Lennox EL280UHE Service manual

Page 1
UNIT INFORMATIONUNIT INFORMATION
Service Literature
©2016 Lennox Industries, Inc.
OFF
ONON
CCCC
HIHI
IIII
LOLO
HIHI
WARNING
Improper installation, adjustment, alteration,
service or maintenance can cause property damage,
personal injury or loss of life. Installation and service
must be performed by a licensed professional HVAC
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 disconnect switch(es). Unit may have multiple
power supplies.
CAUTION
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal
injury. Take care while handling this equipment and
wear gloves and protective clothing.
EL280UHE(X) series units are 80% e󰀩ciency gas furnac-
es used for upow or horizontal applications only, manu-
factured with Lennox Duralok heat exchangers formed of
aluminized steel. Units are available in heating capacities
of 44.000 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. EL280UHE(X)
model units are equipped with the SureLight® two-stage
integrated control. EL280UHE(X) unit meets the California
Nitrogen Oxides (NOx) Standards and California Season-
al E󰀩ciency requirements. All units use a redundant gas
valve to assure safety shut-o󰀨 as required by C.S.A.
All specications in this manual are subject to change.
Procedures outlined in this manual are presented as a
recommendation only and do not supersede or replace lo-
cal or state codes. In the absence of local or state codes,
the guidelines and procedures outlined in this manual (ex-
cept where noted) are recommendations only and do not
constitute code.
TABLE OF CONTENTS
Specications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 2
Blower Performance Data . . . . . . . . . . . . . . . . . . Page 5
Parts Identication. . . . . . . . . . . . . . . . . . . . . . . . Page 7
I Unit Components . . . . . . . . . . . . . . . . . . . . . . . . Page 8
II Installation . . . . . . . . . . . . . . . . . . . . . . . . . . Page 25
III Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 25
IV Heating System Service Checks . . . . . . . . . Page 25
V Typical Operating Characteristics . . . . . . . . . Page29
VI Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . Page 30
VII Wiring and Sequence of Operation . . . . . . Page 34
VIII Field Wiring and DIP Switch Settings . . . . Page 37
IX Troubleshooting Flow Chart . . . . . . . . . . . . . Page 41
EL280UHE(X)
Corp 1901-L1
EL280UHE(X) SERIES UNITS

Page 2
SPECIFICATIONS
Gas
Heating
Performance
Model No. EL280UH045E36A EL280UH070E36A
Model No. - Low NOx - - - EL280UH070XE36A
1 AFUE 80% 80%
High
Fire
Input - Btuh 44,000 66,000
Output - Btuh 35,000 53,000
Temperature rise range - °F 30 - 60 30 - 60
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
3.5 / 10.0 3.5 / 10.0
Low
Fire
Input - Btuh 29,000 43,000
Output - Btuh 23,000 35,000
Temperature rise range - °F 20 - 50 20 - 50
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
1.7 / 4.5 1.7 / 4.5
High static - in. w.g. Heating 0.5 0.5
Cooling 0.5 0.5
Connections
in.
Flue connection − in. round 4 4
Gas pipe size IPS 1/2 1/2
Indoor
Blower
Wheel nominal diameter x width - in. 10 x 8 10 x 8
Motor output - hp 1/2 1/2
Tons of add-on cooling 1.5 - 3.5 2 - 3.5
Air Volume Range - cfm 250 - 1500 350 - 1375
Electrical Data Voltage 120 volts - 60 hertz - 1 phase
Blower motor full load amps 6.1 6.1
Maximum overcurrent protection 15 15
Shipping Data lbs. - 1 package 111 121
NOTE - Filters and provisions for mounting are not furnished and must be eld provided.
1 Annual Fuel Utilization E󰀩ciency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized furnaces.
SPECIFICATIONS
Gas
Heating
Performance
Model No. EL280UH090E36B EL280UH090E48B
Model No. - Low NOx - - - EL280UH090XE48B
1 AFUE 80% 80%
High
Fire
Input - Btuh 88,000 88,000
Output - Btuh 70,000 69,000
Temperature rise range - °F 35 - 65 30 - 60
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
3.5 / 10.0 3.5 / 10.0
Low
Fire
Input - Btuh 57,000 57,000
Output - Btuh 46,000 46,000
Temperature rise range - °F 25 - 55 20 - 50
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
1.7 / 4.5 1.7 / 4.5
High static - in. w.g. Heating 0.5 0.5
Cooling 0.5 0.5
Connections
in.
Flue connection − in. round 4 4
Gas pipe size IPS 1/2 1/2
Indoor
Blower
Wheel nominal diameter x width - in. 10 x 9 10 x 10
Motor output - hp 1/2 3/4
Tons of add-on cooling 2 - 3.5 3 - 4
Air Volume Range - cfm 350 - 1600 765 - 1800
Electrical Data Voltage 120 volts - 60 hertz - 1 phase
Blower motor full load amps 6.1 8.2
Maximum overcurrent protection 15 15
Shipping Data lbs. - 1 package 136 140
NOTE - Filters and provisions for mounting are not furnished and must be eld provided.
1 Annual Fuel Utilization E󰀩ciency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized furnaces.

Page 3
SPECIFICATIONS
Gas
Heating
Performance
Model No. EL280UH110E48C EL280UH110E60C
Model No. - Low NOx - - - EL280UH110XE60C
1 AFUE 80% 80%
High
Fire
Input - Btuh 110,000 110,000
Output - Btuh 86,000 87,000
Temperature rise range - °F 35 - 65 30 - 60
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
3.5 / 10.0 3.5 / 10.0
Low
Fire
Input - Btuh 72,000 72,000
Output - Btuh 58,000 58,000
Temperature rise range - °F 25 - 55 20 - 50
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
1.7 / 4.5 1.7 / 4.5
High static - in. w.g. Heating 0.5 0.5
Cooling 0.5 0.5
Connections
in.
Flue connection − in. round 4 4
Gas pipe size IPS 1/2 1/2
Indoor
Blower
Wheel nominal diameter x width - in. 10 x 10 11-1/2 x 10
Motor output - hp 3/4 1
Tons of add-on cooling 3 - 4 4 - 5
Air Volume Range - cfm 865 - 1780 1100 - 2200
Electrical Data Voltage 120 volts - 60 hertz - 1 phase
Blower motor full load amps 8.2 10
Maximum overcurrent protection 15 15
Shipping Data lbs. - 1 package 152 156
NOTE - Filters and provisions for mounting are not furnished and must be eld provided.
1 Annual Fuel Utilization E󰀩ciency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized
furnaces.

Page 4
OPTIONAL ACCESSORIES - ORDER SEPARATELY
“A” Width
Models
“B” Width
Models
“C” Width
Models
CABINET
Horizontal Suspension Kit - Horizontal only 51W10 51W10 51W10
Return Air Base - Upow only 65W75 50W98 50W99
High Performance Economizer (Commercial only) 10U53 10U53 10U53
CONTROLS
iComfort®E30 Smart Wi-Fi Thermostat 20A65 20A65 20A65
Remote Outdoor Temperature Sensor X2658 X2658 X2658
Furnace Twinning Kit 16W72 16W72 16W72
FILTERS
1Air Filter and Rack Kit Horizontal (end) 87L95 87L96 87L97
Size of lter - in. 14 x 25 x 1 18 x 25 x 1 20 x 25 x 1
Side Return Single 44J22 44J22 44J22
Ten Pack 66K63 66K63 66K63
Size of lter - in. 16 x 25 x 1 16 x 25 x 1 16 x 25 x 1
NIGHT SERVICE KIT
Night Service Kit 17B59 17B59 17B59
VENTING
Vent Adaptor − 6 in. conn. size upow applications only 18M79 18M79 18M79
1 Cleanable polyurethane, frame-type lter.

Page 5
EL280UH045E36A PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High
(Black)
Medium-High
(Brown)
Medium
(Blue)
Medium-Low
(Yellow)
Low
(Red)
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1500 300 1220 175 1050 114 850 65 800 48
0.10 1485 311 1200 179 1025 118 810 68 790 50
0.20 1460 323 1170 188 980 125 725 73 580 53
0.30 1420 334 1140 195 930 133 670 76 455 54
0.40 1395 343 1095 203 890 138 600 86 375 60
0.50 1355 355 1050 212 840 149 550 93 325 64
0.60 1325 368 1020 222 790 158 495 96 275 67
0.70 1290 369 980 228 745 164 420 103 238 69
0.80 1260 381 945 238 700 172 380 107 - - - - - -
EL280UH070E36A PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High
(Black)
Medium-High
(Brown)
Medium
(Blue)
Medium-Low
(Yellow)
Low
(Red)
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1375 340 1350 240 1110 190 970 93 780 50
0.10 1350 346 1325 254 1100 194 940 104 725 57
0.20 1330 346 1310 264 1080 200 895 113 680 64
0.30 1315 353 1280 272 1060 204 860 118 610 70
0.40 1300 368 1250 283 1040 212 810 125 550 76
0.50 1285 369 1220 293 1010 222 765 132 510 78
0.60 1260 384 1190 301 975 227 725 140 460 83
0.70 1240 391 1150 314 950 236 680 147 400 89
0.80 1210 399 1120 319 915 244 640 152 355 95
EL280UH090E36B PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High
(Black)
Medium-High
(Brown)
Medium
(Blue)
Medium-Low
(Yellow)
Low
(Red)
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1605 313 1475 240 1320 173 1,050 99 865 60
0.10 1565 323 1430 251 1270 185 995 108 800 68
0.20 1515 334 1380 264 1225 196 935 115 730 76
0.30 1475 347 1340 275 1170 207 870 124 645 83
0.40 1435 360 1300 285 1120 215 805 133 550 91
0.50 1395 369 1250 295 1065 225 715 140 470 98
0.60 1355 378 1205 307 1010 235 655 147 395 101
0.70 1305 391 1160 318 935 246 560 156 345 107
0.80 1265 404 1105 329 875 254 510 162 300 112

Page 6
EL280UH090E48B PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High
(Black)
Medium-High
(Brown)
Medium
(Blue)
Medium-Low
(Yellow)
Low
(Red)
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1800 370 1555 260 1425 207 1370 172 1240 131
0.10 1765 381 1525 272 1390 218 1320 184 1190 144
0.20 1725 397 1485 283 1350 229 1255 195 1130 157
0.30 1685 416 1450 296 1310 241 1205 206 1075 165
0.40 1635 425 1390 312 1260 250 1165 217 1015 174
0.50 1600 438 1350 322 1205 263 1100 230 955 185
0.60 1560 453 1300 332 1140 270 1050 239 905 193
0.70 1520 467 1255 344 1110 284 1000 249 840 202
0.80 1470 474 1215 352 1050 294 935 258 765 211
EL280UH110E48C PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High
(Black)
Medium-High
(Brown)
Medium
(Blue)
Medium-Low
(Yellow)
Low
(Red)
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1780 349 1570 248 1465 190 1370 169 1250 131
0.10 1750 365 1540 260 1420 205 1330 177 1205 140
0.20 1720 382 1500 271 1365 220 1280 187 1155 150
0.30 1675 397 1460 279 1330 228 1250 197 1110 159
0.40 1645 407 1415 291 1290 241 1200 211 1070 166
0.50 1605 424 1395 307 1250 249 1165 219 1015 177
0.60 1580 432 1345 316 1205 258 1105 228 960 186
0.70 1565 448 1300 328 1165 271 1060 237 915 194
0.80 1525 449 1270 339 1125 283 1025 246 865 203
EL280UH110E60C PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Di󰀨erent Blower Speeds
Bottom Return Air, Side Return Air from Both Sides or
Return Air from Bottom and One Side.
Single Side Return Air - Air volumes in bold (over
1800 cfm) require Optional Return Air Base and eld
fabricated transition to accommodate 20 x 25 x 1 in. air
lter in order to maintain proper air velocity.
High
(Black)
Medium-
High
(Brown)
Medium
(Blue)
Medium-
Low
(Yellow)
Low
(Red)
High
(Black)
Medium-
High
(Brown)
Medium
(Blue)
Medium-
Low
(Yellow)
Low
(Red)
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 2175 590 2050 410 1850 310 1695 275 1510 195 2175 605 1930 420 1785 320 1675 260 1500 195
0.10 2158 607 1943 421 1778 328 1650 283 1461 205 2129 628 1892 441 1733 345 1627 288 1458 209
0.20 2131 620 1897 436 1719 345 1591 299 1405 215 2091 649 1838 458 1691 360 1586 297 1407 220
0.30 2085 639 1847 456 1678 354 1563 308 1351 228 2072 660 1806 471 1631 371 1529 313 1353 232
0.40 2055 652 1806 466 1641 371 1499 317 1297 238 2014 677 1772 485 1591 385 1485 327 1302 243
0.50 2030 668 1767 476 1588 387 1462 333 1256 254 1977 690 1742 498 1554 395 1444 337 1252 256
0.60 1976 686 1724 495 1550 399 1419 348 1215 265 1960 707 1696 511 1511 410 1412 348 1204 265
0.70 1949 700 1685 510 1512 408 1371 357 1168 271 1913 720 1661 525 1480 424 1351 359 1149 274
0.80 1896 716 1649 527 1473 419 1332 372 1121 287 1873 738 1617 538 1440 437 1313 371 1117 285

Page 7
EL280UHE(X) Parts Arrangement
Combustion Air
Pressure Switch
Combustion Air
Inducer
Gas Valve and Manifold
Assembly
Limit Switch
(under collector box)
Collector Box
Heat Exchanger
Indoor Blower and Motor Assembly
(installed in cabinet)
Make Up Box
Constant Torque Indoor Blower Motor
(removed from cabinet)
Two-Stage Integrated Control
Figure 1

Page 8
I-UNIT COMPONENTS
EL280UHE(X) unit components are shown in gure 1. The
gas valve, combustion air inducer and burners can be ac-
cessed by removing the access panel. Electrical compo-
nents are in the control box (gure 2) found in the blower
section.
EL280UHE(X) units are factory equipped with a bottom
return air panel in place. The panel is designed to be eld
removed as required for bottom air return. Markings are
provided for side return air and may be cut out in the eld.
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can a󰀨ect
electronic components. Take precautions
to neutralize electrostatic charge by
touching your hand and tools to metal
prior to handling the control.
A- Control Box
1. Control Transformer (T1)
A transformer located in the control box provides power to
the low voltage section of the unit. Transformers on all
models are rated 40VA with a 120V primary and a 24V
secondary.
2. Door Interlock Switch (S51)
A door interlock switch is wired in series with line voltage.
When the inner blower access panel is removed the unit
will shut down.
CONTROL BOX
Transformer
SureLight®Integrated Control
Interlock Switch
Circuit Breaker
Figure 2
3. Circuit Breaker (CB8)
A 24V circuit breaker is also located in the control box.
The switch provides overcurrent protection to the trans-
former (T1). The breaker is rated 3A at 32V. If the current
exceeds this limit the breaker will trip and all unit opera-
tion will shutdown. The breaker can be manually reset by
pressing the button on the face. See gure 3.
CIRCUIT BREAKER CB8
PRESS TO RESET
Figure 3
WARNING
Shock hazard.
Disconnect power before servicing. Integrated
control is not eld repairable. If control is inoperable,
simply replace entire control.
Can cause injury or death. Unsafe operation will
result if repair is attempted.
4. Integrated Control (A92)
Units are equipped with the SureLight® two-stage, inte-
grated control. The system consists of a ignition / blower
control (gures 4 and 5) with control pin designations in
tables 1 and 2 and ignitor. The control and ignitor work in
combination to ensure furnace ignition and ignitor durabil-
ity. The control provides gas ignition, safety checks and
indoor blower control with two-stage gas heating. The fur-
nace combustion air inducer, gas valve and indoor blower
are controlled in response to various system inputs such
as thermostat signal, pressure and limit switch signal and
ame signal. The control features a seven-segment LED
display, indicating furnace status and error codes. The
LED ashes in single digits. For example using table 4
under LIMIT CODE, an “E” followed by “2” followed by “5”
followed by “0”, the limit switch circuit is open. The control
also has two unpowered (dry) 1/4” contacts for a humid-
ier and a 120 volt accessory terminal. Both rated at (1)
one amp each.
Electronic Ignition
At the beginning of the heat cycle the integrated control
monitors the rst stage and second stage combustion air
inducer pressure switch. The control will not begin the
heating cycle if the rst stage pressure switch is closed
(bypassed). Likewise the integrated control will not be-
gin the second stage heating cycle if the second stage
pressure switch is closed, and will remain in rst stage
heat. However, if the second stage pressure switch closes
during the rst stage heat pre-purge, the control will allow
second stage heat. Once the rst stage pressure switch
is determined to be open, the combustion air inducer is
energized on low (rst stage) heat speed. When the di󰀨er-
ential in the pressure switch is great enough, the pressure
switch closes and a 15-second pre-purge begins.

Page 9
After the 15-second pre-purge period, the SureLight®ig-
nitor warms up for 20 seconds after which the gas valve
opens for a 4-second trial for ignition. The ignitor remains
energized during the trial until ame is sensed. If ignition
is not proved during the 4-second period, the control will
try four more times with an inter purge and warm-up time
between trials of 35 seconds. After a total of ve trials
for ignition(including the initial trial), the control goes into
Watchguard- Flame Failure mode. After a 60-minute reset
period, the control will begin the ignition sequence again.
NOTE - During abnormal conditions such as low supply
voltage or low outdoor temperatures and the low re pres-
sure switch does not close, the combustion air inducer will
switch to high speed. After the low & high pressure switch
close, the unit will proceed with a 15 sec pre-purge, fol-
lowed by a 20 sec ignitor warm up, then ignition on high-
re. After 10 to 20 seconds of high re operation the unit
will switch to low re.
Two Stage Operation / Thermostat Selection DIP
Switch
The control can be utilized in two modes: SINGLE-STAGE
thermostat or TWO-STAGE thermostat. The thermo-
stat selection is made using a DIP switch and must be
positioned for the particular application. DIP switch 1,
labeled T”STAT HEAT STAGE is factory-set in the OFF
position for use with a two-stage thermostat. Move the
DIP switch to ON for use with a single stage thermostat.
While in the single-stage thermostat mode, the burn-
ers will always re on rst-stage heat. The com-
bustion air inducer will operate on low speed and
indoor blower will operate on low heat speed.
The unit will switch to second stage heat after a “recog-
nition period”. DIP switch 2, labeled SECOND STAGE
DELAY, is factory set in the OFF position for a 7 minute
recognition period. The switch can be moved to the ON
position for a 12 minute recognition period, after which
time the unit will switch to second-stage heat. While in the
two-stage thermostat mode, the burners will re on rst-
stage heat. The combustion air inducer will operate on low
speed and indoor blower will operate on low heat speed.
The unit will switch to second-stage heat on call from the
indoor thermostat. If there is a simultaneous call for rst
and second stage heat, the unit will re on rst stage heat
and switch to second stage heat after 30 seconds of oper-
ation. See Sequence of Operation ow charts in the back
of this manual for more detail.
TABLE 1
SureLight®Control 5 Pin Terminal Designation
Pin # Function
1Ignitor
2Combustion Air Inducer High Speed
3 Combustion Air Inducer Low Speed
4 Combustion Air Inducer Neutral
5Ignitor Neutral
TABLE 2
SureLight® Control 12 Pin Terminal Designation
Pin # Function
1Gas Valve Second Stage
2Pressure Switch Second Stage
3 Rolout Switch
4 Ground
524V Hot
6Primary Limit In
7 Gas Valve First Stage
8Gas Valve Common
9 24V Neutral
10 Ground
11 Primary Limit Out
12 Pressure Switch First Stage

Page 10
INTEGRATED CONTROL
THERMOSTAT CONNECTIONS (TB1)
1/4” QUICK CONNECT TERMINALS
DS = DEHUMIDIFICATION SIGNAL
W2 = HEAT DEMAND FROM 2ND STAGE T/STAT
W1 = HEAT DEMAND FROM 1ST STAGE T/STAT
R = CLASS 2 VOLTAGE TO THERMOSTAT
G = MANUAL FAN FROM T'STAT
C = THERMOSTAT SIGNAL GROUND CONNECTED TO
TRANSFORMER GRD (TR) & CHASIS GROUND (GRD)
Y1 = THERMOSTAT 1ST STAGE COOL SIGNAL
Y2 = THERMOSTAT 2ND STAGE COOL SIGNAL
O = THERMOSTAT SIGNAL TO HEAT PUMP
REVERSING VALVE
L = NOT USED
DH = NOT USED
HUM = UNPOWERED NORMALLY OPEN (DRY) CONTACTS
LI = 120 VAC INPUT TO CONTROL
A
CC = 120 VAC OUTPUT TO OPTIONAL ACCESSORY
NEUTRALS = 120 VAC NEUTRAL
3/16” QUICK CONNECT TERMINALS
FLAME SENSE SIGNAL
HI COOL 24VAC
HI HEAT 24VAC
LO COOL 24VAC
LO HEAT 24VAC
PARK
PARK
COMMON 24VAC
Flame Sense
S4 DIP Switches
24VAC Indoor
Blower Terminals
HUM ACC
Ignitor and Combustion
Air Inducer
Neutrals
On Board Links
LED
Diagnostic Push
Button
Figure 4

Page 11
HEATING BLOWER−OFF DELAY
60 SECOND
HTG BLOWER
OFF DELAY
120 SECOND
HTG BLOWER
OFF DELAY
180 SECOND
HTG BLOWER
OFF DELAY
FLAME
15
HSI/CAI
2ND STAGE HEAT ON DELAY
7 MIN
UPSTAGE
DELAY
12 MIN
UPSTAGE
DELAY
*
W915
2 STAGE
COMPR
1−STG COMPRESSOR
2−STAGE
COMPRESSOR LINK
(JUMPERS Y1 to Y2)
W915
DO NOT CUT
2−STG COMPRESSOR
HEAT PUMP LINK
(JUMPERS R to O)
W951
(JUMPERS R to DS)
W914
W915
2 STAGE
COMPR
CUT LINK
A/C UNIT
DO NOT CUT
HEAT PUMP UNIT
CUT LINK
W951
HEAT
PUMP
W951
HEAT
PUMP
W914
DEHUM
NO SIGNATURESTAT
W/ DS CONNECTION
DO NOT CUT
SIGNATURESTAT W/
DS CONNECTION
CUT LINK
W914
DEHUM
1
1
1
ON−BOARD LINK
OPTION SELECTION
1234567
1234567
123567
4
123567
4
NEUTRALS
L1
ACC
HUM
14
36
P79
110
312
J2
4 7
W915
2 STAGE
COMPR
W951
HEAT
PUMP
W914
DEHUM
CUT FOR
OPTION
SELECTION
123456
ON
SureLight

W1W2 GY2 Y1 CC DH LODSR
W1 W2
G
Y2
Y1
C C
R
L
DH
7
−PROTECTIVE PLASTIC FILM ON DIP SWITCHES MAY BE
REMOVED FOR EASE IN SETTING OF DIP SW.
−CUT ON−BOARD LINK (SOLDER TRACE) COMPLETELY THROUGH
BOTH LAYERS ON THE CONTROL BOARD
−LINKS CUT IN ERROR −INSTALL A JUMPER ON THE APPROPRIATE
TERMINALS ON THE TERMINAL STRIP
1
ON
ON
ON
ON
90 SECOND
HTG BLOWER
OFF DELAY
*1234567
ON
1234567
ON
THERMOSTAT SELECTION
1−STAGE
THERMOSTAT
(TIMED STAGING)
−SEE SW #2
TWO STAGE
THERMOSTAT
*1234567
1234567
ON
ON
−BLOWER ON DELAY − 30 SEC. FIXED
1234567
ON
SENSE
IGN
CAI2
CAI1
N N
J3
S1
S4S3
* FACTORY DEFAULT
DIAGNOSTIC
LED
DIAGNOSTIC
PUSH BUTTON
INTEGRATED CONTROL CONFIGURATION GUIDE
*45 SECOND
COOL BLOWER
OFF DELAY
2 SECOND
COOL BLOWER
OFF DELAY
123567
4
123567
4
ON
ON
COOLING BLOWER-OFF DELAY
1234567
ON
1234567
ON
1234567
ON
CONTINUOUS FAN SETTINGS
LOW HEAT SPEED
LOW COOL SPEED
HIGH HEAT SPEED
HIGH COOL SPEED
DEHUMIFICATION LINK
Figure 5

Page 12
TABLE 3
Integrated Control Diagnostic Modes
Display Action (when button released)
No Change Remain in idle mode
Solid “E” Enter diagnostic recall mode
Solid “F” Enter ame signal mode
TABLE 4
Integrated Diagnostic Codes/Status of Equipment
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).
C Cooling stage (1 second ON, 0.5 second OFF)
1 or 2 displayed / Pause / Repeat codes.
dDehumidication mode (1 second ON, 1
second OFF) / Pause / Repeat Codes).
HGas Heat Stage (1 second ON, 0.5 second
OFF) 1 or 2 displayed / Pause / Repeat codes.
Blinking during ignition.
h Heat pump stage.
E110 Low line voltage. Line Voltage Low (Voltage lower than nameplate rating). Check power
line voltage and correct. Alarm clears 5 seconds after fault recovered.
E111 Line voltage polarity reversed. Reverse line power voltage wiring. System resumes normal operation
5 seconds after fault recovered.
E112 Ground not detected. System shuts down. Provide proper earth ground. System resumes
normal operation 5 seconds after fault recovered.
E113 High line voltage. Line Voltage High (Voltage higher than nameplate rating). Provide
power voltage within proper range. System resumes normal operation
5 seconds after fault recovered.
E114 Line voltage frequency out-of-range. No 60 Hertz Power. Check voltage and line power frequency. Correct
voltage and frequency problems. System resumes normal operation 5
seconds after fault recovered.
E115 Low 24V - Control will restart if the error
recovers.
24-Volt Power Low (Range is 18 to 30 volts). Check and correct
voltage. Check for additional power-robbing equipment connected
to system. May require installation of larger VA transformer to be
installed in furnace / air handler. Clears after fault recovered.
E117 Poor ground detected (Warning only). Provide proper grounding for unit. Check for proper earth ground to
the system. Warning only will clear 30 seconds after fault recovered.
* No change implies the display will continue to show whatever is currently being displayed for normal operation (blinking decimal, active error code, heat state, etc.)
Diagnostic LED (Figure 4)
The seven-segment diagnostic LED displays operating
status, error codes and other information. Table be4 lists
diagnostic LED codes.
Diagnostic Push Button (Figure 4)
The diagnostic push button is located adjacent to the sev-
en-segment diagnostic LED. This button is used to enable
the Error Code Recall “E” mode and the Flame Signal
“F” mode. Press the button and hold it to cycle through a
menu of options. Every ve seconds a new menu item will
be displayed. When the button is released, the displayed
item will be selected. Once all items in the menu have
been displayed, the menu resumes from the beginning
until the button is released.
Error Code Recall Mode
Select ”E” from the menu to access the most recent 10
error codes. Select “c” from the Error Code Recall menu
to clear all error codes. Button must be pressed a second
time while “c” is ashing to conrm command to delete
codes.
Press the button until a solid “≡” is displayed to exit the
Error Code Recall mode.
Flame Signal Mode
Select ”F” from the menu to access the ame signal mode.
The integrated control will display the ame current on
seven-segment LED in in micro amps (uA). Flame signal
mode is exited after any of the following:
• Power is reset
• Pressing and holding push button until 3 horizontal lines “≡” are
displayed
• 10 minutes after entering the ame sense mode.

Page 13
TABLE 4 Continued
Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover
E125 Control failed self-check, internal error,
failed hardware. Will restart if error recovers.
Integrated control not communicating. Covers
hardware errors (ame sense circuit faults, pin
shorts, etc.).
Hardware problem on the control. Cycle power on control. Replace
if problem prevents service and is persistent. Critical alert. Cleared
300 seconds after fault recovered.
E200 Hard lockout - Rollout circuit open or previously
open.
Correct cause of rollout trip, or replace ame rollout switch. Test
furnace operation. Cleared after fault recovered.
E204 Gas valve mis-wired. Check gas valve operation and wiring. Clears when repaired.
E205 Gas valve control relay contact shorted. Check wiring on control and gas valve. If wiring is correct, replace
control.
E206 Gas valve second-stage relay failure. Furnace will operate on 1st stage for remainder of the heating
demand. Will clear after fault recovered. If unable to operate 2nd
stage, replace control.
E207 Hot surface ignitor sensed open. Measure resistance of hot surface ignitor. Replace if open or not
within specied range found in IOM. Resumes normal operation
after fault is cleared.
E223 Low pressure switch failed open. Check pressure (inches w.c.) of low pressure switch closing on
heat call. Measure operating pressure (inches w.c.). Inspect vent
and combustion air inducer for correct operation and restriction.
Resumes normal operation after fault is cleared.
E224 Low pressure switch failed closed. Check pressure (inches w.c.) of low pressure switch closing on
heat call. Measure operating pressure (inches w.c.). Inspect vent
and combustion air inducer for correct operation and restriction.
Resumes normal operation after fault is cleared.
E225 High pressure switch failed open. Check pressure (inches w.c.) of high pressure switch closing on
heat call. Measure operating pressure (inches w.c.). Inspect vent
and combustion air inducer for correct operation and restriction.
Resumes normal operation after fault is cleared.
E226 High pressure switch failed closed. Check operation of high pressure switch closing on heat call.
Measure operating pressure (inches w.c.). Inspect vent and
combustion air inducer for correct operation and restriction.
Resumes normal operation after fault is cleared.
E227 Low pressure switch open during trial for
ignition or run mode.
Check pressure (inches w.c.) of low pressure switch closing on
heat call. Measure operating pressure (inches w.c.). Inspect vent
and combustion air inducer for correct operation and restriction.
Resumes normal operation after fault is cleared.
E229 Ignition on High Fire - Information Only. Code is displayed if 1) low pressure switch fails to close, then
furnace will switch to high speed inducer to close both low and
high pressure switches, then furnace lights on high re, or 2) if
continuous fan is active, furnace lights on high re for 60 seconds
to improve heat exchanger warm up time.
E240 Low ame current - Run mode. Check micro-amperes of ame sensor using control diagnostics
or eld-installed mode. Clean or replace sensor. Measure voltage
of neutral to ground to ensure good unit ground. Alert clears after
current heat call has been completed.
E241 Flame sensed out of sequence - Flame still
present.
Shut o󰀨 gas. Check for gas valve leak. Replace, if necessary. Alert
clears when fault is recovered.
E250 Limit switch circuit open. Check for proper ring rate on furnace. Ensure there is no blockage
in heater. Check for proper air ow. If limit not closed within 3
minutes, unit will go into 1-hour soft lockout. Resumes normal
operation after fault is cleared.

Page 14
TABLE 4 Continued
Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover
E270 Soft lockout - Exceeded maximum number of
retries. No ame current sensed.
Check for proper gas ow. Ensure that ignitor is lighting burner.
Check ame sensor current. Clears when heat call nishes
successfully.
E271 Soft lockout - Exceeded maximum number of
retries. Last retry failed due to the pressure
switch opening.
Check pressure (inches w.c.) of low pressure switch closing on heat
call. Measure operating pressure (inches w.c.). Inspect vent and
combustion air inducer for correct operation and restriction. Clears
when heat call nishes successfully.
E272 Soft lockout - Exceeded maximum number
of recycles. Last recycle due to the pressure
switch opening.
Check operation of low pressure switch to see if it is stuck closed
on heat call. Check pressure (inches w.c.) of high pressure switch
closing on heat call. Measure operating pressure (inches w.c.).
Inspect vent and combustion air inducer for correct operation and
restriction. Clears when heat call nishes successfully.
E273 Soft lockout - Exceeded maximum number of
recycles. Last recycle due to ame failure.
Check micro-amperes of ame sensor using control diagnostics or
eld-installed mode. Clean or replace sensor. Measure voltage of
neutral to ground to ensure good unit ground. Clears when heat call
nishes successfully.
E274 Soft lockout - Exceeded maximum number of
recycles. Last recycle failed due to the limit
circuit opening or limit remained open longer
than 3 minutes.
Shut down system. 1-hour soft lockout. Check ring rate and
air ow. Check for blockage. Clears when heat call nishes
successfully.
E275 Soft lockout - Flame sensed out of sequence.
Flame signal is gone.
Shut o󰀨 gas. Check for gas valve leak. 1-hour soft lockout. Clears
when ame has been proven stable.
E290 Ignitor circuit fault - Failed ignitor or triggering
circuitry.
Measure resistance of hot surface ignitor. Replace if open or not
within specications. 1-hour soft lockout. Clears when ame has
been proven stable.

Page 15
Integrated Control DIP Switches
EL280UHE(X) units are equipped with a two-stage inte-
grated control. This control manages ignition timing, heat-
ing mode fan o󰀨 delays and indoor blower speeds based
on selections made using the control dip switches and
jumpers.
The control includes an internal watchguard feature which
automatically resets the ignition control when it has been
locked out. After one hour of continuous thermostat de-
mand for heat, the watchguard will break and remake
thermostat demand to the furnace and automatically reset
the control to relight the furnace.
Heating Operation DIP Switch Settings
Switch 1 -- Thermostat Selection -- This unit may be
used with either a single-stage or two-stage thermostat.
The thermostat selection is made using a DIP switch
which must be properly positioned for the particular appli-
cation. The DIP switch is factory-positioned for use with a
twostage thermostat. If a single-stage thermostat is to be
used, the DIP switch must be repositioned.
a. Select “OFF” for two-stage heating operation controlled by
a two-stage heating thermostat (factory setting);
b. Select “ON” for two-stage heating operation controlled by
a single-stage heating thermostat. This setting
provides a timed delay before second-stage heat
is initiated.
Switch 2 a --- Second Stage Delay (Used with Single-
Stage Thermostat Only) -- This switch is used to deter-
mine the second stage on delay when a single-stage ther-
mostat is being used. The switch is factory-set in the OFF
position, which provides a 7-minute delay before second-
stage heat is initiated. If the switch is toggled to the ON
position, it will provide a 12-minute delay before second-
stage heat is initiated. This switch is only activated when
the thermostat selector jumper is positioned for SINGLE-
stage thermostat use.
Indoor Blower Operation DIP Switch Settings
Switches 3 and 4 -- Heating Mode Blower-O󰀨 Delay --
The blower-on delay of 30 seconds is not adjustable. The
blower-o󰀨 delay (time that the blower operates after the
heating demand has been satised) can be adjusted by
moving switches 3 and 4 on the integrated control. The
unit is shipped from the factory with a blower-o󰀨 delay of
90 seconds.
The blower o󰀨 delay a󰀨ects comfort and is adjustable to
satisfy individual applications. Adjust the blower o󰀨 de-
lay to achieve a supply air temperature between 90° and
110°F at the exact moment that the blower is de-ener-
gized. Longer o󰀨 delay settings provide lower supply air
temperatures; shorter settings provide higher supply air
temperatures. Table 5 provides the blower o󰀨 timings that
will result from di󰀨erent switch settings.
TABLE 5
Blower O󰀨 Heating Mode Delay Switch Settings
Blower O󰀨 Delay
Seconds Switch 3 Switch 4
60 On O󰀨
90 (factory) O󰀨 O󰀨
120 O󰀨 On
180 On On
Switch 5 -- Cooling Mode Blower-O󰀨 Delay-- The unit
is shipped from the factory with the dip switch positioned
OFF for a 45 second delay. Table 11 provides the cooling
mode o󰀨 delay settings.
TABLE 6
Blower O󰀨 Cooling Mode Delay Switch Settings
Blower O󰀨 Delay Seconds Switch 5
45 (factory) O󰀨
2On
Switches 6 and 7 -- Continuous Fan Mode -- Continu-
ous fan speed can be controlled by changing DIP switch
positions. Table 12 below provides DIP switch settings for
continuous fan mode.
TABLE 7
Continuous Fan Mode Settings
Continuous Fan
Mode Switch 6 Switch 7
Low Heat Speed
(Factory Setting) O󰀨 O󰀨
On-Board Link W914 Dehum
On-board link W914, is a clippable connection between
terminals R and DS on the integrated control. W914 must
be cut when the furnace is installed with a thermostat
which features humidity control. If the link is not cut, termi-
nal “DS” will remain energized not allowing the blower to
reduce to low cool speed upon a call for dehumidication.
On-Board Link W951 Heat Pump (R to O)
On-board link W951 is a clippable connection between
terminals R and O on the integrated control. W951 must
be cut when the furnace is installed in applications which
include a heat pump unit and a thermostat which features
dual fuel use. If the link is left intact, terminal “O” will re-
main energized eliminating the HEAT MODE in the heat
pump.
On-Board Link W915 2 Stage Compr (Y1 to Y2)
On-board link W915 is a clippable connection between
terminals Y1 and Y2 on the integrated control. W915 must
be cut if two-stage cooling will be used. If the Y1 to Y2 link
is not cut the outdoor unit will operate in second-stage
cooling only.
IMPORTANT
If any onboard link is cut by mistake, install a jumper
across the corresponding terminals on the low
voltage terminal strip. Do not replace control.

Page 16
B- Indoor Blower
IMPORTANT
Each blower is statically and dynamically balanced
as an assembly before installation in the unit.
EL280UHE(X) units are equipped with a constant torque
ECM motor. It has a DC motor coupled to an electronicco-
ntrol module both contained in the same motor housing.
The motor is programmed to provide constant torque at
each of the ve selectable speed taps. Each tap requires
24 volts to energize.
Input Voltage Requirements
The circuit is designed to be operated with AC voltage. To
enable a tap requires 12 to 33VAC. Expected current draw
will be less than 20mA.
Troubleshooting the Motor
Troubleshooting the motor is an easy process. Follow
steps below.
1 - Shut o󰀨 power to unit.
2 - Remove input plugs P48 and P49 from motor. See
gure 8 for troubleshooting procedure.
If correct voltage is present in tests 1 and 2 and motor
is not operating properly, replace motor. The motor is not
eld repairable.
If replacing the indoor blower motor or blower wheel is
necessary, placement is critical. The blower wheel must
be centered in the blower housing as shown in gure 6.
When replacing the indoor blower motor the set screw
must be aligned and tightened with the motor shaft as
shown in gure 7.
Center Blower Wheel
in Blower Housing
BLOWER WHEEL REPLACEMENT
Figure 6
Set Screw
Housing Hub
ALIGN AND TIGHTEN SET SCREW WITH
FLAT SIDE OF MOTOR SHAFT
Motor
Shaft
Figure 7

Page 17
1
2
3
4
5
C
L
G
N
Multi−Meter
(set to VAC)
P48
P49
120 120
Turn on power to unit. Check for 120 volts across terminals
“L” and “N” on input plug P48. If voltage is present continue
stream of plug P48 and proceed to test 3.
1
2
3
4
5
C
L
G
N
Multi−Meter
(set to VAC)
P48
P49 24
Switch thermostat to CONTINUOUS FAN MODE. Check for
24 volts across terminal “C” on input plug P48and speed tap
used for continuous fan. (1, 2, 3, 4 or 5) on input plug P49. If
24 volts is not present problem may be up stream of plug P49.
Proceed to test 4.
Multi−Meter
(set to VAC)
120 120
24
Multi−Meter
(set to VAC)
ent, problem is with the harness. If voltage is not present
problem may be may be with the integrated control
Check for 120 volts across terminals “L1” and “Neutrals” on
the integrated control. If voltage is present, problem is with
the harness. If voltage is not present problem may be may
be with the integrated control.
Test 1
Test 2
Test 3 (if necessary)
Test 4 (if necessary)
Figure 8

Page 18
Replacing the Motor Module
1 - Disconnect electrical power to unit.
2 - Remove unit access panel.
3 - Unplug the two harnesses from the motor control
module. See gure 9.
4 - Remove the two hex head bolts securing the motor
control module to the motor (see gure 10).
5 - Slide the motor control module away from the motor
to access and disconnect the internal three wire
connector. It is not necessary to remove blower
motor itself. Set both hex head bolts aside.
TWO HARNESS
CONNECTIONS
MOTOR CONTROL MODULE
MOTOR
Unplug the Two Harness Connection
Figure 9
REMOVE BOTH HEX
HEAD BOLTS
Remove the Hex Head Bolts
Figure 10
Testing the Motor (Figure11)
If any motor fails the below tests, do not install the new
control module. The motor is defective and it also must be
replaced. The new control can fail if placed on a defective
motor.
1 - Using an ohmmeter check the resistance from any
one of the motor connector pins to the aluminum
end plate of the motor. This resistance should be
greater than 100k ohms.
2 - Check the resistances between each of the three
motor connector pins. These should all read
approximately the same resistance within an ohm.
3 - Check to see if the blower wheel spins freely.
Motor Test
Figure 11
Motor Module Installation
All replacement motor control modules look similar; how-
ever, each module is designed for a specic motor size.
It is very important to make sure that you are using the
correct replacement motor control module. USE OF THE
WRONG MOTOR CONTROL MODULE MAY RESULT IN
UNEXPECTED UNIT OPERATION.
1 - Verify electrical power to unit is disconnected.
2 - Connect three-wire harness from motor to control
module.
3 - Mount new motor control module to motor using two
hex head bolts removed in gure 10. Torque bolts to
22 inch pounds or 1/16th clock wise turn.
4 - Reconnect the two harnesses to the motor control
module.
5 - The electrical connectors of the motor should be
facing down to form a drip loop (gure12). This
will directs moisture away from the motor and its
electric connections on the motor.
TABLE 8
Scale Measurement range inwords ohms
2 M two megohm-two million ohms 0 - 2,000,000
200 K two hundred kilo-ohm-two hun-
dred thousand ohms 0 - 200,000
20 K twenty kilo-ohm-twenty thousand
ohms 0 - 20,000
2 K two kilo-ohm two-thousand ohms 0 - 2,000
200 two hundred ohms 0 - 200
CONNECTOR
ORIENTATION
BETWEEN 4 AND 8
O'CLOCK
BACK OF CONTROL
MODULE
DRIP LOOP
Drip Loop
FIGURE 12

Page 19
C- Heating Components
1. Ignitor
The SureLight® ignitor is made of durable silicon nitride.
Ignitor longevity is enhanced by controlling voltage to the
ignitor. The integrated control provides a regulated 120
volts to the ignitor for a consistent ignition and long ignitor
life. Ohm value should be 39 to 70. See gure 13 for ignit-
or location and gure 15 for ignitor check out.
NOTE - The EL280UHE(X) furnace contains electronic
components that are polarity sensitive. Make sure that the
furnace is wired correctly and is properly grounded.
2. Flame Sensor
A ame sensor is located on the left side of the burner
support. See gure 13. The sensor protrudes into the
ame envelope of the left-most burner. The sensor can
be removed for service without removing any part of the
burners. During operation, ame is sensed by current
passed through the ame and sensing electrode. The
SureLight control allows the gas valve to remain open as
long as ame signal is sensed. A microamp DC meter is
needed to check the ame signal on the integrated con-
trol. See gure 14 and table 9 for ame signal check and
measurement.
3. Gas Valve
The two-stage gas valve (gure 18) is internally redun-
dant to assure safety shut-o󰀨. If the gas valve must be
replaced, the same type valve must be used. 24VAC ter-
minals and ON/OFF switch are located on the valve. A
wire harness connects the terminals from the gas valve to
the electronic ignition control. 24V applied to the terminals
energizes the valve.
Inlet and outlet pressure taps are located on the valve. A
regulator adjustment screw is located on the valve. LPG
change over kits are available from Lennox. Kits include
burner orices.
4. Flame Rollout Switches (S47)
The EL280UHE(X) is equipped with two rollout switches.
See gure 13 for location. The limits are a N.C. SPST
manual-reset limit. When S47 senses rollout, the circuit
breaks and the ignition control immediately stops igni-
tion and closes the gas valve. Rollout can be caused by
a blocked heat exchanger, ue or lack of combustion air.
The switches are factory set to trip (open) at 210°F and
cannot be adjusted. To manually reset a tripped switch,
push the reset button located on the control.
5. Burners
All units use inshot burners. Burners are factory set and
require no adjustment. Always operate the unit with the
burner box front panel in place. Each burner uses an ori-
ce that is precisely matched to the burner input. Burners
can be removed as a one piece assembly for service. If
burner assembly has been removed, it is critical to align
center of each burner to the center of the clamshell when
re-installing.
6. Primary Limit Control (S10)
The primary limit (S10) is located in the heating vestibule
panel. When excess heat is sensed in the heat exchanger,
the limit will open. If the limit is open, the furnace control
energizes the supply air blower and closes the gas valve.
The limit automatically resets when unit temperature re-
turns to normal. The switch must reset within three min-
utes or the SureLight control will go into Watchguard for
one hour. The switch is factory set and cannot be adjust-
ed. The switch may have a di󰀨erent set point for each unit
model number. See Lennox Repair Parts Handbook if limit
switch must be replaced.

Page 20
HEATING COMPONENTS
Ignitor Burners
Sensor
Gas Valve
Manifold and Gas Orifices
Rollout Switch
FIGURE 13