Lennox SL280DFV Information
Sl280dfv series gas furnaces
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- Unit information (67 pages) ,
- Installation instructions manual (60 pages) ,
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Service Literature
SL280DFV 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
110,000 Btuh and cooling applications up to 5 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. SL280DFV mod-
el units are equipped with the SureLight
speed integrated control. 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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IX SureLight Integrated Control TroubleshootingPage 33
Corp. 1002−L1
Revised 10−2010
SL280DFV SERIES UNITS
®
two−stage variable
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Page 1
SL280DFV
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.
WARNING
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.
WARNING
Sharp edges.
Be careful when servicing unit to avoid sharp edges
which may result in personal injury.
© 2010 Lennox Industries Inc.
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Summary of Contents for Lennox SL280DFV
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Page 1: Table Of Contents
Corp. 1002−L1 Revised 10−2010 Service Literature SL280DFV SERIES UNITS SL280DFV 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 110,000 Btuh and cooling applications up to 5 tons. -
Page 2: Specifications
SPECIFICATIONS Model No. SL280DF070V36A SL280DF090V48B SL280DF090V60C SL280DF110V60C Heating AFUE Performance High Input - Btuh 66,000 88,000 88,000 110,000 Fire Output - Btuh 52,000 69,000 70,000 87,000 Temperature rise range - °F 35-65 35-65 35-65 35-65 Gas Manifold Pressure (in. w.g.) 3.5 / 10.0 3.5 / 10.0 3.5 / 10.0... -
Page 3: Parts Identification
PARTS IDENTIFICATION BLOWER ASSEMBLY SECONDARY LIMIT GASKET FLUE CHASE CONTROL BOX (Includes two−stage integrated control, transformer and circuit breaker) INTERNAL FLUE PIPE ASSEMBLY DOOR INTERLOCK SWITCH PRIMARY LIMIT LOCATION ROLLOUT SWITCH HEAT EXCHANGER COMBUSTION AIR INDUCER PRESSURE SWITCHES COMBUSTION AIR INDUCER GAS VALVE INNER BLOWER ACCESS PANEL BURNER BOX ASSEMBLY... -
Page 4: I Unit Components
LED indi- cates the requested blower speed. CONTROL BOX SL280DFV CFM LED (green) − indicates blower cfm STATUS LED (red) − Flashes diagnostic codes E−COM LED (green) Indicates that the control is re- ceiving and processing commands and inputs This unit may be used with either a single−stage or two−... - Page 5 Electronic Ignition After the 15−second pre−purge period, the SureLight ignitor ® At the beginning of the heat cycle the SureLight control warms up for 20 seconds after which the gas valve opens monitors the first stage and second stage combustion air for a 4−second trial for ignition.
- Page 6 DIAGNOSTIC LEDs INDOOR BLOWER DIP HEATING SWITCHES H= 24V HUMIDIFIER OUTPUT SWITCHES L= LENNOX SYSTEM OPERATION MONITOR 1= FUTURE USE ON−BOARD LINKS DIP SWITCH FUNCTIONS HTG DIP SWITCH(ES) FUNCTION T’stat Heat Stages (single or two−stage) Second Stage ON Delay (single−stage t’stat)
- Page 7 TWO−STAGE, VARIABLE SPEED INTEGRATED CONTROL BOARD STATUS Comfort- ® Sense 7000 FIGURE 5 Page 7...
- Page 8 TABLE 4 ® The SureLight integrated control features a red LED light, for furnace status and troubleshooting. The LED flashes in X" + Y" codes. For example using table 4 under PRESSURE SWITCH CODES", if the red LED flashes 2 times, then off for 2 seconds then flashes 3 times, the low pressure switch is failed open.
- Page 9 2 − Continue to hold the short between R (2) to (1). After 5 TABLE 5 Blower Off Delay Switch Settings seconds, STATUS LED will go from being continuously lit to off. Blower Off Delay Switch 3 Switch 4 (Seconds) 3 −...
- Page 10 (Factory) also lead to control damage. Refer to table 10 for operation 3 − Medium High sequence in applications including SL280DFV, a thermo- 4 − High stat which features humidity control and a single−speed outdoor unit. Table 11 gives the operation sequence in ap- plications with a two−speed outdoor unit.
- Page 11 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 approximately 38% of the same second stage COOL speed position - minimum 500 cfm. Lennox Harmony III™ Zoning System - Minimum blower speed is 426 cfm. Page 11...
- Page 12 TABLE 10 ® SL280DFV, ComfortSense and SINGLE STAGE OUTDOOR UNIT OPERATING SYSTEM DEMAND SYSTEM RESPONSE SEQUENCE Thermostat Demand Relative Humidity Blower System Compres- Step Comments Condition Status (COOL) NO CALL FOR DEHUMIDIFICATION Compressor and indoor Normal Operation Acceptable High 100%...
- Page 13 TABLE 11 ® SL280DFV, ComfortSense 7000 thermostat and TWO STAGE OUTDOOR UNIT OPERATING SYSTEM DEMAND SYSTEM RESPONSE SEQUENCE Thermostat Demand Relative Humidity Blower System Compres- Step Comments Condition Y1 Y2 Status (COOL) NO CALL FOR DEHUMIDIFICATION Normal Operation − 60%, 65%...
- Page 14 All SL280DFV blower motors use single phase power. To Remove Blower From Unit: An external run capacitor is not used. The motor uses 1.
- Page 15 Figure 9 show the two quick-connect jacks (J48 and J49) show up as small specks or lines which randomly appear which connect the motor to the SL280DFV. Jack J48 is the on the TV screen accompanied by pops or clicks in the sound.
- Page 16 TWO STAGE VARIABLE SPEED CONTROL 120V to the motor must not be interrupted. All connections for check out will be from 24VAC to plug J46, after disconnecting from blower control board. REMOVE PLUG FROM BOARD If transformer T1 is used, double check all wiring connections before placing unit back in operation. HIGH COOL COOL...
- Page 17 MOTOR SPEED CONTROL WITH D.C. PULSE-WIDTH MODULATION Motor speed is determined by the size of the electrical pulse sent to the motor windings. The longer the pulse, the faster the motor. OUTPUT FROM CONTROLLER TO MOTOR WINDINGS WINDINGS TURNED OFF WINDINGS TURNED ON Ç...
- Page 18 If limit switch must be valve. All terminals on the gas valve are connected to wires replaced, see Lennox Repair Parts Handbook for correct re- from the electronic ignition control. 24V applied to the terminals placement.
- Page 19 −110 1.844 NOTE − Each furnace model uses a unique CAI. Refer to Lennox Repair Parts listing for correct inducer for re- placement. A pressure switch connected to the combustion air inducer orifice plate is used to prove inducer operation. The combus- tion air inducer orifice will be different for each model.
- Page 20 TABLE 13 (pressure becomes more equal with atmospheric pres- Set Point High SL280DFV Unit Set Point Low Heat Heat sure) and opens the circuit to the furnace control and gas −070 0.55...
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Page 21: Installation
3 − Remove access panel. Shock and burn hazard. 4 − Turn switch on gas valve clockwise to OFF. Do not SL280DFV units are equipped with a hot surface igni- force. tion system. Do not attempt to light manually. 5 − Replace access panel. -
Page 22: Heating System Service Checks
Use of a specialty Gas Leak Detector is strongly recommended. It is available A−CSA Certification through Lennox under part number 31B2001. See Corp. All units are CSA design certified without modifications. 8411−L10, for further details. - Page 23 F− Proper Gas Flow (Approximate) IMPORTANT Furnace should operate at least 5 minutes before check- ing gas flow. Determine time in seconds for two revolu- For safety, shut unit off and remove manometer as soon as an accurate reading has been obtained. tions of gas through the meter.
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Page 24: Typical Operating Characteristics
I−Flame Signal When the SL280DFV is running on high fire or low fire (low fire is 91% of high fire), the indoor blower will run A microamp DC meter is needed to check the flame signal on the heating speed designated by the positions of on the ignition control. -
Page 25: Maintenance
Measuring Flame Signal remove sensor wire form integrated control and connect alligator clip (+) to terminal on control integrated control remove sensor wire from integrated control and connect alligator clip (−) to flame sensor lead flame sensor terminal DIGITAL METER set dial to measure vdc flame sensor transducer... - Page 26 3 − Label the wires from gas valve, rollout switches, prima- five screws from the left side or right side of cabinet. ry limit switch and make−up box then disconnect them. See figure 20. SL280DFV BURNER, C.A.I ASSEMBLY & HEAT EXCHANGER REMOVAL gasket orifice plate...
- 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.
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Page 28: Wiring And Sequence Of Operation
VII− Wiring and Sequence of Operation SL280DFV Schematic Wiring Diagram Page 28... - Page 29 Switch set at SINGLE" See figure 22 Sequence depends on type thermostat used. 1− SureLight control energizes combustion air inducer B6 SL280DFV units are applicable for single stage or two on low heat speed. Combustion air inducer runs until stage thermostats. Both type thermostats are de- S128 low heat prove switch contacts close (switch scribed below.
- Page 30 HEATING OPERATION WITH TWO−STAGE THERMOSTAT 5 SEC blower 45 second É É off" blower Trial For Post Pre−Purge Ignitor Warm−up delay on" delay Ignition Purge É É 1 stg heat demand low speed CAI ignitor low fire gas valve indoor blower low heat 30 seconds 2 stg heat demand RECOGNITION PERIOD...
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Page 31: Field Wiring And Jumper Settings
VIII− Field Wiring & Jumper Settings (See figure 4) DIP Switch Settings and On−Board Links W915 W914 Dehu- Two−Stage midification W951 Thermostat Wiring Connections DIP Switch 1 Cooling or Harmony Heat Pumps 1Heat / 1 Cool Intact Intact Intact CONTROL OUTDOOR T’STAT TERM. - Page 32 (See figure 4) DIP Switch Settings and On−Board Links W915 W914 Dehu- Two−Stage midification W951 Thermostat Wiring Connections DIP Switch 1 Heat Pumps Cooling or Harmony 2 Heat / 2 Cool Intact Intact CONTROL OUTDOOR T’STAT TERM. STRIP UNIT 2 Heat / 2 Cool Intact CONTROL OUTDOOR...
- Page 33 IX− Troubleshooting Two Stage Variable Speed Control Board UPON INITIAL POWER UP, REMOVE ALL THERMOSTAT DEMANDS TO THE UNIT PROBLEM: 1 UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE Flash Code Possible Cause Corrective Action / Comments LED X + Y 1.1.1 ACTION 1 −...
- Page 34 PROBLEM 2: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOES NOT ENERGIZE Flash Code Corrective Action / Comments Possible Cause LED X + Y ACTION 1 − Check continuity across switch(es). 2.1.1 Switches reset automatically upon cool down. Unit operates with a cooling or ACTION 2 −...
- Page 35 PROBLEM 4: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR INDUCER ENERGIZES, IGNITOR IS NOT ENERGIZED. Flash Code Possible Cause Corrective Action/Comments LED X + Y 4.1.1 ACTION 1 − Check for restricted vent. Remove all blockage. − Unit operates with a cooling and Prove switch does not close due to ACTION 2: Check for proper vent sizing.
- Page 36 PROBLEM 5: UNIT FIRES ON LOW FIRE, FAILS TO GO TO HIGH FIRE OPERATION Flash Code Possible Cause Corrective Action/Comments LED X + Y 5.1.1 ACTION 1 − Check for restricted vent. Remove all blockage. − Unit light s normally during low fire Prove switch does not close due to ACTION 2: Check for proper vent sizing.
- Page 37 PROBLEM 6: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER ENERGIZES, IGNITOR IS ENERGIZED. Flash Code Possible Cause Corrective Action/Comments LED X + Y ACTION 1 − Check line pressure at the gas valve. 6.1.1 Pressure should not exceed 13" WC for both nat- Unit operates with a cooling and ural and propane.
- Page 38 PROBLEM 7: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN PREMATURELY (CONT.) Flash Code Possible Cause Corrective Action/Comments LED X + Y ACTION 1 − Check that the manifold pressure matches value listed on nameplate. See installa- Combustion air inducer energizes 7.3.1 tion instructions for proper procedure.
- Page 39 PROBLEM 7: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN PREMATURELY (CONT.) Flash Code Possible Cause Corrective Action/Comments LED X + Y ACTION 1 − Check that the sensor is properly lo- Combustion air inducer energizes 7.5.1 cated. with a heating demand. ACTION 2 −...
- Page 40 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 SWITCH WATCHGUARD − INDOOR AFTER HEAT FAN LIMIT SWITCH CODE CLOSED WITHIN 3...
- Page 41 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 42 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 43 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 44 Troubleshooting: Continuous Fan Sequence of Operation CALL FOR FAN CALL FOR FAN INDOOR BLOWER ON LOW 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 FOR HEAT...
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Questions and answers
how to remove blower motor for cleaning? how to remove flue pipe to remove blower motor?
To remove the blower motor for cleaning on a Lennox SL280DFV:
1. Disconnect Power – Ensure the unit is powered off.
2. Remove Internal Flue Pipe and Chase – This provides access to the blower motor.
3. Remove Control Box – Detach the control box to clear space.
4. Remove Bolts – Unscrew the bolts securing the blower motor.
5. Unplug Motor Wires from Control Board – Disconnect the wiring.
6. Slide Out Front of Unit – Carefully remove the blower motor from the unit.
To remove the flue pipe for accessing the blower motor:
1. Ensure Power is Disconnected – Safety first.
2. Remove Internal Flue Pipe and Chase – This must be detached before accessing the blower motor.
These steps allow proper removal and cleaning of the blower motor.
This answer is automatically generated