Lennox SL280UHNV Series Unit Information
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Lennox SL280UHNV Series Unit Information

Communicating-enabled units
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Service Literature
COMMUNICATING-ENABLED SL280UHNV SERIES UNITS
SL280UHNV series units are 80% efficiency gas furnaces
used for upflow or horizontal applications only, manufac­
tured with Lennox Duralokt heat exchangers formed of
aluminized steel. SL280UHNV units are available in heat­
ing capacities of 40,000 to 100,000 Btuh and cooling ap­
plications up to 5 tons. Refer to Engineering Handbook for
proper sizing.
SL280UHNV model units are equipped with a communicat­
®
ing enabled SureLight
two-stage variable speed integrated
control. SL280UHNV 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.

TABLE OF CONTENTS

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VIII Field Wiring and Jumper Settings
IX Program Unit Capacity Size Mode
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Corp. 1601-L8
Revised 02/2021
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Page 1
SL280UHNV
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 HVAC in­
staller (or equivalent), service agency or the gas sup­
plier.
CAUTION
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.
© 2021 Lennox Industries Inc.

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Summary of Contents for Lennox SL280UHNV Series

  • Page 1: Table Of Contents

    Service Literature Revised 02/2021 COMMUNICATING-ENABLED SL280UHNV SERIES UNITS SL280UHNV series units are 80% efficiency gas furnaces used for upflow or horizontal applications only, manufac­ tured with Lennox Duralokt heat exchangers formed of aluminized steel. SL280UHNV units are available in heat­...
  • Page 2 SPECIFICATIONS Model No. SL280UH060NV36A SL280UH080NV48B Heating AFUE Performance High Input - Btuh 60,000 80,000 Fire Output - Btuh 48,000 64,000 Temperature rise range - °F 30 - 60 30 - 60 Gas Manifold Pressure (in. w.g.) Natural Gas Only Input - Btuh 39,000 52,000 Fire...
  • Page 3 Heat Exchanger Combustion Air Inducer Gas Valve Intake Screen Intake Air Elbow Control Box (includes integrated control, Inner Access Access Panel interlock switch and transformer) Panel Blower Assem Power Choke (4 and 5 Ton Only) FIGURE 1 Page 3...

  • Page 4: 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 SL280UHNV 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 5 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 6 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 7 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 8 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 9 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 10 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 11 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 12 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 13 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 14 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 15 -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 16: 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%, 38%, 70% and 100% of the selected second stage cooling speed - minimum 250 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 250 cfm.
  • Page 17 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%, 38%, 70% and 100% of the selected second stage cooling speed - minimum 380 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 380 cfm.
  • Page 18 Continuous Fan Only speed is selectable at 28%, 38%, 70% and 100% of the selected second stage cooling speed - minimum 380 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 380 cfm for 08048B and 450cfm for 08060C ®...
  • Page 19 BLOWER DATA SL280UH080NV60C BLOWER PERFORMANCE (less filter) Single Side Return Air - Air volumes in bold require Optional Return Air base and field fabricated transition to accommodate 20 x 25 x 1 in. air filter in order to maintain proper air velocity. 0 through 0.8 in.
  • Page 20 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%, 38%, 70% and 100% of the selected second stage cooling speed - minimum 450 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 450 cfm.
  • Page 21 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 22 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 23 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 SL280UHNV furnace line.
  • Page 24 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 25 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 26 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 27 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 28 SL280UHNV 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 28...
  • Page 29 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 30 8. Combustion Air Inducer Prove Switch (S18) SL280UHNV 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 single-pole single-throw proving switch electrically connected to the in­...

  • Page 31: Installation

    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 32 Valve is not adjustable. Do not adjust manifold Gas Leak Detector is strongly recommended. It is available pressure. through Lennox under part number 31B2001. See Corp. 5 - Record signal pressure and compare to value in table 8411-L10, for further details.
  • Page 33 TABLE 18 1 - Turn off the electrical power and gas supply to the fur­ Manifold and Pressure Signal wc. Natural nace. Manifold Signal 2 - Remove the air hose fitting from the brass fitting on the Unit High Fire Low Fire High Fire Low Fire...
  • Page 34 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 1.250 (06) 1.281...
  • Page 35 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 36: 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 37: 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 38 A-Heat Exchanger and Burners 10- To clean the combustion air inducer visually inspect and using a wire brush clean where necessary. Use com­ Cleaning the Heat Exchanger and Burners pressed air to clean off debris and any rust. NOTE - Use papers or protective covering in front of the fur­ 11- Reinstall heat exchanger in vestibule.
  • Page 39 Heat Exchanger and Burner Removal * Re−install screws per the numbered sequence shown Air Fuel Plenum Heat Exchanger Gasket *Air Fuel Plenum Gas Valve Burner Gasket Gasket (replace) Air Intake Assembly FIGURE 24 Remove 5 screws if necessary (either side of cabinet) FIGURE 25 Page 39...

  • Page 40: Wiring And 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 41 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 42 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 43 Optional Accessories for use with any Communicating System 120V CONNECTIONS NOTE: COMMUNICATING THERMOSTAT SENSES HUMIDITY & CONTROLS HUM CONTACTS TO CYCLE HUMIDIFIER BASED ON DEMAND. NO OTHER CONTROL OR HUMIDISTAT REQUIRED. “HUM” CONTACT IS CLOSED ANYTIME OPTIONAL OUTDOOR AIR SENSOR FOR USE WITH HUMIDIFIER HUMIDITY DEMAND (IF NOT ALREADY IN THE SYSTEM FOR OTHER FUNCTIONS.
  • Page 44 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 45 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 46 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 47 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 48 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 49 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 50: 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 51 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 52 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 53 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...

This manual is also suitable for:

Sl280uh060nv36aSl280uh080nv48bSl280uh080nv60cSl280uh100nv60c

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