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Lennox EL280DFE Series Unit Information

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Service Literature
EL280DFE series units are 80% efficiency gas furnaces
used for downflow applications only, manufactured with
Lennox Duralokt heat exchangers formed of aluminized
steel. Units are available in heating capacities of 66,000 to
88,000 Btuh and cooling applications up to 4 tons. Refer to
Engineering Handbook for proper sizing.
Units are factory equipped for use with natural gas. Kits are
available for conversion to LPG operation. EL280DFE mod­
el units are equipped with the SureLight
All units use a redundant gas valve to assure safety shut-off
as required by CSA.
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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II Installation
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IX Troubleshooting Flow Chart
EL280DFE SERIES UNITS
®
integrated control.
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Corp. 1902-L1
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.
Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at discon­
nect switch(es). Unit may have multiple
power supplies.
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
EL280DFE
WARNING
WARNING
CAUTION
© 2019 Lennox Industries Inc.

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Summary of Contents for Lennox EL280DFE Series

  • Page 1: Table Of Contents

    EL280DFE Corp. 1902-L1 Service Literature EL280DFE SERIES UNITS EL280DFE series units are 80% efficiency gas furnaces used for downflow applications only, manufactured with Lennox Duralokt heat exchangers formed of aluminized steel. Units are available in heating capacities of 66,000 to 88,000 Btuh and cooling applications up to 4 tons.

  • Page 2: Specifications

    SPECIFICATIONS Model No. EL280DF070E36A EL280DF090E48B Heating AHRI Ref. No. Performance AFUE High Input - Btuh 66,000 88,000 Fire Output - Btuh 52,000 69,000 Temperature rise range - °F 30 - 60 35 - 65 Gas Manifold Pressure (in. w.g.) 3.5 / 10.0 3.5 / 10.0 Nat.

  • Page 3: Blower Performance Data

    BLOWER DATA EL280DF070E36A PERFORMANCE (Less Filter) External Air Volume / Watts at Various Blower Speeds Static High Medium-High Medium Medium-Low Pressure Watts Watts Watts Watts Watts in. w.g. 0.00 1475 1345 1190 0.10 1440 1325 1165 0.20 1410 1280 1135 0.30 1260 1250...

  • Page 4: Parts Identification

    PARTS IDENTIFICATION Top Cap Secondary Limit Indoor Blower Control Box (includes integrated control, transformer and door switch) Internal Flue Pipe Assembly Heat Exchanger Combustion Air Inducer Burner Box Assembly Primary Limit Gas Valve Access Panel FIGURE 1 Page 4...

  • Page 5: 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 Unit components are shown in figure 1. The gas valve, former (T1). The breaker is rated 3A at 32V. If the current combustion air inducer and burners can be accessed by re­...
  • Page 6 ® After the 15-second pre-purge period, the SureLight igni­ TABLE 1 tor warms up for 20 seconds after which the gas valve ® SureLight Control 5 Pin Terminal Designation opens for a 4-second trial for ignition. The ignitor remains PIN # Function energized during the trial until flame is sensed.
  • Page 7 INTEGRATED CONTROL 24VAC Indoor Blower Terminals Ignitor and Combustion Air Inducer Neutrals Flame Sense S4 DIP Switches Diagnostic Push Button On Board Links THERMOSTAT CONNECTIONS (TB1) 3/16” QUICK CONNECT TERMINALS DS = DEHUMIDIFICATION SIGNAL FLAME SENSE SIGNAL W2 = HEAT DEMAND FROM 2ND STAGE T/STAT HI COOL 24VAC W1 = HEAT DEMAND FROM 1ST STAGE T/STAT HI HEAT 24VAC...
  • Page 8 INTEGRATED CONTROL CONFIGURATION GUIDE 2ND STAGE HEAT ON DELAY 7 MIN UPSTAGE THERMOSTAT SELECTION DELAY COOLING BLOWER-OFF DELAY TWO STAGE THERMOSTAT 12 MIN UPSTAGE *45 SECOND COOL BLOWER DELAY 1−STAGE OFF DELAY THERMOSTAT (TIMED STAGING) −SEE SW #2 HSI/CAI 2 SECOND COOL BLOWER HEATING BLOWER−OFF DELAY OFF DELAY...
  • Page 9 TABLE 3 Integrated Control Diagnostic Modes Display Action (when button released) No change (idle)* Remain in idle mode Solid “E” Enter diagnostic recall mode Solid “F” Enter flame signal mode TABLE 4 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).
  • Page 10 TABLE 4 Continued E 125 Control failed self-check, internal error, failed hardware. Will restart if Hardware problem on the control. Cycle power on error control. Replace if problem prevents service and is recovers. Integrated control not communicating. Covers hardware errors persistent.
  • Page 11 TABLE 4 Continued E 270 Soft lockout - Exceeded maximum number of retries. No flame current Check for proper gas flow. Ensure that ignitor is sensed. lighting burner. Check flame sensor current. Clears when heat call finishes successfully. Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E 271 Soft lockout - Exceeded maximum number of retries.
  • Page 12 Integrated Control DIP Switches TABLE 5 Blower Off Heating Mode Delay Switch Settings EL280DFE units are equipped with a two-stage integrated Blower Off Delay control. This control manages ignition timing, heating Switch 3 Switch 4 (Seconds) mode fan off delays and indoor blower speeds based on selections made using the control dip switches and jump­...
  • Page 13 BLOWER WHEEL REPLACEMENT IMPORTANT Center Blower Wheel If any onboard link is cut by mistake, install a jump­ in Blower Housing er across the corresponding terminals on the low voltage terminal strip. Do not replace control. B- Indoor Blower 1. Secondary Limit Control (S21) The secondary limit (S21) is located in the blower compart­...
  • Page 14 Multi−Meter (set to VAC) Multi−Meter (set to VAC) Test 1 Test 3 (if necessary) Turn on power to unit. Check for 120 volts across terminals Check for 120 volts across terminals “L1” and “Neutrals” on “L” and “N” on input plug P48. If voltage is present continue the integrated control.
  • Page 15 Replacing the Motor Module Motor Test 1. Disconnect electrical power to unit. 2. Remove unit access panel. 3. Unplug the two harnesses from the motor control mod­ ule. See figure 9. Unplug the Two Harness Connection TWO HARNESS FIGURE 11 CONNECTIONS TABLE 8 MOTOR...
  • Page 16 C- Heating Components LPG change over kits are available from Lennox. Kits include burner orifices. 1. Ignitor ® The SureLight ignitor is made of durable silicon nitride. Ig­ 4. Flame Rollout Switches (S47) nitor longevity is enhanced by controlling voltage to the ig­...
  • Page 17 EL280DFE HEATING COMPONENTS Ignitor Burners Rollout Switch Sensor Gas Valve Manifold and Gas Orifices FIGURE 13 Page 17...
  • Page 18 EL280DFE Ignitor Check Test 1 Check ignitor circuit for correct resistance. Remove 5−pin plug from control. Check ohms reading across terminals 1 and 5. If value is correct, this is the only test needed. If the reading on the meter is not correct, (0 or infinity) then a second test is needed.
  • Page 19 To Measure Flame Signal - Integrated Control: 6 - Turn supply voltage on and close thermostat contacts to cycle system. Use a digital readout meter capable of reading DC micro­ 7 - When main burners are in operation for two minutes, take amps.

  • Page 20: Start Up

    NOTE - Each furnace model uses a unique CAI. Refer to Lennox Repair Parts listing for correct inducer for re­ Bracket placement. A pressure switch connected to the combustion air inducer orifice plate is used to prove inducer operation.
  • Page 21 7 - Wait five minutes to clear out any gas. If you then smell 3 - Remove access panel. gas, STOP! Immediately call your gas supplier from a 4 - Turn switch on gas valve to OFF. Do not force. See fig­ neighbor's phone.

  • Page 22: Heating System Service Checks

    Refer to the EL280DFE Installation Instruction. Gas Leak Detector is strongly recommended. It is available B-Gas Piping through Lennox under part number 31B2001. See Corp. 8411-L10, for further details. CAUTION Do not use matches, candles, flame or any other source of ignition to check for gas leaks.
  • Page 23 F- Proper Gas Flow (Approximate) G- Proper Combustion Furnace should operate at least 5 minutes before check­ Furnace should operate minimum 15 minutes with correct ing gas flow. Determine time in seconds for two revolu­ manifold pressure and gas flow rate before checking com­ tions of gas through the meter.

  • Page 24: Typical Operating Characteristics

    V-TYPICAL OPERATING CHARACTERISTICS C-External Static Pressure A-Blower Operation and Adjustment 1 - Tap locations shown in figure 20. 1 - Blower operation is dependent on thermostat control 2 - Punch a 1/4” diameter hole in supply and return air ple­ system.

  • Page 25: Maintenance

    At the beginning of each heating season, and to comply sized, open and unobstructed to provide combustion with the Lennox Limited Warranty, your system should be checked by a licensed professional technician (or equiva­ lent) as follows:...
  • Page 26 Cleaning the Heat Exchanger and Burners 5 - Remove the collector box located behind the combus­ tion air inducer. Be careful with the collector box gas­ NOTE - Use papers or protective covering in front of the fur­ ket. If the gasket is damaged, it must be replaced to nace during cleaning.
  • Page 27 10- Back wash using steam. Begin from the burner opening 22- If a leak is detected, shut gas and electricity off and on each clam. Steam must not exceed 275°F. repair leak. 11- To clean burners, run a vacuum cleaner with a soft brush attachment over the face of burners.

  • Page 28: Wiring And Sequence Of Operation

    VII- Wiring and Sequence of Operation EL280DFE Schematic Wiring Diagram Page 28...
  • Page 29 Electronic Ignition When the delay ends, the indoor blower motor is ener­ gized on the low fire heating speed, the HUM contacts The two-stage integrated control used in EL280DFE(X) close energizing the humidifier and 120V ACC termi­ units has an added feature of an internal Watchguard con­ nal is energized.
  • Page 30 Applications Using A Single-Stage Thermostat 4 - After the 20-second warm-up period has ended, the gas See figure 24 for ignition control sequence valve is energized on low fire (first stage) and ignition oc­ curs. At the same time, the control module sends a sig­ B - Heating Sequence -- Integrated Control Thermostat nal to begin an indoor blower 30-second ON-delay.

  • Page 31: Field Wiring And Dip Switch Settings

    VIII- Field Wiring and DIP Switch Settings TABLE 16 EL280DFE Field Wiring Applications 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...
  • Page 32 TABLE 16 EL280DFE Field Wiring Applications (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 33 TABLE 16 EL280DFE Field Wiring Applications (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 L7724U TERM.
  • Page 34 TABLE 16 EL280DFE Field Wiring Applications (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 35 IX- Troubleshooting Troubleshooting: Heating Sequence of Operation HEATING SEQUENCE OF OPERATION NORMAL AND ABNORMAL HEATING MODE POWER ON GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER OFF. (RESET CONTROL BY CONTROL SELF-CHECK OKAY? TURNING MAIN POWER OFF.) POLARITY REVERSED. POLARITY OKAY? STATUS ERROR CODE 5 + 4.
  • Page 36 Troubleshooting: Heating Sequence of Operation (Continued) HEATING SEQUENCE OF OPERATION CONTINUED THERMOSTAT CALLS FOR HEAT STATUS LED - HEARTBEAT. (Refer to box A on previous page) GAS VALVE OFF. COMBUSTION AIR INDUCER FIRST-STAGE (LOW FIRE) PRESSURE OFF. INDOOR BLOWER OFF. UNIT WILL RETRY SWITCH CLOSED WITHIN 2.5 MINUTES? AFTER 5-MINUTE WAIT PERIOD.
  • Page 37 Troubleshooting: Heating Sequence of Operation (Continued) HEATING SEQUENCE OF OPERATION CONTINUED THERMOSTAT CALLS FOR HEAT. STATUS LED -- HEARTBEAT. SEE BOX A. FLAME SIGNAL ABOVE (u1.40 microamps) LOW FLAME SIGNAL (Does not affect control operation) STATUS ERROR CODE 1 + 2. SINGLE-STAGE THERMOSTAT MODE TWO STAGE THERMOSTAT MODE (DIP SWITCH SET AT “ON”)
  • Page 38 Troubleshooting: Heating Sequence of Operation (Continued) HEATING SEQUENCE OF OPERATION CONTINUED SEE BOX A NORMAL OPERATION. SEE BOX B THERMOSTAT CALLS FOR HEAT. RETURN TO FIRST-STAGE HEAT MODE. FIRST-STAGE CONTINUES UNTIL SECOND- STAGE PRESSURE SWITCH CAN BE PROVEN SECOND-STAGE (HIGH FIRE) HEAT or HEAT DEMAND IS SATISFIED.
  • Page 39 Troubleshooting: Cooling Sequence of Operation COOLING SEQUENCE OF OPERATION POWER ON SIGNAL POLARITY REVERSED. CONTROL WILL CONTINUE TO CALL FOR COOLING IS POLARITY REVERSED? IN THIS CONDITION. STATUS ERROR CODE 5 + 4. SIGNAL IMPROPER GROUND AT LED. CONTROL WILL CONTINUE TO CALL FOR COOLING IS THERE IN THIS CONDITION.
  • Page 40 Troubleshooting: Continuous Fan Sequence of Operation CONTINUOUS LOW SPEED FAN SEQUENCE OF OPERATION MANUAL FAN SELECTION MADE AT THERMOSTAT. AFTER 2 SECOND DELAY, INDOOR BLOWER IS ENERGIZED ON CONTINUOUS FAN SPEED. THERMOSTAT CALLS FOR FIRST STAGE COOL. THERMOSTAT CALLS FOR FIRST-STAGE HEAT. INDOOR BLOWER RAMPS TO FIRST STAGE AFTER 45-SECOND DELAY, INDOOR BLOWER COOLING SPEED AFTER A 2-SECOND DELAY.

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