, Texas
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
INSTALLATION
INSTRUCTIONS
G24M Series 50HZ
GAS FURNACE
Direct Spark Ig itio
503,876M
05/2000
Supersedes 03/99
Table of Co te ts
G24M Unit Di ensions 2. . . . . . . . . . . . . . . . . . . . . .
G24M Parts Arrange ent 3. . . . . . . . . . . . . . . . . . . .
G24M Gas Furnace 3. . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 3. . . . . . . . . . . . . . . . . . .
Require ents 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Co bustion, Dilution & Ventilation Air 5. . . . . . . . .
Setting Equip ent 8. . . . . . . . . . . . . . . . . . . . . . . . . .
Duct Syste 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Venting 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start-up 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Adjust ent 24. . . . . . . . . . . . . . . . . . .
High Altitude Infor ation 24. . . . . . . . . . . . . . . . . . .
Other Unit Adjust ents 24. . . . . . . . . . . . . . . . . . . . .
Service 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 27. . . . . . . . . . . . . . . . . . . . . . . . . . .
G24M Start-up & Perfor ance Check List 27. . . .
Ignition Control Board Diagnostic Codes 28. . . . . .
Troubleshooting 29. . . . . . . . . . . . . . . . . . . . . . . . . . .
WHAT TO DO IF YOU SMELL GAS:
If the i formatio i this ma ual is ot
followed exactly, a fire or explosio
may result causi g property damage,
perso al i jury or loss of life.
WARNING
Do ot store or use gasoli e or other
flammable vapors a d liquids i the
vici ity of this or a y other applia ce.
I stallatio a d service must be perĆ
formed by a qualified i staller, serĆ
vice age cy or the gas supplier.
Do ot try to light a y applia ce.
Do ot touch a y electrical switch; do ot
use a y pho e i your buildi g.
Immediately call your gas supplier from a
eighbor's pho e. Follow the gas supplier's
i structio s.
If you ca ot reach your gas supplier, call
the fire departme t.
Exti guish a y ope flames.
Litho USA

Page 2
G24M U it Dime sio s - i ches (mm)
SUPPLY
AIR
OPENING
A
B
*C
**C
RETURN AIR
KNOCKOUT
(Either Side)
Retur Air
Ope i g
Retur Air
Ope i g
GAS PIPING
INLET
(Both Sides)
ELECTRICAL
INLETS
(Both Sides)
FLUE
OUTLET
D
AIR FLOW
FRONT VIEW SIDE VIEW
TOP VIEW
F Left Side
G Right Side
2 (51)
29Ć5/8
(752)
*19Ć1/2
(495)
**19Ć1/2
(495)
19Ć1/2
(495)
15
(381)
2 (51)
E
1
(25)
1
(25)
1
(25)
1
(25)
1
(25)
1
(25)
1
(25)
GAS PIPING
INLET
ELECTRICAL INLETS
(Top & Bottom)
3/4 (19)
4Ć1/4
(105)
*19
(483) 1
(25)
U it show i upflow positio . Rotate 1805 for
dow flow applicatio s a d 905 clockwise or
cou terclockwise for horizo tal applicatio s.
*NOTE – The supply air opening is equipped with a 3/4 inch (19 mm) scored
flange that may be bent 90_ for plenum connection. The dimensions shown
were taken after the flange was bent.
The double scored flange at the front of the supply air opening may be
bent for a total opening dimension (front to rear) of either 19-1/2 inches
(495 mm) or 19 inches (483 mm).
**NOTE – The return air opening is
equipped with a 3/4 inch (19 mm) scored
flange that may be bent 90_ for plenum con-
nection. The dimensions shown were taken
after the flange was bent.
Model No. A B C D E F G
G24M2Ć45
G24M2Ć60
G
24M2Ć7
5
in. 17 36Ć1/4 15 6Ć3/4 2Ć7/16 11Ć1/2 6Ć1/2
G24M2
Ć
75
G24M3Ć60
G24M3Ć75
G24M4Ć75
432 921 381 171 62 293 165
G24M3/4Ć100
G24M3/4Ć120 in. 20Ć1/2 39 18Ć1/2 8Ć3/8 4Ć1/4 13 8
G24M3/4Ć120
G24M4/5Ć100
G24M4/5Ć120 521 991 470 213 108 331 203
G24M4/5 140
in. 23Ć1/4 39 21Ć1/4 9-3/4 4Ć1/4 12Ć31/32 7Ć3/32
G24M4/5Ć140 591 991 540 248 108 329 180

Page 3
G24M Parts Arra geme t
VENT ADAPTER CABINET TOP
G24M
CABINET
CABINET
BOTTOM
HEAT EXCHANGER
ASSEMBLY
BURNER
ASSEMBLY
BLOWER ASSEMBLY
COMBUSTION AIR
BLOWER
FLUE BOX
SECONDARY
LIMITS
FRONT LOUVERED
PANEL
DOOR INTERLOCK SWITCH
CONTROL
BOARD
TRANSFORMER
PRESSURE
SWITCH
NOx
TURBULATOR
LOW PRESSURE SWITCH
(Propa e O ly)
PRIMARY
LIMIT
G24M Gas Fur ace
G24M ulti-position gas furnace is shipped ready for
installation in the upflow position. Unit can easily be conĆ
verted for installation in either downflow or horizontal apĆ
plications. the furnace is shipped with a botto seal panel
in place for side return air in upflow applications.
Shippi g a d Packi g List
Package 1 of 1 co tai s:
1 - Asse bled unit
1 - Vent adapter is factoryĆprovided and fieldĆinstalled
The following additional items may be ordered separately,
if required:
1 - Additive base (downflow applications)
1 - Ther ostat
1 - Hanging bracket kit
1 - External filter rack kit
1 - Propane/LP Changeover kit
Check equip ent for shipping da age. If you find any
da age, i ediately contact the last carrier.
Requireme ts
Lennox G24M units are A erican Gas Association (AGA)
and Canadian Gas Association (CGA) certified.
In the USA, installation of Lennox gas central furnaces
ust confor with local building codes. In the absence of
local codes, units ust be installed according to the current
National Fuel Gas Code (ANSI-Z223.1) in the United
States. The National Fuel Gas Code is available fro :
A erican National Standards Institute, Inc.
11 West 42Nd Street
New York, NY 10036
In Canada, installation ust confor with current National
Standard of Canada CAN/CGA-B149.1 Installation Code
for Natural Gas Burning Appliances and Equip ent" and
CAN/CGA-B149.2 Installation Code for Propane Gas
Burning Appliances and Equip ent," local plu bing or
waste water codes and other applicable local codes.

Page 4
Adequate clearance ust be ade around the air openĆ
ings into the vestibule area. Provisions ust be ade for
proper operation and for co bustion air and ventilation air
supply according to the current National Fuel Gas Code or
CAN/CGAĆB149 standards.
Vent installations shall be in accordance with the provided
venting tables and applicable provisions of local building
codes.
This furnace is AGA and CGA certified for installation clearĆ
ances to co bustible aterial as listed on the unit rating plate
and in the tables in figures 5, 7 and 9. Accessibility and serĆ
vice clearances ust 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 ust be
installed so that the burner(s) and the ignition source are loĆ
cated no less than 18 inches (457 ) above the floor. The
furnace ust be located or protected to avoid physical da Ć
age by vehicles. When a furnace is installed in a public garage,
hangar, or other building that has a hazardous at osphere,
the furnace ust be installed according to reco ended
good practice require ents and current National Fuel Gas
Code or CAN/CGA B149.1 and B149.2 standards.
The furnace ust be adjusted to obtain a te perature rise
within the range specified on the unit rating plate.
G24M unit ust be installed so that electrical co ponents
are protected fro water.
When the furnace is used with cooling units, it shall be
installed in parallel with, or on the upstrea side of, cooling
units to avoid condensation in the heating co part ent.
With a parallel flow arrange ent, a da per (or other eans
to control the flow of air) ust adequately prevent chilled air
fro entering the furnace. If the da per is anually operĆ
ated, it ust 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, the furnace ust be electrically grounded
according to local codes. In addition, in the United States,
installation ust confor with the current National Electric
Code, ANSI/NFPA No. 70. The National Electric Code
(ANSI/NFPA No. 70) is available fro the following adĆ
dress:
National Fire Protection Association
1 Battery March Park
Quincy, MA 02269
In Canada, all electrical wiring and grounding for the unit
ust be installed according to the current regulations of the
Canadian Electrical Code Part I (CSA Standard C22.1)
and/or local codes.
Field wiring connections ust eet or exceed specificaĆ
tions of type T wire and withstand a axi u te perature
rise of 180°F (82°C).
When the furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside of the space conĆ
taining the furnace, return air shall be handled by a duct(s)
sealed to the furnace casing and ter inating outside space
containing furnace.
NOTE - 24M series units must not be used as a
construction heater during any phase of construction.
Very low return air temperatures, harmful vapors and misĆ
placement of the filters will damage the unit and lower its
efficiency.
The Lennox G24M furnace ay be installed in alcoves,
closets, attics, base ents, garages and utility roo s in any
of its approved installation positions.
This furnace design has not been AGA or CGA certified for
installation in obile ho es, recreational vehicles, or outĆ
doors.
WARNING
The blower access pa el must be securely i place
whe the blower a d bur ers are operati g. Gas
fumes, which could co tai carbo mo oxide, ca
be draw i to livi g space resulti g i perso al i juĆ
ry or death.
Ge eral
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
In addition to the require ents outlined previously, the folĆ
lowing general reco endations should be considered
when installing the Lennox G24M furnace.
The furnace should be placed as close to the center of the
air distribution syste as possible. The furnace should also
be located close to the chi ney or vent ter ination point.
Do not install the furnace where drafts ight blow directly
into it. This could cause i proper co bustion and unsafe
operation.
Do not block furnace co bustion air openings with clothĆ
ing, boxes, doors, etc. Co bustion air is needed for proper
co bustion and safe unit operation.
When the furnace is installed in an attic or other insulated
space, keep insulation away fro the furnace.

Page 5
WARNING
Product co tai s fiberglass wool.
Disturbi g the i sulatio i this product duri g
i stallatio , mai te a ce, or repair will expose you
to fiberglass wool. Breathi g this may cause lu g
ca cer. (Fiberglass wool is k ow to the State of
Califor ia to cause ca cer.)
Fiberglass wool may also cause respiratory, ski ,
a d eye irritatio .
To reduce exposure to this substa ce or for further
i formatio , co sult material safety data sheets
available from address show below, or co tact your
supervisor.
Le ox I dustries I c.
P.O. Box 799900
Dallas, TX 75379-9900 USA
Combustio , Dilutio & Ve tilatio Air
In the past, there was no proble in bringing in sufficient
outdoor air for co bustion. Infiltration provided all the air
that was needed. In today's ho es, tight construction pracĆ
tices ake it necessary to bring in air fro outside for co Ć
bustion. Take into account that exhaust fans, appliance
vents, chi neys, and fireplaces force additional air that
could be used for co bustion out of the house. Unless outĆ
side air is brought into the house for co bustion, negative
pressure (outside pressure is greater than inside pressure)
will build to the point that a downdraft can occur in the furĆ
nace vent pipe or chi ney. As a result, co bustion gases
enter the living space creating a potentially dangerous situĆ
ation.
In the absence of local codes concerning air for co busĆ
tion and ventilation, use the guidelines and procedures in
this section to install G24M furnaces to ensure efficient and
safe operation. You ust consider co bustion air needs
and require ents for exhaust vents and gas piping. A porĆ
tion of this infor ation has been reprinted with per ission
fro the National Fuel Gas Code (ANSIĆZ223.1). This reĆ
printed aterial is not the co plete and official position of
the ANSI on the referenced subject, which is represented
only by the standard in its entirety.
In Canada, refer to the standard CAN/CGA B149.1 and
B149.2 installation codes.
CAUTION
Do ot i stall fur ace i a corrosive or co tami ated
atmosphere. Meet all combustio a d ve tilatio air
requireme ts, as well as all local codes.
CAUTION
I sufficie t combustio air ca cause headaches,
ausea, dizzi ess or asphyxiatio . It will also cause
excess water i the heat excha ger resulti g i rustĆ
i g a d premature heat excha ger failure. Excessive
exposure to co tami ated combustio air will result
i safety a d performa ce related problems. Avoid
exposure to the followi g substa ces i the combusĆ
tio air supply:
Perma e t wave solutio s
Chlori ated waxes a d clea ers
Chlori e base swimmi g pool chemicals
Water softe i g chemicals
DeĆici g salts or chemicals
Carbo tetrachloride
Haloge type refrigera ts
Clea i g solve ts (such as perchloroethyle e
Pri ti g i ks, pai t removers, var ishes, etc.
Hydrochloric acid
Ceme ts a d glues
A tistatic fabric softe ers for clothes dryers
Maso ry acid washi g materials
All gasĆfired appliances require air for the co bustion proĆ
cess. If sufficient co bustion air is not available, the furĆ
nace or other appliance will operate inefficiently and unĆ
safely. Enough air ust be provided to eet the needs of all
fuelĆburning appliances and appliances such as exhaust
fans which force air out of the house. When fireplaces, exĆ
haust fans, or clothes dryers are used at the sa e ti e as
the furnace, uch ore air is required to ensure proper
co bustion and to prevent a downdraft. Insufficient air
causes inco plete co bustion which can result in carbon
onoxide.
In addition to providing co bustion air, fresh outdoor air diĆ
lutes conta inants in the indoor air. These conta inants
ay include bleaches, adhesives, detergents, solvents
and other conta inants which can corrode furnace co poĆ
nents.
The require ents for providing air for co bustion and venĆ
tilation depend largely on whether the furnace is installed in
an unconfined or a confined space.
U co fi ed Space
An unconfined space is an area such as a base ent or
large equip ent roo with a volu e greater than 50 cubic
feet (1.42 3) per 1,000 Btu (.29 kW) per hour of the co Ć
bined input rating of all appliances installed in that space.
This space also includes adjacent roo s which are not
separated by a door. Though an area ay appear to be unĆ
confined, it ight be necessary to bring in outdoor air for
co bustion if the structure does not provide enough air by

Page 6
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
fro outside section.
Co fi ed Space
A confined space is an area with a volu e less than 50 cuĆ
bic feet (1.42 3) per 1,000 Btu (.29 kW) per hour of the
co bined input rating of all appliances installed in that
space. This definition includes furnace closets or s all
equip ent roo s.
When the furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside the space containĆ
ing the furnace, the return air ust be handled by ducts
which are sealed to the furnace casing and which ter inate
outside the space containing the furnace. This is especially
i portant when the furnace is ounted on a platfor in a
confined space such as a closet or s all equip ent roo .
Even a s all leak around the base of the unit at the platfor
or at the return air duct connection can cause a potentially
dangerous negative pressure condition. Air for co bustion
and ventilation can be brought into the confined space either
fro inside the building or fro outside.
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM INSIDE
WATER
HEATER
OPENINGS
(To Adjacent
Roo )
NOTE-Each opening shall have a free area of at least one square
inch (645 mm2) per 1,000 Btu (.29 kW) per hour of the total input ratĆ
ing of all equipment in the enclosure, but not less than 100 square
inches (64516 mm2).
G24M
FURNACE
CHIMNEY
OR GAS
VENT
FIGURE 1
Air from I side
If the confined space that houses the furnace adjoins a
space categorized as unconfined, air can be brought in by
providing two per anent openings between the two
spaces. Each opening ust have a ini u free area of 1
square inch (645 2) per 1,000 Btu (.29 kW) per hour of
total input rating of all gas-fired equip ent in the confined
space. Each opening ust be at least 100 square inches
(64516 2). One opening shall be within 12 inches (305
) of the top of the enclosure and one opening within 12
inches (305 ) of the botto . See figure 1.
Air from Outside
If air fro outside is brought in for co bustion and ventilaĆ
tion, the confined space ust have two per anent openĆ
ings. One opening shall be within 12 inches (305 ) of the
top of the enclosure and one opening within 12 inches (305
) of the botto . These openings ust co unicate diĆ
rectly or by ducts with the outdoors or spaces (crawl or atĆ
tic) that freely co unicate with the outdoors or indirectly
through vertical ducts. Each opening shall have a ini u
free area of 1 square inch (645 2) per 4,000 Btu (1.17
kW) per hour of total input rating of all equip ent in the enĆ
closure. See figures 2 and 3. When co unicating with
the outdoors through horizontal ducts, each opening shall
have a ini u free area of 1 square inch (645 2) per
2,000 Btu (.56 kW) per total input rating of all equip ent in
the enclosure. See figure 4.
When ducts are used, they shall be of the sa e cross-secĆ
tional area as the free area of the openings to which they
connect. The ini u di ension of rectangular air ducts
shall be no less than 3 inches (75 ). In calculating free
area, the blocking effect of louvers, grilles, or screens ust
be considered. If the design and free area of protective covĆ
ering is not known for calculating the size opening required,
it ay be assu ed that wood louvers will have 20 to 25 perĆ
cent free area and etal louvers and grilles will have 60 to
75 percent free area. Louvers and grilles ust be fixed in
the open position or interlocked with the equip ent so that
they are opened auto atically during equip ent operaĆ
tion.

Page 7
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
(I let Air from Crawlspace a d Outlet Air to
Ve tilated Attic)
NOTE-The inlet and outlet air openings shall each have a free area of at least one
square inch (645 2) per 4,000 Btu (1.17 kW) per hour of the total input rating of
all equipment in the enclosure.
VENTILATION LOUVERS
(Each end of attic)
OUTLET
AIR WATER
HEATER
INLET
AIR
CHIMNEY OR
GAS VENT
G24M
FURNACE
VENTILATION
LOUVERS
(For unheated crawl space)
FIGURE 2
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
(All Air Through Ve tilated Attic)
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 equipĆ
ment in the enclosure.
CHIMNEY
OR GAS
VENT
WATER
HEATER
OUTLET
AIR
VENTILATION LOUVERS
(Each end of attic)
INLET AIR
(Ends 12" above
botto )
G24M
FURNACE
FIGURE 3
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
OUTLET AIR
INLET AIR
WATER
HEATER
CHIMNEY
OR GAS
VENT
NOTE-Each air duct opening shall have a free area of at least
one square inch (645 mm2) 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 openĆ
ing shall 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.
G24M
FURNACE
FIGURE 4

Page 8
Setti g Equipme t
The Lennox G24M ulti-position gas furnace can be
installed as shipped in upflow position or in horizontal
position with right-hand or left-hand discharge. The furĆ
nace can easily be converted for downflow applications.
Select a location that allows for required clearances
listed on the unit rating plate. Also consider gas supply
connections, electrical supply, vent connection and
installation and service clearances [24 inches (610 )
at unit front].
NOTE - 1/3 and 1/2 hp blower motors are equipped with eiĆ
ther four flexible mounting legs or three flexible legs and
one rigid leg. The rigid leg is equipped with a shipping bolt
and a flat white plastic washer (rather than the rubber
mounting grommet used with a flexible mounting leg). This
shipping bolt and flat washer must be removed before the
furnace is put into operation. Once the shipping bolt and
washer are removed, the rigid leg will not touch the fan
housing.
Upflow Applicatio s
The Lennox G24M furnace is shipped in a standard upflow
position. Level the furnace using shi s or leveling bolts. AlĆ
low for clearances to co bustible aterials as indicated on
the unit rating plate. Mini u clearances for closet or alĆ
cove installations are shown in figure 5.
In upflow applications, return air can be brought in through
the botto or either side of the furnace. If a furnace with
botto return air is installed on a platfor , ake an airtight
seal between the botto of the furnace and the platfor to
ensure proper and safe operation.
Knockouts are provided on both sides of the furnace cabinet
for installations with side return air. When side return air is
used, seal the botto of the furnace using the panel provided.
An upflow filter rack is available and ust be ordered sepaĆ
rately. The adjustable rack can be installed beneath the furĆ
nace (flush with cabinet edges) for botto return air apĆ
plications or on the side of the furnace for side return air.
NOTE - A sheet metal filter puller is provided along with the
filter kit. In bottom return air applications, filter puller must
be installed between frame and filter to hold filter in place.
6 in. (152 )
0
0
2 in. (51 )
1 in. (25 )
Upflow Applicatio
I stallatio Cleara ces
Ve t
Co ector
Type Type C Type B1
TOP 1 in. (25 )
*FRONT 2 in. (51 )
BACK 0
SIDES 0
VENT 1 in. (25 )
0**FLOOR 0**
*Fro t cleara ce i alcove i stallatio must be 24 i . (610
mm). Mai tai a mi imum of 24 i . (610 mm) for fro t service
access.
** For i stallatio s o a combustible floor, do ot i stall the
fur ace directly o carpeti g, tile or other combustible mateĆ
rials other tha wood floori g.
RIGHT
SIDE
LEFT
SIDE
TOP
BOTTOM
FIGURE 5
UNIT CONVERSION FOR DOWNFLOW APPLICATION
REMOVE
TOP CAP
REMOVE
BOTTOM
REMOVE
FOUR
SCREWS
DISCONNECT
WIRE HARNESS AT
CONTROL BOARD
CONNECTOR
DISCONNECT
IGNITOR & SENSOR
LEADS
REINSTALL
TOP CAP ON
UNIT BOTTOM
REINSTALL
BOTTOM
ON UNIT
TOP
ROTATE HEAT
EXCHANGER
& REINSTALL
RECONNECT
IGNITOR & SENSOR
LEADS
UPFLOW CONFIGURATION DOWNFLOW CONFIGURATION
SINGLE-WALLED VENT
PIPE FROM COMBUSTION
AIR FAN FLUE ADAPTER TO
FURNACE FLUE OUTLET
(Fur ished by i staller)
RECONNECT WIRE
HARNESS AT
CONTROL BOARD
CONNECTOR
FIGURE 6

Page 9
Dow flow Applicatio s
The Lennox G24M furnace is shipped in the upflow configĆ
uration and ust be converted for downflow installation.
Refer to figure 6 and the following steps to convert the unit
for downflow installation:
1 - Place unit on its back and re ove access panel.
2 - Disconnect wire harness jackplug fro control board.
3 - Disconnect ignition lead fro control board.
4 - Re ove four screws securing cabinet top cap to cabiĆ
net.
5 - Re ove four screws holding heat exchanger asse Ć
bly in place. Slide heat exchanger out through top of
cabinet.
6 - Rotate heat exchanger 180o and slide back into cabiĆ
net through top. Resecure using four screws.
7 - Re ove four screws securing cabinet botto piece
to cabinet. Replace with cabinet top cap.
8 - Use four screws to install cabinet botto piece where
cabinet top was.
9 - Reconnect ignition lead to control board.
10- Reconnect wire harness jackplug to control board.
11- Replace unit access panel.
12- Use cord clip located o right side of fur ace to
hold wiri g away from hot surfaces i heati g
compartme t. Install two #10 sheet etal screws in
cabinet top to provide a better air seal.
In downflow applications, the unit can be installed in three difĆ
ferent ways: on non-co bustible flooring, on co bustible
floor using an additive base, or on a reverse-flow cooling cabĆ
inet. Do not drag unit across floor.
Allow clearances to co bustible aterials as outlined on
unit rating plate. Mini u clearances for closet or alcove
installations are outlined in figure 7.
NC**
DOWNFLOW APPLICATION
INSTALLATION CLEARANCES
VENT
CONNECTOR
TYPE
TYPE C TYPE B1
TOP 1 i . (25mm) 1 i . (25mm)
*FRONT 2 i . (51mm) 2 i . (51mm)
BACK
SIDES
VENT 6 i . (152mm) 1 i . (25mm)
NC - No -combustible floor
*Fro t cleara ce i alcove i stallatio must be
a mi . of 24 i . (610mm) for service access.
**With additive base o combustible floor.
BOTTOM NC**
1 i . (25mm) 1 i . (25mm)
1 i . (25mm) 1 i . (25mm)
TOP
BOTTOM
RIGHT
SIDE
LEFT
SIDE
FIGURE 7
A separate downflow filter kit is available for use in downĆ
flow applications.
A-I stallatio o No -Combustible Floori g
1 - Cut floor opening keeping in ind the clearances
listed on the unit rating plate. Also, keep in ind gas
supply and electrical supply, vent connections and
sufficient installation and service clearances. See
table 1 for correct floor opening size.
TABLE 1
NONCOMBUSTIBLE FLOOR OPENING
UNIT Fro t to Rear Side to Side
i mm i mm
G24M-45/60/75 502 388
NOTE-Floor opening dimensions listed are 1/4" (6mm) larger than
unit openings.
19-3/4 15-1/4
G24M-100/120 502 47719-3/4 18-3/4
G24M-140 502 54619-3/4 21-1/2
2 - Flange war air plenu and lower into opening.
3 - Set unit over plenu .
4 - Check to see that an adequate seal is ade.
B-I stallatio o Combustible Floori g
1 - When unit is installed on a co bustible floor, an addiĆ
tive base (ordered separately) ust be installed beĆ
tween the furnace and the floor. See table 2 for openĆ
ing size to cut in the floor.
TABLE 2
ADDITIVE BASE FLOOR OPENING
UNIT Fro t to Rear Side to Side
i mm i mm
G24M-45/60/75 556 440
NOTE-Floor opening dimensions listed are 1/4" (6mm) larger than
additive base openings.
21-7/8 17-5/16
G24M-100/120 556 52821-7/8 20-3/4
G24M-140 556 59721-7/8 23-1/2
G24M UNIT
SUPPLY AIR
PLENUM
ADDITIVE
BASE
PROPERLY
SIZED FLOOR
OPENING
1. Cut correct size floor ope i g
2. Set additive base i to ope i g.
3. Set supply air ple um i to additive base.
4. Set u it.
FIGURE 8

Page 10
2 - After opening is cut, set the additive base into opening.
3 - Check fiberglass strips on additive base to ake sure
they are properly glued and positioned.
4 - Lower supply air plenu into additive base until pleĆ
nu flanges seal against fiberglass strips.
5 - Set unit on additive base so unit flanges drop into pleĆ
nu . Refer to figure 8.
NOTE-Be careful not to damage fiberglass strips.
Check for tight seal.
C-I stallatio o Cooli g Cabi et
1 - Refer to reverseĆflow coil installation instructions for
correctly sized opening in floor and installation of cabiĆ
net.
2 - When cooling cabinet is in place, install furnace so
flanges drop inside cabinet opening.
3 - Seal cabinet and check for air leakage.
Horizo tal Applicatio s
The Lennox G24M furnace can be installed in horizontal
applications in either upflow or downflow configuration
(See figure 6). It is preferable to install the furnace in the
standard upflow configuration, if possible, because the
vent pipe will not interfere with service access for the blowĆ
er. Install two #10 screws in the cabinet botto (upflow conĆ
figuration) or cabinet top (downflow configuration) to proĆ
vide a better air seal. Do ot i stall the fur ace o its
back.
Horizo tal Applicatio
I stallatio Cleara ces
Ve t
Co ector
Type
Type C Type B1
TOP 00
*FRONT 2 in. (51 ) 2 in. (51 )
BACK 00
SIDES 2 in. (51 ) 2 in. (51 )
VENT 6 in. (152 ) 1 in. (25 )
FLOOR 0** 0**
*Fro t cleara ce i alcove i stallatio must be 24 i .
(610 mm). Mai tai a mi imum of 24 i . (610 mm) for
fro t service access.
** For i stallatio s o a combustible floor, do ot i stall
the fur ace directly o carpeti g, tile or other combusĆ
tible materials other tha wood floori g.
BOTTOM
TOP
RIGHT
SIDE
LEFT
SIDE
FIGURE 9
Allow for clearances to co bustible aterials as indicated
on the unit rating plate. Mini u clearances for closet or
alcove installations are shown in figure 9.
Furnaces ay be installed in either an attic or a crawlĆ
space. Either suspend the furnace fro roof rafters or floor
joists, as shown in figure 10, or install the furnace on a platĆ
for , as shown in figure 11.
NOTE - When the furnace is installed on a platform in a
crawlspace, it must be elevated enough to avoid water
damage and to allow the air conditioning coil to drain.
Horizo tal Applicatio
U it Suspe ded i Attic or Crawlspace
1/4 in. ROD
ANGLE
IRON
SUPPORT TIES TO
PREVENT SPREADING
Leave sufficient clearance between rod and unit to
re ove access panel.
FIGURE 10
Horizo tal Applicatio
U it I stalled o Platform
WORKING
PLATFORM
GAS
ENTRY
VENT
PIPE
NOTE - Line contact is perĆ
missible. See the unit rating
plate for clearances.
FIGURE 11

Page 11
WARNING
Improper i stallatio of the fur ace ca result i perĆ
so al i jury or death. Combustio a d flue products
must ever be allowed to e ter the retur air system
or the livi g space. Use screws a d joi t tape to seal
the retur air system to the fur ace.
I platform i stallatio s with bottom retur air, the
fur ace should be sealed airtight to the retur air pleĆ
um. A door must ever be used as a portio of the
retur air duct system. The base must provide a
stable support a d a airtight seal to the fur ace. AlĆ
low absolutely o saggi g, cracks, gaps, etc.
The retur a d supply air duct systems must ever
be co ected to or from other heati g devices such
as a fireplace or stove, etc. Fire, explosio , carbo
mo oxide poiso i g, perso al i jury a d/or properĆ
ty damage could result.
Duct System
Use industryĆapproved standards to size and install the
supply and return air duct syste . This will result in a quiet
and lowĆstatic syste that has unifor air distribution.
Supply Air Ple um
Furnaces installed without a cooling coil require the installaĆ
tion of a re ovable access panel in the supply air duct. The
access panel should be large enough to per it inspection (eiĆ
ther by s oke or reflected light) of the heat exchanger for
leaks after installation . The furnace access panel ust alĆ
ways be in place when the furnace is operating and it ust
not allow leaks into the supply air duct syste .
Retur Air Ple um
Retur air must ot be draw from a room where this
fur ace, or a y other gas applia ce (ie., a water heatĆ
er), is i stalled. When return air is drawn fro a roo ,
a negative pressure is created in the roo . If a gas apĆ
pliance is operating in a roo with negative pressure, the
flue products can be pulled back down the vent pipe and
into the roo . This reverse flow of the flue gas ay result
in inco plete co bustion and the for ation of carbon
onoxide gas. This toxic gas ight then be distributed
throughout the house by the furnace duct syste .
In upflow applications, return air can be brought in through
the botto or either side of the furnace. If a furnace with
botto return air is installed on a platfor , ake an airtight
seal between the botto of the furnace and the platfor to
ensure proper and safe operation. Use fiberglass sealing
strips between the plenu and the furnace cabinet to enĆ
sure a tight seal. If a filter is installed, size the return air duct
to fit the filter fra e.
In downflow applications, use the following steps when instalĆ
ling return air plenu :
1 - Flange botto edge of plenu with a he ed edge.
See figure 12.
2 - Use fiberglass sealing strips between plenu and the
unit cabinet to ensure a tight seal.
3 - In all cases, secure the plenu to the top flanges of the
furnace using sheet etal screws. See figure 12.
SECURE
HEMMED EDGE
PLENUM
CABINET
SIDE PANEL
FIBERGLASS
SEALING STRIP
FIGURE 12
4 - In closet installations, it ay be necessary to install
sheet etal screws fro the inside. If this is the case,
ake plenu with a re ovable front to install screws
as shown in figure 13.
SECURE FROM
INSIDE HEMMED EDGE
FIBERGLASS
SEALING STRIP
CABINET
SIDE PANEL
PLENUM
FIGURE 13
Ve ti g
A vent adapter is supplied with the furnace. It ust be
installed between the induced draft blower flue outlet and
the vent connector using one or two corrosion-resistant
sheet etal screws. Modificatio of, or failure to i stall,
the adapter will cause u safe u it operatio a d will
void A.G.A. a d C.G.A. u it certificatio . The vent conĆ
nector does not require insulation.
The G24M series units are classified as fan-assisted CateĆ
gory I furnaces when vertically vented according to the latest
edition of ANSI Z21.47 Central Furnace Standard in the
USA and the current standards of CAN/CGA B149.1 and
B149.2 of the Natural Gas and Propane Installation Code in
Canada. A fan-assisted Category I furnace is an appliance
equipped with an integral echanical eans to either draw
or force products of co bustion through the co bustion
cha ber and/or heat exchanger.
NOTE - Use these instructions as a guide. They do not suĆ
persede local codes.
The vent sizing tables in this anual were extracted fro
the National Fuel Gas Code (NFPA 54 / ANSI Z223.1) and
are provided as a guide for proper vent installation. Proper
application, ter ination, construction and location of vents
ust confor to local codes having jurisdiction. In the abĆ
sence of local codes, the NFGC serves as the defining docĆ
u ent.
Refer to the tables and the venting infor ation contained in
these instructions to properly size and install the venting
syste .
Install first vent connector elbow a ini u of 6 in.
(152 ) fro furnace vent outlet.

Page 12
Ve ti g Usi g a Maso ry Chim ey
The following additional require ents apply when a lined
asonry chi ney is used to vent an G24M furnace.
Masonry chi neys used to vent Category I central furĆ
naces ust be either tileĆlined or lined with a listed etal
lining syste or dedicated gas vent. Unlined asonry
chi neys are prohibited. See figures 14 and 15 for co Ć
on venting.
A Category I appliance ust never be connected to a chi Ć
ney that is servicing a solid-fuel appliance. If a fireplace
chi ney flue is used to vent this appliance, the fireplace
opening ust be per anently sealed.
A fan-assisted furnace ay be co only vented into an
existing lined asonry chi ney if the following conditions
are et:
1 - The chi ney is currently serving at least one draftĆ
hood equipped appliance.
2 - The vent connectors and chi ney are sized according
to the provided venting tables for the USA, and the apĆ
propriate venting tables in the standards of CAN/CGA
B149.1 and B149.2 of the Natural Gas and Propane
Installation Code in Canada.
IMPORTANT
SINGLE applia ce ve ti g of a fa Ćassisted furĆ
ace i to a tileĆli ed maso ry chim ey (i terior or
outside wall) is PROHIBITED. The chim ey must
first be li ed with either type B1 ve t or a i suĆ
lated si gle wall flexible ve t li i g system, sized
accordi g to the provided ve ti g tables.
A type B1 vent or asonry chi ney liner shall ter inate above
the roof surface with a listed cap or a listed roof asse bly acĆ
cording to the ter s of their respective listings and the vent
anufacturer's instructions.
Do not install a anual da per, baro etric draft regulator,
or flue restrictor between the furnace and the chi ney.
If type B1 doubleĆwall vent is used inside a chi ney, no othĆ
er appliance can be vented into the chi ney. Outer wall of
type B1 vent pipe ust not be exposed to flue products.
Insulation for the flexible vent pipe ust be an encapsuĆ
lated fiberglass sleeve reco ended by the flexible vent
pipe anufacturer. See figure 14.
The space betwee the li er a d the chim ey wall
should NOT be i sulated with puffed mica or a y other
loose gra ular i sulati g material.
If B1 vent or an insulated flexible vent pipe cannot be used
as liners, the chi ney ust be rebuilt to acco odate one
of these ethods or so e alternate approved ethod
ust be found to vent the appliance.
When inspection reveals that an existing chi ney is not safe
for the intended purpose, it shall be rebuilt to confor to naĆ
tionally recognized standards, lined or relined with suitable
aterials or replaced with a gas vent or chi ney suitable for
venting G24M series units. The chi ney passageway ust
be checked periodically to ensure that it is clear and free of
obstructions.
Commo Ve ti g Usi g
Metal-li ed Maso ry Chim ey
4 i . (102 mm)
mi imum
5 ft. (1.5 m)
mi imum MIN. LENGTH -- AS
SHORT AS PRACTICAL
MAX. LENGTH
-- SEE NOTE 1
BELOW.
SEALED
PERMANENTLY
SEALED FIREPLACE
OPENING
EXTERIOR
CHIMNEY WITH
B1 VENT OR
INSULATED
FLEXIBLE
VENT PIPE.
VENT CONNECTOR
SEE NOTE 2
NOTE 1 - Refer to the provided venting tables for installations in the USA and the
venting tables in CAN/CGA-B1 9.1 for installations Canada.
NOTE 2 - Either singleĆwalled or doubleĆwalled vent connector may be
used. Refer to the capacity requirements shown in the provided venting
tables for installations in USA and the venting tables in current CAN/
CGA-B1 9.1 for installations in Canada.
G24M
OTHER
APPLIANCE
FIGURE 14

Page 13
Commo Ve ti g Usi g Tile-li ed I terior Maso ry
Chim ey a d Combi ed Ve t Co ector
G24M
OTHER
APPLIANCE
MINIMUM LENGTH = AS SHORT AS PRACTICAL.
FOR MAXIMUM LENGTH SEE NOTE TO LEFT
INTERIOR TILE-LINED
MASONRY CHIMNEY
NOTE - chimney must be properly
sized per provided venting tables
or lined with listed metal lining
system.
PERMANENTLY
SEALED FIREPLACE
OPENING
VENT
CONNECTOR
SEE NOTE 1 BELOW
Note 1 - Either singleĆwalled or doubleĆwalled vent connector may be used. Refer to the capacity requirements as shown in the proĆ
vided venting tables for installations in USA and the venting tables in current CAN/CGA-B1 9.1 for installations in Canada.
NOTE- Refer to provided venting tables
for installations in the USA and the
venting tables in current CAN/CGA-
B1 9.1 for installations in Canada.
FIGURE 15
Ge eral Ve ti g Requireme ts
All G24M furnaces ust be vented according to these
instructions.
1 - Vent dia eter reco endations and axi u alĆ
lowable piping runs are found in the provided venting
tables for the USA, and the appropriate venting tables
in the standards of CAN/CGA B149.1 and B149.2 of
the Natural Gas and Propane Installation Code for
Canada.
2 - In no case should the vent or vent connector dia eter
be less than the dia eter specified in the provided
venting tables for the USA, and the appropriate ventĆ
ing tables in the standards of CAN/CGA B149.1 and
B149.2 of the Natural Gas and Propane Installation
Code for Canada.
3 - For single appliance vents: If the vertical vent or tileĆ
lined chi ney has a larger dia eter or flow area than
the vent connector, use the vertical vent diameter to
deter ine the minimum vent capacity and the ve t
co ector diameter to deter ine the maximum
ve t capacity. The flow area of the vertical vent, howĆ
ever, shall not exceed 7 ti es the flow area of the
listed appliance categorized vent area, drafthood outĆ
let area or flue collar area unless designed according
to approved engineering ethods.
4 - For multiple appliance vents: The flow area of the largĆ
est section of vertical vent or chi ney shall not exceed
7 ti es the s allest listed appliance categorized vent
area, drafthood outlet area or flue collar area unless
designed according to approved engineering ethĆ
ods.
5 - The entire length of single wall etal vent connector
shall be readily accessible for inspection, cleaning,
and replace ent.
6 - Single appliance venting configurations with zero latĆ
eral lengths, see tables 4 and 5, are assu ed to have
no elbows in the vent syste . For all other vent configĆ
urations, the vent syste is assu ed to have two 90_
elbows. For each additional 90_ elbow or equivalent
(for exa ple two 45_ elbows equal one 90_ elbow) beĆ
yond two, the axi u capacity listed in the venting
table should be reduced by 10 percent (0.90 x axiĆ
u listed capacity).
7 - The co on venting tables 6, 7, 8, and 9 were generĆ
ated using a axi u horizontal vent connector
length of 1-1/2 feet (.46 ) for each inch (25 ) of
connector dia eter as follows:
TABLE 3
Co ector
Diameter
i ches (mm)
Maximum Horizo tal
Co ector Le gth
feet (m)
3 (76) 4-1/2 (1.37)
4 (102) 6 (1.83)
5 (127) 7-1/2 (2.29)
6 (152) 9 (2.74)
7 (178) 10-1/2 (3.20)

Page 14
8 - If the co on vertical vent is offset, the axi u
co on vent capacity listed in the co on venting
tables should be reduced by 20%, the equivalent of
two 90_ elbows (0.80 x axi u co on vent caĆ
pacity). The horizontal length of the offset shall not exĆ
ceed 1Ć1/2 feet (.46 ) for each inch (25 ) of co Ć
on vent dia eter.
9 - The vent pipe should be as short as possible with
the least nu ber of elbows and angles required to
co plete the job. The vent connector should be
routed to the vent using the shortest possible route.
10 - A vent connector shall be supported without any dips
or sags and shall slope a ini u of 1/4 inch (6.4
) per linear foot (305 ) of connector, back toĆ
ward the appliance. See local and national installation
codes for support intervals and methods. National
installation code in the U.S.A is current edition of Na-
tional fuel Gas Code (ANSI–Z223.1). National installa-
tion codes in Canada are current editions of CAN/
CGA–B149 codes.
11 - Vent connectors shall be fir ly attached to furnace
flue collars by screws or other approved eans, exĆ
cept vent connectors of listed type B vent aterial
which shall be asse bled according to the anufacĆ
turer's instructions. Joints between sections of single
wall connector piping shall be fastened by screws or
other approved eans.
12 - When the vent connector used for Category I apĆ
pliances ust be located in or pass through a crawlĆ
space or other areas which ay be cold, that portion of
the vent connector shall be constructed of listed
doubleĆwall type B vent aterial or aterial having
equivalent insulation qualities.
13 - All venting pipe passing through floors, walls, and ceilĆ
ings ust be installed with the listed clearance to co Ć
bustible aterials and be fire stopped according to loĆ
cal codes. In absence of local codes, refer to NFGC
(Z223.1).
14 - No portion of the venting syste can extend into, or pass
through any circulation air duct or plenu .
15 - Vent connectors serving Category I appliances shall
not be connected to any portion of echanical draft
syste s operating under positive pressure such as
Category III or IV venting syste s.
16 - If vent connectors are co bined prior to entering the
co on vent, the axi u co on vent capacity
listed in the co on venting tables ust be reduced by
10%, the equivalent of one 90_ elbow (0.90 x axi u
co on vent capacity).
17 - The co on vent dia eter ust always be at least as
large as the largest vent connector dia eter.
18 - In no case, shall the vent connector be sized ore
than two consecutive table size dia eters over the
size of the draft hood outlet or flue collar outlet.
19 - Do not install a anual da per, baro etric draft reguĆ
lator or flue restrictor between the furnace and the
chi ney.
20 - When connecting this appliance to an existing dedicated
or co on venting syste , the venting syste ust be
inspected for signs of corrosion and general condition.
The sizing of the vent syste ust be reviewed and
ust confor to these instructions and the provided
venting tables for the USA, and the appropriate venting
tables in the standards of CAN/CGA B149.1 and
B149.2 of the Natural Gas and Propane Installation
Code for Canada. If the existing syste is in conflict with
these require ents, the venting syste ust be reĆ
sized.

Page 15
TABLE 4
CAPACITY OF TYPE B DOUBLE-WALL VENTS WITH TYPE B DOUBLE-WALL CONNECTORS
SERVING A SINGLE CATEGORY I APPLIANCE
Ve t a d Co ector Diameter - D (i ches)
Height
H
Lateral
L
3 I ch 4 I ch 5 I ch 6 I ch
H
(
feet
)
L
(
feet
)
Applia ce I put Rati g i Thousa ds of Btu Per Hour
(feet)
(feet)
MIN MAX MIN MAX MIN MAX MIN MAX
0 0 78 0 152 0 251 0 375
6
2 13 51 18 97 27 157 32 232
64 21 49 30 94 39 153 50 227
6 25 46 36 91 47 149 59 223
0 0 84 0 165 0 276 0 415
8
2 12 57 16 109 25 178 28 263
85 23 53 32 103 42 171 53 255
8 28 49 39 98 51 164 64 247
0 0 88 0 175 0 295 0 447
10
2 12 61 17 118 23 194 26 289
10 5 23 57 32 113 41 187 52 280
10 30 51 41 104 54 176 67 267
0 0 94 0 191 0 327 0 502
211 69 15 136 20 226 22 339
15 5 22 65 30 130 39 219 49 330
10 29 59 40 121 51 206 64 315
15 35 53 48 112 61 195 76 301
0 0 97 0 202 0 349 0 540
2 10 75 14 149 18 250 20 377
20
5 21 71 29 143 38 242 47 367
20 10 28 64 38 133 50 229 62 351
15 34 58 46 124 59 217 73 337
20 48 52 55 116 69 206 84 322
0 0 100 0 213 0 374 0 587
2 9 81 13 166 14 283 18 432
5 21 77 28 160 36 275 45 421
30 10 27 70 37 150 48 262 59 405
15 33 64 44 141 57 249 70 389
20 56 58 53 132 66 237 80 374
30 NR NR 73 113 88 214 104 346
NOTE: Single appliance venting configurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other vent configurations, the vent
system is assumed to have two 90_ elbows. For each additional 90_ elbow or equivalent (for example two 45_ elbows equal one 90_ elbow) beyond two, the maximum
capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).

Page 16
TABLE 5
CAPACITY OF TYPE B DOUBLE-WALL VENTS WITH SINGLE-WALL METAL CONNECTORS
SERVING A SINGLE CATEGORY I APPLIANCE
Ve t a d Co ector Diameter - D (i ches)
Height
H
Lateral
L
3 I ch 4 I ch 5 I ch 6 I ch
H
(
feet
)
L
(
feet
)
Applia ce I put Rati g i Thousa ds of Btu Per Hour
(feet)
(feet)
MIN MAX MIN MAX MIN MAX MIN MAX
0 38 77 59 151 85 249 126 373
6
2 39 51 60 96 85 156 123 231
64 NR NR 74 92 102 152 146 225
6 NR NR 83 89 114 147 163 220
0 37 83 58 164 83 273 123 412
8
2 39 56 59 108 83 176 121 261
85 NR NR 77 102 107 168 151 252
8 NR NR 90 95 122 161 175 243
0 37 87 57 174 82 293 120 444
10
2 39 61 59 117 82 193 119 287
10 5 52 56 76 111 105 185 148 277
10 NR NR 97 100 132 171 188 261
0 36 93 56 190 80 325 116 499
2 38 69 57 136 80 225 115 337
15 5 51 63 75 128 102 216 144 326
10 NR NR 95 116 128 201 182 308
15 NR NR NR NR 158 186 220 290
0 35 96 54 200 78 346 114 537
2 37 74 56 148 78 248 113 375
20
5 50 68 73 140 100 239 141 363
20 10 NR NR 93 129 125 223 177 344
15 NR NR NR NR 155 208 216 325
20 NR NR NR NR 186 192 254 306
0 34 99 53 211 76 372 110 584
2 37 80 55 164 76 281 109 429
5 49 74 72 157 98 271 136 417
30 10 NR NR 91 144 122 255 171 397
15 NR NR 115 131 151 239 208 377
20 NR NR NR NR 181 223 246 357
30 NR NR NR NR NR NR NR NR
NOTE: Single appliance venting configurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other vent configurations, the vent
system is assumed to have two 90_ elbows. For each additional 90_ elbow or equivalent (for example two 45_ elbows equal one 90_ elbow) beyond two, the maximum
capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).

Page 17
TABLE 6
CAPACITY OF TYPE B DOUBLE-WALL VENTS WITH TYPE B DOUBLE-WALL CONNECTORS
SERVING TWO OR MORE CATEGORY I APPLIANCES
VENT CONNECTOR CAPACITY
Ve t
Co ector
Ve t a d Co ector Diameter - D (i ches)
V
e
t
Hei
g
ht
C
o ec
t
or
Rise 3 I ch 4 I ch 5 I ch 6 I ch
Height
H
(feet)
Rise
R
(feet)
Applia ce I put Rati g i Thousa ds of Btu Per Hour
(feet) (feet) MIN MAX MIN MAX MIN MAX MIN MAX
1 22 37 35 66 46 106 58 164
62 23 41 37 75 48 121 60 183
6
3 24 44 38 81 49 132 62 199
1 22 40 35 72 49 114 64 176
82 23 44 36 80 51 128 66 195
3 24 47 37 87 53 139 67 210
1 22 43 34 78 49 123 65 189
10 2 23 47 36 86 51 136 67 206
3 24 50 37 92 52 146 69 220
1 21 50 33 89 47 142 64 220
15 2 22 53 35 96 49 153 66 235
3 24 55 36 102 51 163 68 248
1 21 54 33 99 46 157 62 246
20 2 22 57 34 105 48 167 64 259
3 23 60 35 110 50 176 66 271
1 20 62 31 113 45 181 60 288
30 2 21 64 33 118 47 190 62 299
3 22 66 34 123 48 198 64 309
TABLE 7
CAPACITY OF TYPE B DOUBLE-WALL VENTS WITH TYPE B DOUBLE-WALL CONNECTORS
SERVING TWO OR MORE CATEGORY I APPLIANCES
COMMON VENT CAPACITY
Ve t
Commo Ve t Diameter - D (i ches)
V
e
t
Hei
g
ht 4 I ch 5 I ch 6 I ch 7 I ch
Height
H
(feet)
Applia ce I put Rati g i Thousa ds of Btu Per Hour
(feet) FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT
6 92 81 140 116 204 161 309 248
8 101 90 155 129 224 178 339 275
10 110 97 169 141 243 194 367 299
15 125 112 195 164 283 228 427 352
20 136 123 215 183 314 255 475 394
30 152 138 244 210 361 297 547 459

Page 18
TABLE 8
CAPACITY OF TYPE B DOUBLE-WALL VENT WITH SINGLE-WALL METAL CONNECTORS
SERVING TWO OR MORE CATEGORY I APPLIANCES - VENT CONNECTOR CAPACITY
Ve t
Co ector
Ve t a d Co ector Diameter - D (i ches)
V
e
t
Hei
g
ht
C
o ec
t
or
Rise 3 I ch 4 I ch 5 I ch 6 I ch
Height
H
(feet)
Rise
R
(feet)
Applia ce I put Rati g i Thousa ds of Btu Per Hour
(feet) (feet) MIN MAX MIN MAX MIN MAX MIN MAX
1 NR NR NR NR NR NR NR NR
62 NR NR NR NR NR NR 168 182
6
3 NR NR NR NR 121 131 174 198
1 NR NR 79 87 116 138 177 214
15 2 NR NR 83 94 121 150 185 230
3 NR NR 87 100 127 160 193 243
1 47 60 77 110 113 175 169 278
30 2 50 62 81 115 117 185 177 290
3 54 64 85 119 122 193 185 300
TABLE 9
CAPACITY OF TYPE B DOUBLE-WALL VENTS WITH SINGLE-WALL METAL CONNECTORS
SERVING TWO OR MORE CATEGORY I APPLIANCES - COMMON VENT CAPACITY
Ve t
Commo Ve t Diameter - D (i ches)
V
e
t
Hei
g
ht 4 I ch 5 I ch 6 I ch 7 I ch
Height
H
(feet)
Applia ce I put Rati g i Thousa ds of Btu Per Hour
(feet) FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT
6 89 78 136 113 200 158 304 244
8 98 87 151 126 218 173 331 269
10 106 94 163 137 237 189 357 292
15 121 108 189 159 275 221 416 343
20 131 118 208 177 305 247 463 383
30 145 132 236 202 350 286 533 446
Removal of U it from Commo Ve t
In the event that an existing furnace is re oved fro a
venting syste co only run with separate gas apĆ
pliances, the venting syste is likely to be too large to
properly vent the re aining attached appliances. The folĆ
lowing test should be conducted while each appliance in
operation and the other appliances not in operation reĆ
ain connected to the co on venting syste . If the
venting syste has been installed i properly, the syste
ust be corrected as indicated in the general venting reĆ
quire ents section.
1 - Seal any unused openings in the co on venting
syste .
2 - Visually inspect the venting syste for proper size and
horizontal pitch. Deter ine there is no blockage or reĆ
striction, leakage, corrosion, or other deficiencies which
could cause an unsafe condition.
3 - To the extent that it is practical, close all building doors
and windows and all doors between the space in
which the appliances re aining connected to the
co on venting syste are located and other spaces
of the building. Turn on clothes dryers and any apĆ
pliances not connected to the co on venting sysĆ
te . Turn on any exhaust fans, such as range hoods
and bathroo exhausts, so they will operate at axiĆ
u speed. Do not operate a su er exhaust fan.
Close fireplace da pers.
4 - Follow the lighting instructions. Place the appliance
being inspected in operation. Adjust ther ostat so apĆ
pliance will operate continuously.
5 - Test for spillage of flue gases at the draft hood relief
opening after 5 inutes of ain burner operation. Use
the fla e of a atch or candle, or s oke fro a cigaĆ
rette, cigar or pipe.
6 - After deter ining that each appliance re aining conĆ
nected to the co on venting syste properly vents
when tested as indicated in step 3, return doors, winĆ
dows, exhaust fans, fireplace da pers and any other
gasĆburning appliance to their previous condition of
use.
7 - If i proper venting is observed during any of the
above tests, the co on venting syste ust be corĆ
rected. The co on venting syste should be reĆ
sized to approach the ini u size as deter ined by
using the appropriate tables in appendix G in the curĆ
rent standards of the National Fuel Gas Code ANSI
Z223.1 in the USA, and the appropriate Category 1
Natural Gas and Propane appliances venting sizing
tables in the current standards of the CAN/CGA
B149.1 and B149.2 in the Natural Gas and Propane
Installation Code in Canada.

Page 19
Gas Pipi g
Gas Supply
1 - This unit is shipped standard for left or right side instalĆ
lation of gas piping (or top entry in horizontal applicaĆ
tions). Connect the gas supply to the piping asse bly.
2 - When connecting the gas supply, factors such as
length of run, nu ber of fittings and furnace rating
ust be considered to avoid excessive pressure drop.
Table 10 lists reco ended pipe sizes for typical apĆ
plications.
3 - The gas piping ust not run in or through air ducts,
clothes chutes, gas vents or chi neys, du b waiters
or elevator shafts.
4 - The piping should be sloped 1/4 inch (6.4 ) per 15 feet
(4.57 ) upward toward the eter fro the furnace. The
piping ust be supported at proper intervals [every 8 to
10 feet (2.44 to 3.01 ) using suitable hangers or straps.
A drip leg should be installed in vertical pipe runs to the
unit.
5 - In so e localities, codes ay require installation of a
anual ain shutĆoff valve and union (furnished by
the installer) external to the unit. Union ust be of the
ground joint type.
IMPORTANT
Compou ds used o threaded joi ts of gas pipi g
must be resista t to the actio s of liquified petroĆ
leum gases.
NOTE - Install a 1/8 inch NPT plugged tap in the field piping
upstream of the gas supply connection to the unit. The tap
must be accessible for test gauge connection. See figure 16.
NOTE - In case emergency shutoff is required, shut off main
manual gas valve and disconnect main power to unit. These
devices should be properly labeled by the installer.
TABLE 10
GAS PIPE CAPACITY - FT3/HR (M3/HR)
Nomi al I ter al Le gth of Pipe - feet (m)
Nomi al
Iro Pipe Size
i ches (mm)
I ter al
Diameter
i ches (mm) 10
(3.048)
20
(6.096)
30
(9.144)
40
(12.192)
50
(15.240)
60
(18.288)
70
(21.336)
80
(24.384)
90
(27.432)
100
(30.480)
1/4
(6.35)
.364
(9.246)
43
(1.13)
29
(.82)
24
(.68)
20
(.57)
18
(.51)
16
(.45)
15
(.42)
14
(.40)
13
(.37)
12
(.34)
3/8
(9.53)
.493
(12.522)
95
(2.69)
65
(1.84)
52
(1.47)
45
(1.27)
40
(1.13)
36
(1.02)
33
(.73)
31
(.88)
29
(.82)
27
(.76)
1/2
(12.7)
.622
(17.799)
175
(4.96)
120
(3.40)
97
(2.75)
82
(2.32)
73
(2.07)
66
(1.87)
61
(1.73)
57
(1.61)
53
(1.50)
50
(1.42)
3/4
(19.05)
.824
(20.930)
360
(10.19)
250
(7.08)
200
(5.66)
170
(4.81)
151
(4.28)
138
(3.91)
125
(3.54)
118
(3.34)
110
(3.11)
103
(2.92)
1
(25.4)
1.049
(26.645)
680
(919.25)
465
(13.17)
375
(10.62)
320
(9.06)
285
(8.07)
260
(7.36)
240
(6.80)
220
(6.23)
205
(5.80)
195
(5.52)
1-1/4
(31.75)
1.380
(35.052)
1400
(39.64)
950
(26.90)
770
(21.80)
660
(18.69)
580
(16.42)
530
(15.01)
490
(13.87)
460
(13.03)
430
(12.18)
400
(11.33)
1-1/2
(38.1)
1.610
(40.894)
2100
(59.46)
460
(41.34)
1180
(33.41)
990
(28.03)
900
(25.48)
810
(22.94)
750
(21.24)
690
(19.54)
650
(18.41)
620
(17.56)
2
(50.8)
2.067
(52.502)
3950
(111.85)
2750
(77.87)
2200
(62.30)
1900
(53.80)
1680
(47.57)
1520
(43.04)
1400
(39.64)
1300
(36.81)
1220
(34.55)
1150
(32.56)
2-1/2
(63.5)
2.469
(67.713)
6300
(178.39)
4350
(123.17)
3520
(99.67)
3000
(84.95
2650
(75.04)
2400
(67.96)
2250
(63.71)
2050
(58.05)
1950
(55.22)
1850
(52.38)
3
(76.2)
3.068
(77.927)
11000
(311.48)
7700
(218.03)
6250
(176.98)
5300
(150.07)
4750
(134.50)
4300
(121.76)
3900
(110.43)
3700
(104.77)
3450
(97.69)
3250
(92.03)
4
(101.6)
4.026
(102.260)
23000
(651.27)
15800
(447.39)
12800
(362.44)
10900
(308.64)
9700
(274.67)
8800
(249.18)
8100
(229.36)
7500
(212.37)
7200
(203.88)
6700
(189.72)
NOTE-Capacity given in cubic feet (m3 ) of gas per hour and based on 0.60 specific gravity gas.

Page 20
GROUND
JOINT
UNION
AUTOMATIC
GAS VALVE
(with anual
shut-off valve)
FIELD
PROVIDED
AND INSTALLED
GROUND
JOINT
UNION
Left Side Pipi g
(Sta dard)
Right Side Pipi g
(Alter ate)
AUTOMATIC
GAS VALVE
(with anual
shut-off valve)
DRIP LEG
DRIP LEG
MANUAL
MAIN SHUT-OFF
VALVE
(With 1/8 in. NPT
Plugged Tap Shown)
MANUAL
MAIN SHUT-OFF
VALVE
(With 1/8 in. NPT
Plugged Tap
Shown)
FIGURE 16
Leak Check
After gas piping is co pleted, carefully check all piping
connections (factory- and field-installed) for gas leaks. Use
a leak detecting solution or other preferred eans.
CAUTION
Some soaps used for leak detectio are corrosive to
certai metals. Carefully ri se pipi g thoroughly afĆ
ter leak test has bee completed. Do ot use
matches, ca dles, flame or other sources of ig itio
to check for gas leaks.
NOTE - In case emergency shutoff is required, shut off the
main manual gas valve and disconnect the main power to
the furnace. These devices should be properly labeled by
the installer.
The furnace must be isolated from the gas supply system
by closing its individual manual shutĆoff valve during any
pressure testing of the gas supply system at pressures
equal to or less than 1/2 psig (3.48 kPa).
IMPORTANT
Whe testi g pressure of gas li es, gas valve must
be disco ected a d isolated. See figure 17. Gas
valves ca be damaged if subjected to more tha 1/2
psig (3.48 kPa).
MANUAL MAIN
SHUT-OFF VALVE
WILL NOT HOLD
NORMAL TEST
PRESSURE
CAP
ISOLATE
GAS VALVE
FURNACE
FIGURE 17
Electrical
ELECTROSTATIC DISCHARGE (ESD)
Precautio s a d Procedures
CAUTION
Electrostatic discharge ca affect electro ic comĆ
po e ts. Take precautio s duri g fur ace i stallaĆ
tio a d service to protect the fur ace's electro ic
co trols. Precautio s will help to avoid co trol exĆ
posure to electrostatic discharge by putti g the furĆ
ace, the co trol a d the tech icia at the same
electrostatic pote tial. Neutralize electrostatic
charge by touchi g ha d a d all tools o a u Ć
pai ted u it surface, such as the gas valve or blowĆ
er deck, before performi g a y service procedure.
These units operate on 240 volt, single phase, 50 hz
electrical power. Refer to figure 18 for field wiring and
figure 20 for sche atic wiring diagra and troubleĆ
shooting.
1 - Select circuit protection and wire size according to the
unit rating plate.
2 - Knockouts are provided on both sides of the furnace
cabinet to facilitate wiring.
3 - Install the roo ther ostat according to instructions
provided with the ther ostat.
4 - Install a separate disconnect switch (protected by eiĆ
ther fuse or circuit breaker) near the unit so power can
be turned off for servicing.
5 - Before connecting the ther ostat or the power wiring,
check to ake sure the wires will be long enough to
facilitate servicing at a later date. Re ove the blower
access panel and open the panel to check wire length
for access.
6 - Co plete wiring connections to the equip ent using
wiring diagra s provided with unit and in field wiring diaĆ
gra s shown in figures 18. Use 18 gauge wire or larger
for ther ostat connections.