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Service Literature
SL280UHV(X) 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. SL280UHV(X) units are available in heat-
ing capacities of 66,000 to 132,000 Btuh and cooling ap-
plications 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. SL280UHV(X)
model units are equipped with the SureLight
variable speed integrated control. SL280UHV(X) unit meets
the California Nitrogen Oxides (NO
nia Seasonal Efficiency requirements. All units use a redun-
dant 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
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Corp. 1001−L1
Revised 10−2010
SL280UHV(X) SERIES UNITS
®
two−stage
) Standards and Califor-
x
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Page 1
SL280UHV(X)
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
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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Table of Contents
Related Manuals for Lennox SL280UHVX Series
Summary of Contents for Lennox SL280UHVX Series
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Page 1: Table Of Contents
SL280UHV(X) 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. SL280UHV(X) units are available in heat- ing capacities of 66,000 to 132,000 Btuh and cooling ap- plications up to 5 tons. -
Page 2: Specifications
SPECIFICATIONS Model No. SL280UH070V36A SL280UH090V36B SL280UH090V48B Heating Model No. - Low Nox SL280UH070XV36A - - - SL280UH090XV48B Performance AFUE High Input - Btuh 66,000 88,000 88,000 Fire Output - Btuh 52,800 70,400 70,400 Temperature rise range - °F 40 - 70 40 - 70 40 - 70 Gas Manifold Pressure (in. - Page 3 OPTIONAL ACCESSORIES - MUST BE ORDERED EXTRA “A” Width “B” Width “C” Width “D” Width Models Models Models Models CABINET ACCESSORIES Horizontal Suspension Kit - Horizontal only 51W10 51W10 51W10 51W10 Return Air Base - Upflow only 65W75 50W98 50W99 51W00 CONTROLS ComfortSense...
- Page 4 HEAT EXCHANGER COMBUSTION AIR INDUCER COMBUSTION AIR INDUCER PRESSURE SWITCH GAS VALVE CABINET ROLLOUT SWITCH BURNER BOX INNER BLOWER PRIMARY LIMIT ACCESS PANEL CONTROL BOX (Includes two−stage integrated control, SIGHT GLASS transformer and circuit breaker) SECONDARY LIMITS (2 switches) ACCESS PANEL BLOWER ASSEMBLY FIGURE 1...
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Page 5: I Unit Components
I−UNIT COMPONENTS 3. Circuit Breaker (CB8) A 24V circuit breaker is also located in the control box. SL280UHV(X) unit components are shown in figure 1. The The switch provides overcurrent protection to the trans- gas valve, combustion air inducer and burners can be ac- former (T1). - Page 6 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 7 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 8 TWO−STAGE, VARIABLE SPEED INTEGRATED CONTROL BOARD STATUS Comfort- ® Sense 7000 FIGURE 5 Page 8...
- Page 9 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 10 4 − Last ten error codes will be flashed on the STATUS off delay settings provide lower supply air temperatures; LED. shorter settings provide higher supply air temperatu- res.Table 5 provides the blower off timings that will result 5 − After final error code is indicated, STATUS LED will from different switch settings.
- Page 11 provides the cooling mode blower speed ramping options Ramping Option C S Motor runs at 100% until demand is satisfied. that will result from different switch settings. The cooling mode blower speed ramping options are detailed on the S Once demand is met, motor runs at 100% for 45 sec- next page.
- Page 12 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 Applications - Minimum blower speed is 426 cfm. Page 12...
- Page 13 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 Applications - Minimum blower speed is 453 cfm. Page 13...
- Page 14 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 Applications - Minimum blower speed is 453 cfm. Page 14...
- Page 15 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 Applications - Minimum blower speed is 478 cfm. Page 15...
- Page 16 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 Applications - Minimum blower speed is 483 cfm. Page 16...
- 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 approximately 38% of the same second stage COOL speed position - minimum 500 cfm. Lennox Harmony III™ Zoning System Applications - Minimum blower speed is 495 cfm. Page 17...
- Page 18 TABLE 10 ® SL280UHV, 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% blower follow thermostat demand BASIC MODE (only active on a Y1 thermostat demand)
- Page 19 TABLE 11 ® SL280UHV, ComfortSense 7000 thermostat and TWO STAGE OUTDOOR UNIT OPERATING SYSTEM DEMAND SYSTEM RESPONSE SEQUENCE Thermostat Demand Relative Humidity Blower System Step Compressor Comments Condition Status (COOL) NO CALL FOR DEHUMIDIFICATION Normal Operation − 60%, 65% Acceptable Compressor and indoor 70%* blower follow thermostat...
- Page 20 5. Blower Motor (Figure 6) A solid-state controller is permanently attached to the motor. The controller is primarily an A.C. to D.C. con- SUPPLY AIR BLOWER verter. Converted D.C. power is used to drive the motor. The controller contains a microprocessor which moni- tors varying conditions inside the motor (such as motor workload).
- Page 21 Initial Power Up Troubleshooting See figure 10 for troubleshooting using 24 volts. Another When line voltage is applied to B3, there will be a large inrush option is to use the TECMate PRO. The TECMate PRO iso- lates the motor from the integrated control. Follow the in- of power lasting less than 1/4 second.
- Page 22 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 23 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 24 Inlet and outlet pressure taps are located on the valve. A regu- lator adjustment screw is located on the valve. 12. Secondary Limit Controls (S21) LPG change over kits are available from Lennox. Kits include The secondary limit (S21) is located in the blower compart- burner orifices and a gas valve.
- Page 25 SL280UHV HEATING COMPONENTS Rollout Switch Ignitor Rollout Switch Burner Assembly Sensor Gas Valve Burner Box Front Panel Screw (remove and panel will swing open and off) FIGURE 12 Page 25...
- Page 26 NOTE − Each furnace model uses a unique CAI. Refer build up. to Lennox Repair Parts listing for correct inducer for re- placement. A proving switch connected to the combustion air inducer ori- COMBUSTION AIR PRESSURE SWITCH fice plate is used to prove inducer operation.
- Page 27 Multiple Venting screws, rotate the assembly (assembly consists of orifice plate, proving switch, gasket and combustion air inducer), The SL280UHV(X) furnace can vent in multiple positions. then reinstall the mounting screws. See unit Installation In- See figure 14. structions for more detail. The make up box may be removed and the combustion air IMPORTANT inducer may be rotated clockwise or counterclockwise 90°...
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Page 28: Installation
II−PLACEMENT AND INSTALLATION Turning Off Gas To Unit 1 − Set thermostat to lowest setting. Make sure unit is installed in accordance with installation 2 − Turn off all electrical power to unit if service is to be per- instructions and applicable codes. formed. - Page 29 3 − After allowing unit to stabilize for 5 minutes, record Gas Leak Detector is strongly recommended. It is available manifold pressure. through Lennox under part number 31B2001. See Corp. NOTE−Shut unit off and remove manometer as soon as 8411−L10, for further details.
- Page 30 TABLE 15 IMPORTANT Firing Rate For Nat For L.P. High Fire 6.8 − 7.4 7.5 − 9.0 For safety, shut unit off and remove manometer as soon as an accurate reading has been obtained. Low Fire 4.2 − 5.7 5.0 − 6.0 Take care to replace pressure tap plug.
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Page 31: Typical Operating Characteristics
(Part To Measure Temperature Rise: #78H5401 available from Lennox Repair Parts) is 1 − Place plenum thermometers in the supply and return air required to measure flame plenums. Locate supply air thermometer in the first hori- signal. See figure 17. The... - Page 32 Measuring Flame Signal remove sensor wire from integrated control and connect alligator clip (−) to flame sensor lead flame sensor flame sensor DIGITAL METER wire set dial to measure vdc integrated transducer control flame sensor red collar idicates terminal positive leads (−) to flame sensor (+) to control...
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Page 33: Maintenance
VI−MAINTENANCE E−Heat Exchanger and Burners Cleaning the Heat Exchanger and Burners WARNING NOTE − Use papers or protective covering in front of the fur- nace during cleaning. Disconnect power before servicing unit. 1 − Turn off both electrical and gas power supplies to fur- nace. - Page 34 SL280UHV BURNER, C.A.I ASSEMBLY & HEAT EXCHANGER REMOVAL gasket pressure switch flue transition heat exchanger collector box burner box assembly orifice plate combustion air inducer gasket burners manifold and gas valve retention rings burner box cover plate cross over FIGURE 20 Remove 5 screws if necessary SL280UHV NOX INSERTS (either side of cabinet)
- Page 35 CAUTION 18− Reconnect all wires. 19− Reconnect top cap and vent pipe to combustion air in- Some soaps used for leak detection are corrosive to ducer outlet. certain metals. Carefully rinse piping thoroughly af- ter leak test has been completed. Do not use 20−...
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Page 36: Wiring And Sequence Of Operation
VII− Wiring and Sequence of Operation A−Wiring Diagram Page 36... - Page 37 B−Sequence of Operation Single−Stage Thermostat, Two Stage Heat. Dip Switch set at SINGLE" (Figure 24) Sequence depends on type thermostat used. 1− SureLight control energizes combustion air inducer B6 SL280UHV(X) units are applicable for single−stage or on low heat speed. Combustion air inducer runs until two−stage thermostats.
- Page 38 HEATING OPERATION WITH TWO−STAGE THERMOSTAT 5 SEC blower 45 second É É off" blower Trial For Post Pre−Purge Ignitor Warm−up on" delay 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...
- Page 39 VIII−Field Wiring & On Board Link Settings DIP Switch and On Board Link Settings (See figure 4) W915 W914 Dehu- Thermostat Wiring Connections W951 Two−Stage midification DIP Switch 1 Cooling or Harmony Heat Pumps IIIt 1Heat / 1 Cool Intact Intact Intact CONTROL...
- Page 40 DIP Switch and On Board Link Settings (See figure 4) W915 W914 Dehu- W951 Two−Stage midification Thermostat Wiring Connections DIP Switch 1 Cooling or Harmony Heat Pumps IIIt 2 Heat / 2 Cool Intact Intact CONTROL OUTDOOR T’STAT TERM. STRIP UNIT 2 Heat / 2 Cool Intact...
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Page 41: Troubleshooting
IX− Troubleshooting 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 42 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 43 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 44 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 45 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 46 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 47 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 48 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 49 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 50 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 51 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 52 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...