Lennox SL280DF060NV36B Instruction Manual
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Lennox SL280DF060NV36B Instruction Manual

Lennox SL280DF060NV36B Instruction Manual

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Service Literature
COMMUNICATING-ENABLED SL280DFNV SERIES UNITS
SL280DFNV series units are ultra low nox, 80% efficiency
gas furnaces used for downflow applications only,
manufactured with Lennox Duralokt heat exchangers
formed of aluminized steel. SL280DFNV units are avail­
able in heating capacities 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 communicat­
®
ing enabled SureLight
two-stage variable speed integrated
control. SL280DFNV unit meets the California Nitrogen Ox­
ides (NO
) Standards and California Seasonal Efficiency re­
x
quirements. 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. Pro­
cedures outlined in this manual are presented as a recom­
mendation only and do not supersede or replace local or
state codes. In the absence of local or state codes, the
guidelines and procedures outlined in this manual (except
where noted) are recommendations only and do not consti­
tute code.

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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.
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal in­
jury. Take care while handling this equipment and
wear gloves and protective clothing.
Page 1
SL280DFNV
WARNING
CAUTION
© 2021 Lennox Industries Inc.

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Summary of Contents for Lennox SL280DF060NV36B

  • Page 1: Table Of Contents

    SL280DFNV series units are ultra low nox, 80% efficiency gas furnaces used for downflow applications only, manufactured with Lennox Duralokt heat exchangers formed of aluminized steel. SL280DFNV units are avail­ able in heating capacities of 60,000 to 80,000 Btuh and cooling applications up to 5 tons.

  • Page 2: Specifications

    SP ECIF ICATIONS Model No. SL280DF060NV36B SL280DF080NV60C Heating AFUE Performance High Input - Btuh 60,000 80,000 Fire Output - Btuh 48,000 64,000 Temperature rise range - °F 35 - 65 25 - 55 Gas Manifold Pressure (in. w.g.) Natural Gas Only...

  • Page 3: Blower Data

    BLOWER DATA SL280DF060NV36B BLOWER PERFORMANCE (less filter) 0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range HEATING Heating Speed DIP Switch First Stage Heating Speed - cfm Second Stage Heating Speed - 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 iHarmony 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) A 24V circuit breaker is also located in the control box. The switch provides overcurrent protection to the trans­ SL280DFNV unit components are shown in figure 1. The former (T1). The breaker is rated 3A at 32V. If the current gas valve, combustion air inducer and burners can be ac­...
  • Page 7 Once the first stage prove switch is determined to be open, TABLE 1 the combustion air inducer is energized on low (first stage) ® SureLight Control 5 Pin Terminal Designation heat speed. When the differential in the prove switch is PIN # Function great enough, the prove switch closes and a 15-second...
  • Page 8 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 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 UPSTAGE − 10% MEDIUM−HIGH DELAY SPEED 1−STAGE (70%)
  • Page 10 TABLE 4 Integrated Control Diagnostic Modes Display 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) Soft disable Two horizontal bars __...
  • Page 11 TABLE 5 Integrated Diagnostic Codes/Status of Equipment I. 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 E 124 Active communicating thermostat signal missing for more than 3 min­ Equipment lost communication with the thermostat. utes. Check 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 E 206 Gas valve second-stage relay failure Furnace will operate on 1 stage for remainder of the heating demand. Will clear after fault recovered. If unable to operate 2nd stage, replace control. E 207 Hot surface ignitor sensed open - Refer to troubleshooting.
  • Page 14 TABLE 5 Continued Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E 271 Soft lockout - Exceeded maximum number of retries. Last retry failed due Check pressure (inches w.c.) of low pressure switch to the pressure switch opening. closing on heat call.
  • Page 15 TABLE 5 Continued Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E 312 Restricted air flow in cooling or continuous fan mode is lower than cfm Warning Only. Restricted airflow - Indoor blower is setting. running at a reduced 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 E 406 LSOM - Compressor open start circuit. Required amount of current is not passing through Start current transformer. Clears the error after cur­ rent is sensed in START sensor, or after power re­ set.
  • Page 17 -10% to better suit the application. Table 8 below provides Ramping Option C S Motor runs at 100% until demand is satisfied. blower speed adjustments that will result from different S Once demand is met, motor runs at 100% for 45 sec­ switch settings.
  • Page 18 With Heat Pump - Cut W914 (R to DS) & W951 (R to O) on SureLight control ® Use Dave Lennox ComfortSense 7500 thermostat Y2081 4 heat / 2 cool for this application *Dehumidification blower speed is 70% of COOL speed for all units .
  • Page 19 With Heat Pump - Cut W914 (R to DS) & W951 (R to O) on SureLight control ® Use Dave Lennox ComfortSense 7500 thermostat Y2081 4 heat / 2 cool for this application. *Normal operation first stage cooling blower speed is 70% COOL speed.
  • Page 20 DC filter capacitors inside the controller. If the discon­ nect switch is bounced when the disconnect is closed, the dis­ Earlier ECM motors used on other Lennox furnace models are not interchangeable with motors used on connect contacts may become welded. Try not to bounce the the SL280DFNV furnace line.
  • Page 21 Motor Start‐Up Troubleshooting Motor Operation When B3 begins start‐up, the motor gently vibrates back and To verify motor operation see steps below and figures 8 forth for a moment. This is normal. During this time the elec­ tronic controller is determining the exact position of the rotor. and 9.
  • Page 22 BLOWER B3 HARNESS CONNECTORS BLOWER B3 HARNESS CONNECTORS P48 5 Pin SHAFT P48 5 Pin P49 4 Pin SHAFT P49 4 Pin MOTOR with INTEGRATED CONTROLLER MOTOR with INTEGRATED CONTROLLER J48 5 Pin J49 4 Pin P48 5 Pin P49 4 Pin J49 4 Pin Control Connector J48 5 Pin Line Voltage Connector J48 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, replace the motor and control module.
  • Page 24 The switch may have a different LPG change over kits are available from Lennox. Kits include set point for each unit model number. See Lennox Repair burner orifices and a gas valve.
  • Page 25 SL280DFNV 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 7. Combustion Air Inducer (B6) negative relative to atmospheric pressure. If the flue be­ comes obstructed during operation, the switch senses a All SL280DFNV units use a two-stage combustion air in­ loss of pressure difference and opens the circuit to the fur­ ducer to move air through the burners and heat exchanger nace control and gas valve.

  • 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 instructions and applicable codes. Turning Off Gas To Unit III-START‐UP 1 - Set thermostat to lowest setting.
  • Page 29 Gas Leak Detector is strongly recommended. It is available 5 - Record signal pressure and compare to value in table through Lennox under part number 31B2001. See Corp. 18 or table 19. If signal pressure is within range contin­ 8411-L10, for further details.
  • Page 30 TABLE 18 termined. If the unit has difficulty igniting the orifice is over­ sized and brings in too much air. If the unit ignites but with Manifold and Pressure Signal wc. Natural loud resonance the orifice is too small and needs more air. Manifold Signal The air orifice is located inside the gray coupling between...
  • 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 0.969 (08) 1.000 19X30 0.937 19X37 1.094 (07) 1.125 19X31 0.995 19X36 G- Proper Combustion H- High Altitude...
  • 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

    V-TYPICAL OPERATING CHARACTERISTICS C-External Static Pressure A-Blower Operation and Adjustment 1 - Tap locations shown in figure 23. 1 - Blower operation is dependent on thermostat control 2 - Punch a 1/4” diameter hole in supply and return air ple­ system.

  • Page 34: Maintenance

    Annual Furnace Maintenance At the beginning of each heating season, and to comply 7- Inspect the combustion air inducer and clean if neces­ with the Lennox Limited Warranty, your system should be sary. checked by a licensed professional technician (or equiva­...
  • 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 preferred Cleaning the Heat Exchanger and Burners means. NOTE - Use papers or protective covering in front of the fur­ nace 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 Integrated Control Self Check WARNING When there is a call for heat, the communicating enabled Electric Shock Hazard. Can cause integrated control runs a self check. The control checks for injury or death. Unit must be properly grounded in accordance with national S10 primary limit and the S47 thermal switch switch nor­...
  • Page 38 8 - When the thermostat demand for low-fire (first stage) CAUTION heat is satisfied, the gas valve is de-energized and the field-selected indoor blower off delay begins. The Failure to use properly sized wiring and circuit combustion air inducer begins a 5-second post-purge breaker may result in property damage.
  • Page 39 Communicating Enabled Furnace and Communicating Enabled Furnace and Non-Communicating Outdoor Unit Communicating Enabled Outdoor Unit COMMUNICATING COMMUNICATING FURNACE FURNACE OPTIONAL DISCHARGE AIR SENSOR OPTIONAL DISCHARGE AIR SENSOR OPTIONAL OUTDOOR OPTIONAL AIR SENSOR OUTDOOR COMMUNICATING AIR SENSOR THERMOSTAT COMMUNICATING THERMOSTAT COMMUNICATING ENABLED OUTDOOR UNIT NON-COMMUNICATING OUTDOOR AIR...
  • Page 40 Optional Accessories for use with any Communicating System NOTE: COMMUNICATING THERMOSTAT SENSES HUMIDITY & CONTROLS HUM CONTACTS TO CYCLE HUMIDIFIER BASED ON 120V CONNECTIONS DEMAND. NO OTHER CONTROL OR HUMIDISTAT REQUIRED. OPTIONAL OUTDOOR AIR SENSOR FOR USE WITH HUMIDIFIER “HUM” CONTACT IS CLOSED ANYTIME (IF NOT ALREADY IN THE SYSTEM FOR OTHER FUNCTIONS.
  • Page 41 Optional Accessories for use with any Communicating System LENNOX COMMUNICATING INDOOR UNIT LENNOX COMMUNICATING THERMOSTAT OR DAMPER CONTROL MODULE CONVENTIONAL LENNOX COMMUNICATING OUTDOOR UNIT INDOOR UNIT (1 OR 2 STAGE) LENNOX COMMUNICATING OUTDOOR UNIT cutting DS to R will not cause...

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

    VIII- Field Wiring Applications With Conventional Thermostat DIP Switch Settings and On-Board Links (See figure 4) 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...
  • Page 43 Field Wiring Applications With Conventional Thermostat (Continued) DIP Switch Settings and On-Board Links (See figure 4) 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 44 Field Wiring Applications With Conventional Thermostat (Continued) DIP Switch Settings and On-Board Links (figure 4) DIP Switch 1 Wiring Connections Thermostat On Board Links Must Be Cut To Select Thermostat Heating System Options Stages Dual Fuel FURNACE HEAT PUMP L7742U TERM.
  • Page 45 Field Wiring Applications With Conventional Thermostat (Continued) DIP Switch Settings and On-Board Links (figure 4) DIP Switch 1 Wiring Connections Thermostat On Board Links Must Be Cut To Select Thermostat Heating System Options Stages Dual Fuel FURNACE HEAT PUMP L7742U TERM.

  • 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 X- 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 WATCHGUARD − SWITCH INDOOR AFTER HEAT FAN LIMIT SWITCH CODE ERROR CODE...

  • Page 48: Troubleshooting

    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? ONLY FOR 1ST EXPIRED? REQUEST FOR 2ND STAGE HEAT INDUCER SWITCHED TO HIGH SPEED HIGH...
  • Page 49 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 50 Troubleshooting: Cooling Sequence of Operation (Continued) 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 Troubleshooting: Continuous Fan Sequence of Operation CALL FOR FAN CALL FOR FAN INDOOR BLOWER ON CONTINUOUS FAN SPEED CALL FOR FAN MAINTAIN INDOOR REMOVED? BLOWER AT CONTINUOUS FAN REQUEST MAINTAIN INDOOR FOR COOLING GO TO CALL FOR COOLING BLOWER AT RECEIVED? CONTINUOUS FAN REQUEST...

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