Lennox SL280DFNV Installation Instructions Manual
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Lennox SL280DFNV Installation Instructions Manual

Lennox SL280DFNV Installation Instructions Manual

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© 2021 Lennox Industries Inc.
Dallas, Texas USA
CAUTION
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal
injury. Take care while handling this equipment and
wear gloves and protective clothing.
Contents
Unit Dimensions - inches (mm) ......................................2
Parts Arrangement..........................................................3
SL280DFNV Gas Furnace..............................................4
Shipping and Packing List ..............................................4
Safety .............................................................................4
General ...........................................................................5
Combustion, Dilution, Ventilation Air...............................5
Setting Equipment ........................................................10
Filters ............................................................................ 11
Duct System .................................................................12
Venting .........................................................................12
INSTALLATION
INSTRUCTIONS
SL280DFNV
DAVE LENNOX SIGNATURE
GAS FURNACE DOWNFLOW
AIR DISCHARGE
508150-02
08/2021
Supersedes 508150-01
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 man-
uals, be alert to the potential for personal injury or death.
Improper
installation,
service or maintenance can cause property damage,
personal injury or loss of life. Installation and service
must be performed by a licensed professional HVAC
installer (or equivalent), service agency or the gas
supplier.
A thermostat is not included and must be ordered
separately.
• A communicating thermostat must be used in
communicating applications.
• In non-communicating applications, the Lennox
ComfortSense® 7500 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 21.
Gas Piping ....................................................................17
Electrical .......................................................................19
Integrated Control Settings ...........................................29
Blower Motor Performance ...........................................33
Unit Start-Up .................................................................37
Gas Pressure Measurement.........................................38
Proper Combustion.......................................................38
Other Unit Adjustments.................................................39
Sequence of Operation.................................................39
Service..........................................................................41
Repair Parts List ...........................................................43
Integrated Control Diagnostic Codes............................44
Program Unit Capacity Size Mode ...............................50
Troubleshooting ............................................................51
Page 1
®
WARNING
adjustment,
alteration,
NOTICE

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Summary of Contents for Lennox SL280DFNV

  • Page 1: Table Of Contents

    A thermostat is not included and must be ordered separately. • A communicating thermostat must be used in communicating applications. • In non-communicating applications, the Lennox CAUTION ComfortSense® 7500 thermostat may be used, as well as other non-communicating thermostats. As with any mechanical equipment, contact with...

  • Page 2: Unit Dimensions - Inches (Mm)

    Unit Dimensions - inches (mm) 3-1/8 9/16 (79) (14) RETURN AIR OPENING FLUE OUTLET 19-7/16 9/16 (Top) (494) (14) 9/16 (14) TOP VIEW 27-3/4 1-1/2 (38) (705) Front Panel 9/16 19-7/16 9/16 (14) (494) (14) AIR FLOW ELECTRICAL INLET (Either Side) (838) 5-3/8 (137) Right GAS PIPING INLET...

  • Page 3: Parts Arrangement

    Parts Arrangement Blower assembly Blower assembly Internal flue pipe assembly Flue chase Control box Combustion air inducer Gas valve Heat exchanger assembly Access panel Air fuel intake assembly FIGURE 1 Page 3...

  • Page 4: Sl280Dfnv Gas Furnace

    Certifications SL280DFNV Gas Furnace SL280DFNV units are CSA International certified. The SL280DFNV gas furnace is equipped with a twostage, In the USA, installation of gas furnaces must conform with variable speed integrated control. the control is compati- local building codes. In the absence of local codes, units...

  • Page 5: Use Of Furnace As A Construction Heaterl

    SL280DFNV furnaces to ensure ef- This furnace design has not been CSA International ficient and safe operation. You must consider combustion certified for installation in mobile homes, recreational air needs and requirements for exhaust vents.
  • Page 6 Confined Space CAUTION A confined space is an area with a volume less than 50 Insufficient combustion air can cause headaches, cubic feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of nausea, dizziness or asphyxiation. It will also cause the combined input rating of all appliances installed in that excess water in the heat exchanger resulting in space.
  • Page 7 Air from Outside When ducts are used, they shall be of the same cross-sec- tional area as the free area of the openings to which they If air from outside is brought in for combustion and ventila- connect. The minimum dimension of rectangular air ducts tion, the confined space must have two permanent open- shall be no less than 3 inches (75 mm).
  • Page 8 Installation on Non-Combustible Flooring (Figure 7) EQUIPMENT IN CONFINED SPACE ALL AIR FROM OUTSIDE 1 - Cut floor opening keeping in mind clearances listed (All Air Through Ventilated Attic) CHIMNEY on unit rating plate. Also keep in mind gas supply OR GAS connections, electrical supply, flue and air intake VENT...
  • Page 9 UNIT UNIT SUPPLY AIR PLENUM DOWNFLOW PROPERLY COMBUSTIBLE COOLING COIL SIZED FLOOR FLOORING BASE OPENING PROPERLY PLENUM SIZED FLOOR OPENING FIGURE 8 FIGURE 9 TABLE 2 Return Air Opening -- Downflow Units COMBUSTIBLE FLOOR OPENING SIZE Cabinet Front to Rear Side to Side The following steps should be taken when installing ple- num:...

  • Page 10: Setting Equipment

    FIGURE 12 Install the SL280DFNV gas furnace as shipped in the downflow position only. Do not install the furnace horizon- WARNING tally.

  • Page 11: Filters

    Lennox Product Specifications bulletin. maximum volume of combustion air required for all Additional information is provided in Service and gas appliances serviced by this space.

  • Page 12: Duct System

    The vent connector does not require insula- tion. VENT CONNECTION “DISCONNECTED VENT” The SL280DFNV series units are classified as fan-assist- WARNING ed Category I furnaces when vertically vented according STICKER to the latest edition of National Fuel Gas Code (NFPA 54 / ANSI Z223.1).
  • Page 13 SL280DFNV series units. The chim- Insulation for the flexible vent pipe must be an encapsu- ney passageway must be checked periodically to ensure lated fiberglass sleeve recommended by the flexible vent that it is clear and free of obstructions.
  • Page 14 7-1/2 General Venting Requirements Vent all SL280DFNV furnaces according to these instruc- 10-1/2 tions: 9 - If the common vertical vent is offset, the maximum...
  • Page 15 19 - In no case, shall the vent connector be sized more 21 - When connecting this appliance to an existing ded- than two consecutive table size diameters over the icated or common venting system, you must inspect the size of the draft hood outlet or flue collar outlet. venting system’s general condition and look for signs of corrosion.
  • Page 16 TABLE 6 Vent Connector Capacity Type B Double-Wall Vents with Type B Double-Wall Connectors Serving Two or More Category I Appliances Vent and Connector Diameter - D (inches) Height Lateral 3 inch 4 inch 5 inch 6 inch Appliance Input Rating in Thousands of Btu Per Hour (feet) (feet) TABLE 7...

  • Page 17: Gas Piping

    Removal of the Furnace from Common Vent Resize the common venting system to the minimum vent pipe size determined by using the appropriate tables in In the event that an existing furnace is removed from a Appendix G. (These are in the current standards of the venting system commonly run with separate gas applianc- National Fuel Gas Code ANSI Z223.1.
  • Page 18 TABLE 8 Gas Pipe Capacity - ft3/hr (m3/hr) Nominal Internal Length of Pipe - feet (m) Iron Pipe Diameter Size Inches inches (3.048) (6.096) (9,144) (12,192) (15.240) (18.288) (21.336) (24.384) (27.432) (30,480) (mm) (mm) .622 (12.7) (17.799) (4.87) (3.34) (2.69) (2.29) (2.03) (1.84)

  • Page 19: Electrical

    The unit is equipped with a field make-up box on the left The furnace must be isolated from the gas supply system hand side of the cabinet. The make-up box may be moved by closing the individual manual shut-off valve during any gas supply system at pressures greater than or equal to ½...
  • Page 20 23 for allowable circulation speeds. 9 - Install the room thermostat according to the 2 - When the SL280DFNV is running in the heating instructions provided with the thermostat. See table mode, the indoor blower will run on the heating 10 for field wiring connections in varying applications.
  • Page 21 Generator Use - Voltage Requirements • The furnace integrated control requires both correct polarity and proper ground. Both polarity and prop- The following requirements must be kept in mind when er grounding should be checked before attempting to specifying a generator for use with this equipment: operate the furnace on either permanent or temporary •...
  • Page 22 Optional Accessories for use with any Communicating System NOTE: ICOMMUNICATING THERMOSTAT SENSES HUMIDITY & CONTROLS HUM CONTACTS TO CYCLE HUMIDIFIER BASED 120V CONNECTIONS QUIRED. “HUM” CONTACT IS CLOSED ANYTIME HUMIDITY DEMAND IS PRESENT TIONS. BUILT INTO ALL COMMUNICATING ENABLED OUT DOOR UNITS).
  • Page 23 LENNOX COMMUNICATING OUTDOOR UNIT INDOOR UNIT (1 OR 2 STAGE) FLOAT SWITCH LENNOX COMMUNICATING OUTDOOR UNIT LENNOX COMMUNICATING FURNACE EL296V, SL280V, SL280VN, SL297V, SLP99V cutting DS to R will not cause communication interuption or error code CUT* R-DS W914 Figure 23...
  • Page 24 TABLE 10 SL280 Field Wiring Applications With Conventional Thermostat DIP Switch Settings and On-Board Links DIP Switch 1 On Board Links Must Be Cut To Select Thermostat Thermostat Wiring Connections System Options Heating Stages 1 Heat / 1 Cool FURNACE OUTDOOR T'STAT TERM.
  • Page 25 TABLE 10 Continued SL280 Field Wiring Applications With Conventional Thermostat DIP Switch Settings and On-Board Links DIP Switch 1 On Board Links Must Be Cut To Select Thermostat Thermostat Wiring Connections System Options Heating Stages 2 Heat / 2 Cool FURNACE OUTDOOR T'STAT...
  • Page 26 TABLE 10 Continued SL280 Field Wiring Applications With Conventional Thermostat DIP Switch Settings and On-Board Links DIP Switch 1 Wiring Connections Thermostat On Board Links Must Be Cut To Select Thermostat Heating System Options Stages Dual Fuel FURNACE HEAT PUMP T'STAT TERM.
  • Page 27 TABLE 10 Continued SL280 Field Wiring Applications With Conventional Thermostat DIP Switch Settings and On-Board Links DIP Switch 1 Wiring Connections Thermostat On Board Links Must Be Cut To Select Thermostat Heating System Options Stages Dual Fuel FURNACE HEAT PUMP T'STAT TERM.
  • Page 28 SL280DFNV Schematic Wiring Diagram FIGURE 24 Page 28...

  • Page 29: Integrated Control Settings

    Integrated Control HS/ CAI LINE 1 NEUTRAL 7 SEGMENT LED FLAME SENSE INDOOR BLOWER DIAGNOSTIC CONNECTOR PUSH BUTTON DIP SWITCHES 12 PIN LOW OUTDOOR AIR VOLTAGE SENSOR CONNECTOR TERMINALS DISCHARGE AIR W915 Y1 TO Y2 SENSOR 2 STAGE COMPR TERMINALS W951 R TO O HEAT PUMP TB83...
  • Page 30 Integrated Control Switch Settings Conventional Thermostat (non-communicating) Blower Off Delay Switch Settings SL280DFNV units are equipped with a two-stage, variable Blower Off Delay Switch 3 Switch 4 speed integrated control. This control manages ignition (Seconds) timing, heating mode fan off delays and indoor blower...
  • Page 31 NOTE - The off portion of the selected ramp profile also Ramping Option D applies during heat pump operation in dual fuel applica- • Motor runs at 100% until demand is satisfied. tions. • Once demand is met, motor ramps down to stop. TABLE 14 Cooling Mode Speed Ramping 100% CFM...
  • Page 32 Refer to table 17 for operation sequence in ap- time while “c” is flashing to confirm command to delete plications including SL280DFNV, a thermostat which fea- codes. Press the button until a solid “≡” is displayed to exit tures humidity control and a single-speed outdoor unit. Ta- the Error Code Recall mode.

  • Page 33: Blower Motor Performance

    First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 380 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 380 cfm.
  • Page 34 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 450 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 450 cfm.
  • Page 35 W914 (R to DS) on SureLight® control With Heat Pump - Cut W914 (R to DS) & W951 (R to O) on SureLight® control Dave Lennox ComfortSense® 7500 thermostat to use for this application - Y2081 4 heat / 2 cool *Dehumidification blower speed is 70% of COOL speed for all units .
  • Page 36 TABLE 18 OPERATING SEQUENCE SL280DFV, Non-Communicating Thermostat with Humidity Control Feature and Two-Speed Outdoor Unit OPERATING SYSTEM DEMAND SYSTEM RESPONSE SEQUENCE Thermostat Demand Relative Humidity Blower System Compre Step Comments ssor Condition Status (cool) NO CALL FOR DEHUMIDIFICATION Normal Operation Acceptable 70%* Compressor and indoor...

  • Page 37: Unit Start-Up

    9 - Replace the access panel. The gas valve on the SL280DFNV unit will be equipped 10 - Turn on all electrical power to to the unit. with either a gas control switch. Use only your hand to move the control switch.

  • Page 38: Gas Pressure Measurement

    5 - Is the filter dirty or plugged? Dirty or plugged filters 2- Start unit and allow 5 minutes for unit to reach steady state. will cause the limit control to shut the unit off. 3 - After allowing unit to stabilize for 5 minutes, record 6 - Is gas turned on at the meter? manifold pressure and compare to value given in 7 - Is the manual main shut-off valve open?

  • Page 39: Other Unit Adjustments

    (second stage) gas valve is energized and The two-stage, variable speed integrated control used the indoor blower motor is energized for operation at in SL280DFNV units has an added feature of an internal the high fire heating speed. Watchguard control. The feature serves as an automat-...
  • Page 40 Applications Using A Single-Stage Thermostat 4 - After the 20-second warm-up period has ended, the gas valve is energized on low fire (first stage) and See figure 28 for ignition control sequence ignition occurs. At the same time, the control module B - Heating Sequence -- Control Thermostat Selection sends a signal to begin an indoor blower 30-second DIP Switch 1 ON in “Single-Stage”...

  • Page 41: Service

    14- Verify operation of CO detectors and replace At the beginning of each heating season, and to comply batteries as required. with the Lennox Limited Warranty, your system should Perform a general system test. Turn on the furnace to be checked as follows:...
  • Page 42 Cleaning the Burners remove the air intake assembly (can stay intact) / air fuel plenum assembly from the unit. The air intake assembly NOTE - Use papers or protective covering in front of the and air fuel plenum can be removed as one component furnace during cleaning.

  • Page 43: Repair Parts List

    Repair Parts List The following repair parts are available through independent Lennox dealers. When ordering parts, include the complete furnace model number listed on the CSA International nameplate -- Example: SL280DF060NV36B-01. All service must be performed by a licensed professional installer (or equivalent), service agency, or gas supplier.

  • Page 44: Integrated Control Diagnostic Codes

    Integrated Control Diagnostic Modes Display Action (when button is released) No change (idle)* Remain in idle mode Solid “E” Enter diagnostic recall mode Solid “D” Discharge Air Installed Solid “F” Enter flame signal mode Solid “F” (variable speed only) Program unit capacity size (Unit Code) soft disable Two Horizontal bars * No change implies the display will continue to show...
  • Page 45 Integrated Control Diagnostic Codes Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover Idle mode (Decimal blinks at 1 Hertz -- 0.5 second ON, 0.5 second OFF). Cubic feet per minute (cfm) setting for indoor blower (1 second ON, 0.5 second OFF) / cfm setting for current mode displayed.
  • Page 46 Integrated Control Diagnostic Codes Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E124 Active communicating thermostat signal Equipment lost communication with the thermostat. Check missing for more than 3 minutes. four wiring connections, ohm wires and cycle power at the thermostat.
  • Page 47 Integrated Control Diagnostic Codes Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E206 Gas valve second-stage relay failure Furnace will operate on 1st stage for remainder of the heating demand. Will clear after fault recovered. If un- able to operate 2nd stage, replace control.
  • Page 48 Integrated Control Diagnostic Codes Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E271 Soft lockout - Exceeded maximum number of re- Check pressure (inches w.c.) of low pressure switch clos- tries. Last retry failed due to the pressure switch ing on heat call.
  • Page 49 Integrated Control Diagnostic Codes Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E312 Restricted air flow in cooling or continu- Warning Only. Restricted airflow - Indoor blower is running at a re- ous fan mode is lower than cfm setting. duced CFM (Cutback Mode - The variable speed motor has pre-set speed and torque limiters to protect the motor from damage caused by operating outside of design parameters (0 to 0.8”...

  • Page 50: Program Unit Capacity Size Mode

    Integrated Control Diagnostic Codes Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E406 LSOM - Compressor open start circuit. Required amount of current is not passing through Start cur- rent transformer. Clears the error after current is sensed in START sensor, or after power reset.

  • Page 51: Troubleshooting

    Troubleshooting: Heating Sequence of Operation CALL FOR FIRST-STAGE HEAT CALL FOR 1ST STAGE HEAT (LOW FIRE) INDOOR BLOWER OFF AFTER HEAT FAN OFF DELAY (LOW HEAT SPEED) INDOOR LIMIT BLOWER OFF HIGH ERROR INDOOR SWITCH WATCHGUARD − AFTER HEAT FAN LIMIT SWITCH CODE BLOWER...
  • Page 52 Troubleshooting: Heating Sequence of Operation (Continued) CALL FOR SECOND-STAGE HEAT CALL FOR 2ND STAGE HEAT (HIGH FIRE) SINGLE STAGE 2 STAGE THERMOSTAT THERMOSTAT 2ND STAGE RECOGNITION DELAY ON DELAY (30 SECONDS) EXPIRED? EXPIRED? ONLY FOR 1ST REQUEST FOR 2ND STAGE HEAT INDUCER SWITCHED TO HIGH SPEED HIGH...
  • Page 53 Troubleshooting: Heating Sequence of Operation (Continued) CALL FOR HEAT SATISFIED FIRST-STAGE HEAT SECOND-STAGE HEAT RUN MODE: 1ST OR 2ND STAGE CALL FOR HEAT. ALL INPUTS MONITORED (LIMIT, PRESSURE, CALL FOR HEAT/COOL, FLAME LEVEL) 2ND STAGE HEAT 2ND STAGE CALL FOR HEAT SATISFIED? DE−ENERGIZE 2ND STAGE GAS VALVE...
  • Page 54 Troubleshooting: Cooling Sequence of Operation CALL FOR COOLING 1ST STAGE COOLING REQUEST RECEIVED WAIT FOR COMPRESSOR TIMED OFF DELAY TO EXPIRE ENERGIZE 1ST STAGE COOLING CONTACTOR (COMPRESSOR & FAN) INDOOR BLOWER 2 SECOND ON DELAY ENERGIZE INDOOR BLOWER (LOW COOLING MODE) MAINTAIN INDOOR BLOWER (LOW COOLING MODE)
  • Page 55 Troubleshooting: Continuous Fan Sequence of Operation CALL FOR FAN CALL FOR FAN INDOOR BLOWER ON CONTINUOUS FAN SPEED CALL FOR FAN MAINTAIN INDOOR BLOWER AT REMOVED? CONTINUOUS FAN REQUEST MAINTAIN INDOOR FOR COOLING GO TO CALL FOR COOLING BLOWER AT RECEIVED? CONTINUOUS FAN REQUEST...

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