Lennox Elite G61MPV36B-045 User manual

Page 1
01/11
*2P0111*
506506−01
*P506506-01*
E2011 Lennox Industries Inc.
Dallas, Texas, USA
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
INSTALLATION
INSTRUCTIONS
G61MPV SERIES UNITS
GAS UNITS
506506−01
01/2011
Supersedes 07/2010
Table of Contents
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
G61MPV Parts Arrangement 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 9. . . . . . . . . . . . . . . . . .
Filters 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipe & Fittings Specifications 16. . . . . . . . . . . . . . . . . . .
Vent Piping Guidelines 19. . . . . . . . . . . . . . . . . . . . . . . . .
Joint Cementing Procedure 20. . . . . . . . . . . . . . . . . . . . .
Venting Practices 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Integrated Control Board 45. . . . . . . . . . . . . . . . . . . . . . .
Unit Start−Up 55. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Adjustment 56. . . . . . . . . . . . . . . . . . . . . .
High Altitude Information 57. . . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments 59. . . . . . . . . . . . . . . . . . . . . . . .
Service 60. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Control Board Diagnostic Codes 63. . . . . . . . .
Troubleshooting 64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 69. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vent Pipe Sizing Worksheet 70. . . . . . . . . . . . . . . . . . . .
Start−Up & Performance Check List 71. . . . . . . . . . . . . .
WHAT TO DO IF YOU SMELL GAS:
Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other ap-
pliance.
Installation and service must be
performed by a qualified installer,
service agency or the gas supplier.
DDo not try to light any appliance.
DDo not touch any electrical switch; do not
use any phone in your building.
DImmediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s
instructions.
DIf you cannot reach your gas supplier, call
the fire department.
FIRE OR EXPLOSION HAZARD.
Failure to follow safety warnings exact-
ly could result in serious injury, death,
or property damage.
WARNING
DLeave the building immediately.
Litho U.S.A.

Page 2
G61MPV Unit Dimensions − inches (mm)
*Bottom Return
Air Opening
*Bottom Return
Air Opening
ELECTRICAL INLET
(Either Side)
SUPPLY AIR
OPENING
AIR FLOW
FRONT VIEW SIDE VIEW
TOP VIEW
A
B9/16 (14)
C3/4 (19)
3/4 (19)
28−1/2
(724)
19−7/16
(494)
23−1/2
(597)
4−1/4
(108)
11−5/8 (295)
Right
9−3/4 (248)
Left
4−7/8 (124) Right
2−1/4 (57) Left
40
(1016)
4
(102)
1−15/16 (49)
23
(584)
14**
(356)
9/16
(14)
16
(406)
14−3/4
(375)
5/8 (16)
23-3/4 (603)
25 (635)
GAS PIPING INLET
(Either Side)
EXHAUST AIR OUTLET
(Either Side)
CONDENSATE
TRAP CONNECTION
(Either Side)
2−1/2
(64)
18-3/4 (476)
1OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)
1OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)
*OPTIONAL
RETURN CUTOUT
(Either Side)
1Optional External Side Return Air Filter Kit is not for use
with the optional RAB Return Air Base.
*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 one side return air.
Refer to Engineering Handbook for additional information.
**Consider sizing requirements for optional IAQ equip-
ment before cutting side return opening.
COMBUSTION AIR INTAKE
(Either Side)
6−1/2
(165)
4−1/8
(103)
6−1/2
(165)
6−3/4
(171)
5−1/2
(140)
3−1/8
(79)
Model No. ABC
in. mm in. mm in. mm
G61MPV−36B−045
G61MPV−36B−070
G61MPV−36B−071
17−1/2 446 16−3/8 416 16 406
G61MPV−36C−090
G61MPV−60C−090
G61MPV−60C−091
G61MPV−60C−110
G61MPV−60C−111
21 533 19−7/8 505 19−1/2 495
G61MPV−60D−135 24−1/2 622 23−3/8 546 23 584

Page 3
G61MPV Parts Arrangement
FIGURE 1
TOP CAP
CABINET
BURNER BOX
ASSEMBLY
SIGHT
GLASS
DuralokPlusTM
HEAT EXCHANGER
ASSEMBLY
CONDENSER COIL
DOOR
INTERLOCK
SWITCH
COLD HEADER
(COLLECTOR)
BOX
COMBUSTION AIR
INDUCER
BLOWER
ACCESS
PANEL
BURNER
ACCESS
PANEL
FLUE
COLLAR
COMBUSTION
AIR PRESSURE
PROVE SWITCHES*
PRIMARY LIMIT
WARM HEADER
(COLLECTOR)
BOX
GAS VALVE
AND MANIFOLD
SECONDARY
LIMITS (2)
POWER CHOKE
(5 Ton Only)
BLOWER MOTOR
TRANSFORMER
*G61MPV−36B−045
units are equipped
with two switches.
Two−Stage, Variable Speed
Integrated Control
CIRCUIT
BREAKER

Page 4
G61MPV Gas Furnace
The G61MPV category IV gas furnace is equipped with a
two−stage, variable speed integrated control. This control
ensures compatibility with Lennox’ Harmony III zone con-
trol system, as well as a thermostat which provides humid-
ity control. Each G61MPV 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 ap-
plications with bottom return air. The bottom panel must
also be removed and discarded in all downflow or horizon-
tal applications.
The furnace is equipped for installation in natural gas ap-
plications. A conversion kit (ordered separately) is re-
quired for use in propane/LP gas applications.
The G61MPV 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.
FIGURE 2
DIRECT VENT INSTALLATION NON−DIRECT VENT
INSTALLATION
EXHAUST
OUTLET
COMBUSTION
AIR INTAKE
OUTSIDE OF
HOUSE
CONDENSATE
DRAIN
EXHAUST
OUTLET
G61MPV
COMBUSTION
AIR INTAKE INSIDE
OF HOUSE
G61MPV
CONDENSATE
DRAIN
Shipping and Packing List
Package 1 of 1 contains
1 − Assembled G61MPV 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)
NOTE − G61MPV−60C−110 and G61MPV−60C−111 units
also include a 2" diameter PVC street elbow, which is
shipped on the blower deck in the heating compartment.
G61MPV−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 G61MPV−60C−110 and
G61MPV−60C−111 units with 2" street elbow Y0162. Re-
place the provided 3" X 2" reducing elbow shipped with the
G61MPV−60D−135 units with 3" X 2" reducing elbow
40W22. Y0162 and 40W22 meet B149 vent requirements.
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.
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
Safety Information
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person-
al 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.
G61MPV units are CSA International certified to ANSI
Z21.47 and CSA 2.3 standards.
In the USA, installation of gas furnaces must conform with lo-
cal 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:

Page 5
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 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. Acces-
sibility 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 haz-
ardous atmosphere, the furnace must be installed accord-
ing to recommended good practice requirements and cur-
rent National Fuel Gas Code or CSA B149 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 G61MPV furnace may be used as a high−static unit
heater. The G61MPV may also be installed in an aircraft
hangar in accordance with the Standard for Aircraft Han-
gars (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 accor-
dance with the Standard for Repair Garages (ANSI/NFPA
No. 88B−1991).
This G61MPV furnace must be installed so that its electri-
cal components are protected from water.
When this furnace is used with cooling units, it shall be
installed in parallel with, or on the upstream side of, cooling
units to avoid condensation in the heating compartment.
With a parallel flow arrangement, a damper (or other means
to control the flow of air) must adequately prevent chilled air
from entering the furnace. If the damper is manually oper-
ated, 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 ad-
dress:
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 continu-
ous return air temperature of 60°F (16°C) or an intermit-
tent operation down to 55°F (13°C) dry bulb for cases
where a night setback thermostat is used. Return air tem-
perature must not exceed 85°F (29°C) dry bulb.
The G61MPV furnace may be installed in alcoves, closets,
attics, basements, garages, and utility rooms.
This furnace design has not been CSA certified for installa-
tion 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 G61MPV units as
a construction heater during any phase of construction.
Very low return air temperatures, harmful vapors and op-
eration of the unit with clogged or misplaced filters will dam-
age the unit.
G61MPV units may be used for heating of buildings or
structures under construction, if the following conditions
are met:
DThe vent system must be permanently installed per
these installation instructions.
DA room thermostat must control the furnace. The use of
fixed jumpers that will provide continuous heating is not
allowed.
DThe return air duct must be provided and sealed to the
furnace.
DReturn air temperature range between 60°F (16°C) and
80°F (27°C) must be maintained.
DAir filters must be installed in the system and must be
maintained during construction.
DAir filters must be replaced upon construction comple-
tion.

Page 6
DThe input rate and temperature rise must be set per the
furnace rating plate.
DOne hundred percent (100%) outdoor air must be pro-
vided for combustion air requirements during construc-
tion. Temporary ducting may supply outdoor air to the
furnace. Do not connect duct directly to the furnace.
Size the temporary duct following these instructions in
section for Combustion, Dilution and Ventilation Air in a
confined space with air from outside.
DThe furnace heat exchanger, components, duct system,
air filters and evaporator coils must be thoroughly
cleaned following final construction clean−up.
DAll furnace operating conditions (including ignition, in-
put rate, temperature rise and venting) must be verified
according to these installation instructions.
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 fol-
lowing general recommendations must be considered
when installing a G61MPV furnace:
•Place the furnace as close to the center of the air dis-
tribution system as possible. The furnace should also be
located close to the chimney or vent termination point.
•When the furnace is installed in non−direct vent applica-
tions, 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 applica-
tions, 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 insu-
lated 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.
CAUTION
G61MPV unit should not be installed in areas normal-
ly subject to freezing temperatures.
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 Cal-
ifornia 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
Combustion, Dilution & Ventilation Air
If the G61MPV is installed as a Non−Direct Vent Fur-
nace, 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.
WARNING
Insufficient combustion air can cause headaches,
nausea, dizziness or asphyxiation. It will also cause
excess water in the heat exchanger resulting in rust-
ing 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 com-
bustion 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, ap-
pliance vents, chimneys, and fireplaces force additional

Page 7
air that could be used for combustion out of the house.
Unless outside air is brought into the house for combus-
tion, 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 po-
tentially 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 G61MPV furnaces to ensure effi-
cient 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/NFPA 54). This reprinted material is not the com-
plete and official position of the ANSI on the referenced
subject, which is represented only by the standard in its
entirety.
In Canada, refer to the standard CSA B149 installation
codes.
CAUTION
Do not install the furnace in a corrosive or contami-
nated atmosphere. Meet all combustion and ventila-
tion air requirements, as well as all local codes.
All gas-fired appliances require air for the combustion pro-
cess. If sufficient combustion air is not available, the fur-
nace or other appliance will operate inefficiently and un-
safely. Enough air must be provided to meet the needs of all
fuel−burning appliances and appliances such as exhaust
fans which force air out of the house. When fireplaces, ex-
haust fans, or clothes dryers are used at the same time as
the furnace, much more air is 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 di-
lutes contaminants in the indoor air. These contaminants
may include bleaches, adhesives, detergents, solvents
and other contaminants which can corrode furnace compo-
nents.
The requirements for providing air for combustion and ven-
tilation depend largely on whether the furnace is installed in
an unconfined or a confined space.
Unconfined Space
An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the com-
bined input rating of all appliances installed in that space.
This space also includes adjacent rooms which are not
separated by a door. Though an area may appear to be un-
confined, it might be necessary to bring in outdoor air for
combustion if the structure does not provide enough air by
infiltration. If the furnace is located in a building of tight
construction with weather stripping and caulking around
the windows and doors, follow the procedures in the air
from outside section.
Confined Space
A confined space is an area with a volume less than 50 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 con-
taining 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 ei-
ther 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.
FIGURE 3
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM INSIDE
OPENINGS
(To Adjacent
Unconfined
Space)
NOTE − Each opening shall have a free area of at least one square
inch per 1,000 Btu (645mm2per .29kW) per hour of the total input
rating of all equipment in the enclosure, but not less than 100 square
inches (64516mm.2).
G61MPV
ROOF TERMINATED
EXHAUST PIPE
SIDE WALL
TERMINATED EX-
HAUST PIPE (ALTER-
NATE LOCATION)

Page 8
Air from Outside
If air from outside is brought in for combustion and ventila-
tion, the confined space shall be provided with two perma-
nent 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 mini-
mum free area of 1 square inch per 4,000 Btu (645mm2
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 mini-
mum free area of 1 square inch per 2,000 Btu (645mm2
per .59kW) per total input rating of all equipment in the en-
closure (See figure 4).
FIGURE 4
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM OUTSIDE
(Inlet Air from Crawl Space and Outlet Air to Ventilated Attic)
NOTE−The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm2per 1.17kW) per
hour of the total input rating of all equipment in the enclosure.
OUTLET
AIR
INLET
AIR
VENTILATION
LOUVERS
(For unheated
crawl space)
G61MPV
ROOF TERMINATED
EXHAUST PIPE
VENTILATION LOUVERS
(Each end of attic)
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
If air from outside is brought in for combustion and ventila-
tion, the confined space must have two permanent open-
ings. One opening shall be within 12 inches (305 mm) of
the top of the enclosure and one opening within 12 inches
(305 mm) of the bottom. These openings must communi-
cate directly or by ducts with the outdoors or spaces (crawl
or attic) that freely communicate with the outdoors or indi-
rectly 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 4 and 5. When communicat-
ing with the outdoors through horizontal ducts, each open-
ing 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−sec-
tional area as the free area of the openings to which they
connect. The minimum dimension of rectangular air ducts
shall be no less than 3 inches (75 mm). In calculating free
area, the blocking effect of louvers, grilles, or screens
must be considered. If the design and free area of protec-
tive 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.
FIGURE 5
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM OUTSIDE
(All Air Through Ventilated Attic)
NOTE−The inlet and outlet air openings shall each have a free area of
at least one square inch per 4,000 Btu (645mm2per 1.17kW) per hour
of the total input rating of all equipment in the enclosure.
OUTLET
AIR
VENTILATION LOUVERS
(Each end of attic)
INLET AIR
(Ends 12" above
bottom)
G61MPV
ROOF TERMINATED
EXHAUST PIPE
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
FIGURE 6
G61MPV
EQUIPMENT IN CONFINED SPACE −
ALL AIR FROM OUTSIDE
OUTLET AIR
INLET AIR
NOTE−Each air duct opening shall have a free area of at least one
square inch per 2,000 Btu (645mm2per .59kW) 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 communi-
cate directly with the outdoors, each opening shall have a free area
of at least 1 square inch per 4,000 Btu (645mm2per 1.17kW) per
hour of the total input rating of all other equipment in the enclosure.
ROOF TERMINATED
EXHAUST PIPE
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)

Page 9
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 fur-
nace. Doing so will adversely affect the operation of
the safety control devices, which could result in per-
sonal 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]. The unit must be level from front to back and 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 − G61MPV−36B and −36C 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 removed before the furnace is placed
into operation. After the bolt and washer have been re-
moved, the rigid leg will not touch the blower housing.
NOTE − G61MPV−60D−135 units are equipped with a ship-
ping pad under the blower housing. Remove the shipping
pad prior to operation.
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or al-
cove installations are shown in figures 8, 13 and 17.
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.
FIGURE 7
SETTING EQUIPMENT
UPFLOW APPLICATION DOWNFLOW APPLICATION
HORIZONTAL APPLICATION
FRONT VIEW
SIDE VIEW
FRONT VIEW
END VIEW
FRONT VIEW
SIDE VIEW
AIR FLOW
AIR FLOW
AIR FLOW
UNIT
FRONT
AIR FLOW
AIR FLOW
UNIT
FRONT
UNIT
FRONT
1/2"
max.
1/2"
max.
1/2"
max.
UNIT MUST BE LEVEL SIDE−TO−SIDE IN ALL APPLICATIONS.
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.

Page 10
WARNING
Improper installation of the furnace can result in per-
sonal 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 fur-
nace should be sealed airtight to the return air ple-
num. 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. Al-
low absolutely no sagging, cracks, gaps, etc.
For no reason should return and supply air duct sys-
tems ever be connected to or from other heating de-
vices such as a fireplace or stove, etc. Fire, explo-
sion, carbon monoxide poisoning, personal injury
and/or property damage could result.
Upflow Applications
The G61MPV gas furnace can be installed as shipped in
the upflow position. Refer to figure 8 for clearances.
Installation Clearances
Top
Bottom (Floor)
Left Side Right Side
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
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 applica-
tion, 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 9.
2 − Return air from single side with optional RAB Return
Air Base. See figure 11.
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.
G61MPV 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−fabri-
cated transition to accommodate an optional IAQ ac-
cessory taller than 14.5".
Side Return Air
(with transition and filter)
FIGURE 9
Return Air
Plenum
Transition
20" X 25" X 1"
(508mm X635mm X 25mm)
Air Filter
Removing the Bottom Panel
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 10.

Page 11
Removing the Bottom Panel
FIGURE 10
Screw
Bottom Panel
Bottom Cap
Optional Return Air Base
(Upflow Applications Only −− For use with B, C and D cabinets only)
FIGURE 11
NOTE− Optional Side Return Air Filter Kits are not for use with RAB Return Air Base.
1Both 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.
2To 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.
1Unit side return air
Opening
FRONT VIEW SIDE VIEW
27−5/8 (702)
4
(102)
123 (584)
Overall
(Maximum)
OPTIONAL RAB
RETURN AIR BASE
23 (584)
7−1/4 (184)
7/8
(22)
3/4
(19)
122−7−16
(570)
Overall
(Maximum)
SIDE RETURN
AIR OPENINGS
(Either Side)
FURNACE
FRONT
14
(356)
AIR FLOW
5−5/8
(143)
1Minimum
11 (279)
2Maximum
14 (356)
21 (533) RAB−C (98M58)
24−1/2 (622) RAB−D (98M59)
17−1/2 (446) RAB−B (98M60)

Page 12
Setting an Upflow Unit
When the side return air inlets are used in an upflow ap-
plication, it may be necessary to install leveling bolts on the
bottom of the furnace. Use field−supplied corrosion−resist-
ant 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 fig-
ure 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 bot-
tom 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.
FIGURE 12
1−3/4
(44)
1−3/4
(44)
3/8
(10)
1−3/4 (44)
3/8
(10)
3/8
(10)
3/8
(10)
1−3/4
(44)
Leveling Bolt Installation
Leveling Bolt
Locations
Leveling Bolt
Locations
Inches (mm)
Furnace Front
Furnace
Bottom
Downflow Applications
The unit may be installed three ways in downflow applica-
tions: on non−combustible flooring, on combustible flooring
using an additive base, or on a reverse−flow cooling cabi-
net. 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 applica-
tions.
Downflow Application Installation Clearances
Top
Bottom
Left Side Right Side
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 op-
tional additive base is installed between the furnace and the com-
bustible floor.
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 connec-
tions, electrical supply, flue and air intake connections
and sufficient installation and servicing clearances.
See table 1 for correct floor opening size.
2 − Flange warm air plenum and lower the plenum into the
opening.
3 − Set the unit over the plenum and seal the plenum to
the unit.
4 − Ensure that the seal is adequate.
TABLE 1
NON−COMBUSTIBLE FLOOR OPENING SIZE
Model No.
Front to Rear Side to Side
in.mm in. mm
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.

Page 13
Installation on Combustible Flooring
1 − When unit is installed on a combustible floor, an addi-
tive base must be installed between the furnace and
the floor. The base must be ordered separately. 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 ma-
terial other than wood flooring.
TABLE 2
ADDITIVE BASE FLOOR OPENING SIZE
Cabinet
Width
Catalog
Number
Front to Rear Side to Side
in. mm in. mm
B Cabinet
(17.5") 11M60 22 559 18 − 3/4 476
C Cabinet
(21") 11M61 22 559 22 − 3/4 578
D Cabinet
(24.5") 11M62 22 559 25 − 3/4 654
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.
G61MPV UNIT
SUPPLY AIR PLENUM
ADDITIVE BASE
PROPERLY
SIZED FLOOR
OPENING
FIGURE 14
Installation on Cooling Coil Cabinet
1 − Refer to reverse−flow coil installation instructions for
correctly sized opening in floor and installation of cabi-
net.
2 − When cooling cabinet is in place, set and secure the
furnace according to the instructions that are provided
with the cooling coil. Secure the furnace to the cabinet.
3 − Seal the cabinet and check for air leaks.
Return Air Opening −− Downflow Units
Return air may be brought in only through the top opening
of a furnace installed in the downflow position.The follow-
ing 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.
ÉÉÉÉ
FIGURE 15
SECURE FROM
OUTSIDE CABINET
PLENUM
(Field Provided)
SEALING STRIP
(Field Provided)
Side View
CABINET
SIDE PANEL
ÉÉÉÉ
SECURE FROM
INSIDE CABINET
PLENUM
(Field Provided)
SEALING STRIP
(Field Provided)
Side View
CABINET
SIDE PANEL
FIGURE 16
Horizontal Applications
The G61MPV furnace can be installed in horizontal ap-
plications with either right− or left−hand air discharge.
The G61MPV 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.

Page 14
Horizontal Application
Installation Clearances
Top
Left End Right End
Right−Hand Discharge
Left−Hand Discharge
Top
Bottom (Floor)**
Bottom (Floor)**
Left End Right End
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, horizon-
tal 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.
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, keep-
ing 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.
FIGURE 18
BLOWER ACCESS PANEL 3/8 in. RODS
SUPPORT FRAME
INTAKE/EXHAUST
CONNECTION
TYPICAL HORIZONTAL CEILING APPLICATION
DRAIN PAN
(to protect finished space)
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 sup-
port platform may be created using cement blocks and
the horizontal support frame kit (ordered separately,
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.

Page 15
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.
INTAKE PIPE *GAS
CONNECTOR
SERVICE PLATFORM
RAISED
PLATFORM
CONDENSATE LINE
*Gas connector may be
used for Canadian
installation if accept-
able by local authority
having jurisdiction.
EXHAUST PIPE
FIGURE 19
G61MPV Installed in Unit Heater Applications
The G61MPV 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−fabri-
cated 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.
Unit Heater Discharge Duct Guidelines
A field−fabricated and installed discharge air duct and grille
cabinet is suitable for use with the G61MPV 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 in-
ternal 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.
FIGURE 20
18 in.
MIN.
NOTE − When installing duct/grille cabinet, take care not to damage internal unit
heater components when drilling holes or installing screws.
DRAIN PAN
(to protect
finished
space)
Return Air −− Horizontal Applications
Return air may be brought in only through the end of a fur-
nace installed in the horizontal position. The furnace is
equipped with a removable bottom panel to facilitate
installation. See figure 10.
Filters
This unit is not equipped with a filter or rack. A field−pro-
vided 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.
NOTE − In upflow applications where side return air fil-
ter is installed on same side as the condensate trap, fil-
ter rack must be installed beyond condensate trap to
avoid interference.
TABLE 3
Furnace
Cabinet Width
Filter Size
Side Return Bottom Return
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)

Page 16
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 exter-
nal static pressure which exceeds 0.8 inches w.c. may re-
sult 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 al-
ways 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 ap-
pliance (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 pres-
sure 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 com-
bustion 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 Ameri-
can Society for Testing and Materials (ANSI/ASTM) stan-
dards. The solvent shall be free flowing and contain no
lumps, undissolved particles or any foreign matter that ad-
versely affects the joint strength or chemical resistance of
the cement. The cement shall show no gelation, stratifica-
tion, or separation that cannot be removed by stirring. Re-
fer to the table 4 below for approved piping and fitting
materials.
CAUTION
Solvent cements for plastic pipe are flammable liq-
uids 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.
TABLE 4
PIPING AND FITTINGS SPECIFICATIONS
PIPE & FITTING MATERIAL ASTM
SPECIFICATION
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) D2661
PVC−DWV (Drain Waste & Vent)
Pipe & Fittings) D2665
PRIMER & SOLVENT CEMENT ASTM
SPECIFICATION
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 D2564, D2235, F493
ABS to PVC or CPVC Transition Solvent
Cement D3138
CANADA PIPE & FITTING & SOLVENT
CEMENT MARKING
PVC & CPVC Pipe and Fittings
ULCS636
PVC & CPVC Solvent Cement
ABS to PVC or CPVC Transition Cement

Page 17
Use PVC primer and solvent cement or ABS solvent cement
meeting ASTM specifications, refer to Table 4. As an alter-
nate, use all purpose cement, to bond ABS, PVC, or CPVC
pipe when using fittings and pipe made of the same materi-
als. Use transition solvent cement when bonding ABS to ei-
ther PVC or CPVC.
Low temperature solvent cement is recommended. Metal or
plastic strapping may be used for vent pipe hangers. Uni-
formly apply a liberal coat of PVC primer for PVC or use a
clean dry cloth for ABS to clean inside socket surface of fit-
ting and male end of pipe to depth of fitting socket.
Canadian Applications Only − Pipe, fittings, primer
and solvent cement used to vent (exhaust) this ap-
pliance must be certified to ULC S636 and supplied by a
single manufacturer as part of an approved vent (ex-
haust) system. When bonding the vent system to the fur-
nace, use ULC S636 approved One−Step Transition Ce-
ment to bond the pipe to the flue collar, or to bond the 90°
elbow or reducing 90° elbow to the flue collar. In addi-
tion, 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 siz-
ing vent pipe. All Lennox vent terminations are PVC.

Page 18
TABLE 5
OUTDOOR TERMINATION KITS AND CORRESPONDING EQUIVALENCIES
UNIT
MODEL
VENT
PIPE
DIA.
(in.)
Vent Pipe Length Equivalency (feet)
Outdoor
Exhaust
Accelera-
tor
(Dia. X
Length)
Outdoor
Exhaust
Acceler-
ator
(Dia. X
Length)
1−1/2"
Concentric
Kit
2"
Concentric
Kit
3"
Concen-
tric Kit
2" Wall
Plate Kit
3" Wall
Plate Kit
2" Wall
Ring
Kit
Flush Mount
Termination
1−1/2" X
12" 2" X 12"
71M80
or
44W92
69M29
or
44W92
60L46
or
44W93
22G44
or
30G28
44J40
or
81J20
15F74
51W11
with
1−1/2
accelera-
tor
51W11
without
1−1/2" ac-
celerator
36B−045
2 4 Not
Allowed 12 Not Allowed
Not
Allowed 4 4* 44Not Allowed
2−1/2 5 Not
Allowed 15 Not Allowed
Not
Allowed 5 5* 57**** Not Allowed
3 7 Not
Allowed 21 Not Allowed
Not
Allowed 7 7* 77Not Allowed
4 14 Not
Allowed 42 Not Allowed
Not
Allowed 14 14* 14 Not Allowed
Not
Allowed
36B−070
36B−071
24Not
Allowed 12 Not Allowed
Not
Allowed 4 4* 4 4 Not Allowed
2−1/2 5Not
Allowed 15 Not Allowed
Not
Allowed 5 5* 5 7**** Not Allowed
38Not
Allowed 24 Not Allowed
Not
Allowed 8 8* 8 8 Not Allowed
414 Not
Allowed 42 Not Allowed
Not
Allowed 14 14* 14 Not Allowed
Not
Allowed
36B−091
60C−090
2Not
Allowed 1Not Allowed 3 3 Not Allowed 11** 4 Not Allowed
2−1/2 Not
Allowed 2Not Allowed 6 6 Not Allowed 22** 7**** Not Allowed
3Not
Allowed 2Not Allowed 6 6 Not Allowed 22** 8 Not Allowed
4Not
Allowed 4Not Allowed 12 12 Not Allowed 44** Not Allowed
Not
Allowed
60C−110
60C−111
2Not
Allowed 1Not Allowed 3 3 Not Allowed 11** Not Allowed 1
2−1/2 Not
Allowed 2Not Allowed 6 6 Not Allowed 22*** Not Allowed 4****
3Not
Allowed 2Not Allowed 6 6 Not Allowed 22*** Not Allowed 7
4Not
Allowed 4Not Allowed 12 12 Not Allowed 44*** Not Allowed
Not
Allowed
60D−135
3Not
Allowed 6Not Allowed
Not
Allowed 15 Not Allowed 6 6*** Not Allowed 7
4Not
Allowed 10 Not Allowed
Not
Allowed 25 Not Allowed 10 10*** Not Allowed
Not
Allowed
*Requires field−provided and installed 1−1/2" exhaust accelerator.
**Requires field−provided and installed 2" exhaust accelerator.
***For use only in non−direct vent applications, when snow riser is not required. Re-
quires field−provided and installed 2" exhaust accelerator.
**** Requires field−provided and installed 2"−2−1/2" coupling on G61MPV−36B−045,
G61MPV−36B−070, 071, G61MPV−36B−090,091 and G61MPV−60C−110 furnaces
 Termination kits 44W92, 44W93, 30G28 & 81J20 are ULC−636 approved for Cana-
dian Installation.
 The 44W92 Concentric kit is provided with a 1−1/2" accelerator which must be
installed on the exhaust outlet when this kit is used with the G61MPV−36B−045,
G61MPV−36B−070 & 071 furnaces.

Page 19
Vent Piping Guidelines
The G61MPV 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 out-
doors 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 mini-
mum 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 ex-
haust 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 fig-
ure 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.
NOTE − On G61MPV−071, −091 and −111 units, sweep el-
bows must be used for all 90° elbows in the venting
system when 2", 2−1/2" or 3" vent pipe is used. On
G61MPV−135, sweep elbows must be used for all 90° el-
bows in the venting system when 3" vent pipe is used.
Sweep elbows are recommended for use in vent sys-
tems of other G61MPV units.
In some applications which permit the use of several differ-
ent sizes of vent pipe, a combination vent pipe may be
used. Contact Lennox’ Application Department for assis-
tance in sizing vent pipe in these applications.
FIGURE 21
Exhaust Pipe Offset
*12" Min.
*12" Min. *12" Min.
12" Min.
Upflow and Downflow Application
Rooftop Termination Upflow and Downflow Application
Side Wall Termination
Horizontal Application
Rooftop Termination
Horizontal Application
Side Wall Termination
*A minimum of 1/4" (6mm) drop for each 12" (305mm) of horizontal run is mandatory for drainage

Page 20
NOTE − The flue collar on all models is sized to accommo-
date 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 proper-
ly transition to the larger diameter flue pipe. This elbow
must be added to the elbow count used to determine ac-
ceptable vent lengths. Assign an equivalent feet value to
this elbow according to the larger size pipe being used.
Contact the Application Department for more information
concerning sizing of vent systems which include multiple
pipe sizes.
Use the following steps to correctly size vent pipe diameter.
Refer to Vent Pipe Size Determination Worksheet on
page 65.
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 7 for the proposed vent pipe di-
ameter. If the total equivalent length required exceeds
the maximum equivalent length listed in the appropri-
ate table, evaluate the next larger size pipe.
IMPORTANT
Do not use screens or perforated metal in exhaust
terminations. Doing so will cause freeze−ups and
may block the terminations.
TABLE 6
MINIMUM VENT PIPE LENGTHS
G61MPV
MODEL
MIN. EQUIV.
VENT LENGTH EXAMPLE
045, 070,
071, 090,
091
15 ft.*
5 ft. plus 2 elbows of 2", 2−1/2", 3"
or 4" diameter pipe
110 5 ft. plus 2 elbows of 2−1/2" 3" or 4"
diameter pipe
135*** 5 ft. plus 2 elbows of 3" or 4"
diameter pipe
*Any approved termination may be added to the minimum equivalent length
listed.
**G61MPV−60C−110 and −111 must have 90° street ell (supplied or field re-
placement Canadian kit) installed directly into unit flue collar.
***G61MPV−60D−135 must have 3" to 2" reducing ell (supplied or field replace-
ment Canadian kit) installed directly into unit flue collar.
TABLE 7
MAXIMUM VENT PIPE LENGTHS
ALTITUDE G61MPV
MODEL
MAXIMUM EQUIVALENT VENT
LENGTH FEET
2"
PIPE
2−1/2"
PIPE
3"
PIPE
4"
PIPE
0 − 4500
(0 − 1371 m)
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
4501−7500
(1372−2286 m)
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
7501 − 10000
(2287 − 3048 m)
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
n/a −− Not allowed.
*G61MPV−60C−110 and −111 must have 90° street ell (supplied or field replace-
ment Canadian kit) installed directly into unit flue collar.
**G61MPV−60D−135 must have 3" to 2" reducing ell (supplied or field replace-
ment Canadian kit) installed directly into unit flue collar.
†On G61MPV−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 sys-
tems of other G61MPV units.
‡On G61MPV−60D−135 units, sweep elbows must be used for all 90° el-
bows in the vent system when 3" vent pipe is used.
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.