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Lennox SL280DFNV Series Unit Information

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S e r v i c e L i t e r a t u r e
COMMUNICATING -ENABLED SL280DFNV SERIES UNITS
SL280DFnVseries units are 80% efficiency gas furnaces
used for upflow or horizontal applications only, manufac-
tured with Lennox Duralok heat exchangers formed of alu-
minized steel. SL28DFV units are available in heating ca-
pacities of 60,000 to 80,000 Btuh and cooling applications
up to 5 tons. Refer to Engineering Handbook for proper
sizing.
SL280DFNV model units are equipped with a communi-
cating enabled SureLight
tegrated control. SL280DFNV unit meets the California
Nitrogen Oxides (NOx) Standards and California Season-
al Efficiency requirements. All units use a redundant gas
valve to assure safety shut-off as required by C.S.A.
All specifications in this manual are subject to change.
Procedures outlined in this manual are presented as a
recommendation only and do not supersede or replace lo-
cal or state codes. In the absence of local or state codes,
the guidelines and procedures outlined in this manual (ex-
cept where noted) are recommendations only and do not
constitute code.

Table of Contents

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Blower Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Parts Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
I Unit Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
II Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
III Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
IV Heating System Service Checks . . . . . . . . . . . . . . 28
V Typical Operating Characteristics . . . . . . . . . . . . . . 33
VI Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
VII Sequence of Operation . . . . . . . . . . . . . . . . . . . . . 37
IX Program Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
X Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
UNIT INFORMATION
UNIT INFORMATION
two-stage variable speed in-
®
. . . . . . 42
100027
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 HVAC installer or
equivalent, service agency, or the gas supplier.
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.
Failure to use properly sized wiring and circuit breaker
may result in property damage. Size wiring and circuit
breaker(s) per Product Specifications bulletin (EHB) and
unit rating plate.
Page 1
SL280DFNV
WARNING
CAUTION
CAUTION
©2016 Lennox Industries, Inc.

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Summary of Contents for Lennox SL280DFNV Series

  • Page 1: Table Of Contents

    SL280DFnVseries units are 80% efficiency gas furnaces used for upflow or horizontal applications only, manufac- tured with Lennox Duralok heat exchangers formed of alu- minized steel. SL28DFV units are available in heating ca- pacities of 60,000 to 80,000 Btuh and cooling applications up to 5 tons.

  • Page 2: Specifications

    51W08 No. and Size of filter - in. (2) 16 x 20 x 1 (2) 16 x 20 x 1 Remote Outdoor Temperature Sensor is used with conventional (non-Lennox Communicating) outdoor units (sensor is furnished with Lennox Communicating outdoor ®...

  • Page 3: Blower Data

    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 Smart Zoning System Applications - Minimum blower speed is 380 cfm.
  • Page 4 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 Smart Zoning System Applications - Minimum blower speed is 450 cfm.

  • Page 5: 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 5...

  • Page 6: I Unit Components

    I-UNIT COMPONENTS 3. Circuit Breaker (CB8) SL280DFNV unit components are shown in FIGURE 1. A 24V circuit breaker is also located in the control box. The gas valve, combustion air inducer and burners can be The switch provides overcurrent protection to the trans- accessed by removing the access panel.
  • Page 7 NOTE - During abnormal conditions such as low supply TABLE 1 voltage or low outdoor temperatures and the low fire pres- SureLight Control 5 Pin Terminal Designation ® sure switch does not close, the combustion air inducer will PIN# Function switch to high fire.
  • Page 8 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 COMMUNICATING...
  • Page 9 INTEGRATED CONTROL CONFIGURATION GUIDE CLG BLOWER SPEED ADJUSTMENT 2ND STAGE HEAT ON DELAY DEFAULT 7 MIN CONTINUOUS FAN MODE BLOWER SPEED UPSTAGE THERMOSTAT SELECTION DELAY + 10% MEDIUM−LOW SPEED TWO STAGE (38%) THERMOSTAT 12 MIN − 10% UPSTAGE MEDIUM−HIGH DELAY SPEED 1−STAGE (70%)
  • Page 10 TABLE 4 Integrated Control Diagnostic Modes Dispaly Action (when button 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 “P” (variable speed only) Program unit capacity/size (Unit Code) Two horizontal bars = Soft disable...
  • Page 11 TABLE 5 Integrated Diagnostic Codes/Status of Equipment 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 12 TABLE 5 Continued 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 13 TABLE 5 Continued 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. E207 Hot surface ignitor sensed open.
  • Page 14 TABLE 5 Continued 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 15 TABLE 5 Continued TABLE 5 Continued 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 16 TABLE 5 Continued 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 17 Ramping Option C TABLE 8 • Motor runs at 100% until demand is satisfied. Cooling Blower Speed Adjustment • Once demand is met, motor runs at 100% for 45 Adjustment Switch 7 Switch 8 seconds then ramps down to stop +10% (approx) Factory Default -10% (approx)
  • Page 18 On-Board Links damage. Refer to TABLE 12 for operation sequence in applications including SL280UHNV, a thermostat which Note: In communicatiung systems with a conventional features humidity control and a single-speed outdoor unit. outdoor unit (non-communicating), the on-board clippable TABLE 13 gives the operation sequence in applications links must be set to properly configure the system.
  • Page 19 TABLE 13 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 20 The messages sent back and Earlier ECM motors used on other Lennox furnace forth between the two controls serve to communicate rota- models are not interchangeable with motors used on the tional direction, demand, motor size, current draw, torque, SL280DF furnace line.
  • Page 21 Troubleshooting Motor Operation WARNING To verify motor operation see steps below and FIGURE 8 Electric Shock Hazard. Can cause injury and FIGURE 9. or death. Unit must be properly grounded 1 - Remove J48 (5 pin power plug) from P48 on the in accordance with national and local motor.
  • Page 22 BLOWER B3 HARNESS CONNECTORS BLOWER B3 HARNESS CONNECTORS P48 5 Pin P49 4 Pin P48 5 Pin SHAFT SHAFT MOTOR with INTEGRATED P49 4 Pin CONTROLLER MOTOR with INTEGRATED CONTROLLER J48 5 Pin P48 5 Pin J49 4 Pin P49 4 Pin J49 4 Pin Control Connector J48 Connector J48 5 Pin Line Voltage Connector...
  • Page 23 Troubleshooting Motor Windings TEST A Measure the resistance between each of the three motor Ensure that motor windings are not damaged by perform- leads (3-pin plug) and the unpainted part of the end shield. ing the following tests: If the winding resistance to ground is <100k ohms, re- NOTE - If your ohm meter is not an auto-ranging type, set place the motor and control module.
  • Page 24 The switch may have a different set point for each unit taps are located on the valve. A regulator adjustment model number. See Lennox Repair Parts Handbook if limit screw is located on the valve. switch must be replaced.
  • Page 25 HEATING COMPONENTS Air Gas Plenum Burner Gas Valve Gasket Sensor Ignitor Orifice Housing Gas Orifice O Ring Air Orifice Thermal Intake Air Intake Air Screen Switch Coupling Elbow (location) FIGURE 13 Page 25...
  • Page 26 Ignitor Check Out Test 1 Remove 5-pin plug from control Check ohms reading across terminals 1and 5 Ohm value should be between 39 - 70. Meter (set to ohms) Integrated control detail Test 2 Seperate the 2-pin jack plug near the manifold and check resistance of the ignitor.
  • Page 27 8. Combustion Air Inducer Prove Switch (S18) SL280DFNV series units are equipped with a single com- bustion air proving switch (first and second stage) located near the gas valve. See FIGURE 15. The switch is a sin- gle-pole single-throw proving switch electrically connect- ed to the integrated control.

  • Page 28: Placement

    II-PLACEMENT AND INSTALLATION NOTE - When unit is initially started, steps 1 through 11 may need to be repeated to purge air from gas line. Make sure unit is installed in accordance with installation Turning Off Gas To Unit instructions and applicable codes. 1 - Set thermostat to lowest setting.
  • Page 29 2 - Remove the threaded plug from the outlet side of specialty Gas Leak Detector is strongly recommended. It the gas valve and install a field-provided barbed is available through Lennox under part number 31B2001. fitting. Connect measuring device positive “+” to See Corp. 8411-L10, for further details.
  • Page 30 The air orifice is located inside the gray coupling between TABLE 18 the clamps. FIGURE 19 shows corresponding steps with Manifold and Pressure Signal wc. Natural the steps below. Manifold Signal 1 - Turn off the electrical power and gas supply to the Altitude Unit High...
  • Page 31 Operating Signal Pressure Measurement FIGURE 20 TABLE 20 Production Resonance (more air) Difficulty Igniting (less air) Unit Orifice Size (Part No) Orifice Size Cat No Orifice Size Cat No -060 0.969 (08) 1.000 19X30 0.937 19X37 -080 1.094 (07) 1.125 19X31 0.995 19X36...
  • Page 32 Troubleshooting Poor Ignition or Combustion Resonance Issues Has the unit inducer RPM been reduced Contact your Service to 4300 RPM? Does not apply to -040 Representative for assistance unit Check Air Orifice See Figure 19 Check the following 1-Does the unit have the correct air orifice size? 2 -Is the orifice fully seated tight against the elbow ?

  • Page 33: Typical Operating Characteristics

    A-Blower Operation and Adjustment C-External Static Pressure 1 - Blower operation is dependent on thermostat control 1 - Tap locations shown in FIGURE 23. system. 2 - Punch a 1/4” diameter hole in supply and return 2 - Generally, blower operation is set at thermostat air plenums.

  • Page 34: Maintenance

    At the beginning of each heating season, and to comply the heat exchanger per the AHRI heat exchanger with the Lennox Limited Warranty, your system should be inspection procedure. This procedure can be checked by a licensed professional technician (or equiva- viewed at www.ahrinet.org...
  • Page 35 A-Heat Exchanger and Burner FIGURE 25 17 - Check all piping connections, factory and field, for gas leaks. Use a leak detecting solution or other Cleaning the Heat Exchanger and Burners preferred means. NOTE - Use papers or protective covering in front of the CAUTION furnace during cleaning.
  • Page 36 Heat Exchanger and Burner * Re−install screws per the numbered sequence shown Air Fuel Plenum Internal flue pipe assembly Flue chase Gasket Burner Gasket Combustion air inducer Gas valve FIGURE 25 Page 36...

  • Page 37: Sequence Of Operation

    VII- Wiring and Sequence of Operation WARNING Integrated Control Self Check When there is a call for heat, the communicating enabled Fire Hazard. Use of aluminum wire with this product integrated control runs a self check. The control checks may result in a fire, causing property damage, for S10 primary limit and the S47 thermal switch switch severe injury or death.
  • Page 38 Applications Using a Two-Stage Thermostat 9 - When the combustion air post-purge period is complete, the inducer, the HUM contacts as well as A - Heating Sequence -- Integrated Control Thermo- the 120V ACC terminals are de-energized. The indoor stat Selection DIP Switch 1 OFF in “Two-Stage” Posi- blower is de-energized at the end of the off delay.
  • Page 39 Communicating Enabled Furnace and Non- Communicating Enabled Furnace and Communicating Outdoor Unit Communicating Enabled Outdoor Unit COMMUNICATING FURNACE COMMUNICATING FURNACE OPTIONAL DISCHARGE AIR SENSOR OPTIONAL DISCHARGE AIR SENSOR OPTIONAL OUTDOOR OPTIONAL COMMUNICATING AIR SENSOR OUTDOOR THERMOSTAT AIR SENSOR COMMUNICATING THERMOSTAT DOOR AIR CONDITIONING OR HEAT PUMP UNIT NON-COMMUNICATING...
  • Page 40 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 41 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 Page 41...

  • Page 42: Field Wiring (Non Communicating T Stat)

    VIII- 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 43 Field Wiring Applications With Conventional Thermostat (Continued) 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 TERM.
  • Page 44 Field Wiring Applications With Conventional Thermostat (Continued) 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. STRIP Single Stage Heat Pump CUT ON-BOARD LINK...
  • Page 45 Field Wiring Applications With Conventional Thermostat (Continued) 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. STRIP Single Stage Heat Pump CUT ON-BOARD LINK...

  • Page 46: Program Capacity

    IX- Program Unit Capacity Size Modes Power-Up - Number displayed represents by integrated control unit size code (furnace model − − and capacity). If three horizontal bars are displayed followed by continuous E203, furnace − control does not recognize unit size code. Configure per the following: Furnace control in IDLE mode No heating, cooling or indoor fan operation)

  • Page 47: Troubleshooting

    X- 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 CLOSED WITHIN 3...
  • Page 48 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 49 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 50 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 51 Continuous Fan Sequence of Operation CALL FOR FAN CALL FOR FAN INDOOR BLOWER ON CONTINUOUS FAN SPEED MAINTAIN INDOOR CALL FOR FAN BLOWER AT REMOVED? CONTINUOUS FAN REQUEST MAINTAIN INDOOR FOR COOLING GO TO CALL FOR COOLING BLOWER AT RECEIVED? CONTINUOUS FAN REQUEST INDOOR BLOWER OFF...

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