Lennox EL280DF070E36A Installation and operation manual

Page 1
UNIT INFORMATIONUNIT INFORMATION
Service Literature
©2016 Lennox Industries, Inc.
OFF
ON
LOLO
HIHI
CCCC
HIHI
IIII
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.
EL280DFE series units are 80% e󰀩ciency gas furnaces
used for downow applications only, manufactured with
Lennox Duralok heat exchangers formed of aluminized
steel. Units are available in heating capacities of 66,000 to
88,000 Btuh and cooling applications up to 4 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. EL280DFE
model units are equipped with the SureLight® integrated
control. All units use a redundant gas valve to assure safe-
ty shut-o󰀨 as required by CSA.
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.
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.
TABLE OF CONTENTS
Specications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 2
Blower Performance Data . . . . . . . . . . . . . . . . . . Page 3
Parts Identication . . . . . . . . . . . . . . . . . . . . . . . . . Page 4
I Unit Components . . . . . . . . . . . . . . . . . . . . . . . . Page 5
IInstallation . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 21
III Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 21
IV Heating System Service Checks . . . . . . . . . Page 23
V Typical Operating Characteristics . . . . . . . . . Page 25
VI Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . Page 26
VII Wiring and Sequence of Operation . . . . . . Page 29
VIII Field Wiring and DIP Switch Settings . . . . Page 33
IX Troubleshooting Flow Chart . . . . . . . . . . . . . Page 37
EL280DFE
Corp 1902-L1
05/2022
EL280DFE SERIES UNITS

Page 2
SPECIFICATIONS
Gas
Heating
Performance
Model No. EL280DF070E36A EL280DF090E48B
1 AFUE 80% 80%
High
Fire
Input - Btuh 66,000 88,000
Output - Btuh 52,000 69,000
Temperature rise range - °F 30 - 60 35 - 65
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
3.5 / 10.0 3.5 / 10.0
Low
Fire
Input - Btuh 43,000 57,000
Output - Btuh 35,000 46,000
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 10
Motor output - hp 1/2 3/4
Tons of add-on cooling 1.5 - 3.5 3 - 4
Air Volume Range - cfm 400 - 1475 780 - 1700
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 123 142
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.
OPTIONAL ACCESSORIES - ORDER SEPARATELY
“A” Width
Models
“B” Width
Models
CABINET
Downow Combustible Flooring Base 11M59 11M60
CONTROLS
iComfort®E30 Smart Wi-Fi Thermostat 15S63 15S63
Remote Outdoor Temperature Sensor X2658 X2658
Furnace Twinning Kit 16W72 16W72
DOWNFLOW FILTER KITS
Downow Filter Kit 51W06 51W07
No. and Size of lter - in. (1) 20 x 20 x 1 (2) 20 x 16 x 1
NIGHT SERVICE KIT
Night Service Kit 17B59 17B59

Page 3
EL280DF090E48B 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
0.10 1700 423 1495 293 1380 233 1295 202 1165 156
0.20 1665 436 1455 307 1330 248 1245 211 1110 166
0.30 1620 452 1415 319 1295 257 1195 221 1055 175
0.40 1585 464 1365 328 1225 269 1140 230 985 185
0.50 1560 471 1325 343 1185 277 1090 240 930 193
0.60 1455 475 1275 355 1120 290 1025 252 875 202
0.70 1405 482 1235 365 1075 295 990 259 840 209
0.80 - - - - - - 1160 369 1025 308 925 268 780 217
BLOWER DATA
EL280DF070E36A 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 1475 346 1345 269 1190 192 970 109 785 71
0.10 1440 355 1325 276 1165 198 935 114 775 74
0.20 1410 365 1280 287 1135 207 905 120 740 79
0.30 1260 401 1250 296 1095 216 855 129 665 86
0.40 1355 380 1225 305 1060 223 815 134 615 92
0.50 1320 394 1200 315 1035 229 770 140 580 97
0.60 1290 401 1160 324 1005 237 745 149 465 105
0.70 1260 410 1130 333 970 245 700 155 445 108
0.80 1215 399 1095 341 935 254 660 158 400 113

Page 4
PARTS IDENTIFICATION
Control Box
(includes integrated control,
transformer and door switch)
Secondary Limit
Internal Flue Pipe Assembly
Gas Valve
Burner Box Assembly
Combustion
Air Inducer
Indoor Blower
Heat Exchanger
Primary Limit
Access Panel
Top Cap
FIGURE 1

Page 5
I-UNIT COMPONENTS
Unit components are shown in FIGURE 1. The gas valve,
combustion air inducer and burners can be accessed by
removing the access panel. Electrical components are in
the control box (FIGURE 2) found in the blower section.
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.
Transformer
Circuit Breaker
SureLight®
Integrated
Control
Interlock Switch
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 FIGURE 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)
103699 and 107048
Units are equipped with the SureLight® two-stage, inte-
grated control. The system consists of a ignition / blower
control (FIGURE 4 and FIGURE 5) with control pin desig-
nations in TABLE 1, TABLE 2 and ignitor. The control and
ignitor work in combination to ensure furnace ignition and
ignitor durability.
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
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 6
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 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 re
on rst-stage heat. The combustion air inducer will oper-
ate on low speed and indoor blower will operate on low
heat speed. The unit will switch to second stage heat af-
ter 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 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
5 Ignitor Neutral
TABLE 2
SureLight®Control 12 Pin Terminal Designation
Pin # Function
1Gas Valve Second Stage
2Second Stage pressure Switch
3 Rollout Switch In
4 Ground
5 24V Hot
6 Primary Limit In
7 Gas Valve First Stage
8Gas Valve Common
9 24V Neutral
10 Ground
11 Primary Limit Out
12 First Stage pressure Switch

Page 7
Integrated Control 103699
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 8
Integrated Control 107048
Flame Sense
Humidifier
Accessories
Line Voltage Ignitor and Combustion
Air Inducer
Neutrals
On Board Links
FIGURE 5

Page 9
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 6

Page 10
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).
H Gas 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
The seven-segment diagnostic LED displays operating
status, error codes and other information. Table be4 lists
diagnostic LED codes.
Diagnostic Push Button
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
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.