Lennox G61MP-60C-090, G61MP-36B-070, G61MP-60C-091, G61MP-48C-110, G61MP-60C-110 Installation Instructions Manual
...
INSTALLATION
E 2009 Lennox Industries Inc.
Dallas, Texas, USA
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
INSTRUCTIONS
G61MP SERIES UNITS
GAS UNITS
506406−01
08/2009
Supersedes 505,124M
Table of Contents
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
G61MP Parts Identification 3. . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 4. . . . . . . . . . . . . . . . . . . . . .
Safety Information 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use of Furnace as Construction Heater 5. . . . . . . . . . .
General 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution & Ventilation Air 6. . . . . . . . . . . .
Installation − Setting Equipment 8. . . . . . . . . . . . . . . . . .
Filters 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipe & Fittings Specifications 16. . . . . . . . . . . . . . . . . . . .
Vent Piping Guidelines 18. . . . . . . . . . . . . . . . . . . . . . . . .
Joint Cementing Procedure 20. . . . . . . . . . . . . . . . . . . . .
Venting Practices 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Integrated Control Board 42. . . . . . . . . . . . . . . . . . . . . . .
Unit Start−Up 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Adjustment 44. . . . . . . . . . . . . . . . . . . . . .
High Altitude Information 45. . . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments 46. . . . . . . . . . . . . . . . . . . . . . . . .
Service 53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Control Board Diagnostic Codes 56. . . . . . . . . .
Troubleshooting 57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 62. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vent Pipe Sizing Worksheet 63. . . . . . . . . . . . . . . . . . . . .
Start−Up & Performance Check List 63. . . . . . . . . . . . . .
Litho U.S.A.
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.
08/09
*2P0809*
WARNING
FIRE OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly could result in serious injury, death,
or property damage.
WHAT TO DO IF YOU SMELL GAS:
D Do not try to light any appliance.
D Do not touch any electrical switch; do not
use any phone in your building.
D Leave the building immediately.
D Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s
instructions.
D If you cannot reach your gas supplier, call
the fire department.
Page 1
*P506406-01*
506406−01
G61MP Unit Dimensions − inches (mm)
*NOTE − 60C and 60D size units installed in upflow applications that require air volumes over 1800 cfm (850 L/s)
must have one of the following:
1. Single side return air with transition, to accommodate
20 x 25 x 1 in. (508 x 635 x 25 mm) air filter.
Required to maintain proper air velocity.
2. Single side return air with optional RAB Return Air Base
3. Bottom return air.
4. Return air from both sides.
5. Bottom and
Refer to Engineering Handbook for additional information.
**Consider sizing requirements for optional IAQ equipment before cutting side return opening.
1
Optional External Side Return Air Filter Kit is not for use
with the optional RAB Return Air Base.
3/4 (19)
one side return air.
A
B 9/16 (14)
11−5/8 (295)
Right
1
OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)
9−3/4 (248)
Left
40
(1016)
14−3/4
(375)
16
(406)
AIR FLOW
5/8 (16)
C
*Bottom Return
Air Opening
3/4 (19)
FRONT VIEW SIDE VIEW
1
OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)
5−1/2
(140)
6−1/2
(165)
4−1/8
(103)
6−3/4
(171)
4−7/8 (124) Right
2−1/4 (57) Left
2−1/2
(64)
18-3/4 (476)
6−1/2
(165)
3−1/8
(79)
4
(102)
4−1/4
(108)
SUPPLY AIR
OPENING
23-3/4 (603)
25 (635)
TOP VIEW
28−1/2
(724)
19−7/16
(378)
COMBUSTION AIR INTAKE
(Either Side)
EXHAUST AIR OUTLET
(Either Side)
GAS PIPING INLET
(Either Side)
CONDENSATE
TRAP CONNECTION
(Either Side)
ELECTRICAL INLET
(Either Side)
23
(584)
*OPTIONAL
RETURN CUTOUT
(Either Side)
1−15/16 (49)
23−1/2
(597)
*Bottom Return
Air Opening
9/16
(14)
14**
(356)
Model No.
G61MP−36B−045
G61MP−36B−070
G61MP−36B−071
G61MP−48C−090
G61MP−60C−090
G61MP−60C−091
G61MP−48C−110
G61MP−60C−110
G61MP−60C−111
G61MP−60D−135 24−1/2 622 23−3/8 546 23 584
in. mm in. mm in. mm
17−1/2 446 16−3/8 416 16 406
21 533 19−7/8 505 19−1/2 495
A B C
Page 2
G61MP Parts Arrangement
G61MP PARTS IDENTIFICATION
TOP CAP
BURNER BOX
ASSEMBLY
GAS VALVE
AND MANIFOLD
FLUE
COLLAR
COMBUSTION
AIR PRESSURE
PROVE SWITCHES*
COMBUSTION AIR
INDUCER
DuralokPlus
HEAT EXCHANGER
ASSEMBLY
TM
CABINET
WARM HEADER
(COLLECTOR)
BOX
CONDENSER COIL
BURNER
ACCESS
PANEL
BLOWER
ACCESS
DOOR
*G61MP−090 shown.
G61MP−045 and −070
are equipped with
two switches.
SIGHT
GLASS
DOOR
INTERLOCK
SWITCH
PRIMARY LIMIT
COLD HEADER
(COLLECTOR)
BOX
SECONDARY
LIMITS (2)
BLOWER
ASSEMBLY
CONTROL BOX
FIGURE 1
Page 3
G61MP Gas Furnace
The G61MP category IV gas furnace is shipped ready for
installation in the upflow, downflow, horizontal left air discharge or horizontal right air discharge position. The furnace is shipped with the bottom panel in place. The bottom panel must be removed if the unit is to be installed in
upflow applications with bottom return air. The bottom
panel must also be removed and discarded in all downflow
or horizontal applications.
The furnace is equipped for installation in natural gas applications. A conversion kit (ordered separately) is required for use in propane/LP gas applications.
The G61MP can be installed as either a Direct Vent or a
Non−Direct Vent gas central furnace.
NOTE − In Direct Vent installations, combustion air is taken
from outdoors and flue gases are discharged outdoors. In
Non−Direct Vent installations, combustion air is taken from
indoors and flue gases are discharged outdoors. See figure
2 for applications involving roof termination.
DIRECT VENT INSTALLATION NON−DIRECT VENT
COMBUSTION
AIR INTAKE
OUTSIDE OF
HOUSE
EXHAUST
OUTLET
INSTALLATION
EXHAUST
OUTLET
COMBUSTION
AIR INTAKE INSIDE
OF HOUSE
NOTE − G61MP−48C−110, G61MP−60C−110 and
G61MP−60C−111 units also include a 2" diameter PVC
street elbow, which is shipped on the blower deck in the
heating compartment. G61MP−60D−135 units are shipped
with a 3" to 2" PVC reducing elbow.
Canadian Installations Only − Replace the provided 2"
street elbow shipped with the G61MP−48C−110,
G61MP−60C−110 and G61MP−60C−111 units with 2" street
elbow Y0162. Replace the provided 3" X 2" reducing elbow
shipped with the G61MP−60D−135 units with 3" X 2" reducing elbow 40W22. Y0162 and 40W22 meet B149 vent requirements.
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
The following items may also be ordered separately:
1 − Thermostat
1 − Propane/LP changeover kit
DANGER
Danger of explosion.
There are circumstances in which odorant used with
LP/propane gas can lose its scent. In case of a leak,
LP/propane gas will settle close to the floor and may
be difficult to smell. An LP/propane leak detector
should be installed in all LP applications.
Safety Information
G61MP
CONDENSATE
CONDENSATE
DRAIN
G61MP
FIGURE 2
Shipping and Packing List
Package 1 of 1 contains
1 − Assembled G61MP unit
1 − Bag assembly containing the following:
3 − Screws
3 − Wire nuts
1 − Snap bushing
1 − Snap plug
1 − Wire tie
1 − Condensate trap
1 − Condensate trap cap
2 − 2" diameter vent / intake plugs
1 − 3" diameter cabinet plug (intake)
1 − 2" diameter debris screen
1 − Logo sticker (for use in downflow applications)
DRAIN
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 licensed professional installer (or
equivalent), 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.
G61MP units are CSA International certified to ANSI
Z21.47 and CSA 2.3 standards.
In the USA, installation of gas furnaces must conform with local building codes. In the absence of local codes, units must
be installed according to the current National Fuel Gas Code
(ANSI-Z223.1/NFPA 54). The National Fuel Gas Code is
available from the following address:
American National Standards Institute, Inc.
11 West 42nd Street
New York, NY 10036
Page 4
In Canada, installation must conform with current National
Standard of Canada CSA-B149 Natural Gas and Propane
Installation Codes, local plumbing or waste water codes
and other applicable local codes.
In order to ensure proper unit operation in non−direct vent
applications, combustion and ventilation air supply must be
provided according to the current National Fuel Gas Code
or CSA-B149 standard.
This furnace is CSA International certified for installation
clearances to combustible material as listed on the unit
nameplate and in the tables in figures 8, 13 and 17. Accessibility and service clearances must take precedence over fire
protection clearances.
NOTE − For installation on combustible floors, the furnace
shall not be installed directly on carpeting, tile, or other
combustible material other than wood flooring.
For installation in a residential garage, the furnace must
be installed so that the burner(s) and the ignition source
are located no less than 18 inches (457 mm) above the
floor. The furnace must be located or protected to avoid
physical damage by vehicles. When a furnace is installed
in a public garage, hangar, or other building that has a hazardous atmosphere, the furnace must be installed according to recommended good practice requirements and current National Fuel Gas Code or CSA B149 standard.
NOTE − Furnace must be adjusted to obtain a temperature
rise within the range specified on the unit nameplate. Failure
to do so may cause erratic limit operation.
This G61MP furnace may be used as a high−static unit
heater. The G61MP may also be installed in an aircraft hangar in accordance with the Standard for Aircraft Hangars
(ANSI/NFPA No. 408−1990).
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).
This G61MP furnace must be installed so that its electrical
components are protected from water.
When this furnace is used with cooling units, it shall be
installed in parallel with, or on the upstream side of, cooling
units to avoid condensation in the heating compartment.
With a parallel flow arrangement, a damper (or other means
to control the flow of air) must adequately prevent chilled air
from entering the furnace. If the damper is 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, this 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.
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.
The G61MP furnace may be installed in alcoves, closets,
attics, basements, garages, and utility rooms.
This furnace design has not been CSA certified for installation in mobile homes, recreational vehicles, or outdoors.
Never use an open flame to test for gas leaks. Check all
connections using a commercially available soap solution
made specifically for leak detection.
Use of Furnace as Construction Heater
Lennox does not recommend the use of G61MP units as a
construction heater 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.
G61MP units may be used for heating of buildings or structures under construction, if the following conditions are
met:
D The vent system must be permanently installed per
these installation instructions.
D A room thermostat must control the furnace. The use of
fixed jumpers that will provide continuous heating is not
allowed.
D The return air duct must be provided and sealed to the
furnace.
D Return air temperature range between 60°F (16°C) and
80°F (27°C) must be maintained.
D Air filters must be installed in the system and must be
maintained during construction.
D Air filters must be replaced upon construction comple-
tion.
D The input rate and temperature rise must be set per the
furnace rating plate.
Page 5
D One hundred percent (100%) outdoor air must be pro-
vided for combustion air requirements during construction. Temporary ducting may supply outdoor air to the
furnace. Do not connect duct directly to the furnace.
Size the temporary duct following these instructions in
section for Combustion, Dilution and Ventilation Air in a
confined space with air from outside.
D The furnace heat exchanger, components, duct system,
air filters and evaporator coils must be thoroughly
cleaned following final construction clean−up.
D All furnace operating conditions (including ignition, in-
put rate, temperature rise and venting) must be verified
according to these installation instructions.
CAUTION
G61MP unit should not be installed in areas normally
subject to freezing temperatures.
Combustion, Dilution & Ventilation Air
If the G61MP is installed as a Non−Direct Vent Furnace, follow the guidelines in this section.
NOTE − In Non−Direct Vent installations, combustion air
is taken from indoors and flue gases are discharged out−
doors.
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 outlined previously, the following general recommendations must be considered
when installing a G61MP furnace:
• Place the furnace 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.
• When the furnace is installed in non−direct vent applications, do not install the furnace where drafts might blow
directly into it. This could cause improper combustion
and unsafe operation.
• When the furnace is installed in non−direct vent applications, do not block the furnace combustion air opening
with clothing, boxes, doors, etc. Air is needed for proper
combustion and safe unit operation.
• When the furnace is installed in an attic or other insulated space, keep insulation away from the furnace.
• When the furnace is installed in an unconditioned
space, consider provisions required to prevent freezing
of condensate drain system.
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
WARNING
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
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 combus−
tion and ventilation, use the guidelines and procedures in
this section to install G61MP 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−
Page 6
Z223.1/NFPA 54). 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 installation
codes.
CAUTION
Do not install the furnace in a corrosive or contaminated atmosphere. Meet all combustion and ventilation air requirements, as well as all local codes.
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 com−
bined 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 3.
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM INSIDE
ROOF TERMINATED
EXHAUST PIPE
OPENINGS
SIDE WALL
TERMINATED EX-
HAUST PIPE (ALTER-
NATE LOCATION)
NOTE − Each opening shall have a free area of at least one square
inch per 1,000 Btu (645mm
rating of all equipment in the enclosure, but not less than 100 square
inches (64516mm.
G61MP
2
2).
(To Adjacent
Unconfined
Space)
per .29kW) per hour of the total input
FIGURE 3
Air from Outside
If air from outside is brought in for combustion and ventilation, the confined space shall be provided with two permanent openings. One opening shall be within 12" (305mm)
of the top of the enclosure and one within 12" (305mm) 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 per 4,000 Btu (645mm
per 1.17kW) per hour of total input rating of all equipment
in the enclosure. When communicating with the outdoors
through horizontal ducts, each opening shall have a minimum free area of 1 square inch per 2,000 Btu (645mm
per .59kW) per total input rating of all equipment in the enclosure (See figure 4).
2
2
Page 7
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM OUTSIDE
(Inlet Air from Crawl Space and Outlet Air to Ventilated Attic)
VENTILATION LOUVERS
OUTLET
AIR
(Each end of attic)
VENTILATION
LOUVERS
(For unheated
crawl space)
2
per 1.17kW) per
ROOF TERMINATED
EXHAUST PIPE
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
NOTE−The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm
hour of the total input rating of all equipment in the enclosure.
G61MP
INLET
AIR
FIGURE 4
in the enclosure. See figures 4 and 5. 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 6.
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
ROOF TERMINATED
EXHAUST PIPE
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM OUTSIDE
ROOF TERMINATED
EXHAUST PIPE
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
NOTE−The inlet and outlet air openings shall each have a free area of
at least one square inch per 4,000 Btu (645mm
of the total input rating of all equipment in the enclosure.
(All Air Through Ventilated Attic)
VENTILATION LOUVERS
(Each end of attic)
OUTLET
AIR
G61MP
2
per 1.17kW) per hour
INLET AIR
(Ends 12" above
bottom)
FIGURE 5
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
OUTLET AIR
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
NOTE−Each air duct opening shall have a free area of at least one
square inch per 2,000 Btu (645mm
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 1 square inch per 4,000 Btu (645mm
hour of the total input rating of all other equipment in the enclosure.
G61MP
2
per .59kW) per hour of the total
INLET AIR
2
per 1.17kW) per
FIGURE 6
Installation − Setting Equipment
WARNING
Do not install the furnace on its front or its back. Do
not connect the return air ducts to the back of the furnace. Doing so will adversely affect the operation of
the safety control devices, which could result in personal injury or death.
Select a location that allows for the required clearances
that are listed on the unit nameplate. Also consider gas
supply connections, electrical supply, vent connection,
condensate trap and drain connections, and installation
and service clearances [24 inches (610 mm) at unit
front].
Page 8
SETTING EQUIPMENT
UPFLOW APPLICATION DOWNFLOW APPLICATION
AIR FLOW
UNIT MUST BE LEVEL SIDE−TO−SIDE IN ALL APPLICATIONS.
AIR FLOW
HORIZONTAL APPLICATION
AIR FLOW
UNIT
FRONT
FRONT VIEW
AIR FLOW
SIDE VIEW
UNIT
FRONT
1/2"
max.
UNIT SHOULD BE LEVEL FROM LEFT TO RIGHT BUT MAY BE
TILTED SLIGHTLY (MAX. 1/2") FROM BACK TO FRONT
TO AID IN THE DRAINING OF THE HEAT EXCHANGER.
FRONT VIEW
The unit must be level from side to side. The unit may be
tilted slightly (maximum 1/2 in.) from back to front to aid
in the draining of the heat exchanger. See figure 7.
NOTE − Units with 1/2 hp blower motors are equipped with
three flexible legs and one rigid leg. The rigid leg is
equipped with a shipping bolt and a flat white plastic washer (rather than the rubber mounting grommet used with a
flexible mounting leg). The bolt and washer must be re-
moved before the furnace is placed into operation. After the bolt and washer have been removed, the rigid leg
will not touch the blower housing.
WARNING
Blower access panel must be securely in place when
blower and burners are operating. Gas fumes, which
could contain carbon monoxide, can be drawn into
living space resulting in personal injury or death.
END VIEW
FIGURE 7
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or alcove installations are shown in figures 8, 13 and 17.
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 air in the living space. Use sheet metal screws and
joint tape to seal return air system to furnace.
In platform installations with furnace return, 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.
For no reason should return and supply air duct systems ever 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.
1/2"
max.
FRONT VIEW
AIR FLOW
UNIT
FRONT
SIDE VIEW
WARNING
1/2"
max.
Page 9
Upflow Applications
The G61MP gas furnace can be installed as shipped in
the upflow position. Refer to figure 8 for clearances.
Installation Clearances
Top
Left Side
Bottom (Floor)
Top/Plenum 1 in. (25 mm)
*Front 0
Back 0
Sides 0†
Vent 0
Floor 0‡
*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
†Allow proper clearances to accommodate condensate trap and
vent pipe installation.
‡For installations on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other
than wood flooring.
FIGURE 8
Right Side
Return Air −− Upflow Units
Return air can be brought in through the bottom or either
side of the furnace installed in an upflow application. If the
furnace is installed on a platform with bottom return, make
an airtight seal between the bottom of the furnace and the
platform to ensure that the furnace operates properly and
safely. The furnace is equipped with a removable bottom
panel to facilitate installation.
Markings are provided on both sides of the furnace cabinet
for installations that require side return air. Cut the furnace
cabinet at the maximum dimensions shown on page 2.
NOTE − When air volumes over 1800 cfm (850 L/s) are
required with 60C or 60D models in an upflow application, the following return air options are available:
1 − Return air from single side with transition which will
accommodate 20 x 25 x 1 in. (508 x 635 x 25 mm) air filter.
(Required to maintain proper air velocity.) See figure 10.
2 − Return air from single side with optional RAB Return
Air Base. See figure 9.
3 − Return air from bottom.
4 − Return air from both sides.
5 − Return air from bottom and
one side.
Refer to Engineering Handbook for additional information.
Page 10
(Upflow Applications Only −− For use with B, C and D cabinets only)
AIR FLOW
FURNACE
7−1/4 (184)
Optional Return Air Base
4
(102)
14
(356)
FRONT
1
23 (584)
Overall
(Maximum)
1
Unit side return air
Opening
5−5/8
(143)
SIDE RETURN
AIR OPENINGS
(Either Side)
1
Minimum
11 (279)
2
Maximum
14 (356)
1
22−7−16
(570)
Overall
(Maximum)
17−1/2 (446) RAB−B (98M60)
21 (533) RAB−C (98M58)
24−1/2 (622) RAB−D (98M59)
OPTIONAL RAB
RETURN AIR BASE
7/8
(22)
23 (584)
27−5/8 (702)
SIDE VIEW
FRONT VIEW
NOTE− Optional Side Return Air Filter Kits are not for use with RAB Return Air Base.
1
Both the unit return air opening and the base return air opening must be covered by a single plenum or IAQ cabinet.
Minimum unit side return air opening dimensions for units requiring 1800 cfm or more of air (W x H): 23 x 11 in.
(584 x 279 mm).
The opening can be cut as needed to accommodate plenum or IAQ cabinet while maintaining dimensions shown.
Side return air openings must be cut in the field. There are cutting guides stenciled on the cabinet for the side return
air opening. The size of the opening must not extend beyond the markings on the furnace cabinet.
2
To minimize pressure drop, the largest opening height possible (up to 14 inches) is preferred.
NOTE− Optional Side Return Air Filter Kits are not for use with RAB Return Air Base.
FIGURE 9
G61MP applications which include side return air and
a condensate trap installed on the same side of the
cabinet require either a return air base or field−fabricated transition to accommodate an optional IAQ accessory taller than 14.2".
Side Return Air
Remove the two screws that secure the bottom cap to the
furnace. Pivot the bottom cap down to release the bottom
panel. Once the bottom panel has been removed, reinstall
the bottom cap. See figure 11.
Removing the Bottom Panel
Removing the Bottom Panel
(with transition and filter)
3/4
(19)
20" X 25" X 1"
(508mm X635mm X 25mm)
Return
Air
Plenum
Transition
FIGURE 10
Air Filter
Screw
Bottom Cap
Bottom Panel
FIGURE 11
Page 11
Setting an Upflow Unit
When the side return air inlets are used in an upflow application, it may be necessary to install leveling bolts on the
bottom of the furnace. Use field−supplied corrosion−resistant 5/16 inch machine bolts (4) and nuts (8). See figure 12.
NOTE − The maximum length of the bolt is 1−1/2 inches.
1 − Lie the furnace on its back and drill a 5/16 inch diame-
ter hole in each corner of the furnace’s bottom. See figure 12 for the correct location of the holes. Drill through
the bottom panel and the bottom flange of the cabinet.
2 − Install one bolt and two nuts into each hole. Screw the
first nut onto a bolt and then insert the bolt into a hole. A
flat washer may be added between the nut and the bottom of the unit.
3 − Screw another nut onto the bolt on the inside of the fur-
nace base. A flat washer may be added between the
nut and the bottom of the unit.
4 − Adjust the outside nut to the appropriate height and
tighten the inside nut to secure the arrangement.
NOTE − The unit may be tilted back−to−front a maximum of
1". This will ensure proper draining of the heat exchanger.
Leveling Bolt Installation
Inches (mm)
3/8
(10)
Furnace Front
3/8
(10)
1−3/4
(44)
Furnace
1−3/4
(44)
Leveling Bolt
Locations
Bottom
Leveling Bolt
Locations
3/8
(10)
1−3/4
(44)
1−3/4 (44)
3/8
(10)
FIGURE 12
Downflow Applications
The unit may be installed three ways in downflow applications: on non−combustible flooring, on combustible flooring
using an additive base, or on a reverse−flow cooling cabinet. Do not drag the unit across the floor in the down-
flow position. Flange damage will result.
After unit has been properly set in place, position provided
logo over existing logo and affix sticker on front panel.
Refer to figure 13 for clearances in downflow applications.
Downflow Application Installation Clearances
Top
Left Side
Bottom
Top 0
*Front 0
Back 0
Sides 0†
Vent 0
Floor NC‡
*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
†Allow proper clearances to accommodate condensate trap and
vent pipe installation.
‡The furnace may be installed on a combustible wood floor if an optional additive base is installed between the furnace and the combustible floor.
Right Side
FIGURE 13
Installation on Non−Combustible Flooring
1 − Cut floor opening keeping in mind clearances listed on
unit rating plate. Also keep in mind gas supply connections, electrical supply, flue and air intake connections
and sufficient installation and servicing clearances.
See table 1 for correct floor opening size.
2 − Flange warm air plenum and lower the plenum into the
opening.
3 − Set the unit over the plenum and seal the plenum to
the unit.
4 − Ensure that the seal is adequate.
TABLE 1
NON−COMBUSTIBLE FLOOR OPENING SIZE
Model No.
B Cabinet (17.5") 19 − 3/4 502 16 − 5/8 422
C Cabinet (21") 19 − 3/4 502 20−1/8 511
D Cabinet (24.5") 19 − 3/4 502 23 − 5/8 600
NOTE − Floor opening dimensions listed are 1/4 inch (6 mm) larger than
the unit opening. See dimension drawing on page 2.
Front to Rear Side to Side
in. mm in. mm
Page 12
Installation on Combustible Flooring
(Using an Additive Base)
1 − When unit is installed on a combustible floor, an addi-
tive base must be installed between the furnace and
the floor. The base must be ordered separately. See
table 2 for opening size to cut in floor.
CAUTION
The furnace and additive base shall not be installed
directly on carpeting, tile, or other combustible material other than wood flooring.
TABLE 2
ADDITIVE BASE FLOOR OPENING SIZE
Cabinet
Width
B Cabinet
(17.5")
C Cabinet
(21")
D Cabinet
(24.5")
Catalog
Number
11M60
11M61
11M62
2 − After opening is cut, set additive base into opening.
3 − Check fiberglass strips on additive base to make sure
they are properly glued and positioned.
4 − Lower supply air plenum into additive base until ple-
num flanges seal against fiberglass strips.
NOTE − Be careful not to damage fiberglass strips.
Check for a tight seal.
5 − Set the furnace over the plenum.
6 − Ensure that the seal between the furnace and plenum
is adequate.
Front to Rear Side to Side
in. mm in. mm
22 559 18 − 3/4 476
22 559 22 − 3/4 578
22 559 25 − 3/4 654
Installation on Cooling Coil 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, set and secure the
furnace according to the instructions that are provided
with the cooling coil. Secure the furnace to the cabinet.
3 − Seal the cabinet and check for air leaks.
Return Air Opening −− Downflow Units
Return air may be brought in only through the top opening
of a furnace installed in the downflow position.The following steps should be taken when installing plenum:
1 − Bottom edge of plenum should be flanged with a
hemmed edge (See figure 15 or 16).
2 − Sealing strips should be used to ensure an airtight seal
between the cabinet and the plenum.
3 − In all cases, plenum should be secured to top of fur-
nace using sheet metal screws.
4 − Make certain that an adequate seal is made.
PLENUM
(Field Provided)
SEALING STRIP
(Field Provided)
SECURE FROM
OUTSIDE CABINET
CABINET
SIDE PANEL
Side View
G61MP UNIT
PROPERLY
SIZED FLOOR
OPENING
FIGURE 14
SUPPLY AIR PLENUM
ADDITIVE BASE
Page 13
PLENUM
(Field Provided)
SECURE FROM
INSIDE CABINET
FIGURE 15
SEALING STRIP
(Field Provided)
CABINET
SIDE PANEL
Side View
FIGURE 16
Horizontal Applications
The G61MP furnace can be installed in horizontal applications with either right− or left−hand air discharge.
The G61MP may also be installed as a unit heater. Either
suspend the furnace as shown in figure 18, or install the
furnace on a field−fabricated raised platform. The unit
must be supported at both ends and beneath the blower
deck to prevent sagging.
Refer to figure 17 for clearances in horizontal applications.
Horizontal Application
Installation Clearances
Right−Hand Discharge
Top
Left End Right End
Bottom (Floor)**
Left−Hand Discharge
Top
3 − If unit is installed above finished space, fabricate a
drain pan fitted with a 1/2 inch or 3/4 inch N.P.T. fitting.
4 − Using 3/8 inch rods and support frame kit or field−fabri-
cated supports, fabricate suspension hangers, keeping in mind front service access clearances.
5 − Mount unit on support frame as shown in figure 18.
6 − Continue with exhaust, condensate and intake line
piping instructions.
7 − If unit is suspended above finished space, hang the
field−provided drain pan below the support frame as
shown in figure 18. Leave 5−1/2 inches for service
clearance below unit for condensate trap.
8 − Route auxiliary drain line so that water draining from
this outlet will be easily noticed by the homeowner. If
necessary, run the condensate line into a condensate
pump to meet drain line slope requirements. The
pump must be rated for use with condensing furnaces.
Protect the condensate discharge line from the pump
to the outside to avoid freezing.
TYPICAL HORIZONTAL CEILING APPLICATION
Left End Right End
Bottom (Floor)**
Top 0
Front* 0
Back 0
Ends 0
Vent 0
Floor 0‡
*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
**A 5−1/2 service clearance must be maintained below the unit to
provide for servicing of the condensate trap.
‡For installations on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other
than wood flooring.
FIGURE 17
Suspended Installation of Horizontal Unit
NOTE − If unit is suspended in attic or crawl space, horizontal support kit (Cat No. 56J18 ordered separately) must be
used to ensure proper unit support and coil drainage.
1 − Select location for unit keeping in mind service and
other necessary clearances. See figure 17.
2 − Provide service platform in front of unit.
BLOWER ACCESS PANEL 3/8 in. RODS
INTAKE/EXHAUST
CONNECTION
SUPPORT FRAME
DRAIN PAN
(to protect finished space)
FIGURE 18
Platform Installation of Horizontal Unit
1 − Select location for unit keeping in mind service and
other necessary clearances. See figure 17.
2 − Construct a raised wooden frame and cover frame
with a plywood sheet. Provide a service platform in
front of unit. If unit is installed above finished space,
fabricate a drain pan to be installed under unit.
When installing the unit in a crawl space, a proper support platform may be created using cement blocks and
the horizontal support frame kit (ordered separately,
Page 14
Lennox part number 56J18). Position the support
frame on top of the blocks and install the unit on the
frame. Leave 5−1/2 inches for service clearance for
condensate trap.
3 − Route auxiliary drain line so that water draining from
this outlet will be easily noticed by the homeowner. If
necessary, run the condensate line into a condensate
pump to meet drain line slope requirements. The
pump must be rated for use with condensing furnaces.
Protect the condensate discharge line from the pump
to the outside to avoid freezing.
4 − Set unit in drain pan as shown in figure 19. Leave 5−1/2
inches for service clearance below unit for condensate
trap.
5 − Continue with exhaust, condensate and intake piping
installation according to instructions.
EXHAUST PIPE
INTAKE PIPE
*GAS
CONNECTOR
Unit Heater Discharge Duct Guidelines
A field−fabricated and installed discharge air duct and grille
cabinet is suitable for use with the G61MP heater. Keep the
following items in mind when constructing the cabinet.
1 − Outer dimensions of cabinet should match those of the
unit heater, so the duct/grille cabinet installs flush with
the unit heater cabinet. See figure 20.
2 − Flange both ends of duct/grille cabinet so that screws
can be used to secure cabinet to discharge end of unit
heater.
3 − To ensure proper operation, the duct/grille cabinet
must be at least 18 inches long.
4 − Use #10−16 x 1/2 inch sheet metal screws to secure
duct/grille cabinet to unit, taking care not to damage internal components of unit heater when drilling holes or
installing screws. See figure 20.
5 − Use adjustable, double−deflection grille(s) to distribute
discharge air. Adjust static pressure to be in the 0.06
inch to 0.10 inch w.c. range.
*Gas connector may be
used for Canadian
installation if acceptable by local authority
having jurisdiction.
RAISED
PLATFORM
CONDENSATE LINE
SERVICE PLATFORM
FIGURE 19
G61MP Installed in Unit Heater Applications
The G61MP may also be installed as a unit heater. Either
suspend the furnace from roof rafters or floor joists, as
shown in figure 18, or install the furnace on a field−fabricated raised platform, as shown in figure 19. The unit must
be supported at both ends and beneath the blower deck to
prevent sagging. The condensate trap must be installed
where it can be serviced at a later date.
18 in.
MIN.
DRAIN PAN
(to protect
finished
space)
NOTE − When installing duct/grille cabinet, take care not to damage internal unit
heater components when drilling holes or installing screws.
FIGURE 20
Return Air −− Horizontal Applications
Return air may be brought in only through the end of a furnace installed in the horizontal position. The furnace is
equipped with a removable bottom panel to facilitate
installation. See figure 11.
Page 15
Filters
This unit is not equipped with a filter or rack. A field−provided filter is required for the unit to operate properly. Table
3 lists recommended filter sizes.
A filter must be in place whenever the unit is operating.
TABLE 3
Furnace
Cabinet Width
17−1/2" 16 X 25 X 1 (1) 16 X 25 X 1 (1)
21" 16 X 25 X 1 (1) 20 X 25 X 1 (1)
24−1/2" 16 X 25 X 1 (2) 24 X 25 X 1 (1)
Side Return Bottom Return
Filter Size
Duct System
Use industry-approved standards to size and install the
supply and return air duct system. This will result in a quiet
and low-static system that has uniform air distribution.
NOTE − Operation of this furnace in heating mode (indoor
blower operating at selected heating speed) with an external static pressure which exceeds 0.5 inches w.c. may result in erratic limit operation.
Supply Air Plenum
If the furnace is installed without a cooling coil, a removable
access panel should be installed in the supply air duct. The
access panel should be large enough to permit inspection
(by reflected light) of the heat exchanger for leaks after the
furnace is installed. If present, this access panel must always be in place when the furnace is operating and it must
not allow leaks into the supply air duct system.
Return Air Plenum
NOTE − Return air must not be drawn from a room
where this furnace, or any other gas−fueled appliance (i.e., water heater), or carbon monoxide−
producing device (i.e., wood fireplace) 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.
Return air can be brought in through the bottom or either
side of the furnace. If a furnace with bottom return air is
installed on a platform, make an airtight seal between the
bottom of the furnace and the platform to ensure that the
unit operates properly and safely. Use fiberglass sealing
strips, caulking, or equivalent sealing method 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.
Pipe & Fittings Specifications
All pipe, fittings, primer and solvent cement must conform
with American National Standard Institute and the American Society for Testing and Materials (ANSI/ASTM) standards. The solvent shall be free flowing and contain no
lumps, undissolved particles or any foreign matter that adversely affects the joint strength or chemical resistance of
the cement. The cement shall show no gelation, stratification, or separation that cannot be removed by stirring. Refer to the table 4 for approved piping and fitting materials.
CAUTION
Solvent cements for plastic pipe are flammable liquids and should be kept away from all sources of
ignition. Do not use excessive amounts of solvent
cement when making joints. Good ventilation should
be maintained to reduce fire hazard and to minimize
breathing of solvent vapors. Avoid contact of cement
with skin and eyes.
PIPING AND FITTINGS SPECIFICATIONS
PIPE & FITTING MATERIAL
Schedule 40 PVC (Pipe) D1785
Schedule 40 PVC (Cellular Core Pipe) F891
Schedule 40 PVC (Fittings) D2466
Schedule 40 CPVC (Pipe) F441
Schedule 40 CPVC (Fittings) F438
SDR−21 PVC or SDR−26 PVC (Pipe) D2241
SDR−21 CPVC or SDR−26 CPVC (Pipe) F442
Schedule 40 ABS Cellular Core DWV (Pipe) F628
Schedule 40 ABS (Pipe) D1527
Schedule 40 ABS (Fittings) D2468
ABS−DWV (Drain Waste & Vent)
(Pipe & Fittings)
PVC−DWV (Drain Waste & Vent)
Pipe & Fittings)
PRIMER & SOLVENT CEMENT
PVC & CPVC Primer F656
PVC Solvent Cement D2564
CPVC Solvent Cement F493
ABS Solvent Cement D2235
PVC/CPVC/ABS All Purpose Cement For Fittings & Pipe of the same material
ABS to PVC or CPVC Transition Solvent
Cement
CANADA PIPE & FITTING & SOLVENT
CEMENT
PVC & CPVC Pipe and Fittings
PVC & CPVC Solvent Cement
ABS to PVC or CPVC Transition Cement
TABLE 4
ASTM
SPECIFICATION
D2661
D2665
ASTM
SPECIFICATION
D2564, D2235,
F493
D3138
MARKING
ULCS636
Page 16
Use PVC primer and solvent cement or ABS solvent cement
meeting ASTM specifications, refer to Table 4. As an alternate, use all purpose cement, to bond ABS, PVC, or CPVC
pipe when using fittings and pipe made of the same materials. Use transition solvent cement when bonding ABS to either PVC or CPVC.
Low temperature solvent cement is recommended. Metal or
plastic strapping may be used for vent pipe hangers. Uniformly apply a liberal coat of PVC primer for PVC or use a
clean dry cloth for ABS to clean inside socket surface of fitting and male end of pipe to depth of fitting socket.
TABLE 5
OUTDOOR TERMINATION KITS AND CORRESPONDING EQUIVALENCIES
Vent Pipe Length Equivalency (feet)
Outdoor Exhaust Accel-
erator
(Dia. X
Length)
UNIT
MODEL
VENT
PIPE
DIA.
(in.)
1−1/2" X 12"
2 4
2−1/2 5
36B−045
36B−070
36B−071
48C−090
60C−090
60C−091
48C−110
60C−110
60C−111
60D−135
3 7
4 14
2 4
2−1/2 5
3 8
4 14
2
2−1/2
3
4
2−1/2
3
4
3
4
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
*Requires field−provided and installed 1−1/2" exhaust accelerator.
**Requires field−provided and installed 2" exhaust accelerator.
Outdoor Ex-
haust Accel-
erator
(Dia. X
Length)
2" X 12"
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
1
2
2
4
2
2
4
6
10
1−1/2"
Concentric
Kit
71M80
or 44W92
12
15
21
42
12
15
24
42
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Canadian Applications Only − Pipe, fittings, primer
and solvent cement used to vent (exhaust) this appliance must be certified to ULC S636 and supplied by a
single manufacturer as part of an approved vent (exhaust) system. When bonding the vent system to the furnace, use ULC S636 approved One−Step Transition Cement to bond the pipe to the flue collar, or to bond the 90°
elbow or reducing 90° elbow to the flue collar. In addition, the first three feet of vent pipe from the furnace flue
collar must be accessible for inspection.
Table 5 lists the available exhaust termination kits, as well
as vent pipe equivalencies which must be used when sizing vent pipe. All Lennox vent terminations are PVC.
2" Con-
centric Kit
69M29
or 44W92
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
3 3
6 6
6 6
12 12
6 6
6 6
12 12
Not
Allowed
Not
Allowed
Termination kits 44W92 (includes 1−1/2" reducer), 44W93,
30G28 and 81J20 approved for use in Canadian installations.
3" Con-
centric Kit
60L46
or 44W93
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
15
25
2" Wall Plate
Kit
22G44
or 30G28
4 4* 4
5 5* 5
7 7* 7
14 14* 14
4 4* 4
5 5* 5
8 8* 8
14 14* 14
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
Not
Allowed
3" Wall Plate
Kit
44J40
or 81J20
1 1**
2 2**
2 2**
4 4**
2 2
2 2
4 4
6
10
2" Wall
Ring Kit
15F74
Not
Allowed
Not
Allowed
Page 17
Vent Piping Guidelines
The G61MP can be installed as either a Non−Direct Vent
or a Direct Vent gas central furnace.
NOTE − In Non-Direct Vent installations, combustion air is
taken from indoors and flue gases are discharged outdoors.
In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged outdoors.
Intake and exhaust pipe sizing in Direct Vent applications
and exhaust pipe sizing in Non-Direct Vent applications −−
Size pipe according to tables 6 and 7. Table 6 lists the minimum equivalent vent pipe lengths permitted. Table 7 lists
the maximum equivalent pipe lengths permitted.
Maximum vent length is defined as:
Total length (linear feet) of pipe,
Plus Equivalent length (feet) of fittings,
Plus Equivalent length (feet) of termination.
NOTE − Include ALL pipe and ALL fittings, both in
doors and outdoors.
Regardless of the diameter of pipe used, the standard roof
and wall terminations described in section Exhaust Piping
Terminations should be used. Exhaust vent termination
pipe is sized to optimize the velocity of the exhaust gas as
it exits the termination. Refer to table 8.
*NOTE − The exhaust pipe should be offset a minimum of
12 inches to avoid the possibility of water droplets being re-
leased from the exhaust termination. The minimum exhaust vent length is 15 ft. Shorter exhaust vent lengths may
result in the discharge of water droplets from the exhaust
termination, in spite of the 12−inch vertical offset. See figure 21.
Each 90° elbow (including those provided with the furnace)
of any diameter is equivalent to 5 feet (1.52m) of vent pipe
of the same diameter. Two 45° elbows are equivalent to
one 90° elbow of the same diameter. One 45° elbow is
equal to 2.5 feet (.76m) of vent pipe of the same diameter.
In some applications which permit the use of several different sizes of vent pipe, a combination vent pipe may be
used. Contact the Application Department for assistance in
sizing vent pipe in these applications.
NOTE − The flue collar on all models is sized to accommodate 2" Schedule 40 flue pipe. When vent pipe which is
larger than 2" must be used in an upflow application, a 2"
elbow must be applied at the flue collar in order to properly transition to the larger diameter flue pipe. This elbow
must be added to the elbow count used to determine acceptable vent lengths. Assign an equivalent feet value to
this elbow according to the larger size pipe being used.
Contact Lennox’ Application Department for more information concerning sizing of vent systems which include
multiple pipe sizes.
*12" Min.
Upflow and Downflow Application
Rooftop Termination
*12" Min.
Horizontal Application
Rooftop Termination
*A minimum of 1/4" (6mm) drop for each 12" (305mm) of horizontal run is mandatory for drainage
Exhaust Pipe Offset
12" Min.
Upflow and Downflow Application
Side Wall Termination
*12" Min.
Horizontal Application
Side Wall Termination
FIGURE 21
Page 18
Use the following steps to correctly size vent pipe diameter.
Refer to Vent Pipe Size Determination Worksheet on
page 53.
1 − Determine the vent termination and its corresponding
equivalent feet value according to table 5.
2 − Determine the number of 90° elbows required for both
indoor and outdoor (e.g. snow riser) use. Calculate the
corresponding equivalent feet of vent pipe.
3 − Determine the number of 45° elbows required for both
indoor and outdoor use. Calculate the corresponding
equivalent feet of vent pipe.
4 − Determine the length of straight pipe required.
5 − Add the total equivalent feet calculated in steps 1
through 4 and compare that length to the maximum
values given in table 6 for the proposed vent pipe diameter. If the total equivalent length required exceeds
the maximum equivalent length listed in the appropriate table, evaluate the next larger size pipe.
TABLE 6
MINIMUM VENT PIPE LENGTHS
G61MP
MODEL
045, 070,
071, 090,
091
110, 111**
135***
*Any approved termination may be added to the minimum equivalent length
listed.
**G61MP−48C−110, G61MP−60C−110 and G61MP−60C−111 must have 90°
street ell (supplied or field replacment Canadian kit) installed directly into unit
flue collar.
***G61MP−60D−135 must have 3" to 2" reducing ell (supplied or field replacment Canadian ki) installed directly into unit flue collar.
MIN. EQUIV.
VENT LENGTH
15 ft.*
EXAMPLE
5 ft. plus 2 elbows of 2", 2−1/2", 3"
or 4" diameter pipe
5 ft. plus 2 elbows of 2−1/2" 3" or 4"
diameter pipe
5 ft. plus 2 elbows of 3" or 4"
diameter pipe
MAXIMUM VENT PIPE LENGTHS
TABLE 7
MAXIMUM EQUIVALENT VENT
ALTITUDE
0 − 4500
(0 − 1371 m)
4501−7500
(1372−2286 m)
7501 − 10000
(2287 − 3048 m)
n/a −− Not allowed.
*G61MP−48C−110, G61MP−60C−110 and G61MP−60C−111must have 90°
street ell (supplied or field replacment Canadian ki) installed directly into unit
flue collar.
**G61MP−60D−135 must have 3" to 2" reducing ell (supplied or field replacment
Canadian ki) installed directly into unit flue collar.
***90° elbows used in configuration of G61MP−60D−135 vent, must be limited to 3" sweep elbows.
†On G61MP−071, −091 and −111 units, sweep elbows must be used for
all 90° elbows in the venting system when 2", 2−1/2" or 3" vent pipe is
used. Sweep elbows are recommended for use in vent systems of
other G61MP units.
G61MP
MODEL
045 59 65 77 234
070 59 65 78 214
071† 59 65 78 214
090 26 42 72 204
091† 26 42 72 204
110* n/a 32 72 179
111*† n/a 32 72 179
135**‡ n/a n/a 61 160
045 59 65 77 234
070 59 65 78 214
071† 59 65 78 214
090 26 42 72 204
091† 26 42 72 204
110* n/a 32 72 179
111*† n/a 32 72 179
135**‡ n/a n/a 46 160
045 59 65 77 234
070 59 65 78 214
071† 59 65 78 214
090 26 42 72 204
091† 26 42 72 204
110* n/a 32 72 179
111*† n/a 32 72 179
135**‡ n/a n/a 46 160
2"
PIPE
LENGTH FEET
2−1/2"
PIPE
PIPE4"PIPE
3"
Page 19
Joint Cementing Procedure
All cementing of joints should be done according to the
specifications outlined in ASTM D 2855.
WARNING
DANGER OF EXPLOSION!
Fumes from PVC glue may ignite during system
check. Allow fumes to dissipate for at least 5 minutes
before placing unit into operation.
1 − Measure and cut vent pipe to desired length.
2 − Debur and chamfer end of pipe, removing any ridges
or rough edges. If end is not chamfered, edge of pipe
may remove cement from fitting socket and result in a
leaking joint.
3 − Clean and dry surfaces to be joined.
4 − Test fit joint and mark depth of fitting on outside of pipe.
5 − Uniformly apply a liberal coat of PVC primer for PVC or
use a clean dry cloth for ABS to clean inside socket
surface of fitting and male end of pipe to depth of fitting
socket.
NOTE − Furnace flue collar and air inlet fitting are both
made of ABS material. Use transition solvent cement
when bonding ABS to either PVC or CPVC, refer to the
procedure specified in ASTM D3138..
6 − Promptly apply solvent cement to end of pipe and in-
side socket surface of fitting. Cement should be applied lightly but uniformly to inside of socket. Take
care to keep excess cement out of socket. Apply second coat to end of pipe.
NOTE − Time is critical at this stage. Do not allow primer to dry before applying cement.
7 − Immediately after applying last coat of cement to pipe,
and while both inside socket surface and end of pipe
are wet with cement, forcefully insert end of pipe into
socket until it bottoms out. Turn PVC pipe 1/4 turn during assembly (but not after pipe is fully inserted) to distribute cement evenly. DO NOT turn ABS or cellular
core pipe.
NOTE − Assembly should be completed within 20 seconds after last application of cement. Hammer blows
should not be used when inserting pipe.
8 − After assembly, wipe excess cement from pipe at end
of fitting socket. A properly made joint will show a
bead around its entire perimeter. Any gaps may indicate a defective assembly due to insufficient solvent.
9 − Handle joints carefully until completely set.
Page 20
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