Lennox G24-200 User Manual
INSTALLATION
PRODUCT LITERATURE
2005 Lennox Industries Inc.
Dallas, Texas
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
INSTRUCTIONS
G24-200
UPFLOW GAS FURNACE
Direct Spark Ignition
503,613M
8/2005
Supersedes 7/2003
Table of Contents
G24−200 Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . .
G24−200 Parts Arrangement 4. . . . . . . . . . . . . . . . . . . .
G24−200 Gas Furnace 6. . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 6. . . . . . . . . . . . . . . . . . . . . .
Safety 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution & Ventilation Air 8. . . . . . . . . . . .
Setting Equipment 11. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Return Air Plenum / Filter Box Installation 11. . . . . . . .
Duct System 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Blower Motor and Drive Installation 13. . . . . . . . . . . . .
Venting 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start−up 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heating Sequence of Operation 34. . . . . . . . . . . . . . . .
Gas Pressure Adjustment 35. . . . . . . . . . . . . . . . . . . . .
High Altitude Information 35. . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments and Operation 35. . . . . . . . . . .
Setting Blower CFM 37. . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
G24−200 Start−up & Performance Check List 39. . . . .
Troubleshooting 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Litho USA
Failure to follow safety warnings exactly could result in serious injury, death,
or property damage.
Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other appliance.
Installation and service must be performed by a qualified installer, service agency or the gas supplier.
08/05
*2P0805*
WARNING
FIRE OR EXPLOSION HAZARD.
WHAT TO DO IF YOU SMELL GAS:
Do not try to light any appliance.
Extinguish any open flame.
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.
503,613M
*P504613M*
G24−200 Unit Dimensions − inches (mm)
52-1/2
(1334)
10-1/2
(267)
VENT
OUTLETS
17
(432)
5/8
(16)
VENT
OUTLETS
5-1/2
(140)
9 (229)
Either Side
29-1/4
(743)
17
(432)
HEAT
EXCHANGER
SUPPLY
AIR
OPENING
2
(51)
7/8
(22)
1-1/16
(27)
CONTROL
BOX
4-1/4 (108)
50-3/4
(1289)
Bottom Return
Air Opening
53
(1346)
7/8
(22)
Either Side
GAS
PIPING
INLET
Either Side)
ELECTRICAL
INLET
(Either Side)
BLOWER
MOTOR
(25)
1
26
(660)
FLOW
Bottom Return
Air Opening
FRONT VIEW SIDE VIEW
52-1/2
(1334)
50-3/8
(1280)
Supply Air
Opening
1-1/16
(27)
AIR
2-1/4
(57)
1
(25)
REAR RETURN
AIR OPENING
BACK VIEW
50-1/2
(1283)
27
(686)
1
(25)
1
(25)
Page 2
G24−200 Filter Box Dimensions − inches (mm)
5
(127)
AIR
FLOW
1
(25)
4-3/4
(121)
26-1/4
(667)
AIR
FLOW
50-1/2
(1283)
OPENING SAME
BOTH SIDES
1
(25)
32
(813)
5 (127)
1
(25)
5
(127)
4-3/4
(121)
26-1/4
(667)
*OPTIONAL
FILTER BOX
*NOTE Return air filter box may be
installed at back or bottom of furnace.
50-1/2
(1283)
(127)
32
(813)
5
(25)
1
(25)
BACK VIEWSIDE VIEW
TOP VIEW
4-3/4
(121)
1
50-1/2
(1283)
26-1/4
(667)
1
*NOTE Return air filter box may be
(25)
installed at back or bottom of furnace.
OPENING SAME
BOTH SIDES
1
(25)
FRONT VIEW
1
(25)
OPENING SAME
BOTH SIDES
32
(813)
Page 3
G24−200 Parts Arrangement
LIMIT CONTROL*
LEFT SIDE PANEL
FLUE BOX GASKET*
COMBUSTION
AIR BLOWER*
FLUE BOX*
BURNER RETENTION
BRACKET*
FLAME ROLLOUT
SWITCH*
G24−200 HEAT SECTION AND CABINET
*
(THIS UNIT CONTAINS TWO HEAT SECTIONS. EACH
HEAT SECTION CONTAINS ONE OF THESE ITEMS.)
CABINET TOP
PRESSURE SWITCH*
HEAT EXCHANGER ASSEMBLY*
FLEXIBLE CONNECTOR
PRESSURE SWITCH*
IGNITION CONTROL*
REAR PANEL − TOP
BURNER MTG
BRACKET*
SENSOR*
IGNITOR*
GAS VALVE*
(two-stage)
CONTROL BOX
REAR PANEL − BOTTOM
RIGHT SIDE PANEL
MAKE−UP BOX*
HEATING COMPARTMENT ACCESS
PANEL*
BLOWER COMPARTMENT AC-
CESS PANEL
CENTER MULLION
Page 4
G24−200 Parts Arrangement Continued
G24−200 BLOWER SECTION
DRIVE BELT
(Drive Kit)
ADJUSTMENT ARM
BLOWER
PULLEY
MOTOR PULLEY
(Drive Kit)
MOTOR BASE
SHAFT
MOTOR
(Drive
Kit)
CUT−OFF PLATE
BLOWER HOUSING
BEARING
WHEEL
BASE ASSEMBLY
MOTOR BASE
VIBRATION ISOLATOR
LOCATING ROD
Page 5
G24−200 Gas Furnace
CLEARANCE
The G24−200 upflow gas furnace is for use with natural
gas only.
Each G24−200 requires the installation of a separately ordered drive kit. The available drive kits are listed in tables 10
and 15. Provided in each drive kit is the following: the furnace’s blower motor, its 24 volt control transformer, and (in
non-208/230 volt models) an autotransformer for each of the
furnaces’s induced draft blowers.
Also available for order separately is a filter box kit for rear or
bottom return air applications.
This furnace has two independently controlled heat sections,
each with an input of 100MBH and each operating in a twostage (low heat/high heat) mode. The C17−090/120 cooling
coil has been designed for use with this furnace and can be
connected to either a single condensing unit or to two condensing units. (See C17 coil installation instructions.)
Shipping and Packing List
Package 1 of 3 contains:
1 − Assembled unit (vent adapters are factory-installed)
1 − Flexible gas connector
Package 2 of 3 contains:
1 − Filter box assembly
Package 3 of 3 contains:
1 − Blower drive kit consisting of:
1 − Blower motor
1 − Motor pulley
1 − Belt
1 or 3 − Transformer(s)
1 − Bag assembly containing wiring parts
1 − Bag assembly containing securing hardware
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
Safety
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal injury or loss of life. Installation and service must
be performed by a qualified installer, service agency
or the gas supplier.
CAUTION
As with any mechanical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
Use only the type of gas approved for use with this furnace.
Refer to unit nameplate.
Lennox G24−200 units are CSA international certified to
ANSI Z21.47 and CSA 2.3 standard.
In the USA, installation of Lennox gas central furnaces
must conform with local building codes. In the absence of
local codes, units must be installed in accordance with the
current National Fuel Gas Code (ANSI−Z223.1/NFPA54).
The National Fuel Gas Code is available from:
American National Standards Institute, Inc.
11 West 42nd Street
New York, NY 10036
In Canada, installation must conform with current National
Standard of Canada CSA−B149.1 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 openings into the vestibule area. Provisions must be made for
proper operation and for combustion air and ventilation air
supply according to the current National Fuel Gas Code or
CSA-B149 standards.
In the U.S.A, vent installations shall be in accordance with
the venting tables provided in this manual and the applicable provisions of local building codes.
In Canada, vent installations shall be in accordance with
the venting tables in the current editions of the CSA B149
codes and the applicable provisions of local building
codes.
This furnace is CSA international certified for installation
clearances to combustible material as listed on unit rating
plate and in table 1. Accessibility and service clearances
must take precedence over fire protection clearances.
TABLE 1
INSTALLATION CLEARANCES INCHES (mm)
VENT CONNECTOR TYPE
TYPE C TYPE B1
TOP 1 (25) 1 (25)
FRONT* 3 (76) 3 (76)
BACK 0 0
SIDES 0 0
VENT 6 (152) 1 (25)
FLOOR 0** 0**
* Front clearance must be 24 inches (610mm) minimum for
service access.
** For installation on combustible floors, appliance shall not be
installed directly on carpeting, tile, or other combustible material other than wood flooring.
Maintain adequate clearance for filter access. See section
on Return Air Plenum/Filter Box Installation."
Page 6
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 hazardous atmosphere,
the furnace must be installed according to recommended
good practice requirements and current National Fuel Gas
Code or CSA B149.1 standard.
The furnace must be adjusted to obtain a temperature rise
range and within the allowable external static pressure on
furnaces with a duct system as listed on unit nameplate.
Installation in parking structures must be in accordance
with the Standard for Parking Structures (ANSI/NFPA No.
88A−1991). Installation in repair garages must be in accordance with the Standard for Repair Garages (ANSI/NFPA
No. 88B−1991).
The G24−200 furnace must be installed so that electrical
components are protected from water.
When the 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 manually 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, the furnace must be electrically
grounded according to local codes. In addition, in the
United States, installation must conform with the current
National Electric Code, ANSI/NFPA No. 70. The National
Electric Code (ANSI/NFPA No. 70) is available from the
following address:
National Fire Protection Association
1 Battery March Park
Quincy, MA 02269
In Canada, all electrical wiring and grounding for the unit
must be installed according to the current regulations of the
Canadian Electrical Code Part I (CSA Standard C22.1)
and/or local codes.
Never test for gas leaks with an open flame. Check all connections with a commercially available soap solution made
specifically for leak detection.
NOTE − Furnace must be adjusted to obtain a temperature rise (high and low fire) within the range(s) specified
on the unit nameplate. Failure to do so may cause erratic
limit operation.
Field wiring connection must meet or exceed specifications
of type T wire and withstand a maximum temperature 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 containing the furnace, return air shall be handled by a duct(s)
sealed to the furnace casing and terminating outside space
containing furnace.
NOTE − This furnace is designed for a minimum continuous return air temperature of 60°F (16°C) or an intermittent operation down to 55°F (13°C) dry bulb for cases
where a night setback thermostat is used. Return air
temperature must not exceed 85°F (29°C) dry bulb.
Use of this unit as a construction heater or air conditioner
is not recommended during any phase of construction.
Very low return air temperatures, harmful vapors and operation of the unit with clogged or misplaced filters will
damage the unit.
If this unit has been used for heating or cooling of buildings
or structures under construction, the following conditions
must be met or the warranty will be void:
The vent hood must be installed per these installation
instructions.
A room thermostat must control the unit. The use of
fixed jumpers that will provide continuous heating or
cooling is not allowed.
A pre−filter must be installed at the entry to the return air
duct.
The return air duct must be provided and sealed to the
unit.
Return air temperature range between 55°F (13°C)
and 80°F (27°C) must be maintained.
Air filters must be replaced and pre−filters must be re-
moved upon construction completion.
The input rate and temperature rise must be set per the
unit rating plate.
The heat exchanger, components, duct system, air fil-
ters and evaporator coil must be thoroughly cleaned
following final construction clean−up.
The unit operating conditions (including airflow, cool-
ing operation, ignition, input rate, temperature rise and
venting) must be verified according to these installation instructions.
NOTE − The Commonwealth of Massachusetts stipulates these additional requirements:
Gas units shall be installed by a licensed plumber
or gas fitter only.
The gas cock must be T handle" type.
The Lennox G24−200 furnace may be installed in alcoves,
closets, basements, garages and utility rooms.
Page 7
This furnace design has not been CSA international certified for installation in mobile homes, recreational vehicles,
or outdoors.
WARNING
The blower access panel must be securely in place
when the blower 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.
In addition to the requirements indicated previously, the following general recommendations should be considered
when installing the Lennox G24−200 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 drafts might blow directly
into it. This could cause improper combustion and unsafe
operation.
Do not block furnace combustion air openings with clothing, boxes, doors, etc. Combustion air is needed for proper
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 fiberglass wool.
Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
to fiberglass wool. Breathing this may cause lung
cancer. (Fiberglass wool is known to the State of California to cause cancer.)
Fiberglass wool may also cause respiratory, skin,
and eye irritation.
To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact your
supervisor.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900 USA
Combustion, Dilution & Ventilation Air
In the past, there was no problem in bringing in sufficient
outdoor 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, 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 living space creating a potentially
dangerous situation.
In the absence of local codes concerning air for combustion and ventilation, use the guidelines and procedures in
this section to install G24−200 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 permission from the National Fuel Gas Code
(ANSI-Z223.1/NFPA54). This reprinted material is not the
complete 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 CSA B149.1 installation
code.
CAUTION
Do not install furnace in a corrosive or contaminated
atmosphere. Meet all combustion and ventilation air
requirements, as well as all local codes.
Combustion Air Requirements
Page 8
CAUTION
Insufficient combustion air can cause headaches,
nausea, dizziness or asphyxiation. It will also cause
excess water in the heat exchanger resulting in rusting and premature heat exchanger failure. Excessive
exposure to contaminated combustion air will result
in safety and performance related problems. Avoid
exposure to the following substances in the combustion air supply:
Permanent wave solutions
Chlorinated waxes and cleaners
Chlorine base swimming pool chemicals
Water softening chemicals
De-icing salts or chemicals
Carbon tetrachloride
Halogen type refrigerants
Cleaning solvents (such as perchloroethylene
Printing inks, paint removers, varnishes, etc.
Hydrochloric acid
Cements and glues
Antistatic fabric softeners for clothes dryers
Masonry acid washing materials
All gas-fired 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 fuel-burning appliances and appliances such as exhaust fans which force air out of the house. When fireplaces, exhaust fans, or clothes dryers are used at the
same time as the furnace, much more air is required 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 contaminants may include bleaches, adhesives, detergents, solvents 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 50 cubic
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 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 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 cubic 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 containing 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.
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
(64516 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 1.
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 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 directly or by ducts with the outdoors or spaces (crawl or attic) 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 enclosure. See figures 2 and 3. When communicating with
the outdoors through horizontal ducts, each opening shall
have a minimum free area of 1 square inch (645 mm2) per
2,000 Btu (.56 kW) per total input rating of all equipment in
the enclosure. See figure 4.
Page 9
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM INSIDE
CHIMNEY
OR GAS
VENT
G24−200
FURNACE
OPENINGS
(To Adjacent
Room)
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 rating of all equipment in the enclosure, but not less than 100 square
inches (64516 mm2).
FIGURE 1
When ducts are used, they shall be of the same cross−sectional 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. If the design and free area of protective covering is not known for calculating the size opening
required, it may be assumed that wood louvers will have
20 to 25 percent 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 Crawl Space and Outlet Air to Ventilated Attic)
CHIMNEY OR
GAS VENT
VENTILATION LOUVERS
(Each end of attic)
G24−200
FURNACE
VENTILATION
LOUVERS
(For unheated crawl space)
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.
OUTLET
AIR
INLET
AIR
FIGURE 2
Page 10
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
(All Air Through Ventilated Attic)
CHIMNEY
OR GAS
VENT
OUTLET
AIR
G24−200
FURNACE
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.
VENTILATION LOUVERS
(Each end of attic)
INLET AIR
(Ends 12 in.
above bottom)
Setting Equipment
WARNING
Do not install the furnace on its front or its back. Doing so will adversely affect the operation of the safety
control devices, which could result in personal injury or death.
The Lennox G24−200 upflow gas furnace can be
installed with rear or bottom return air. If unit is installed
on a platform with bottom return air, furnace/filter box must
be sealed airtight at the platform to ensure proper and safe
operation.
Select a location that allows for required clearances listed
on unit rating plate. Also consider gas supply connections,
electrical supply, vent connection, installation and service
clearances [24 inches (610mm) at unit front] and filter accessibility.
The furnace must be leveled using shims or leveling bolts
(field provided). The corner gussets provided in the furnace
base will accept leveling bolts.
FIGURE 3
EQUIPMENT IN CONFINED SPACE
(ALL AIR FROM OUTSIDE)
CHIMNEY
OR GAS
VENT
G24−200
FURNACE
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 opening 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.
OUTLET AIR
INLET AIR
FIGURE 4
Return Air Plenum / Filter Box Installation
Return air openings are provided at rear and in bottom of
unit. A return air closure panel is shipped secured to the
rear opening.
A − Bottom Return Air (Refer to figure 5)
1 − Determine the location of the furnace/filter box.
2 − Cut 50-5/8 x 26-1/8 (128.6cm x 66.4cm) opening in the
return air platform.
3 − Fabricate the return air plenum with right angle flanges
and insert into the floor opening.
4 − Remove filter box access door and filters.
5 − Apply adhesive-backed foam tape to the bottom of the
filter box all around the opening. Position the filter box
over the return air plenum. Fasten as required using
self-tapping screws provided.
Make sure there is an air tight seal between the
platform/return air plenum and filter box.
6 − Apply adhesive-backed foam to the top of the filter box
all around the opening. Place furnace over the filter box
with sides and rear of furnace and filter box flush. Fasten as required.
Make sure there is an air tight seal between the furnace and the filter box.
Page 11
7 − Install the filters and the filter access door.
BOTTOM RETURN AIR FILTER BOX INSTALLATION
2-3/4
(70)
1
(25)
4-3/4
(121)
ADHESIVEBACKED
FOAM TAPE
RETURN AIR PLENUM
29-1/4 (743)
27-1/4 (692)
26-1/4 (667)
26-1/8 (664) x 50-5/8 (1286)
Floor Opening
Furnace
Opening
Filter Box
Opening
AIR
FLOW
UNIT
1
(25)
FILTER
BOX
PLATFORM
INCHES (mm)
SIDE VIEW
FIGURE 5
WARNING
Improper installation of the furnace can result in personal injury or death. Combustion and flue products
must never be allowed to enter the return air system
or the living space. Use screws and joint tape to seal
the return air system to the furnace.
In platform installations with bottom return air, the
furnace should be sealed airtight to the return air plenum. A door must never be used as a portion of the
return air duct system. The base must provide a
stable support and an airtight seal to the furnace. Allow absolutely no sagging, cracks, gaps, etc.
The return and supply air duct systems must never
be connected to or from other heating devices such
as a fireplace or stove, etc. Fire, explosion, carbon
monoxide poisoning, personal injury and/or property damage could result.
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B − Rear Return Air (Refer to figure 6)
Duct System
REAR RETURN AIR FILTER BOX INSTALLATION
UNIT
FILTER
ACCESS
PANEL
REPOSITION REAR PANEL WITH FLANGES AS SHOWN.
(Seal air-tight with adhesive-backed foam tape.)
FOUR FILTERS (Filters may be
also installed through top of frame)
ADHESIVE-BACKED
FOAM TAPE
(Apply to filter box)
FILTER
ACCESS
PANEL
RETURN AIR
FILTER BOX
FIGURE 6
1 − Determine the location of the furnace/filter box.
NOTE − Filter box can be installed with right or left side
filter access or top-rear filter access. Allow enough
room when positioning the furnace for filter access.
2 − Remove the bottom-rear panel from the furnace and
re-install on the bottom of the furnace as shown. Seal
air-tight with adhesive-backed foam tape.
3 − Apply adhesive-backed foam tape to the filter box (side
facing furnace) all around the opening. Refer to figure 6.
4 − Position the filter box over the furnace return air open-
ing. The top of the filter box should be in the up" position and the filter box and the furnace edges flush at the
sides and bottom.
5 − Fasten using self-drilling self-tapping screws provided
with the filter box. Use the frame clearance holes as a
guide.
6 − Install the four filters and the filter access door.
7 − Size the return air plenum to fit the filter box and then
seal the joint air tight.
Size and install supply and return air duct system using industry-approved standards that result in a quiet and lowstatic system with uniform air distribution.
Supply Air Plenum
Furnaces installed without a cooling coil require the installation 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 always be in place when the furnace is operating and it must
not allow leaks into the supply air duct system.
In applications requiring air conditioning, see installation
instructions provided with C17-090/120 evaporator coil for
supply air plenum size and connection.
Return Air Plenum
Return air must not be drawn from a room where this
furnace, or any other gas appliance (i.e., a water heater), is installed. When return air is drawn from a room, a
negative pressure is created in the room. If a gas appliance 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.
Size and install return air plenum as indicated in previous
section.
Blower Motor / Drive Installation
A − Motor Installation
Refer to figure 7.
1 − Check the box on the rating plate to indicate which of
the drive kits are being installed.
2 − Secure the blower motor to the motor base with the
hardware provided.
3 − Slide the motor pulley onto the motor shaft and align
with the blower pulley.
4 − Install the belt.
5 − Refer to Setting Blower CFM Section" to determine
blower RPM setting and the following section for adjusting belt tension.
Page 13
TYPICAL MOTOR/DRIVE INSTALLATION
MOTOR PULLEY
MOTOR
MOTOR SECURING
HARDWARE
MOTOR BASE
Example: Deflection distance of a 400mm span would
be 6mm.
3 − Measure the belt deflection force. For a used belt, the
deflection force should be 5 lbs. (35kPa). A new belt
deflection force should be 7 lbs. (48kPa).
A force below these values indicates an under-tensioned belt. A force above these values indicates an
over-tensioned belt.
MEASURE BELT TENSION
BELT TENSION ADJUSTING HARDWARE
PULLEY ALIGNMENT
BLOWER
PULLEY
MOTOR
PULLEY
FIGURE 7
B − Blower Belt Adjustment
Maximum life and wear can be obtained from belts only if
the proper pulley alignment and belt tension are maintained. Tension new belts after a 24 to 48 hour period of operation. This will allow the belt to stretch and seat in the
grooves.
1 − Loosen belt adjusting hardware. See figure 7.
2 − To increase belt tension −
Move the motor base away from the blower housing.
To loosen belt tension −
Move the motor toward the blower housing.
3 − Tighten the belt adjusting hardware.
C − Check Belt Tension
Over-tensioning a belt shortens belt and bearing life.
Check belt tension as follows:
1 − Measure span length X. See figure 8.
2 − Apply perpendicular force to the center of span (X)
with enough pressure to deflect belt 1/64 inch for every inch of span length or 1.5mm per 100mm of span
length.
Example: Deflection distance of a 40 inch span would
be 40/64 inch or 5/8 inch.
FORCE
DEFLECTION 1/64 INCH PER INCH OF SPAN
OR 1.5 mm PER 100 mm OF SPAN
FIGURE 8
Venting
A vent adapter is factory-installed on each of the combustion air blower outlets. Modification of, or removal of the
adapter(s) will cause unsafe unit operation and will
void CSA unit certification. The vent adapter does not re-
quire insulation.
The G24−200 units are classified as fan assisted Category I
type furnaces when vertically vented according to the latest
edition of ANSI Z21.47 Gas-fired Central Furnace Standard
in the USA and the current standard CSA 2.3 Gas-fired Central Furnace in Canada. The definition of a fan assisted furnace is an appliance equipped with an integral mechanical
means to either draw or force products of combustion
through the combustion chamber and/or heat exchanger.
NOTE − Use these instructions as a guide. They do not supersede local codes.
The vent sizing tables in this manual have been extracted
from the Current edition of the National Fuel Gas Code
(NFPA 54 / ANSI Z223.1) and are provided as a guide for
proper vent installation. Proper application, termination,
construction and location of vents must conform to local
codes having jurisdiction. In the absence of local codes,
the NFGC serves as the defining document in the U.S.A.,
while the CSA−B149 codes serve as the defining documents in Canada.
Refer to the tables and the venting information contained in
these instructions to properly size and install the venting
system.
Install the first vent connector elbow a minimum of 6 in.
(152mm) from the furnace vent outlet.
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