Lennox SLP98DFV SERIES User manual

Page 1
2015 Lennox Industries Inc.
Dallas, Texas, USA
AIR FLOW
DOWNFLOW
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 HVAC in
staller (or equivalent), service agency or the gas sup
plier.
INSTALLATION
INSTRUCTIONS
SLP98DFV
DAVE LENNOX SIGNATURE®
COLLECTION GAS FURNACE
DOWNFLOW AIR DISCHARGE
507027-01
10/2015
Supersedes 09/2015
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.
NOTICE
A thermostat is not included and must be ordered
separately.
The Lennox icomfort Wi-Fi®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-com
municating applications is illustrated in diagrams,
which begin on Page 33.
Table of Contents
Unit Dimensions 2.................................
Parts Arrangement 3...............................
SLP98DFV Gas Furnace 4..........................
Shipping and Packing List 4.........................
Safety Information 4................................
Use of Furnace as a Construction Heater 5............
General 6.........................................
Setting Equipment 6................................
Filters 9..........................................
Duct System 9....................................
Pipe and Fittings Specifications 10...................
Venting Options 12.................................
Joint Cementing Procedure 13.......................
Venting Practices 14...............................
Vent Piping Guidelines 14...........................
Gas Piping 29.....................................
Electrical 31.......................................
Integrated Control 39...............................
Blower Motor Performance 43.......................
Unit Start Up 48....................................
Gas Pressure Measurement 49......................
High Altitude Information 49.........................
Proper Combustions 49.............................
Other Unit Adjustments 52..........................
Heating Sequence of Operation 52...................
Service 54........................................
Repair Parts List 55................................
Integrated Control Diagnostic Codes 56...............
Configuring Unit Size Codes 59......................
Troubleshooting 60.................................
Litho U.S.A.

Page 2
Unit Dimensions - inches (mm)
AIR
EXHAUST AIR
OUTLET
COMBUSTION
AIR INTAKE
FLOW
2−1/16 (52)
SLP98DF090V48C
ABC
Model No. in. mm in. mm in. mm
SLP98DF070V36B 17−1/2 446 16−3/8 416 16 406
SLP98DF090V36C
21 533 19−7/8 505 19−1/2 495
SLP98DF090V60C
SLP98DF110V60C
GAS PIPING INLET
(Either Side)
RETURN AIR
OPENING
FRONT VIEW SIDE VIEW
TOP VIEW
A
B
C3/4
(19)
27−3/4
(705)
19−1/4
(489)
9−1/8 (232) Right
6−9/16 (167) Left
2 (51)
Either Side
33
(838)
3/4
(19)
B
Supply
Air
Supply
Air
9/16
(14)
9/16
(14)
9/16
(14)
9/16
(14)
19−7/16
(494)
3/4
(19)
CONDENSATE
TRAP CONNECTION
5
(127)
6−7/16 (163)
Either Side
9 (229)
Either Side
2−1/4
(57)
(Either Side)
1−1/2 (38)
Front Panel
1−7/8 (48)
1 (25)
6−1/4
(157)
2−1/16
(52)
5−3/16
(132)
OPTIONAL LEFT SIDE
VENT LOCATION
(Kit Required)
ALTERNATE RIGHT SIDE
VENT LOCATION
(Parts Furnished)
ELECTRICAL INLET
(Either Side)
ELECTRICAL INLET
(Either Side)

Page 3
Parts Arrangement
FIGURE 1
BURNER BOX ASSEMBLY
GAS VALVE
ACCESS PANEL
COMBUSTION AIR INDUCER
BLOWER
ACCESS
PANEL
BLOWER ASSEMBLY
(Variable Speed Blower
Motor Is Hidden)
BAG ASSEMBLY
CONTROL BOX
(includes variable capacity
integrated control,
transformer, circuit breaker
and door switch)
PRIMARY LIMIT
SIDE VENT
PATCH PLATE

Page 4
SLP98DFV Gas Furnace
The SLP98DFV category IV gas furnace is equipped with a
variable-capacity, variable-speed integrated control. This
control ensures compatibility with the Lennox icomfort Wi-
Fi®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 ap
plications only. A changeover kit may be ordered for LP ap
plications.
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.
FIGURE 2
DIRECT VENT INSTALLATION
EXHAUST OUTLET
COMBUSTION
AIR INTAKE
OUTSIDE OF
HOUSE
Shipping and Packing List
Package 1 of 1 contains
1 - Assembled SLP98DFV unit
1 - Bag assembly containing the following:
1 - Snap bushing
1 - Snap plug
1 - Wire tie
1 - Condensate trap
1 - 3/4” Threaded street elbow
2 - 2” Street elbows
2 - Side vent sealing plates
2 - Side vent sealing gaskets
6 - Sheet metal screws
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
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.
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 com
bustible 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 at
mosphere, the furnace must be installed according to rec
ommended good practice requirements and current Na
tional 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 ex
changer failure.
This SLP98DFV furnace must be installed so that its elec
trical components are protected from water.

Page 5
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 op
eration of either the heating or the cooling unit, unless it is in
the full HEAT or COOL setting.
FIGURE 3
AIR HANDLER
GAS UNIT
Dampers
(open during cooling
operation only)
Dampers
(open during heating
operation only)
SLP98DFV INSTALLED PARALLEL
WITH COOLING COIL
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
NOTE - This furnace is designed for a minimum continuous
return air temperature of 60°F (16°C) or an intermittent op
eration 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, clos
ets, 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 op
eration of the unit with clogged or misplaced filters will dam
age the unit.
SLP98DFV 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.
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.
DThe furnace heat exchanger, components, duct sys
tem, 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.

Page 6
General
WARNING
The State of California has determined that this prod
uct may contain or produce a chemical or chemicals,
in very low doses, which may cause serious illness
or death. It may also cause cancer, birth defects or
reproductive harm.
CAUTION
SLP98DFV unit should not be installed in areas nor
mally 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 fol
lowing general recommendations must be considered
when installing a SLP98DFV 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 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.
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 con
trol 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 posi
tioned from level to 1/2” toward the front to aid in draining.
See figure 4.
FIGURE 4
SETTING EQUIPMENT
FRONT VIEW SIDE VIEW
AIR FLOW AIR FLOW
1/2”
max.
AIR FLOW
SIDE VIEW
Unit must be level side-to-side. Unit may be positioned
from level to 1/2” toward the front to aid in draining.
FIGURE 5
Front
NOTE - Do not install the furnace on its front, back or in the horizontal position
Back Horizontal

Page 7
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 op
eration. After the bolt and washer have been removed, the
rigid leg will not touch the blower housing.
FIGURE 6
RIGID LEG
remove shipping bolt and washer
SLP98DF070V36B and
SL98DF090V036C WITH 1/2 HP
BLOWER MOTOR
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or al
cove 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 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.
The unit may be installed three ways in downflow applica
tions: 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 posi
tion. Floor and flange damage will result.
Refer to figure 7 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
optional base is installed between the furnace and the combus
tible 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 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.

Page 8
TABLE 1
NON-COMBUSTIBLE FLOOR OPENING SIZE
Cabinet Width
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
NOTE - Floor opening dimensions listed are 1/4 inch (6 mm) larger than
the unit opening. See dimension drawing on page 2.
FIGURE 8
SUPPLY AIR
PLENUM
PROPERLY
SIZED FLOOR
OPENING
SLP98DF UNIT
Installation on Combustible Flooring (Figure 9)
1 - When unit is installed on a combustible floor, a down
flow combustible flooring base must be installed be
tween the furnace and the floor. The base must be or
dered 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 com
bustible material other than wood flooring.
TABLE 2
COMBUSTIBLE FLOORING BASE 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
FIGURE 9
SLP98DF UNIT
SUPPLY AIR
PLENUM
COMBUSTIBLE
FLOORING BASE
PROPERLY
SIZED FLOOR
OPENING
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 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.

Page 9
FIGURE 10
COOLING COIL
PLENUM
PROPERLY
SIZED FLOOR
OPENING
SLP98DF UNIT
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 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.
ÉÉÉÉ
FIGURE 11
SECURE FROM
OUTSIDE CABINET
PLENUM
(Field Provided)
SEALING STRIP
(Field Provided)
Side View
CABINET
SIDE PANEL
ÉÉÉÉ
ÉÉÉÉ
SECURE FROM
INSIDE CABINET
PLENUM
(Field Provided)
SEALING STRIP
(Field Provided)
Side View
CABINET
SIDE PANEL
FIGURE 12
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 size.
A filter must be in place whenever the unit is operating.
IMPORTANT
If a highefficiency filter is being installed as part of
this system to ensure better indoor air quality, the fil
ter must be properly sized. Highefficiency filters
have a higher static pressure drop than standardef
ficiency glass/foam filters. If the pressure drop is too
great, system capacity and performance may be re
duced. The pressure drop may also cause the limit to
trip more frequently during the winter and the indoor
coil to freeze in the summer, resulting in an increase
in the number of service calls.
Before using any filter with this system, check the
specifications provided by the filter manufacturer
against the data given in the appropriate Lennox
Product Specifications bulletin. Additional informa
tion is provided in Service and Application Note
ACC002 (August 2000).
TABLE 3
Furnace
Cabinet Width Filter Size
B Cabinet (17-1/2”) 16 X 25 X 1 (1)
C Cabinet (21-1/2”)
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.
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 pres
sure, the flue products can be pulled back down the vent
pipe and into the room. This reverse flow of the flue gas
may result in incomplete combustion and the formation of
carbon monoxide gas. This toxic gas might then be distrib
uted throughout the house by the furnace duct system.
Use fiberglass sealing strips, caulking, or equivalent seal
ing 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 10
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 table 4 for approved piping and fitting materials.
TABLE 4
PIPING AND FITTINGS SPECIFICATIONS
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
CANADIAN PIPE, FITTINGS &
SOLVENT CEMENT MARKING
PVC & CPVC Pipe and Fittings
ULCS636
PVC & CPVC Solvent Cement
ABS to PVC or CPVC Transition Cement
POLYPROPYLENE VENTING SYSTEM
ULC-S636
PolyPro®by Duravent
InnoFlue®by Centrotherm ULC-S636
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 ce
ment 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 con
nections to the PVC fittings in the unit.
Use PVC primer and solvent cement or ABS solvent ce
ment 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) sys
tem. In addition, the first three feet of vent pipe from the fur
nace flue collar must be accessible for inspection.
Table 5 lists the available exhaust termination kits.

Page 11
TABLE 5
OUTDOOR TERMINATION USAGE*
Input Size
Vent
Pipe
Dia. in.
STANDARD CONCENTRIC
Flush
Mount
Kit
Wall Kit Wall Ring Kit
Field
Fabricated
1-1/2 inch 2 inch 3 inch
2 inch 3 inch 2 inch
51W11
(US)
51W12
(CA)
22G44 (US)
430G28 (CA)
44J40
(US)
481J20 (CA)
15F74
71M80
(US)
444W92
(CA)
69M29
(US)
444W92
(CA)
60L46 (US)
444W93 (CA)
070
23YES YES 1YES 1YES 5YES 2YES
2-1/2 3YES YES 1YES 1YES 5YES 2YES
33YES YES 1YES 1YES 5YES 2YES
090
23YES YES YES 5YES YES YES
2-1/2 3YES YES YES 5YES YES YES
33YES YES YES 5YES YES YES
110
2 YES YES YES 5YES YES YES
2-1/2 YES YES 5YES YES YES
3 YES YES 5YES YES YES
NOTE - Standard Terminations do not include any vent pipe or elbows external to the structure. Any vent pipe or elbows external to the structure must be included in total vent length
calculations. See vent length tables.
* Kits must be properly installed according to kit instructions.
1Requires field-provided outdoor 1-1/2” exhaust accelerator.
2Concentric kits 71M80 and 44W92 include 1-1/2” outdoor accelerator, when used with 045 and 070 input models.
3Flush mount kits 51W11 and 51W12 includes 1-1/2 in. outdoor exhaust accelerator, required when used with 045, 070 and 090 input models.
4Termination kits 30G28, 44W92, 4493 and 81J20 are certified to ULC S636 for use in Canada only.
5See table 9 for vent accelerator requirements.

Page 12
Venting Options
The SLP98DF is shipped with vent exhaust / air intake con
nection at the top cap. See figure 13. Using parts provided,
the furnace may be field modified to have these connec
tions on the right side of the furnace cabinet. See figure 15
and follow the steps below. For left side venting order kit
87W73.
1 - Remove inner blower door.
2 - Loosen hose clamps which attach rubber fittings to the
white PVC pipes inside the vestibule area. See figure
13.
3 - Loosen the clamp which secures the pipes at the blow
er deck. See figure 13.
4 - Remove white PVC pipes, slide up and out thru the top
cap.
5 - Remove the remaining parts of the pipe clamp at the
blower deck.
6 - Remove the black plastic fitting in top cap which pre
viously aligned the PVC pipes.
7 - Remove the sheet metal patch plate on the side of the
cabinet which covers the openings for side venting op
tion. Save screws for reuse.
8 - Re-use the patch plate to cover the hole in the top cap.
See figure 14. Remove the 2 screws which secure the
top cap to the furnace on the right side and re-install
securing the right edge of the patch plate and the right
side of the top cap to the furnace. Use 2 self-drilling
sheet metal screws (provided) to finish securing the
left edge of the patch plate on the left side.
9 - Use a utility knife to cut out the cabinet insulation for
the right side vent / air intake.
10 -Install the two 90° street elbows (provided) through the
side of the cabinet. The male side of each elbow
should extend down through the blower deck and con
nect to the rubber fittings below. Once the elbows are
properly positioned, tighten each clamp.
11 -Peel protective backing from side vent sealing gaskets
(2) and apply to side vent sealing plates (2) as shown
in figure 15.
12 -Install the side vent sealing plates and gaskets on the
exterior of the cabinet as shown in figure 15. Secure
with six mounting screws (four reused and two pro
vided from bag assembly). Holes are pre-punched in
the parts and cabinet, no drilling is required.
13 -Install sheet metal screws (provided) to seal extra two
holes in cabinet not used with side vent clamps.
IMPORTANT
Side vent sealing plates and side vent sealing gas
kets must be used when converting to right side
venting. Failure to use gaskets and plates may lead
to improper operation of unit.
FIGURE 13
Top Vent
Configuration Exhaust/Air
Intake Connections
Pipe Clamp
Hose Clamp
FIGURE 14
Sheet Metal
Patch Plate
Patch Plate Top Cap

Page 13
FIGURE 15
Right Side Vent Configuration
Side Vent
Sealing Plate
Side Vent
Sealing Gaskets
Street Elbows (2)
Intake
Exhaust
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.
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.
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.
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 ap
plied lightly but uniformly to inside of socket. Take care
to keep excess cement out of socket. Apply second
coat to end of pipe.
NOTE - Time is critical at this stage. Do not allow prim
er 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 dur
ing assembly (but not after pipe is fully inserted) to dis
tribute cement evenly. DO NOT turn ABS or cellular
core pipe.
NOTE - Assembly should be completed within 20 sec
onds 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 14
Venting Practices
FIGURE 16
* See table 4 for allowable pipe.
Piping Suspension Guidelines
NOTE - Isolate piping at the point where it exits the outside wall or
roof in order to prevent transmission of vibration to the structure.
SCHEDULE 40 PVC --
Support every 5 feet.
all other pipe* --
Support every 3 feet.
Wall
inside outside
24” maximum
3/4” minimum
Wall Thickness Guidelines
REPLACING FURNACE THAT WAS PART OF A
COMMON VENT SYSTEM
CHIMNEY
OR GAS
VENT
(Check sizing
for water
heater only)
FURNACE
(Replaced
by SLP98)
WATER
HEATER
OPENINGS
(To Adjacent
Room)
If an SLP98 furnace replaces a furnace which was com
monly 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.
FIGURE 17
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 conden
sate collection trap and lines.
Exhaust Piping (Figures 19 and 21)
Route piping to outside of structure. Continue with installa
tion following instructions given in piping termination sec
tion.
WARNING
Carbon Monoxide Poisoning Hazard
Cutting or altering exhaust or air intake pipes, which
are located in the blower compartment, could result
in Carbon Monoxide Poisoning or Death.
CAUTION
Do not discharge exhaust into an existing stack or
stack that also serves another gas appliance. If verti
cal discharge through an existing unused stack is re
quired, insert PVC pipe inside the stack until the end
is even with the top or outlet end of the metal stack.
CAUTION
The exhaust vent pipe operates under positive pres
sure and must be completely sealed to prevent leak
age of combustion products into the living space.
Vent Piping Guidelines
NOTE - Lennox has approved the use of DuraVent®and
Centrotherm manufactured vent pipe and terminations as
an option to PVC. When using the PolyPro®by DuraVent or
InnoFlue®by Centrotherm venting system the vent pipe re
quirements stated in the unit installation instruction – min
imum & maximum vent lengths, termination clearances,
etc. – apply and must be followed. Follow the instructions
provided with PoyPro by DuraVent and InnoFlue®by Cen
trotherm venting system for assembly or if requirements
are more restrictive. The PolyPro by Duravent and In
noFlue by Centrotherm venting system must also follow
the uninsulated and unconditioned space criteria listed in
table 9.
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. Count all elbows inside and outside the
home. Table 6 lists the minimum vent pipe lengths per
mitted. Table 7 lists the maximum pipe lengths permitted.

Page 15
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 9.
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.
TABLE 6
MINIMUM VENT PIPE LENGTHS
SLP98DF
MODEL
MIN. EQUIV.
VENT LENGTH EXAMPLE
070, 090, 110 15 ft.* 5 ft. plus 2 elbows of 2”, 2-1/2”
or 3” diameter pipe
*Any approved termination may be added to the minimum equivalent
length listed.
NOTE - It is acceptable to use any pipe size which fits within
the guidelines allowed in table 7.
NOTE - The exhaust collar on all models is sized to accom
modate 2” Schedule 40 vent pipe. Contact the Application
Department for more information concerning sizing of vent
systems which include multiple pipe sizes.
NOTE - If right side venting option is used, you must include
the elbow at the furnace in the elbow count. If transitioning
to 3” dia pipe, this elbow equates to 20' of equivalent vent
length for all models.
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.
IMPORTANT
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze-ups
and may block the terminations. FIGURE 18
Piping Size Process
1
2
3
4
5
6
Which style termination
being used?
Standard or concentric?
See table 5.
Which needs
most elbows?
Intake or
exhaust?
How many elbows?
Count all elbows inside
and outside house.
Desired pipe size?
2”, 2-1/2”, 3”
Use table 7 to find max
intake or exhaust pipe
length. Includes all vent
pipe and elbows inside
and outside the house.
What is the altitude of
the furnace installation?
7
What is the
furnace capacity?
070, 090 or 110?

Page 16
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.
NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation.
Standard Termination at Elevation 0 - 4500'
Number Of
90° Elbows
Used
2” Pipe 2-1/2” Pipe 3” Pipe
Model Model Model
070 090 110 070 090 110 070 090 110
1 91 69 14 140 93 43 162 143 118
2 86 64 9 135 88 38 157 138 113
3 81 59
n/a
130 83 33 152 133 108
4 76 54 125 78 28 147 128 103
5 71 49 120 73 23 142 123 98
6 66 44 115 68 18 137 118 93
7 61 39 110 63 13 132 113 88
8 56 34 105 58
n/a
127 108 83
9 51 29 100 53 122 103 78
10 46 24 95 48 117 98 73
Standard Termination Elevation 4501' - 7500'
Number Of
90° Elbows
Used
2” Pipe 2-1/2” Pipe 3” Pipe
Model Model Model
070 090 110 070 090 110 070 090 110
1 66 69 14 115 93 43 137 143 118
2 61 64 9 110 88 38 132 138 113
3 56 59
n/a
105 83 33 127 133 108
4 51 54 100 78 28 122 128 103
5 46 49 95 73 23 117 123 98
6 41 44 90 68 18 112 118 93
7 36 39 85 63 13 107 113 88
8 31 34 80 58
n/a
102 108 83
9 26 29 75 53 97 103 78
10 21 24 70 48 92 98 73
Standard Termination at Elevation 7501' - 10,000''
Number Of
90° Elbows
Used
2” Pipe 2-1/2” Pipe 3” Pipe
Model Model Model
070 090 110 070 090 110 070 090 110
1 41 44
n/a
90 68
n/a
112 118 93
2 36 39 85 63 107 113 88
3 31 34 80 58 102 108 83
4 26 29 75 53 97 103 78
5 21 24 70 48 92 98 73
6 16 19 65 43 87 93 68
7 11 14 60 38 82 88 63
8
n/a n/a
55 33 77 83 58
9 50 28 72 78 53
10 45 23 67 73 48
NOTE - Table 7 continued on next page with concentric terminations.

Page 17
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 Termination at Elevation 0 - 4500'
Number Of
90° Elbows
Used
2” Pipe 2-1/2” Pipe 3” Pipe
Model Model Model
070 090 110 070 090 110 070 090 110
1 83 67 12 130 89 39 146 139 114
2 78 62 7 125 84 34 141 134 109
3 73 57
n/a
120 79 29 136 129 104
4 68 52 115 74 24 131 124 99
5 63 47 110 69 19 126 119 94
6 58 42 105 64 14 121 114 89
7 53 37 100 59
n/a
116 109 84
8 48 32 95 54 111 104 79
9 43 27 90 49 106 99 74
10 38 22 85 44 101 94 69
Concentric Termination Elevation 4501' - 7500'
Number Of
90° Elbows
Used
2” Pipe 2-1/2” Pipe 3” Pipe
Model Model Model
070 090 110 070 090 110 070 090 110
1 58 67 12 105 89 39 121 114 114
2 53 62 7 100 84 34 116 109 109
3 48 57
n/a
95 79 29 111 104 104
4 43 52 90 74 24 106 99 99
5 38 47 85 69 19 101 94 94
6 33 42 80 64 14 96 89 89
7 28 37 75 59
n/a
91 84 84
8 23 32 70 54 86 79 79
9 18 27 65 49 81 74 74
10 13 22 60 44 76 69 69
Concentric Termination at Elevation 7501' - 10,000''
Number Of
90° Elbows
Used
2” Pipe 2-1/2” Pipe 3” Pipe
Model Model Model
070 090 110 070 090 110 070 090 110
1 33 42
n/a
80 64
n/a
96 114 89
2 28 37 75 59 91 109 84
3 23 32 70 54 86 104 79
4 18 27 65 49 81 99 74
5 13 22 60 44 76 94 69
6
n/a
17 55 39 71 89 64
7 12 50 34 66 84 59
8
n/a
45 29 61 79 54
9 40 24 56 74 49
10 35 19 51 69 44

Page 18
FIGURE 19
TYPICAL EXHAUST PIPE CONNECTIONS AND CONDENSATE TRAP INSTALLATION
TRANSITION
2” 2”
2”
3”
TOP VIEW
Exhaust
Air Intake
DO NOT transition
from smaller to larger
pipe size in horizontal
runs of exhaust pipe.
* 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.
*2“
FIGURE 20
TYPICAL AIR INTAKE PIPE CONNECTIONS
2” 2”
TRANSITION
3”
TRANSITION
2”
3”
TOP VIEW
Exhaust
Air Intake
*2”
*2”
*2”
* 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.

Page 19
FIGURE 21
TYPICAL EXHAUST CONNECTIONS WITH RIGHT SIDE VENT OPTION
TRANSITION
2” 3”
TOP VIEW
*2”
* 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.
Pipe Length
4” Maximum
(Not Furnished)
2”
2”
Plate
(Furnished)
Street Ell
(Not Furnished)
FIGURE 22
TRANSITION
2” 3”
TOP VIEW
*2”
* 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.
2”
Plate
(Furnished)
TYPICAL AIR INTAKE PIPE CONNECTIONS WITH RIGHT SIDE VENT OPTION
*2”
Street Ell
(Not Furnished)

Page 20
FIGURE 23
VENT TERMINATION CLEARANCES
FOR DIRECT VENT INSTALLATIONS IN THE USA AND CANADA
K
D
E
L
B
C
F
G
A
B
J
A
M
I
H
INSIDE CORNER
DETAIL
VENT TERMINAL AIR SUPPLY INLET AREA WHERE TERMINAL
IS NOT PERMITTED
Fixed
Closed
Operable
B
Fixed
Closed
Operable
B
B
A =
B =
C =
D =
E =
F =
G =
H =
I =
J =
K =
L =
M =
US Installations1Canadian Installations2
12 inches (305mm) or 12 in. (305mm)
above average snow accumulation.
12 inches (305mm) or 12 in. (305mm)
above average snow accumulation.
Clearance above grade, veranda,
porch, deck or balcony
Clearance to window or
door that may be opened
6 inches (152mm) for appliances <10,000
Btuh (3kw), 9 inches (228mm) for ap
pliances > 10,000 Btuh (3kw) and <50,000
Btuh (15 kw), 12 inches (305mm) for ap
pliances > 50,000 Btuh (15kw)
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)
Clearance to permanently
closed window
Vertical clearance to ventilated soffit
located above the terminal within a
horizontal distance of 2 feet (610mm)
from the center line of the terminal
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
Clearance to service regulator
vent outlet
Clearance to non-mechanical air
supply inlet to building or the com
bustion air inlet to any other ap
pliance
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
* 12”
*
*
* 7 feet (2.1m)
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 (228mm) for ap
pliances > 10,000 Btuh (3kw) and <50,000
Btuh (15 kw), 12 inches (305mm) for ap
pliances > 50,000 Btuh (15kw)
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)
3 feet (.9m) above if within 10 feet
(3m) horizontally
6 feet (1.8m)
7 feet (2.1m)†
12 inches (305mm)‡
1In accordance with the current ANSI Z223.1/NFPA 54 Natural Fuel Gas Code
2In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code *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.”
† 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.
* 12”
* Equal to or greater than soffit depth * Equal to or greater than soffit depth* Equal to or greater than soffit depth
* Equal to or greater than soffit depth * Equal to or greater than soffit depth
* No minimum to outside corner * No minimum to outside corner
3 feet (.9m) within a height 15 feet (4.5m)
above the meter / regulator assembly
3 feet (.9m)
*
*12 inches (305mm)‡