Lennox G24MCE2-45, G24MCE3-60, G24MCE3-75, G24MCE4-75, G24MCE4-100 Installation Instructions Manual
...
INSTALLATION
2000 Lennox Industries Inc.
Dallas, Texas
PRODUCT LITERATURE
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
INSTRUCTIONS
G24MCE Series
GAS-FIRED FURNACE
Direct Spark Ignition
503,956M
05/2000
Supersedes 11/99
Table of Contents
G24MCE Unit Dimensions 2. . . . . . . . . . . . . . . . . . . .
G24MCE GasĆFired Furnace 3. . . . . . . . . . . . . . . . . .
Shipping and Packing List 3. . . . . . . . . . . . . . . . . . . . .
Requirements 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution & Ventilation Air 4. . . . . . . . . .
Setting Equipment 6. . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Venting 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vertical Flue Using Metal Flue Pipe 9. . . . . . . . . . .
Vertical Flue Using Lined Masonry Chimney 11. .
Horizontal Flue Using Metal Flue Pipe 12. . . . . . .
Gas Piping 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start-up 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Adjustments 19. . . . . . . . . . . . . . . . . . . . . . . . . . .
Service 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Technical Data Table 22. . . . . . . . . . . . . . . . . . . . . . . .
Ignition Control Board Diagnostic Codes 23. . . . . . .
Troubleshooting 24. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 27. . . . . . . . . . . . . . . . . . . . . . . . . . . .
G24MCE Parts Arrangement 27. . . . . . . . . . . . . . . . .
G24MCE Start-up & Performance Check List 28. . .
Litho USA
If the information in this manual is not
followed exactly, a fire or explosion
may result causing property damage,
personal injury or loss of life.
Do not store or use petrol or other
flammable vapours and liquids in the
vicinity of this or any other appliance.
Installation and service must be perĆ
formed by a qualified installer, serĆ
vice agency or the gas supplier.
WARNING
WHAT TO DO IF YOU SMELL GAS:
Do not try to light any appliance.
Extinguish any open flames.
Do not touch any electrical switch; do not
use any telephone in your building.
Immediately call your gas supplier from a
neighbor's telephone. Follow the gas supĆ
plier's instructions.
If you cannot reach your gas supplier, call
the local fire brigade.
Page 1
G24MCE Unit Dimensions - millimeters
G24MCE4/5Ć100
GAS PIPING
INLET
G24MCE Series
D
Unit shown in upflow position. Rotate 180° for
downflow applications and 90° clockwise or
counterclockwise for horizontal applications.
*NOTE - The supply air opening is equipped with a 19 mm scored
flange that may be bent 90_ for plenum connection.
The dimensions shown were taken after
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 495 mm or 483 mm.
the flange was bent.
A
AIR FLOW
FLUE
OUTLET
F Left Side
G Right Side
ELECTRICAL INLETS
(Top & Bottom)
25
E
105
*C
25
*495
*483
SUPPLY
AIR
OPENING
25
25
TOP VIEW
752
51
GAS PIPING
INLET
(Both Sides)
B
ELECTRICAL
INLETS
(Both Sides)
381
**NOTEĊ The return air opening is
equipped with a 19 mm scored flange
Return Air
**C
Opening
FRONT VIEW
Model No. A B C D E F G
G24MCE2Ć45
G24MCE3Ć60/75
G24MCE4Ć75
G24MCE4/5Ć100
G24MCE4/5Ć120
G24MCE4/5Ć140 mm 591 991 540 248 108 329 180
mm 432 921 381 171 62 293 165
mm 521 991 470 213 108 331 203
that may be bent 90_ for plenum conĆ
2525 25
nection. The dimensions shown were
taken after
the flange was bent.
SIDE VIEW
495
RETURN AIR
KNOCKOUT
(Either Side)
19
495
Return Air
Opening
25
Page 2
G24MCE GasĆFired Furnace
The G24MCE multi-position gas furnace is shipped ready
for installation in the upflow position. The unit can easily
be converted for installation in either downflow or horizonĆ
tal applications. The furnace is shipped with a bottom seal
panel in place for side return air in upflow applications.
Shipping and Packing List
Package 1 of 1 contains:
1 - Assembled unit
1 - Flue adapter (requires fieldĆinstallation)
1 - Upflow/horizontal filter rack
1 - Filter
The following additional items may be ordered separately,
if required:
1 - Additive base (downflow applications)
1 - Thermostat
1 - Hanging bracket kit
1 - External filter rack kit (downflow applications)
1 - LP Changeover kit
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
Requirements
Lennox G24MCE units carry CE marking and are certified
for installation in the following countries using the gas
categories shown:
II
: GB, IE, ES, PT and CH
2H3P
I
: DK and IT
2H
II
: NL
2L3P
II
: FR
2Er3P
I
and I
2ELL
*I
2E+(S)
* Units for installation in Belgium are set and sealed for use with
G20 reference gas and must not
Units must be adjusted or converted in accordance with
specific instructions provided by Lennox Industries prior
to installation or use in the other countries listed.
These appliances must only be installed, adjusted, conĆ
verted or serviced by properly qualified personnel. Failure
to comply with this requirements may result in a dangerĆ
ous situation.
The installation must comply with all relevant local and
national gas, electrical, building and fire regulations.
Proper ventilation is essential for safe operation and must
be provided as detailed in these instructions.
The flue system must be properly designed to comply with
any relevant regulations and the requirements set out in
these instructions.
Installation clearances must be provided around the apĆ
pliance and access provided for servicing requirements.
See figures 5, 7 and 9.
:DE
3P
:BE
be adjusted by installer.
Before installation, check that the local distribution condiĆ
tions, nature of gas and pressure and adjustment of the
appliance are compatible.
NOTE-For installation on combustible floors, appliance shall
not be installed directly on carpeting, tile, or combustible maĆ
terial such as wood flooring. Protection via a non-combusĆ
tible material must be provided.
The G24MCE unit must not be installed in a residential
or commercial garage.
Unit must be adjusted to obtain a temperature rise within the
range specified on appliance rating plate.
G24MCE unit must be installed so that electrical compoĆ
nents are protected from water.
When furnace is used in conjunction with cooling units, it
shall be installed on the upstream side of cooling units to
avoid condensation in the heating compartment.
When installed, furnace must be electrically earthed in
accordance with national regulations.
Electrical supply must be properly fused and should be
provided with means of isolating the unit from the supply.
When the furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside of the space
containing the furnace, return air shall be handled by a
duct(s) sealed to the furnace casing and terminating outĆ
side of the space containing the furnace.
NOTE Ċ G24MCE series units must not be used as a
construction furnace" at any time during any phase of
construction. Very low return air temperatures, harmful
vapors and misplacement of the filters will damage the
unit and its efficiency.
The Lennox G24MCE furnace may be installed in alĆ
coves, cupboards, attics, basements, and utility rooms in
any of its approved installation positions.
The G24MCE unit must not be installed in a residential
or commercial garage.
The air furnace must not be installed in a room conĆ
taining a bath or shower. In addition, it is recomĆ
mended that the furnace should not be fitted in a bedĆ
room.
A compartment used to enclose the air furnace must be
designed and constructed specifically for this purpose.
An existing cupboard or compartment may be used proĆ
vided that it is modified for the purpose.
WARNING
The Fan door must be securely in place when the
fan and burners are operating. Gas fumes, which
could contain carbon monoxide, can be drawn into
living space resulting in personal injury or death.
General
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
Page 3
In addition to the requirements outlined previously, the folĆ
lowing general recommendations should be considered
when installing the Lennox G24MCE furnace.
The furnace should be placed as close to the center of the
air distribution system as possible. The furnace should
also be located close to the chimney or vent termination
point.
Do not install the furnace where draughts might blow diĆ
rectly into it. This could cause improper combustion and
unsafe operation.
Do not block furnace combustion air openings with clothĆ
ing, boxes, doors, etc. Combustion air is needed for propĆ
er combustion and safe unit operation.
When the furnace is installed in an attic or other insulated
space, keep insulation away from the furnace.
WARNING
Product contains glass fibre.
Surface tears due to rough handling during shipĆ
ping or installation should be repaired straight
away to avoid respiratory, skin and eye irritation.
Combustion, Dilution & Ventilation Air
In the past, there was no problem in bringing in sufficient outĆ
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 combustion.
Take into account that exhaust fans, appliance vents, chimĆ
neys, 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 chimĆ
ney. As a result, combustion gases enter the living space
creating a potentially dangerous situation.
In the absence of local codes concerning air for combustion
and ventilation, this section outlines guidelines and recomĆ
mends procedures for installing G24MCE Furnaces in a
manner that ensures efficient and safe operation. Special
consideration must be given to combustion air needs as
well as requirements for exhaust vents and gas piping.
CAUTION
Do not install furnace in a corrosive or contaminated
atmosphere. Meet all combustion and ventilation air
requirements, as well as all local codes.
CAUTION
Insufficient combustion air can cause headaches,
nausea, dizziness or asphyxiation.
Combustion Air Requirements
All gasĆfired appliances require air for the combustion
process. If sufficient combustion air is not available, the
furnace or other appliance will operate inefficiently and
unsafely. Enough air must be provided to meet the needs
of all fuelĆburning appliances and appliances such as exĆ
haust fans which force air out of the house. When fireĆ
places, exhaust fans, or clothes dryers are used at the
same time as the furnace, much more air is required to enĆ
sure proper combustion and to prevent a downdraft. InĆ
sufficient air causes incomplete combustion which can reĆ
sult in carbon monoxide.
In addition to providing combustion air, fresh outdoor air
dilutes contaminants in the indoor air. These contamiĆ
nants may include bleaches, adhesives, detergents, solĆ
vents and other contaminants which can corrode furnace
components.
The requirements for providing air for combustion and
ventilation 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 4.85m
per 1 kW (50 ft3 per 1000 Btuh) of the combined input ratĆ
ing 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 unconfined, 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 sealing around the windows
and doors, follow the procedures in the air from outside
section.
Confined Space
A confined space is an area with volume less than 4.85m
per 1 kW (50 ft3 per 1000 Btuh of the combined input rating
of all appliances installed in that space. This definition inĆ
cludes furnace cupboards or small equipment rooms.
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 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 cupboard 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 poĆ
tentially dangerous negative pressure condition. Air for comĆ
bustion and ventilation can be brought into the confined
space either from inside the building or from outside.
3
3
Page 4
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
2
22cm
per 1 kW (1 square inch per 1000 Btuh) of total input
rating of all gas-fired equipment in the confined space. Each
opening must be at least 646cm
2 (
100 square inches). One
opening shall be within 305mm (12 inches) of the top of the
enclosure and one opening within 305mm (12 inches) of the
bottom. See figure 1.
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM INSIDE
CHIMNEY
OR GAS
VENT
G24MCE
FURNACE
WATER
FURĆ
NACE
OPENINGS
(To Adjacent
Room)
Air from Outside
If air from outside is brought in for combustion and ventilation,
the confined space must have two permanent openings.
One opening shall be within 305mm (12 inches) of the top
of the enclosure and one within 305mm (12 inches) of the
bottom. These openings must communicate directly or by
ducts with the outdoors or spaces (underfloor or attic) that
freely communicate with the outdoors or indirectly through
vertical ducts. Each opening shall have a minimum free area
of 5.5cm
2
per 1 kW (1 square inch per 4000 Btuh) of total
input rating of all equipment in the enclosure. See figures 2
and 3. When communicating with the outdoors through horiĆ
zontal ducts, each opening shall have a minimum free area
of 3cm
2
per 1 kW (1 square inch per 2000 Btuh) of total inĆ
put rating of all equipment in the enclosure. See figure 4.
When ducts are used, they shall be of the same cross-secĆ
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 75mm (3 inches). In calculating free
area, the blocking effect of louvers, grilles, or screens must
be considered. If the design and free area of protective covĆ
ering is not known for calculating the size opening required,
it may be assumed that wood louvers will have 20 to 25 perĆ
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.
NOTE-Each opening shall have a free are a of at least 22cm
per 1 kW (1 square inch per 1,000 Btuh) of the total input rating
of all equipment in the enclosure, but not less than 646cm
(100 square inches).
FIGURE 1
CHIMNEY
OR GAS
VENT
VENTILATION LOUVERS
(Each end of attic)
G24MCE
FURNACE
VENTILATION
LOUVERS
(For unheated underfloor
space)
OUTLET
AIR
2
2
EQUIPMENT IN CONFINED SPACE
(Inlet Air from Underfloor Space and Outlet Air to Ventilated Attic)
WATER
FURĆ
NACE
INLET
AIR
NOTE-The inlet and outlet air openings shall each have a free
area of at least 5.5cm
of the total input rating of all equipment in the enclosure.
ALL AIR FROM OUTSIDE
2
per 1 kW (1 square inch per 4000 Btuh)
FIGURE 2
Page 5
EQUIPMENT IN CONFINED SPACE
CHIMNEY
OR GAS
VENT
G24MCE
FURNACE
NOTE-The inlet and outlet air openings shall each have a free area
of at least 5.5cm
input rating of all equipment in the enclosure.
2
per 1 kW (1 square inch per 4000 Btuh) of the total
ALL AIR FROM OUTSIDE
(All Air Through Ventilated Attic)
VENTILATION LOUVERS
(Each end of attic)
OUTLET
AIR
FURNACE
FIGURE 3
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
CHIMNEY
OR GAS
VENT
WATER
FURNACE
OUTLET AIR
G24MCE
FURNACE
INLET AIR
INLET AIR
[Ends 305mm
(12") above botĆ
tom]
WATER
NOTE - 1/3 and 1/2 hp fan 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 beĆ
fore the furnace is put into operation. Once the shipping
bolt and washer are removed, the rigid leg will not touch
the fan housing.
UPFLOW APPLICATIONS
The Lennox G24MCE furnace is shipped in a standard
upflow position. Level the furnace using shims or leveling
bolts. Knockouts are provided in unit base to install fieldprovided leveling bolts. Allow for clearances to combusĆ
tible materials as indicated on the unit rating plate. MiniĆ
mum clearances for cupboard or alcove installations are
shown in figure 5.
In upflow applications, return air can be brought in
through the bottom or either side of the furnace. If a furĆ
nace with bottom return air is installed on a platform,
make an airtight seal between the bottom of the furnace
and the platform to ensure proper and safe operation.
Knockouts are provided on both sides of the furnace cabiĆ
net for installations with side return air. When side return
air is used, seal the bottom of the furnace using the panel
provided.
An upflow filter rack is provided. The adjustable rack can
be installed beneath the furnace (flush with cabinet
edges) for bottom return air applications or on the side of
the furnace for side return air.
NOTE - A sheet metal filter puller is provided along with
filter kit. In bottom return air applications, filter puller must
be installed between frame and filter to hold filter in place.
UPFLOW APPLICATION
INSTALLATION CLEARANCES
TOP
NOTE-Each air duct opening shall have a free area of at least 3cm2 per 1 kW
(1 square inch per 2000 Btuh) 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 opening shall
have a free area of at least 5.5cm
the total input rating of all other equipment in the enclosure.
2
per 1 kW (1 square inch per 4000 Btuh) of
FIGURE 4
Setting Equipment
The Lennox G24MCE multi-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 unit location that will allow for required clearances
listed on the unit rating plate. Also consider gas supply
connections, electrical supply, vent connection and
installation and service clearances [610mm (24 in.)] at
unit front.
Page 6
LEFT
SIDE
BOTTOM
VENT
CONNECTOR
TYPE
TOP
*FRONT 51mm (2 in.)
BACK
SIDES
FLUE 25mm (1 in.)
BOTTOM **NC
*Front clearance in alcove installation must be a miniĆ
mum of 610mm (24 in.) for service access.
**On combustible floor with non-combustible protecĆ
tion. NC - Non-Combustible
SINGLE WALL
25mm (1 in.)
51mm (2 in.)
25mm (1 in.)
25mm (1 in.)
152mm (6 in.)
**NC
RIGHT
SIDE
TWIN WALL
25mm (1 in.)
25mm (1 in.)
25mm (1 in.)
FIGURE 5
REMOVE
TOP CAP
REMOVE
FOUR
SCREWS
DISCONNECT
IGNITOR & SENSOR
LEADS
REMOVE
BOTTOM
SINGLE-WALLED VENT
PIPE FROM COMBUSTION
AIR FAN FLUE ADAPTER TO
FURNACE FLUE OUTLET
(Furnished by installer)
DISCONNECT
WIRE HARNESS AT
CONTROL BOARD
CONNECTOR
UPFLOW CONFIGURATION DOWNFLOW CONFIGURATION
FIGURE 6
DOWNFLOW APPLICATIONS
The Lennox G24MCE furnace is shipped in the upflow
configuration and must be converted for downflow instalĆ
lation. Refer to figure 6 and the following steps to convert
the unit for downflow installation:
1 - Place unit on its back and remove access panel.
2 - Disconnect wire harness in control area.
3 - Disconnect ignition lead and sensor wire located in
burner box. Use pliers to remove strain relief plugs
from holes on side of burner box.
4 - Remove four no. 10 screws securing cabinet bottom
to unit and remove bottom.
5 - Remove four no. 10 screws securing cabinet top cap to
cabinet. Remove top cap and replace with bottom.
6 - Remove four screws holding heat exchanger assemĆ
bly in place. Slide heat exchanger out through top of
cabinet.
UNIT CONVERSION FOR DOWNFLOW APPLICATION
7 - Rotate heat exchanger 180
o
and slide back into cabiĆ
net through top. Resecure using four screws.
8 - Install cabinet bottom using four no. 10 screws.
9 - Position strain relief grommets on ignition and flame
sensor wires. Insert wires and grommets through
holes on side of burner box. Reconnect wires to igniĆ
tor and flame sensor.
10- Reconnect wire harness plug.
11- Replace unit access panel.
In downflow applications, the unit can be installed in three difĆ
ferent ways: on non-combustible flooring, on combustible
floor using an additive base, or on a reverse-flow cooling cabĆ
inet. Do not drag unit across floor.
Allow clearances to combustible materials as outlined on
unit rating plate. Minimum clearances for cupboard or alĆ
cove installations are outlined in figure 7.
REINSTALL
TOP CAP ON
UNIT BOTTOM
RECONNECT WIRE
HARNESS AT
CONTROL BOARD
CONNECTOR
ROTATE HEAT
EXCHANGER
& REINSTALL
RECONNECT
IGNITOR & SENSOR
LEADS
REINSTALL
BOTTOM
ON UNIT
A separate downflow filter kit is available for use in downĆ
flow applications. Filter rack provided with unit is for use in
horizontal or upflow applications only.
DOWNFLOW APPLICATION
INSTALLATION CLEARANCES
TOP
LEFT
SIDE
BOTTOM
VENT
CONNECTOR
TYPE
TOP 25mm (1 in.)
*FRONT 51mm (2 in.)
BACK
SIDES
FLUE 152mm (6 in.) 25mm (1 in.)
BOTTOM NC** NC**
NC - Non-combustible floor
*Front clearance in alcove installation must be a min. of 610mm
(24 in.) for service access.
**With additive base on combustible floor.
SINGLE WALL TWIN WALL
25mm (1 in.)
51mm (2 in.)
RIGHT
SIDE
25mm (1 in.)25mm (1 in.)
25mm (1 in.)25mm (1 in.)
FIGURE 7
A-Installation on Non-Combustible Flooring
1 - Cut floor opening keeping in mind the clearances
listed on the unit rating plate. Also, keep in mind gas
supply and electrical supply, vent connections and
sufficient installation and service clearances. See
table 1 for correct floor opening size.
TOP
Page 7
TABLE 1
NONCOMBUSTIBLE FLOOR OPENING
UNIT
G24MCE-45/60/75 502 388
G24MCE-100/120 502 47719-3/4 18-3/4
G24MCE-140 502 54619-3/4 21-1/2
NOTE-Floor opening dimensions listed are 6mm (1/4") larger
than unit openings.
Front to Rear Side to Side
inmm inmm
19-3/4 15-1/4
2 - Flange warm air plenum and lower into opening.
3 - Set unit over plenum.
4 - Check to see that an adequate seal is made.
B-Installation on Combustible Flooring
1 - When unit is installed on a combustible floor, an addiĆ
tive base (ordered separately) must 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
G24MCE-45/60/75 556 440
G24MCE-100/120
G24MCE-140
NOTE-Floor opening dimensions listed are 1/4" (6mm) larger
than additive base openings.
G24MCE UNIT
Front to Rear Side to Side
in mm in mm
21-7/8 17-5/16
556 52821-7/8 20-3/4
556 59721-7/8 23-1/2
SUPPLY AIR
PLENUM
3 - Check glass fibre strips on additive base to make
sure they are properly glued and positioned.
4 - Lower supply air plenum into additive base until pleĆ
num flanges seal against glass fibre strips.
5 - Set unit on additive base so unit flanges drop into pleĆ
num. Refer to figure 8.
NOTE-Be careful not to damage glass fibre strips.
Check for tight seal.
C-Installation on Cooling Cabinet
1 - Refer to reverse flow coil installation instructions for
correctly sized opening in floor and installation of
cabinet.
2 - When cooling cabinet is in place, install furnace so
flanges drop inside cabinet opening.
3 - Seal cabinet and check for air leakage.
HORIZONTAL APPLICATIONS
The Lennox G24MCE furnace can be installed in horizonĆ
tal applications in either upflow or downflow configuration
(See figure 6). It is preferable to install the unit in the stanĆ
dard upflow configuration, if possible, because the vent
pipe will not interfere with service access for fan. The unit
cannot be installed on its back.
Filter rack is provided. Adjustable rack can be installed
flush with cabinet edges.
Allow for clearances to combustible materials as indicated
on the unit rating plate. Minimum clearances for cupboard
or alcove installations are shown in figure 9.
HORIZONTAL APPLICATION
INSTALLATION CLEARANCES
TOP
LEFT
SIDE
RIGHT
SIDE
ADDITIVE
BASE
1. Cut correct size floor opening
2. Set additive base into opening.
3. Set supply air plenum into additive base.
4. Set unit.
FIGURE 8
2 - After opening is cut, set the additive base into
opening.
PROPERLY
SIZED FLOOR
OPENING
Page 8
BOTTOM
VENT
CONNECTOR
TYPE
TOP 25mm (1 in.) 25mm (1 in.)
*FRONT 51mm (2 in.) 51mm (2 in.)
BACK
SIDES
FLUE 152mm (6 in.)
BOTTOM **NC **NC
*Front clearance in alcove installation must be a miniĆ
mum of 610mm (24 in.) for service access.
**On combustible floor with non-combustible protection.
NC - Non-Combustibles
SINGLE WALL TWIN WALL
25mm (1 in.) 25mm (1 in.)
51mm (2 in.) 51mm (2 in.)
25mm (1 in.)
FIGURE 9
Furnaces may be installed in either an attic or a crawlspace.
See figure 10 for furnace installations on a platform.
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.
Horizontal Application
NOTE - Line contact is permiss ible. See the unit rating plate for clearan ces
Unit Installed on Platform
GAS
ENTRY
VENT
PIPE
WARNING
Improper installation of unit can result in personal
injury or death. Flue gases must never be allowed
to enter the return air system or the living space.
Sheet metal screws and sealing tape should be
used to seal ducting to the furnace. In platform
installations, return air must always be ducted to
the unit. A unit must never be installed so that it
draws return air from the furnace chamber, attic or
underfloor space. The furnace platform must be
level with no sagging, cracks or gaps.
Furnaces must always be isolated from other heatĆ
ing appliances to prevent fire, explosion, and carĆ
bon monoxide poisoning. Personal injury and/or
property damage could result..
Duct System
NON-COMBUSTIBLE
UNIT PLATFORM
NON-COMBUSTIBLE
WORKING PLATFORM
FIGURE 10
Anyone of the following methods may be used to suspend
the furnace from roof rafters or floor joists:
1 - Using Lennox hanging bracket kit catalog number
46J66 -
Install as indicated in the installation instructions
provided with the hanging bracket kit.
2 - Using angle iron with at least 1/4 in. diameter rods -
Install as shown in figure 11.
Note - Rods must not interfere with plenum or exĆ
haust piping; cooling coils and supply and return
air plenums must be supported separately.
Horizontal Application
Unit Suspended in Attic or Crawlspace
Using Angle Iron and Rods
Level unit - side to side and end to end.
Leave sufficient clearance between rod and unit to
remove access panels.
1/4 in. ROD
ANGLE
SUPPORT TIES -
INSTALL TO PREVENT
SPREADING
Secure the angle iron to the unit with sheetmetal screws:
maximum screw length - 3/4 in. and minimum screw size - # 10.
IRON
Use industryĆapproved standards to size and install the
supply and return air duct system. This will result in a quiet
and lowĆstatic system that has uniform air distribution.
SUPPLY AIR PLENUM
Furnaces installed without a cooling coil require the installaĆ
tion of a removable access panel in the supply air duct. The
access panel should be large enough to permit inspection
(either by smoke or reflected light) of the heat exchanger for
leaks after installation . The furnace access panel must alĆ
ways be in place when the furnace is operating and it must
not allow leaks into the supply air duct system.
RETURN AIR PLENUM
Return air must not be drawn from a room where
this furnace, or any other gas appliance (ie., a water
heater), is installed. When return air is drawn from a
room, a negative pressure is created in the room. If a
ga s appliance is oper ati ng in a ro om with negative presĆ
sure, 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.
In upflow applications, return air can be brought in
through the bottom or either side of the furnace. If a furĆ
nace with bottom return air is installed on a platform,
make an airtight seal between the bottom of the furnace
and the platform to ensure proper and safe operation.
Use fiberglass sealing strips between the plenum and the
furnace cabinet to ensure a tight seal. If a filter is installed,
size the return air duct to fit the filter frame.
FIGURE 11
Page 9
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