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.