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.
INSTRUCTIONS
SLP98DFV
DAVE LENNOX SIGNATURE
COLLECTION GAS FURNACE
DOWNFLOW AIR DISCHARGE
506611−01
02/2011
Supersedes 10/2010
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
This is a safety alert symbol and should never be ignored.
When you see this symbol on labels or in manuals, be alert
to the potential for personal injury or death.
CAUTION
As with any mechanical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
A thermostat is not included and must be ordered
separately.
The Lennox icomfort Touch thermostat must be
used in communicating applications.
In non−communicating applications, the Lennox
ComfortSense® 7000 thermostat may be used, as
well as other non−communicating thermostats.
In all cases, setup is critical to ensure proper system operation.
Field wiring for both communicating and non−communicating applications is illustrated in diagrams,
which begin on Page 30.
The SLP98DFV category IV gas furnace is equipped with
a variable−capacity, variable−speed integrated control.
This control ensures compatibility with the Lennox icomfort Touch thermostat and Harmony III zone control
system, as well as a thermostat which provides humidity
control.
The furnace is equipped for installation in natural gas applications only. A changeover kit may be ordered for LP
applications.
The SLP98DFV must be installed only as a Direct Vent
gas central furnace.
NOTE − In Direct Vent installations, combustion air is taken
from outdoors and flue gases are discharged outdoors. See
figure 2 for applications including roof termination.
DIRECT VENT INSTALLATION
COMBUSTION
AIR INTAKE
OUTSIDE OF
HOUSE
SLP98DFV
EXHAUST OUTLET
FIGURE 2
Shipping and Packing List
Package 1 of 1 contains
1 − Assembled SLP98DFV unit
1 − Bag assembly containing the following:
3 − Wire nuts
1 − Snap bushing
1 − Snap plug
1 − Wire tie
1 − Condensate trap
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 − Natural to LP gas conversion kit
1 − High altitude kit
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.
Building Codes
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
Installation Locations and Clearances
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.
This furnace is designed for installation clearances to combustible material as listed on the unit nameplate and in the
table in figure 7. Accessibility and service clearances must
take precedence over fire protection clearances.
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 (100% percent capacity) within the range(s) specified on
the unit nameplate. Failure to do so may cause erratic limit
operation and may also result in premature heat exchanger
failure.
This SLP98DFV furnace must be installed so that its electrical components are protected from water.
Page 4
Installed in Combination with a Cooling Coil
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 (figure 3). 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.
SLP98DFV INSTALLED PARALLEL
WITH COOLING COIL
GAS UNIT
Dampers
(open during heating
operation only)
AIR HANDLER
Dampers
(open during cooling
operation only)
FIGURE 3
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
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.
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.
CAUTION
Do not set thermostat below 60°F (16°C) in heating
mode. Setting thermostat below 60°F (16°C) reduces
the number of heating cycles. Damage to the unit
may occur that is not covered by the warranty.
The SLP98DFV furnace may be installed in alcoves, closets, attics, basements, garages, and utility rooms.
This furnace is not designed 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 SLP98DFV 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.
SLP98DFV 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.
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.
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.
Page 5
General
• 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
CAUTION
SLP98DFV unit should not be installed in areas normally subject to freezing temperatures.
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 SLP98DFV 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 an attic or other insulated space, keep insulation away from the furnace.
Installation − Setting Equipment
WARNING
Do not install the furnace on its front, back or in the
horizontal position. See figure 5. 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]. The unit must be level from side to side. Unit may
be positioned from level to 1/2" toward the front to aid in
draining. See figure 4.
SETTING EQUIPMENT
AIR FLOW
FRONT VIEWSIDE VIEW
Unit must be level side−to−side. Unit may be positioned
from level to 1/2" toward the front to aid in draining.
AIR FLOW
SIDE VIEW
FIGURE 4
AIR FLOW
1/2"
max.
Front
Horizontal
Back
NOTE − Do not install the furnace on its front, back or in the horizontal position.
FIGURE 5
Page 6
NOTE − The 1/2 hp blower motor used in some SLP98DFV
unit is 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 removed, the
rigid leg will not touch the blower housing.
SLP98DF070V36B and
SL98DF090V036C WITH 1/2 HP
BLOWER MOTOR
RIGID LEG
remove shipping bolt and washer
The unit may be installed three ways in downflow applications: on non−combustible flooring, on combustible flooring
using a base, or on a reverse−flow cooling coil cabinet. Do
not drag the unit across the floor in the downflow position. Floor and flange damage will result.
Refer to figure 7 for clearances in downflow applica-
tions.
Downflow Application Installation Clearances
Top
Left SideRight Side
FIGURE 6
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or alcove installations are shown in figure 7.
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.
WARNING
Improper installation of the furnace can result in personal injury or death. Combustion and flue products
must never be allowed to enter the return air system
or 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.
Bottom
Top0
*Front0
Back0
Sides0†
Vent0
FloorNC‡
*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 base is installed between the furnace and the combustible
floor.
FIGURE 7
Installation on Non−Combustible Flooring (Figure 8)
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.
Page 7
TABLE 1
NON−COMBUSTIBLE FLOOR OPENING SIZE
Cabinet Width
B Cabinet (17.5")19 − 3/450216 − 5/8422
C Cabinet (21")19 − 3/450220−1/8511
NOTE − Floor opening dimensions listed are 1/4 inch (6 mm) larger than
the unit opening. See dimension drawing on page 2.
SLP98DF UNIT
Front to RearSide to Side
in.mmin.mm
SLP98DF UNIT
PROPERLY
SIZED FLOOR
OPENING
SUPPLY AIR
PLENUM
COMBUSTIBLE
FLOORING BASE
PROPERLY
SIZED FLOOR
OPENING
SUPPLY AIR
PLENUM
FIGURE 8
Installation on Combustible Flooring (Figure 9)
1 − When unit is installed on a combustible floor, a down-
flow combustible flooring 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 combustible flooring base shall not
be installed directly on carpeting, tile, or other combustible material other than wood flooring.
TABLE 2
COMBUSTIBLE FLOORING BASE OPENING SIZE
Cabinet
Width
B Cabinet
(17.5")
C Cabinet
(21")
Catalog
Number
11M60
11M61
Front to RearSide to Side
in.mmin.mm
2255918 − 3/4476
2255922 − 3/4578
FIGURE 9
2 − After opening is cut, set combustible flooring base into
opening.
3 − Check fiberglass strips on combustible flooring base
to make sure they are properly glued and positioned.
4 − Lower supply air plenum into combustible flooring
base until plenum 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.
Installation on Cooling Coil Cabinet (Figure 10)
NOTE − Downflow combustible flooring base is not used.
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.
Page 8
PROPERLY
SIZED FLOOR
OPENING
FIGURE 10
SLP98DF UNIT
COOLING COIL
PLENUM
PLENUM
(Field Provided)
SECURE FROM
INSIDE CABINET
Side View
SEALING STRIP
(Field Provided)
CABINET
SIDE PANEL
FIGURE 12
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 size.
A filter must be in place whenever the unit is operating.
TABLE 3
Furnace
Cabinet Width
Filter Size
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 11 or 12).
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
FIGURE 11
B Cabinet (17−1/2")
C Cabinet (21−1/2")
16 X 25 X 1 (1)
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 0.8 inches w.c. may result in erratic limit operation.
Return Air Plenum
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.
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.
Page 9
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 table 4 for approved piping and fitting materials.
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.
IMPORTANT
SLP98DFV exhaust and intake connections are
made of PVC. Use PVC primer and solvent cement
when using PVC vent pipe. When using ABS vent
pipe, use transitional solvent cement to make connections to the PVC fittings in the unit.
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
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. 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.
Page 10
SLP98DF
UNIT
OUTDOOR TERMINATION KITS USAGE
TABLE 5
STANDARDCONCENTRIC
Outdoor
VENT
PIPE
DIA.
(in.)
2YESYESYES*YESYESYES
Exhaust
Accelerator
(Dia. X
Length)
1−1/2" X 12"2" X 12"
Outdoor
Exhaust
Accelerator
(Dia. X
Length)
2" Wall Plate
Kit
22G44
or 30G28
3" Wall Plate
Kit
44J40
or 81J20
2" Wall
Ring Kit
15F7451W11**
FlushMount
Kit
Concentric
44W92
1−1/2"
Kit
71M80
or
2"
Concentric
Kit
69M29
or
44W92
3"
Concentric
Kit
60L46
or 44W93
070
090
110
*Requires field−provided and installed 1−1/2" exhaust accelerator.
** Kit 51W11 includes h a 1−1/2" accelerator which must be used for all SLP98DFV−070 and −090 installations.
Termination kits 44W92, 44W93, 30G28 and 81J20 approved for use in Canadian installations.
The 44W92 concentric kit includes a 1−1/2" accelerator which must be installed on the exhaust outlet when this kit is used with the SL98DF070V36B furnaces.
Joint Cementing Procedure
All cementing of joints should be done according to the
specifications outlined in ASTM D 2855.
NOTE − A sheet metal screw may be used to secure
the intake pipe to the connector, if desired. Use a drill
or self tapping screw to make a pilot hole.
2−1/2YESYESYES*YESYESYES
3YESYESYES*YESYESYES
2YESYESYESYESYESYES
2−1/2YESYESYESYESYESYES
3YESYESYESYESYESYES
2YESYESYESYESYESYES
2−1/2YESYESYESYESYES
3YESYESYESYESYES
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.
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.
DANGER
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.
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 dis-
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.
NOTE − Check the inside of vent pipe thoroughly for
any obstruction that may alter furnace operation.
4 − Test fit joint and mark depth of fitting on outside of pipe.
tribute 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 11
Venting Practices
Piping Suspension Guidelines
SCHEDULE 40 PVC −−
Support every 5 feet.
all other pipe* −−
Support every 3 feet.
* See table 4 for allowable pipe.
NOTE − Isolate piping at the point where it exits the outside wall or
roof in order to prevent transmission of vibration to the structure.
Wall Thickness Guidelines
24" maximum
3/4" minimum
1 − In areas where piping penetrates joists or interior
walls, hole must be large enough to allow clearance on
all sides of pipe through center of hole using a hanger.
2 − When furnace is installed in a residence where unit is
shut down for an extended period of time, such as a
vacation home, make provisions for draining condensate collection trap and lines.
Exhaust Piping (Figure 16)
Route piping to outside of structure. Continue with installation following instructions given in piping termination section.
CAUTION
Do not discharge exhaust into an existing stack or
stack that also serves another gas appliance. If vertical discharge through an existing unused stack is required, insert PVC pipe inside the stack until the end
is even with the top or outlet end of the metal stack.
insideoutside
Wall
FIGURE 13
REPLACING FURNACE THAT WAS PART OF A
CHIMNEY
OR GAS
VENT
(Check sizing
for water
heater only)
FURNACE
(Replaced
by SLP98)
If an SLP98 furnace replaces a furnace which was commonly vented with another gas appliance, the size of the
existing vent pipe for that gas appliance must be checked.
Without the heat of the original furnace flue products, the
existing vent pipe is probably oversized for the single water
heater or other appliance. The vent should be checked for
proper draw with the remaining appliance.
COMMON VENT SYSTEM
WATER
HEATER
OPENINGS
(To Adjacent
Room)
FIGURE 14
CAUTION
The exhaust vent pipe operates under positive pressure and must be completely sealed to prevent leakage of combustion products into the living space.
Vent Piping Guidelines
The SLP98DFV is installed only as a Direct Vent gas
central furnace.
NOTE − In Direct Vent installations, combustion air is taken
from outdoors and flue gases are discharged outdoors.
Intake and exhaust pipe sizing −− Size pipe according to
tables 6 and 7. Table 6 lists the minimum vent pipe lengths
permitted. Table 7 lists the maximum pipe lengths per-
mitted.
Regardless of the diameter of pipe used, the standard roof
and wall terminations described in section Exhaust PipingTerminations 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 9.
In some applications which permit the use of several different sizes of vent pipe, a combination vent pipe may be
used. Contact Lennox’ Application Department for assistance in sizing vent pipe in these applications.
15 ft.*
TABLE 6
EXAMPLE
5 ft. plus 2 elbows of 2", 2−1/2"
or 3" diameter pipe
MINIMUM VENT PIPE LENGTHS
SLP98DF
MODEL
070, 090, 110
*Any approved termination may be added to the minimum equivalent length
listed.
MIN. EQUIV.
VENT LENGTH
NOTE − It is acceptable to use any pipe size which fits within
the guidelines allowed in table 7.
Page 12
NOTE − The exhaust collar on all models is sized to accommodate 2" Schedule 40 vent pipe. Contact the Application Department for more information concerning
sizing of vent systems which include multiple pipe sizes.
NOTE − All horizontal runs of exhaust pipe must slope back
toward unit. A minimum of 1/4" (6mm) drop for each 12"
(305mm) of horizontal run is mandatory for drainage.
NOTE − Exhaust pipe MUST be glued to furnace exhaust
fittings.
NOTE − Exhaust piping should be checked carefully to
make sure there are no sags or low spots.
Use the following steps to correctly size vent pipe diameter.
Furnace
1
2
Capacity?
Which termination?
070, 090, 110
btuh
Standard or
Concentric?
See table 5
IMPORTANT
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze−ups
and may block the terminations.
3
4
5
6
7
Which needs
most elbows?
How many?
Desired pipe size?
What is the altitude?
Use table 7 to find
max intake or
exhaust pipe length.
Intake or
exhaust?
2", 2−1/2", 3"
Page 13
FIGURE 15
Maximum Allowable Intake or Exhaust Vent Length in Feet
TABLE 7
*Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Both Intake and Exhaust must be same pipe size.
Standard Terminatiuon at Elevation 7501’ − 10,000’’
2" Pipe2−1/2" Pipe3" Pipe
ModelModelModel
n/a
n/a
9068
n/a
5533778358
11211 893
NOTE − Table 7 continued on next page with concentric terminations.
Page 14
TABLE 7
Maximum Allowable Intake or Exhaust Vent Length in Feet
*Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Both Intake and Exhaust must be same pipe size.
Concentric Terminatioin at Elevation 7501’ − 10,000’’
2" Pipe2−1/2" Pipe3" Pipe
ModelModelModel
8064
175539718964
n/a
n/a
4529617954
n/a
11610984
918484
9611 489
Page 15
TYPICAL EXHAUST PIPE CONNECTIONS AND CONDENSATE TRAP INSTALLATION
TRAP
2”
2”
2”
DO NOT transition
from smaller to larger
pipe size in horizontal
3”
TRANSITION
*2“
Use only the factory−supplied
trap. Trap can be installed on
either side of cabinet within 5 ft.
of the furnace.
* When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible.
NOTE − Exhaust pipe and intake pipe must be the same diameter.
runs of exhaust pipe.
Air Intake
FIGURE 16
TYPICAL AIR INTAKE PIPE CONNECTIONS
2”
2”
2”
Exhaust
TOP VIEW
TRAP
TRANSITION
*2”
*2”
Use only the factory−supplied
trap. Trap can be installed on
either side of cabinet within 5 ft.
of the furnace.
* When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible.
NOTE − Intake pipe and exhaust pipe must be the same diameter.
3”
3”
TRANSITION
*2”
Air Intake
FIGURE 17
Exhaust
TOP VIEW
Page 16
VENT TERMINATION CLEARANCES
FOR DIRECT VENT INSTALLATIONS IN THE USA AND CANADA
INSIDE CORNER
DETAIL
G
D
A
E
B
L
C
Fixed
F
Closed
Operable
B
B
B
VENT TERMINAL
AIR SUPPLY INLET
US Installations
A =
B =
Clearance above grade, veranda,
porch, deck or balcony
Clearance to window or
door that may be opened
12 inches (305mm) or 12 in. 305mm)
above average snow accumulation.
6 inches (152mm) for appliances <10,000
Btuh (3kw), 9 inches (mm) for appliances
> 10,000 Btuh (3kw) and <50,000 Btuh
(15 kw), 12 inches (305mm) for ap-
pliances > 50,000 Btuh (15kw)
C =
Clearance to permanently
closed window
D =
Vertical clearance to ventilated soffit
located above the terminal within a
* Equal to or greater than soffit depth
horizontal distance of 2 feet (mm)
from the center line of the terminal
E =
F =
G =
H =
Clearance to unventilated soffit
Clearance to outside corner
Clearance to inside corner
Clearance to each side of center line ex-
tended above meter / regulator assembly
I =
Clearance to service regulator
vent outlet
J =
Clearance to non−mechanical air
supply inlet to building or the com-
bustion air inlet to any other ap-
pliance
* Equal to or greater than soffit depth* Equal to or greater than soffit depth
* No minimum to outside corner
3 feet (.9m) within a height 15 feet (4.5m)
above the meter / regulator assembly
*
3 feet (.9m)
6 inches (152mm) for appliances <10,000
Btuh (3kw), 9 inches (mm) for appliances
> 10,000 Btuh (3kw) and <50,000 Btuh
(15 kw), 12 inches (305mm) for ap-
pliances > 50,000 Btuh (15kw)
K =
L =
M =
1
2
A vent shall not terminate directly above a sidewalk or paved driveway that is located
between two single family dwellings and serves both dwellings.
Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two
sides beneath the floor. Lennox recommends avoiding this location if possible.
Clearance to mechanical air sup-
ply inlet
Clearance above paved sidewalk or
paved driveway located on public property
Clearance under veranda, porch,
deck or balcony
In accordance with the current ANSI Z223.1/NFPA 54 Natural Fuel Gas Code
In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code
3 feet (.9m) above if within 10 feet
(3m) horizontally
* 7 feet (2.1m)
*12 inches (305mm)
FIGURE 18
H
Operable
A
Fixed
Closed
J
B
I
M
AREA WHERE TERMINAL
IS NOT PERMITTED
1
Canadian Installations
12 inches (305mm) or 12 in. 305mm)
above average snow accumulation.
6 inches (152mm) for appliances <10,000
Btuh (3kw), 12 inches (305mm) for
appliances > 10,000 Btuh (3kw) and
<100,000 Btuh (30kw), 36 inches (.9m)
for appliances > 100,000 Btuh (30kw)
* 12"
* 12"
* Equal to or greater than soffit depth* Equal to or greater than soffit depth
* No minimum to outside corner
*
*
3 feet (.9m) within a height 15 feet (4.5m)
above the meter / regulator assembly
3 feet (.9m)
6 inches (152mm) for appliances <10,000
Btuh (3kw), 12 inches (305mm) for
appliances > 10,000 Btuh (3kw) and
<100,000 Btuh (30kw), 36 inches (.9m)
for appliances > 100,000 Btuh (30kw)
6 feet (1.8m)
7 feet (2.1m)
12 inches (305mm)
*For clearances not specified in ANSI Z223.1/NFPA 54 or CSA B149.1, clearance
will be in accordance with local installation codes and the requirements of the gas
supplier and these installation instructions."
K
2
Page 17
Details of Intake and Exhaust Piping Terminations for
Direct Vent Installations
NOTE − In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged to outdoors.
NOTE − Flue gas may be slightly acidic and may adversely
affect some building materials. If any vent termination is
used and the flue gasses may impinge on the building material, a corrosion−resistant shield (minimum 24 inches
square) should be used to protect the wall surface. If the
optional tee is used, the protective shield is recommended.
The shield should be constructed using wood, plastic,
sheet metal or other suitable material. All seams, joints,
cracks, etc. in the affected area should be sealed using an
appropriate sealant. See figure 21.
Intake and exhaust pipes may be routed either horizontally
through an outside wall or vertically through the roof. In attic
or closet installations, vertical termination through the roof
is preferred. Figures 19 through 28 show typical terminations.
1 − Exhaust and intake exits must be in same pressure
zone. Do not exit one through the roof and one on the
side. Also, do not exit the intake on one side and the
exhaust on another side of the house or structure.
2 − Intake and exhaust pipes should be placed as close
together as possible at termination end (refer to illustrations). Maximum separation is 3" (76mm) on roof
terminations and 6" (152mm) on side wall terminations.
3 − On roof terminations, the intake piping should termi-
nate straight down using two 90° elbows (See figure
19).
4 − Exhaust piping must terminate straight out or up as
shown. A reducer may be required on the exhaust piping at the point where it exits the structure to improve
the velocity of exhaust away from the intake piping.
See table 9.
NOTE − Care must be taken to avoid recirculation of
exhaust back into intake pipe.
Inches(mm)
8" (203mm) MIN
12" (305mm) ABOVE
AVERAGE SNOW
ACCUMULATION
3" (76mm) OR
2" (51mm) PVC
PROVIDE SUPPORT
FOR INTAKE AND
EXHAUST LINES
DIRECT VENT ROOF TERMINATION KIT
3"(76mm) MAX.
(15F75 or 44J41)
SIZE TERMINATION
PIPE PER TABLE 9.
UNCONDITIONED
ATTIC SPACE
1/2" (13mm) FOAM
INSULATION IN
UNCONDITIONED
SPACE
FIGURE 19
FIELD−SUPPLIED WALL TERMINATION OR
(15F74) WALL RING TERMINATION KIT
NOTE − FIELD−PROVIDED
REDUCER MAY BE
REQUIRED TO ADAPT
LARGER VENT PIPE SIZE
TO TERMINATION.
1/2" (13mm) ARMAFLEX
INSULATION IN
UNCONDITIONED SPACE
SIZE TERMINATION
PER TABLE 9
D
B
C
A
1/2" (13mm) ARMAFLEX INSULATION
IN UNCONDITIONED SPACE
STRAIGHT
APPPLICATION
D
* WALL
SUPPORT
E
B
A
C
EXTENDED
APPLICATION
See venting table 7 for maximum venting lengths with this
arrangement.
* Use wall support every 24" (610 mm). Use two wall supports if
extension is greater than 24" (610 mm) but less than 48" (1219
mm). NOTE − One wall support must be 6" (152 mm) from top
of each pipe (intake and exhaust).
A−Minimum clearance
above grade or average
snow accumulation
B−Maximum horizontal
separation between
intake and exhaust
C−Minimum from
end of exhaust to
inlet of intake
D−Maximum exhaust
pipe length
E−Maximum wall support
distance from top of each
pipe (intake/exhaust)
2" (51mm)
Vent Pipe
12" (508MM)12" (508MM)
6" (152MM)6" (152MM)
8" (203MM)8" (203MM)
12" (305MM)20" (508MM)
6" (152MM)6" (152MM)
3" (76mm)
Vent Pipe
FIGURE 20
Page 18
B
D
B
D
Intake
C
1
C
A
Exhaust
2
A
3
Front View of
Intake and Exhaust
Intake
Exhaust
TABLE 8
D
E
1
B
12"
C
2
A
A− Clearance above
grade or average snow
accumulation
B−Horizontal
separation between
intake and exhaust
C−Minimum from
end of exhaust to
inlet of intake
D−Exhaust pipe length
E−Wall support distance
from top of each pipe
(intake/exhaust)
2" (51mm)
Vent Pipe
12" (508MM) Min.
6" (152MM) Min.
24" (610 MM) Max
9" (227MM) Min.
12" (305MM) Min.
16" (405 MM) Max.
6" (152MM) Max.
3" (76mm)
Vent Pipe
12" (508MM) Min.
6" (152MM) Min.
24" (610 MM) Max
9" (227MM) Min.
12" (305MM) Min.
20" (508MM) Max.
6" (152MM) Max.
1
not use an accelerator in applications that include an exhaust termination tee. The accelerator is not required.
2
termination is used and flue gases will impinge on the building materials, a corrosion−resistant shield (24 inches
square) should be used to protect the wall surface. If optional tee is used, the protective shield is recommended. The shield should be constructed using wood, sheet metal or other suitable material. All seams, joints,
cracks, etc. in affected area, should be sealed using an appropriate sealant.
3
Exhaust pipe 45° elbow can be rotated to the side away from the combustion air inlet to direct exhaust away
from adjacent property. The exhaust must never be directed toward the combustion air inlet.
NOTE − See unit installation instructions for proper exhaust pipe termination size reduction.
The exhaust termination tee should be connected to the 2" or 3" PVC flue pipe as shown in the illustration. Do
As required. Flue gas may be acidic and may adversely affect some building materials. If a side wall vent
FIGURE 21
Page 19
FIELD−SUPPLIED WALL TERMINATION OR
(15F74) WALL RING TERMINATION KIT
With INTAKE ELBOW
NOTE − FIELD−PROVIDED
REDUCER MAY BE
REQUIRED TO ADAPT
LARGER VENT PIPE SIZE
TO TERMINATION.
1/2" (13mm) ARMAFLEX
INSULATION IN UN-
CONDITIONED SPACE
SIZE TERMINATION
PER TABLE 9
D
* WALL
SUPPORT
B
C
A
1/2" (13mm) ARMAFLEX INSULATION
IN UNCONDITIONED SPACE
E
STRAIGHT
APPPLICATION
D
B
A
C
See venting table 7 for maximum venting lengths with this
arrangement.
* Use wall support every 24" (610 mm). Use two wall supports if
extension is greater than 24" (610 mm) but less than 48" (1219
mm). NOTE − One wall support must be 6" (152 mm) from top of
each pipe (intake and exhaust).
EXTENDED
APPLICATION
EXHAUST PIPE TERMINATION SIZE REDUCTION
SLP98DFV
MODEL
*0702", 2−1/2" or 3"1−1/2"
*0902", 2−1/2" or 3"2"
1102", 2−1/2" or 3"2"
Exhaust Pipe SizeTermination Pipe Size
*SLP98DF −070 and −090 units with the flush−mount termination must use the 1−1/2" accelerator supplied with the
kit.
5 − On field−supplied terminations for side wall exit, ex-
haust piping may extend a maximum of 12 inches
(305mm) for 2" PVC and 20 inches (508mm) for 3"
(76mm) PVC beyond the outside wall. Intake piping
should be as short as possible. See figures 20 and 22.
6 − On field−supplied terminations, a minimum distance
between the end of the exhaust pipe and the end of
the intake pipe without a termination elbow is 8" and a
minimum distance of 6" with a termination elbow. See
figures 20 and 22.
7 − If intake and exhaust piping must be run up a side wall
to position above snow accumulation or other obstructions, piping must be supported every 24"
(610mm) as shown in figures 20 and 22. In addition,
close−coupled wall termination kits must be extended
for use in this application. See figures 30 and 31.
When exhaust and intake piping must be run up an
outside wall, the exhaust piping must be terminated
with pipe sized per table 9.The intake piping may be
equipped with a 90° turndown elbow. Using a turndown elbow will add 5 feet (1.5m) to the equivalent
length of the pipe.
8 − Based on the recommendation of the manufacturer, a
multiple−furnace installation may use a group of up to
four terminations assembled together horizontally, as
shown in figure 25.
TABLE 9
A−Minimum clearance
above grade or average
snow accumulation
B−Maximum horizontal
separation between
intake and exhaust
C−Minimum from
end of exhaust to
inlet of intake
D−Maximum exhaust
pipe length
E−Maximum wall support
distance from top of each
pipe (intake/exhaust)
2" (51mm)
Vent Pipe
12" (508MM)12" (508MM)
6" (152MM)6" (152MM)
6" (152MM)
12" (305MM)20" (508MM)
6" (152MM)6" (152MM)
3" (76mm)
Vent Pipe
6" (152MM)
FIGURE 22
Page 20
1−1/2" (38mm) accelerator
provided on 71M80 &
44W92 kits for
SLP98DFV−36B−070
12” (305mm)
Minimum
Above Average
Snow
Accumulation
CLAMP
DIRECT VENT CONCENTRIC ROOFTOP TERMINATION
71M80, 69M29 or 60L46 (US)
41W92 or 41W93 (Canada)
INTAKE
SHEET METAL STRAP
(Clamp and sheet metal strap
must be field installed to support
the weight of the termination kit.)
REDUCER MAY BE REQUIRED
PIPE SIZE TO TERMINATION
FLASHING
(Not Furnished)
FIELD−PROVIDED
TO ADAPT LARGER VENT
FIGURE 23
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