Lennox EL280UHE Installation and operation manual

Page 1 ©2019 Lennox Industries Inc.
Corp. 1901-L1 EL280UHE(X)
Service Literature
EL280UHE(X) SERIES UNITS
EL280UHE(X) series units are 80% efficiency gas furnaces
used for upflow or horizontal applications only, manufac
tured with Lennox Duraloktheat exchangers formed of
aluminized steel. EL280UHE(X) units are available in heat
ing capacities of 44,000 to 110,000 Btuh and cooling ap
plications up to 5 tons. Product Specifications manual 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 in
tegrated control. EL280UHE(X) unit meets the California Ni
trogen Oxides (NOx) Standards and California Seasonal Ef
ficiency requirements. 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
Specifications Page 2.............................
Blower Data Page 5..............................
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 Page 29.........
VI Maintenance Page 30..........................
VII Wiring and Sequence of Operation Page 34......
VIII Field Wiring and DIP Switch Settings Page 37....
IX Troubleshooting Page 41.......................
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.

Page 2
SPECIFICATIONS
Gas
Heating
Performance
Model No. EL280UH045E36A EL280UH070E36A
Model No. - Low Nox - - - EL280UH070XE36A
AHRI Ref. No. Non “X” Models N/A N/A
“X” Models N/A N/A
1AFUE 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 / 4.9 1.7 / 4.9
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 113 126
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
AHRI Ref. No. Non “X” Models N/A N/A
“X” Models N/A N/A
1AFUE 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 / 4.9 1.7 / 4.9
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 141 144
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
AHRI Ref. No. Non “X” Models N/A N/A
“X” Models N/A N/A
1AFUE 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 / 4.9 1.7 / 4.9
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 161 169
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 (Commerical only) 10U53 10U53 10U53
controls
iComfort®E30 Smart Wi-Fi Thermostat 15S63 15S63 15S63
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 84W47 84W47 84W47
VENTING
Vent Adaptor − 6 in. conn. size upow applications only 18M79 18M79 18M79
1 Cleanable polyurethane, frame-type lter.

Page 5
BLOWER DATA
EL280UH045E36A PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High Medium-High Medium Medium-Low Low
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 Medium-High Medium Medium-Low Low
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 Medium-High Medium Medium-Low Low
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
BLOWER DATA
EL280UH090E48B PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High Medium-High Medium Medium-Low Low
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 Medium-High Medium Medium-Low Low
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 Med-High Medium Med-Low Low High Med-High Medium Med-Low Low
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
FIGURE 1
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

Page 8
I-UNIT COMPONENTS
EL280UHE(X) unit components are shown in figure 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 (figure 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 field removed
as required for bottom air return. Markings are provided for
side return air and may be cut out in the field.
CAUTION
Electrostatic discharge can affect elec
tronic 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 sec
ondary.
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.
FIGURE 2
CONTROL BOX EL280UHE(X)
Transformer
SureLight®Integrated Control
Interlock Switch
Circuit Breaker
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 figure 3.
FIGURE 3
CIRCUIT BREAKER CB8
PRESS TO RESET
WARNING
Shock hazard.
Disconnect power before servicing. Integrated
control is not field repairable. If control is inoper
able, simply replace entire control.
Can cause injury or death. Unsafe operation will re
sult 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 (figures 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 in
door 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
flame signal. The control features a seven-segment LED
display, indicating furnace status and error codes. The LED
flashes in single digits. For example using table 4 under
LIMIT CODE, an “E” followed by “2” followed by “5” fol
lowed by “0”, the limit switch circuit is open. The control also
has two unpowered (dry) 1/4” contacts for a humidifier 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 first stage and second stage combustion air
inducer pressure switch. The control will not begin the
heating cycle if the first stage pressure switch is closed (by-
passed). Likewise the integrated control will not begin the
second stage heating cycle if the second stage pressure
switch is closed, and will remain in first stage heat. Howev
er, if the second stage pressure switch closes during the
first stage heat pre-purge, the control will allow second
stage heat. Once the first stage pressure switch is deter
mined to be open, the combustion air inducer is energized
on low (first stage) heat speed. When the differential 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®igni
tor 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 flame 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 be
tween trials of 35 seconds. After a total of five trials for igni
tion (including the initial trial), the control goes into Watch
guard-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 fire 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-
fire. After 10 to 20 seconds of high fire operation the unit will
switch to low fire.
Two Stage Operation / Thermostat Selection DIP
Switch
The control can be utilized in two modes: SINGLE-STAGE
thermostat or TWO-STAGE thermostat. The thermostat
selection is made using a DIP switch and must be posi
tioned 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 burners will
always fire on first-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
after a “recognition 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
fire on first-stage heat. The combustion air inducer will op
erate 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 first and second stage heat, the unit will fire on first
stage heat and switch to second stage heat after 30 sec
onds of operation. See Sequence of Operation flow charts
in the back of this manual for more detail.
TABLE 1
SureLight®Control 5 Pin Terminal Designation
PIN # Function
1 Ignitor
2Combustion Air Inducer High Speed
3Combustion Air Inducer Low Speed
4Combustion Air Inducer Neutral
5Ignitor Neutral
TABLE 2
SureLight®Control 12 Pin Terminal Designation
PIN # Function
1Gas Valve Second Stage
2Second Stage pressure Switch
3Rollout Switch In
4 Ground
524V Hot
6Primary Limit In
7Gas Valve First Stage
8Gas Valve Common
924V Neutral
10 Ground
11 Primary Limit Out
12 First Stage pressure Switch

Page 10
FIGURE 4
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
ACC = 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

Page 11
FIGURE 5
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 C C DH L O DSR
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

Page 12
TABLE 3
Integrated Control Diagnostic Modes
Display Action (when button released)
No change (idle)* Remain in idle mode
Solid “E” Enter diagnostic recall mode
Solid “F” Enter flame signal mode
TABLE 4
Integrated Diagnostic Codes/Status of Equipment I.
Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover
.Idle mode (Decimal blinks at 1 Hertz -- 0.5 second ON, 0.5 second OFF).
CCooling stage (1 second ON, 0.5 second OFF) 1 or 2 displayed / Pause
/ Repeat codes.
dDehumidification 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.
hHeat pump stage.
E 110 Low line voltage. Line Voltage Low (Voltage lower than nameplate
rating). Check power line voltage and correct. Alarm
clears 5 seconds after fault recovered.
E 111 Line voltage polarity reversed. Reverse line power voltage wiring. System resumes
normal operation 5 seconds after fault recovered.
E 112 Ground not detected System shuts down. Provide proper earth ground.
System resumes normal operation 5 seconds after
fault recovered.
E 113 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.
E 114 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.
E 115 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-rob
bing equipment connected to system. May require
installation of larger VA transformer to be installed
in furnace / air handler. Clears after fault recovered.
E 117 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
seven-segment diagnostic LED. This button is used to en
able 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 five 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 flashing to confirm 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 flame signal mode.
The integrated control will display the flame current on
seven-segment LED in in micro amps (uA).
Flame signal mode is exited after any of the following:
DPower is reset
DPressing and holding push button until 3 horizontal
lines “≡” are displayed
D10 minutes after entering the flame sense mode.

Page 13
TABLE 4 Continued
E 125 Control failed self-check, internal error, failed hardware. Will restart if
error
recovers. Integrated control not communicating. Covers hardware errors
(flame 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.
E 200 Hard lockout - Rollout circuit open or previously open. Correct cause of rollout trip, or replace flame rollout
switch. Test furnace operation. Cleared after fault
recovered.
E 204 Gas valve mis-wired. Check gas valve operation and wiring. Clears when
repaired.
E 205 Gas valve control relay contact shorted. Check wiring on control and gas valve. If wiring is
correct, replace control.
E 206 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.
E 207 Hot surface ignitor sensed open Measure resistance of hot surface ignitor. Replace if
open or not within specified range found in IOM.
Resumes normal operation after fault is cleared.
E 223 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 in
ducer for correct operation and restriction. Re
sumes normal operation after fault is cleared
E 224 Low pressure switch failed closed. Check operation of low pressure switch to see if it is
stuck closed on heat call longer than 150 seconds.
Measure operating pressure (inches w.c.). Inspect
vent and combustion air inducer for correct opera
tion and restriction. Resumes normal operation after
fault is cleared.
E 225 High pressure switch failed open. Check pressure (inches w.c.) of high pressure
switch closing on heat call. Measure operating pres
sure (inches w.c.). Inspect vent and combustion air
inducer for correct operation and restriction. Re
sumes normal operation after fault is cleared.
E 226 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 opera
tion after fault is cleared.
E 227 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 in
ducer for correct operation and restriction. Re
sumes normal operation after fault is cleared.
E 229 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 fire, or 2) if continuous fan is
active, furnace lights on high fire for 60 seconds to
improve heat exchanger warm up time.
E 240 Low flame current - Run mode. Check micro-amperes of flame sensor using control
diagnostics or field-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.
E 241 Flame sensed out of sequence - Flame still present. Shut off gas. Check for gas valve leak. Replace, if
necessary. Alert clears when fault is recovered.
E 250 Limit switch circuit open. Check for proper firing rate on furnace. Ensure
there is no blockage in heater. Check for proper air
flow. 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
E 270 Soft lockout - Exceeded maximum number of retries. No flame current
sensed.
Check for proper gas flow. Ensure that ignitor is
lighting burner. Check flame sensor current. Clears
when heat call finishes successfully.
Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover
E 271 Soft lockout - Exceeded maximum number of retries. 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 in
ducer for correct operation and restriction. Clears
when heat call finishes successfully.
E 272 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 opera
tion and restriction. Clears when heat call finishes
successfully.
E 273 Soft lockout - Exceeded maximum number of recycles. Last recycle due
to flame failure.
Check micro-amperes of flame sensor using control
diagnostics or field-installed mode. Clean or replace
sensor. Measure voltage of neutral to ground to
ensure good unit ground. Clears when heat call
finishes successfully.
E 274 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 firing
rate and air flow. Check for blockage. Clears when
heat call finishes successfully.
E 275 Soft lockout - Flame sensed out of sequence. Flame signal is gone. Shut off gas. Check for gas valve leak. 1-hour soft
lockout. Clears when flame has been proven stable.
E 290 Ignitor circuit fault - Failed ignitor or triggering circuitry. Measure resistance of hot surface ignitor. Replace if
open or not within specifications. 1-hour soft lock
out. Clears when flame 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 off delays and indoor blower speeds based on
selections made using the control dip switches and jump
ers. 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
demand 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 application.
The DIP switch is factory-positioned for use with a two-
stage thermostat. If a single-stage thermostat is to be used,
the DIP switch must be repositioned.
a-a -Select “OFF” for two-stage heating operation con
trolled by a two-stage heating thermostat (factory set
ting);
b - Select “ON” for two-stage heating operation con
trolled by a single-stage heating thermostat. This set
ting 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-Off Delay --
The blower-on delay of 30 seconds is not adjustable. The
blower-off delay (time that the blower operates after the
heating demand has been satisfied) can be adjusted by
moving switches 3 and 4 on the integrated control. The unit
is shipped from the factory with a blower-off delay of 90 se
conds. The blower off delay affects comfort and is adjust
able to satisfy individual applications. Adjust the blower off
delay to achieve a supply air temperature between 90° and
110°F at the exact moment that the blower is de-energized.
Longer off delay settings provide lower supply air tempera
tures; shorter settings provide higher supply air temperatu
res.Table 5 provides the blower off timings that will result
from different switch settings.
TABLE 5
Blower Off Heating Mode Delay Switch Settings
Blower Off Delay
(Seconds) Switch 3 Switch 4
60 On Off
90 (Factory) Off Off
120 Off On
180 On On
Switch 5 -- Cooling Mode Blower-Off Delay-- The unit is
shipped from the factory with the dip switch positioned OFF
for a 45 second delay. Table 6 provides the cooling mode
off delay settings.
TABLE 6
Blower Off Cooling Mode Delay Switch Settings
Blower Off Delay
(Seconds) Switch 5
45 (Factory) Off
2 On
Switches 6 and 7 -- Continuous Fan Mode -- Continuous
fan speed can be controlled by changing DIP switch posi
tions. Table 7 below provides DIP switch settings for contin
uous fan mode.
TABLE 7
Continuous Fan Mode Settings
Continuous Fan
Mode Switch 6 Switch 7
Low Heat Speed
(factory) Off Off
Low Cool Speed Off On
High High Speed On Off
High Cool Speed On On
Onboard Links
W914 Dehum
Onboard link W914, is a clippable connection between ter
minals 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, terminal “DS'
will remain energized not allowing the blower to reduce to
low cool speed upon a call for dehumidification.
W951 Heat Pump (R to O)
Onboard link W951 is a clippable connection between ter
minals 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 remain ener
gized eliminating the HEAT MODE in the heat pump.
W915 2 Stage Compr (Y1 to Y2)
Onboard link W915 is a clippable connection between ter
minals 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 cool
ing only.
IMPORTANT
If any onboard link is cut by mistake, install a jump
er 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 bal
anced 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 electronic con
trol module both contained in the same motor housing. The
motor is programmed to provide constant torque at each of
the five 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 off power to unit.
2- Remove input plugs P48 and P49 from motor. See
figure 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 field re
pairable.
If replacing the indoor blower motor or blower wheel is nec
essary, placement is critical. The blower wheel must be cen
tered in the blower housing as shown in figure 6. When re
placing the indoor blower motor the set screw must be
aligned and tightened with the motor shaft as shown in figure
7.
FIGURE 6
Center Blower Wheel
in Blower Housing
BLOWER WHEEL REPLACEMENT
FIGURE 7
Set Screw
Housing Hub
ALIGN AND TIGHTEN SET SCREW WITH
FLAT SIDE OF MOTOR SHAFT
Motor
Shaft

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
to test 2. If voltage is not present problem may be may be up
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)
Check for 24 volts across terminals “24 COM” and the “ac
tive speed tap” on the integrated control. If voltage is pres
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

12
3
4
5
6
7
8
9
10
11 12
1/16
TURN
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 mod
ule. See figure 9.
TWO HARNESS
CONNECTIONS
MOTOR CONTROL MODULE
MOTOR
FIGURE 9
Unplug the Two Harness Connection
4. Remove the two hex head bolts securing the motor
control module to the motor (see figure 10).
REMOVE BOTH HEX
HEAD BOLTS
FIGURE 10
Remove the Hex Head Bolts
5. Slide the motor control module away from the motor to
access and disconnect the internal three wire connec
tor. It is not necessary to remove blower motor itself.
Set both hex head bolts aside.
Testing the Motor (Figure11)
If any motor fails the below tests, do not install the new con
trol module. The motor is defective and it also must be re
placed. The new control can fail if placed on a defective mo
tor.
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 mo
tor connector pins. These should all read approxim
ately the same resistance within an ohm.
3. Check to see if the blower wheel spins freely.
FIGURE 11
Motor Test
TABLE 8
Scale Measurement range in
words ohms
2 M two megohm-two million
ohms 0 - 2,000,000
200 K two hundred kilo-ohm-two
hundred 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
Motor Module Installation
All replacement motor control modules look similar; how
ever, each module is designed for a specific 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 UNEX
PECTED 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 figure 10. Torque bolts
to 22 inch pounds or 1/16th clock
turn as exampled to the right.
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 (figure12). This will directs
moisture away from the motor and its electric connec
tions on the motor.
CONNECTOR
ORIENTATION
BETWEEN 4 AND 8
O'CLOCK
BACK OF CONTROL
MODULE
DRIP LOOP
FIGURE 12
Drip Loop

Page 19
C- Heating Components
1. Ignitor
The SureLight®ignitor is made of durable silicon nitride. Ig
nitor longevity is enhanced by controlling voltage to the ig
nitor. 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 figure 13 for ignitor
location and figure 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 flame sensor is located on the left side of the burner sup
port. See figure 13. The sensor protrudes into the flame en
velope of the left-most burner. The sensor can be removed
for service without removing any part of the burners. During
operation, flame is sensed by current passed through the
flame and sensing electrode. The SureLight control allows
the gas valve to remain open as long as flame signal is
sensed. A microamp DC meter is needed to check the
flame signal on the integrated control. See figure 14 and
table 9 for flame signal check and measurement.
3. Gas Valve
The two-stage gas valve (figure 18) is internally redundant
to assure safety shut-off. If the gas valve must be replaced,
the same type valve must be used.
24VAC terminals 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 termi
nals energizes the valve.
Inlet and outlet pressure taps are located on the valve. A regu
lator adjustment screw is located on the valve.
LPG change over kits are available from Lennox. Kits include
burner orifices.
4. Flame Rollout Switches (S47)
The EL280UHE(X) is equipped with two rollout switches.
See figure 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 ignition
and closes the gas valve. Rollout can be caused by a
blocked heat exchanger, flue 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 re
quire no adjustment. Always operate the unit with the burner
box front panel in place. Each burner uses an orifice that is
precisely matched to the burner input. Burners can be re
moved as a one piece assembly for service. If burner assem
bly has been removed, it is critical to align center of each
burner to the center of the clamshell when re-installing. See
more detail in Section VI- MAINTENANCE sub-section
NO TAG Heat Exchanger and Burners.
6. Primary Limit Control (S10)
The primary limit (S10) is located in the heating vestibule pan
el. 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 auto
matically resets when unit temperature returns to normal. The
switch must reset within three minutes or the SureLight control
will go into Watchguard for one hour. The switch is factory
set and cannot be adjusted. The switch may have a different
set point for each unit model number. See Lennox Repair
Parts Handbook if limit switch must be replaced,

Page 20
EL280UHE(X) HEATING COMPONENTS
FIGURE 13
Gas Valve
Gas Orifices
Sensor
Ignitor
Burners
Rollout Switches