Lennox EL180UHNE Series Installation and operation manual

Page 1 ©2019 Lennox Industries Inc.
EL180UHNE
Service Literature
Corp. 1803-L1
Revised 10/2019
EL180UHNE series units are mid-efficiency gas furnaces
used for upflow or horizontal applications only, manufac
tured with Lennox Duraloktheat exchangers formed of
aluminized steel. EL180UHNE units are available in heat
ing capacities of 40,000 to 100,000 Btuh and cooling ap
plications 2 to 5 tons. Refer to Engineering Handbook for
proper sizing.
EL180UHNE model units are equipped with a hot surface
ignition system. The EL180UHNE unit meets the new Cali
fornia 14 ng/J Nitrogen Oxides (NOx) Standards and Califor
nia Seasonal Efficiency requirements. All units use a redun
dant gas valve to assure safety shut-off as required by
C.S.A.
All specifications in this manual are subject to change. Pro
cedures outlined in this manual are presented as a recom
mendation only and do not supersede or replace local or
state codes. In the absence of local or state codes, the
guidelines and procedures outlined in this manual (except
where noted) are recommended only and do not constitute
code.
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.
TABLE OF CONTENTS
Specifications Page 2.............................
Blower Data Page 3..............................
Parts Identification Page 5.........................
I Unit Components Page 6........................
II Installation Page 17.............................
III Start Up Page 17..............................
IV Heating System Service Checks Page 17.........
V Typical Operating Characteristics Page 21.........
VI Maintenance Page 21..........................
VII Wiring and Sequence of Operation Page 24......
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.
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 discon
nect switch(es). Unit may have multiple
power supplies.

Page 2
SPECIFICATIONS
Gas
Heating
Performance
Model No. EL180UH040NE36A EL180UH060NE36A EL180UH080NE48B EL180UH100NE60C
1AFUE 80% 80% 80% 80%
Input - Btuh 40,000 60,000 80,000 100,000
Output - Btuh 32,700 49,000 70,500 81,500
Temperature rise range - °F 20 - 50 30 - 60 35 – 65 35 – 65
Gas Manifold Pressure (in. w.g.)
Natural Gas Only
1.8 3.4 3.4 304
High Static - in. w.g. 0.50 0.50 0.50 0.50
Connections
in.
Flue connection - in. round 4 4 4 4
Gas pipe size IPS 1/2 1/2 1/2 1/2
Indoor
Blower
Wheel nominal dia. x width - in. 10 x 8 10 x 10 10 x 10 11-1/2 x 10
Motor Type DC Brushless DC Brushless DC Brushless DC Brushless
Motor output - hp 1/2 1/2 3/4 1
Tons of add-on cooling 1.5 - 3 1.5 - 3 2.5 - 4 3 - 5
Air Volume Range - cfm 350 - 1380 395 - 1415 750 - 1785 920 - 2315
Electrical
Data
Voltage 120 volts - 60 hertz - 1 phase
Blower motor full load amps 6.8 6.8 8.4 10.9
Maximum overcurrent protection 15 15 15 15
Shipping Data lbs. - 1 package 100 113 125 149
NOTE - Filters and provisions for mounting are not furnished and must be eld provided.
1 Annual Fuel Utilization Efciency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized furnaces.
OPTIONAL ACCESSORIES - ORDER SEPARATELY
NOTE - FURNACES CANNOT BE TWINNED!
“A” Width
Models
“B” Width
Models
“C” Width
Models
CABINET ACCESSORIES
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
Blower Relay Kit (for two-stage outdoor units) 85W66 85W66 85W66
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
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 3
BLOWER DATA
EL180UH040NE36A 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 1430 243 1200 140 1025 86 945 66 945 45
0.10 1395 253 1165 151 1005 99 940 75 930 50
0.20 1370 264 1130 157 930 99 825 80 795 68
0.30 1345 278 1100 170 895 110 775 85 650 63
0.40 1320 289 1085 182 875 120 745 90 615 70
0.50 1295 302 1035 189 820 126 705 102 545 76
0.60 1245 308 1010 200 795 135 655 107 515 85
0.70 1220 320 980 210 755 147 615 115 445 87
0.80 1200 332 930 215 700 152 570 121 400 95
EL180UH060NE36A 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 1410 243 1190 141 1030 86 930 73 835 55
0.10 1380 251 1165 150 990 95 890 89 790 65
0.20 1360 264 1115 158 950 99 840 78 730 68
0.30 1315 278 1090 171 910 110 790 89 660 61
0.40 1295 290 1070 182 865 122 740 93 600 71
0.50 1270 300 1025 191 825 127 695 103 545 75
0.60 1235 300 1000 197 785 136 650 108 495 84
0.70 1215 317 975 208 750 147 615 118 450 88
0.80 1185 331 920 216 700 153 555 121 390 96
EL180UH080NE48B 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 1785 344 1570 236 1455 183 1390 161 1230 116
0.10 1745 360 1535 249 1420 194 1360 172 1190 129
0.20 1725 373 1500 266 1375 212 1310 189 1145 135
0.30 1695 386 1475 279 1340 224 1280 201 1100 146
0.40 1665 405 1440 293 1305 237 1235 208 1065 156
0.50 1640 418 1410 307 1275 250 1190 223 1015 170
0.60 1595 433 1370 323 1235 263 1160 234 970 182
0.70 1570 446 1330 336 1190 277 1120 249 930 187
0.80 1530 461 1300 349 1155 289 1095 260 900 201

Page 4
BLOWER DATA
EL180UH100NE60C (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Different Blower Speeds
Bottom Return Air, Side Return Air with Return Air from Both
Sides or Return Air from Bottom and One Side.
Single Side Return Air − Air volumes in bold 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 2205 623 1950 415 1710 275 1575 220 1425 160 2235 595 1945 382 1725 262 1590 202 1430 165
0.10 2175 639 1910 427 1685 287 1545 234 1400 176 2205 611 1915 397 1695 280 1550 218 1400 193
0.20 2145 658 1885 449 1635 309 1490 246 1325 181 2165 629 1885 424 1660 293 1510 235 1335 175
0.30 2100 681 1845 466 1605 327 1465 259 1275 196 2135 652 1850 441 1615 312 1475 247 1275 182
0.40 2095 700 1815 481 1565 337 1415 280 1225 204 2085 676 1800 456 1580 330 1430 261 1240 197
0.50 2045 717 1780 499 1525 356 1375 286 1195 218 2055 685 1775 474 1535 347 1395 281 1195 206
0.60 2025 737 1735 516 1500 374 1350 304 1145 230 2025 700 1755 494 1505 359 1355 300 1155 222
0.70 1995 746 1715 533 1465 389 1320 323 1090 248 1990 720 1725 515 1480 377 1310 308 1120 237
0.80 1950 769 1675 547 1430 401 1255 331 1065 259 1965 742 1685 532 1445 396 1275 325 1060 248

Page 5
FIGURE 1
Control Box
(includes integrated control,
interlock switch and transformer)
Blower Assembly
Power Choke
(4 and 5 Ton Only)
PARTS ARRANGEMENT
Heat Exchanger
Combustion Air Inducer
Gas Valve
Intake Air Elbow
Access Panel Inner Access
Panel
Intake Screen

Page 6
I-UNIT COMPONENTS
EL180UHNE unit components are shown in figure 1.The
gas valve, combustion air inducer and burners can be ac
cessed by removing the upper access panel. Electrical
components are in the control box (figure 2) found in the
blower section.
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.
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 blower door is removed the unit will shut down.
NOTE - The door interlock switch is a safety switch. Do not
by-pass or jumper switch.
FIGURE 2
CONTROL BOX EL180UHNE
DOOR INTERLOCK
SWITCH (S51)
INTEGRATED IGNITION
CONTROL
(A92)
TRANSFORMER
(T1)
CIRCUIT
BREAKER
(CB8)
3. Circuit Breaker (CB8)
A 24V circuit breaker is also located in the control box. The
switch provides overcurrent protection to the transformer
(T1). The breaker is rated at 3A at 32V. If the current ex
ceeds this limit the breaker will trip and all unit operation will
shutdown. The breaker can be manually reset by pressing
the button on the face.
4. Integrated Control (A92)
WARNING
Shock hazard.
Disconnect power before servicing. Control is not
field repairable. If control is inoperable, simply re
place entire control.
Can cause injury or death. Unsafe operation will re
sult if repair is attempted.
The hot surface ignition control system consisting of an in
tegrated control (figure 3 with control terminal designa
tions in tables 1, 2 and 3), sensor and ignitor (figure 6). The
integrated control and ignitor work in combination to en
sure furnace ignition and ignitor durability. The integrated
control, controls all major furnace operations. The inte
grated control also features a RED LED for troubleshoot
ing and two accessory terminals rated at (1) one amp. See
table 4 for troubleshooting diagnostic codes. The nitride
ignitor is made from a non-porous, high strength propri
etary ceramic material that provides long life and trouble
free maintenance.
Electronic Ignition (Figure 4)
On a call for heat the integrated control monitors the com
bustion air inducer pressure switch. The control will not be
gin the heating cycle if the pressure switch is closed (by-
passed). Once the pressure switch is determined to be
open, the combustion air inducer is energized. When the
differential in the pressure switch is great enough, the pres
sure switch closes and a 15-second pre-purge begins. If
the pressure switch is not proven within 2-1/2 minutes, the
integrated control goes into Watchguard-Pressure Switch
mode for a 5-minute re-set period.
After the 15-second pre-purge period, the ignitor warms up
for 20 seconds during which the gas valve opens at 19 sec
onds for a 4-second trial for ignition. The ignitor remains
energized for the first 3 seconds during the 4 second trial. If
ignition is not proved during the 4-second period, the inte
grated control will try four more times with an inter purge
and warm-up time between trials of 35 seconds. After a to
tal of five trials for ignition (including the initial trial), the inte
grated control goes into Watchguard-Flame Failure mode.
After a 60-minute reset period, the integrated control will
begin the ignition sequence again.

Page 7
TABLE 1
4-Pin Terminal Designation
PIN # FUNCTION
1Combustion Air Inducer Line
2Ignitor Line
3Combustion Air Inducer Neutral
4Ignitor Neutral
TABLE 2
12-Pin Terminal Designations
PIN # FUNCTION
1High Limit Output
2Not Used
324V Line
4Not Used
5Rollout Switch Out
624V Neutral
7High Limit Input
8 Ground
9Gas Valve Common
10 Pressure Switch In
11 Rollout Switch In
12 Gas Valve Out
TABLE 3
1/4” QUICK CONNECT TERMINALS
120HUM Humidifier 120VAC
LINE 120VAC
XFMR Transformer 120VAC
CIRC Indoor blower 120VAC
EAC Indoor air quality accessory 120VAC
NEUTRALS Common 120VAC
HUM24 Humidifier 24VAC
3/16” QUICK CONNECT TERMINALS
COOL Cooling tap 24VAC
HEAT Heating tap 24VAC
FAN Continuous blower 24 VAC
PARK (no power) Park terminal for speed taps
FS Flame sense
24 COM Common 24VAC
FIGURE 3
INTEGRATED CONTROL
(Automatic Hot Surface Ignition System)
BLOWER OFF DELAY
RED LED RECALL BUTTON

Page 8
TABLE 4
The integrated control is equipped with an LED light for troubleshooting. The diagnostic codes are listed below in table 4.
RED LED
Flash Code2Diagnostic Codes / Status of Furnace
Off No power to control or board fault detected
Heartbeat1Normal Operation - Idle, Continuous Fan, Cool
Continuous Rapid Flash Call For Heat / Burner Operation
1Reverse Line Voltage Polarity
2Improper Earth Ground
3Burner failed to light, or lost flame during heat demand
4Low Flame Signal - check flame sensor
5Watchguard - burner failed to light, exceeded maximum number of retries or recycles.
6Ignitor Circuit Failure - not available on this control
7Primary or Secondary Limit Open or Watchguard Mode - Limit Switch Open longer than 3 minutes
8Rollout Switch Open
9Pressure Switch failed to close or opened during heat demand
10 Watchguard - Pressure Switch opened 5 times during one heat demand
11 Pressure Switch stuck closed prior to activation of combustion air inducer
12 Flame Sensed without gas valve energized
13 Low Line Voltage
Notes
Note 1 A ”Heartbeat” is indicated by a ”Slow Flash” - 1 sec on 1 sec off, repeating
Note 2 Error codes are indicated by a “rapid flash” - the LED flashes X times at ½ second on ½ second off, remains
off for 3 seconds then repeats.
Note 3
Last 10 error codes are stored in memory including when power is shut off to the unit. - To recall, press
and release button, most recent will be displayed first, LED off for 3 sec, then next error code is displayed,
etc. To clear error codes, depress and hold button longer than 5 seconds.

Page 9
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉ
DEMAND
CAI
GAS VALVE
15
ON
OFF
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉ
38
ÉÉÉÉÉÉÉÉÉÉ
IGNITOR
341
Pre -Purge Ignitor Warm-up Trial for
Ignition Post
Purge
5 SEC80
*Blower on time will be 30 seconds after flame is sensed. Blower off time will depend on “OFF TIME” Setting.
INDOOR BLOWER
ÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉ
Blower “On”*
Delay
ELECTRONIC IGNITION
FIGURE 4
Fan Time Control
Heating Fan On Time
The fan on time of 30 seconds is not adjustable.
Heating Fan Off Time
Fan off time (time that the blower operates after the heat
demand has been satisfied) can be adjusted by moving the
jumper to a different setting. The unit is shipped with a fac
tory fan off setting of 90 seconds. For customized comfort,
monitor the supply air temperature once the heat demand
is satisfied. Note the supply air temperature at the instant
the blower is de-energized.
Adjust the fan-off delay to achieve a supply air temperature
between 90° - 110° at the instant the blower is de-ener
gized. (Longer delay times allow for lower air temperature,
shorter delay times allow for higher air temperature). See
figure 5.
Cooling Fan On Time
The fan on time is 2 seconds and is not adjustable.
Cooling Fan Off Time
The control has a 45 second fan off delay after cooling de
mand has been met. This delay is factory set and not ad
justable.
HEAT FAN‐OFF TIME IN SECONDS
To adjust fan-off timing, reposition jumper across pins to
achieve desired setting.
NO JUMPER
FIGURE 5
60 90
120
180
60 90
120
180
60 90
120
180
60 90
120
180
60 Second
off Time
90 Second
off Time
120 Second
off Time
180 Second
off Time

Page 10
HEATING COMPONENTS
FIGURE 6
Air Gas Plenum
Burner
Gasket
Orifice Housing
Gas Valve
Air Orifice
Sensor
Ignitor
Gas Orifice
Thermal
Switch
(location)
Intake Air Screen Intake Air
Elbow
Coupling
O Ring
5. Thermal Switch (Figure 6)
The auto-reset switch is located on the front of the intake air
elbow. The switch will safely shut the unit down if excessive
temperatures are detected. When the switch senses ex
cessive temperature, the circuit breaks and the ignition
control immediately stops ignition and closes the gas
valve.
6. Primary Limit Control
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 en
ergizes the supply air blower and closes the gas valve. The
limit automatically resets when unit temperature returns to
normal. The switch must reset within three minutes or the
SureLight control will go into Watch guard 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.
7. Gas Valve (Figure 6)
The valve 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 gas control knob 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.
EL180UHN units are equipped with a Honeywell gas valve
rated for ambient temperatures between -40º F and +175º
F.
8. Flame Sensor (Figure 6)
A flame sensor is located on the top of the air gas plenum.
The sensor can be removed for service without removing
the the burner. During operation, flame is sensed by cur
rent passed through the flame and sensing electrode. The
SureLight control allows the gas valve to remain open as
long as flame signal is sensed. To check flame sense signal
use the push-button found on the integrated control and go
to Field Test Mode. The menu will display the flame signal.
See Table 15 for flame signal.
TABLE 5
Flame Signal in Microamps
Normal Low Drop Out
1.5 or greater 0.5 - 1.4 0.4 or less

Page 11
9. Combustion Air Inducer (B6)
All EL180UHNE units use a combustion air inducer to
move air through the burners and heat exchanger during
heating operation. The blower uses a 120VAC motor. The
motor operates during all heating operation and is con
trolled by integrated control A92. The inducer also oper
ates for 15 seconds before burner ignition (pre‐purge) and
for 5 seconds after the gas valve closes (post‐purge).
10. Combustion Air Inducer Prove Switch (S18)
EL180UHNE series units are equipped with a combustion
air pressure switch (figure 7) located near the gas valve. The
switch is connected to the combustion air inducer housing
by means of a flexible silicone hose. It monitors negative air
pressure in the intake air elbow.
The switch is a single‐pole single‐throw proving switch elec
trically connected to the furnace control. The purpose of the
switch is to prevent burner operation if the combustion air in
ducer is not operating or if the flue becomes obstructed.
On heat demand the switch senses that the combustion air
inducer is operating. It closes a circuit to the integrated con
trol when pressure inside the combustion air inducer de
creases to a certain set point. The pressure sensed by the
switch is negative relative to atmospheric pressure. If the
flue becomes obstructed during operation, the switch
senses a loss of pressure difference and opens the circuit
to the furnace control and gas valve. See table 6 for set
point.
If replacing the inducer switch or tubing is necessary, make
note of the tubing connections to the gas valve. See figure
8.
NOTE - The switch is factory set and is not field adjustable.
It is a safety shut‐down control in the furnace and must not
be by-passed for any reason. If switch is closed or by-
passed, the control will not initiate ignition at start up.
TABLE 6
Prove Switch Set Points
EL180
Model Make inches w.c. Break inches w.c.
040 0.35 0.20
060 0.35 0.20
080 0.35 0.20
100 0.35 0.20
FIGURE 7
COMBUSTION AIR PRESSURE SWITCH
Positive +
to air intake pipe
Negative -
to air intake
elbow
11. Burner and Orifice
Burners are factory set and require no adjustment. Always
operate the unit with air gas plenum in place. The burner
has one orifice located between the gas valve and the air
intake assembly (Figure 6). To check or replace the orifice
remove the intake air screen, coupling and intake air elbow.
Using a 5/8” socket, go through the elbow and unscrew the
gas orifice. The burner uses an orifice (see Table 7) that is
precisely matched to the burner input. The burner can be
removed for service. If burner has been removed, it is criti
cal to replace all gaskets.
TABLE 7
Gas Orifice Nat Gas
Unit Input Orifice Size
40 0.0595
60 0.0595
80 0.0689
100 0.0810
12. Ignitor (Figure 6)
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 9 for resistance, and voltage check.
NOTE - The EL180UHNE furnace contains electronic
components that are polarity sensitive. Make sure that the
furnace is wired correctly and is properly grounded.

Page 12
FIGURE 8
Replacing the Pressure Switch or Tubing

Page 13
FIGURE 9
Ignitor Check Out
Test 1
Meter
(set to ohms)
Remove 5-pin plug from control
Check ohms reading across terminals 1and 5
Ohm value should be between 39 - 70.
Integrated control detail
.
Test 2
Seperate the 2-pin jack plug near the manifold
and check resistance of the ignitor. If the reading
is correct, then then there is a problem with the
wiring between the jack plug and control. If the
reading is not correct the issue is the ignitor.
Meter
(set to ohms)
Test 3
Insert meter probes into the terminals 1 and 5. (Use small
diameter probes in order to not damage plug). Check
voltage during 20 second warm up period. Voltage should
read 120 volts + 10%. If voltage is above these values,
check for correct supply voltage to furnace.
Integrated control detail
Integrated control detail
Meter
(set to AC volts)

Page 14
13. Blower Motor
IMPORTANT
Each blower is statically and dynamically bal
anced as an assembly before installation in the
unit.
EL180UHNE 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 12 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 10. When re
placing the indoor blower motor the set screw must be
aligned and tightened with the motor shaft as shown in figure
11.
FIGURE 10
Center Blower Wheel
in Blower Housing
BLOWER WHEEL REPLACEMENT
FIGURE 11
Set Screw
Housing Hub
ALIGN AND TIGHTEN SET SCREW WITH
FLAT SIDE OF MOTOR SHAFT
Motor
Shaft

Page 15
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 inpult 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 “FAN” ter
minals on the integrated control. If voltage is present, prob
lem is with the harness. If voltage is not present problem
may be may be with the integrated control
Check for 120 volts across terminals “CIRC” 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 necesssary)
Test 4 (if necessary)
FIGURE 12

12
3
4
5
6
7
8
9
10
11 12
1/16
TURN
Page 16
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 13.
TWO HARNESS
CONNECTIONS
MOTOR CONTROL MODULE
MOTOR
FIGURE 13
Unplug the Two Harness Connection
4. Remove the two hex head bolts securing the motor
control module to the motor (see figure 14).
REMOVE BOTH HEX
HEAD BOLTS
FIGURE 14
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 (Figure15)
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 approximate
ly the same resistance within an ohm.
3. Check to see if the blower wheel spins freely.
FIGURE 15
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 14. 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 (figure16). 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 16
Drip Loop

Page 17
II- PLACEMENT AND INSTALLATION
Make sure unit is installed in accordance with installation
instructions and applicable codes.
III- START‐UP
A- Heating Start‐Up
WARNING
Shock and burn hazard.
EL180UHNE units are equipped with a hot surface
ignition system. Do not attempt to light manually.
Gas Valve Operation
FIGURE 17
HONEYWELL VALVE
Negative Air
Pressure Port Positive Air
Pressure Port
Manifold
Pressure Tap
Supply
Pressure Tap
Gas Valve Shown in ON Position
1 - STOP! Read the safety information at the beginning of
this section.
2 - Set the thermostat to the lowest setting.
3 - Turn off all electrical power to the unit.
4 - This furnace is equipped with an ignition device which
automatically lights the burners. Do not try to light the
burners by hand.
5 - Remove the upper access panel.
6 - Move gas valve switch to OFF position. Do not
force. See figure 17.
7 - Wait five minutes to clear out any gas. If you then smell
gas, STOP! Immediately call your gas supplier from a
neighbor's phone. Follow the gas supplier's instruc
tions. If you do not smell gas go to next step.
8 - Move gas valve switch toON position. Do not force.
See figure 17.
9 - Replace the upper access panel.
10- Turn on all electrical power to to the unit.
11- Set the thermostat to desired setting.
NOTE - When unit is initially started, steps 1 through 11
may need to be repeated to purge air from gas line.
12- If the appliance will not operate, follow the instructions
“Turning Off Gas to Unit” and call the gas supplier.
Turning Off Gas to Unit
1 - Set the thermostat to the lowest setting.
2 - Turn off all electrical power to the unit if service is to be
performed.
3 - Remove the upper access panel.
4 - Move gas valve switch to OFF position. Do not
force. See figure 17.
5 - Replace the upper access panel.
B- Safety or Emergency Shutdown
Disconnect main power to unit. Close manual and main gas
valves.
C- Extended Period Shutdown
Turn off thermostat or set to “UNOCCUPIED” mode. Close
all gas valves (both internal and external to unit) to guaran
tee no gas leaks into combustion chamber. Turn off power
to unit. All access panels and covers must be in place and
secured.
IV-HEATING SYSTEM SERVICE CHECKS
A- C.S.A. Certification
All units are C.S.A. design certified without modifications.
Refer to the EL180UHNE Installation Instruction.
B- Gas Piping
Gas supply piping should not allow more than 0.5”W.C. drop
in pressure between gas meter and unit. Supply gas pipe
must not be smaller than unit gas connection.
Compounds used on gas piping threaded joints should be
resistant to action of liquefied petroleum gases.
C- Testing Gas Piping
CAUTION
If a flexible gas connector is required or allowed by
the authority that has jurisdiction, black iron pipe
shall be installed at the gas valve and extend outside
the furnace cabinet.
IMPORTANT
In case emergency shutdown is required, turn off
the main shut‐off valve and disconnect the main
power to unit. These controls should be properly
labeled by the installer.
WARNING
Do not over torque (800 in-lbs) or under torque (350
in-lbs) when attaching the gas piping to the gas
valve.
When pressure testing gas lines, the gas valve must be dis
connected and isolated. Gas valves can be damaged if
subjected to more than 0.5psig (14” W.C.). See figure 18. If
the pressure is equal to or less than 0.5psig (14”W.C.),
close the manual shut-off valve before pressure testing to
isolate furnace from gas supply.

Page 18
FIGURE 18
MANUAL MAIN SHUT-OFF VALVE
WILL NOT HOLD TEST PRESSURE
IN EXCESS OF 0.5 PSIG (14”W.C.)
GAS VALVE
CAP
GAS PIPING TEST PROCEDURE
FIELD PROVIDED
LINE PRESSURE TAP
When checking piping connections for gas leaks, use pre
ferred means. Kitchen detergents can cause harmful corro
sion on various metals used in gas piping. Use of a specialty
Gas Leak Detector is strongly recommended. It is available
through Lennox under part number 31B2001. See Corp.
8411-L10, for further details.
Do not use matches, candles, flame or any other source of
ignition to check for gas leaks.
D- Gas Pressure Adjustment
Gas Flow (Approximate)
TABLE 9
GAS METER CLOCKING CHART
EL180UHNE
Unit
Seconds for One Revolution
Natural LP / Propane
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
Dial
-040 90 180 N/A N/A
-060 60 120 150 300
-080 45 90 112 224
-100 36 72 N/A
Natural-1000 btu/cu ft LP /Propane - 2500 btuh/cu ft
Furnace should operate at least 5 minutes before check
ing gas flow. Determine time in seconds for two revolu
tions of gas through the meter. (Two revolutions assures a
more accurate time.) Divide by two and compare to time
in table 9. If manifold pressure matches table 10 and rate
is incorrect, check gas orifices for proper size and restric
tion. Remove temporary gas meter if installed.
NOTE - To obtain accurate reading, shut off all other gas
appliances connected to meter.
E- Supply and Manifold Pressure
Supply Pressure Measurement
A port on the inlet side of the gas valve provides access to
the supply pressure tap. See figure 16. Loosen the screw
and connect a manometer to measure supply pressure.
See table10 for supply line pressure. Tighten screw after
measurements have been taken.
Manifold Pressure Measurement
To correctly measure manifold pressure, follow the steps
below.
1 - Remove the threaded plug from the outlet side of the
gas valve and install a field-provided barbed fitting.
Connect measuring device “+” connection to barbed
fitting to measure manifold pressure.
2 - Start unit and allow 5 minutes for unit to reach steady
state.
3 - After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in Ta
ble 10. Make manifold adjustment if necessary.
4 - Shut unit off and remove manometer as soon as an ac
curate reading has been obtained.
5 - Start unit and perform leak check. Seal leaks if found..
TABLE 10
Supply Line and Manifold Pressure
Honeywell Gas Valve
Natural LP/Propane
Manifold Supply Manifold Supply
040 1.6 - 2.0
4.5 - 13.0
N/A N/A
060, 080 3.2 - 3.6 4.0 11.0 - 13.0
100 3.2 - 3.6 4.5 - 13.0 N/A N/A
IMPORTANT
For safety, shut unit off and remove manometer as
soon as an accurate reading has been obtained.
Take care to replace pressure tap plug.
F- Proper Combustion
Furnace should operate a minimum 15 minutes with cor
rect manifold pressure and gas flow rate before checking
combustion. Take combustion sample beyond the flue out
let and compare to the tables below. The maximum carbon
monoxide reading should not exceed 100 ppm.
TABLE 11
EL180UHNE Unit CO2%For Nat CO2%For LP
040
6.5 - 7.5
N/A
060 7.5 - 9.0
080 7.5 - 9.0
100 N/A
The maximum carbon monoxide reading is 100 ppm.
G- High Altitude
Units are NOT approved for installations over 4500 ft

Page 19
H- Proper Ground and Voltage
A poorly grounded furnace can contribute to poor flame
sense signal. Use the following procedure to check for
ground and voltage to the integrated control.
1 - Measure the AC voltage between Line Neutral (spade
terminals) and “C” terminal (low voltage terminal
block) on the integrated control. See figure 19. A wide
variation in the voltage between Line Neutral and “C”
as a function of load indicates a poor or partial ground.
Compare the readings to the table below. If the read
ings exceed the maximum shown in table 12, make re
pairs before operating the furnace.
2 - In addition, measure the AC voltage from Line Hot to
Line Neutral (spade terminals) on the integrated con
trol. See figure 20. This voltage should be in the range
of 97 to 132 Vac
TABLE 12
Furnace Status Measurement VAC
Expected Maximum
Power On Furnace Idle 0.3 2
CAI / Ignitor Energized 0.75 5
Indoor Blower Energized Less than 2 10
CHECK VOLTAGE BETWEEN LINE NEUTRAL
AND LOW VOLTAGE “C” TERMINAL
FIGURE 19
CHECK VOLTAGE BETWEEN LINE HOT
AND LINE NEUTRAL
FIGURE 20

Page 20
V-TYPICAL OPERATING CHARACTERISTICS
A-Blower Operation and Adjustment
NOTE- The following is a generalized procedure and
does not apply to all thermostat controls.
1 - Blower operation is dependent on thermostat control
system.
2 - Generally, blower operation is set at thermostat sub
base fan switch. With fan switch in ON position, blower
operates continuously. With fan switch in AUTO position,
blower cycles with demand or runs continuously while
heating or cooling circuit cycles.
3 - Depending on the type of indoor thermostat, blower
and entire unit will be off when the system switch is in
OFF position.
B-Temperature Rise (Figure 21)
Temperature rise for EL180UHNE units depends on unit in
put, blower speed, blower horsepower and static pressure
as marked on the unit rating plate. The blower speed must
be set for unit operation within the range of “TEMP. RISE
°F” listed on the unit rating plate.
FIGURE 21
Supply Air
Return Air
TEMPERATURE RISE
Supply Duct Temperature
Return Duct Temperature _
Temperature Rise =
C-External Static Pressure
1 - Tap locations shown in figure 22 .
2 - Punch a 1/4” diameter hole in supply and return air
plenums. Insert manometer hose flush with inside
edge of hole or insulation. Seal around the hose with
permagum. Connect the zero end of the manometer to
the discharge (supply) side of the system. On ducted
systems, connect the other end of manometer to the
return duct as above.
3 - With only the blower motor running and the evaporator
coil dry, observe the manometer reading. Adjust blow
er motor speed to deliver the air desired according to
the job requirements. For heating speed external static
pressure drop must not be more than 0.5” W.C. For
cooling speed external static pressure drop must not
be more than 0.8” W.C.
4 - Seal the hole when the check is complete.
EXTERNAL STATIC PRESSURE
Supply Duct Static
Return Duct Static +
Total Duct Static =
(dry coil)
Supply Air
Return Air -
+
or
FIGURE 22
High
Low
D-Blower Speed Taps
Blower speed tap changes are made on the integrated con
trol. See figure 3. The heating tap is connected to the
“HEAT” terminal and the cooling tap is connected to the
“COOL” terminal. The continuous blower tap is connected
to the “FAN” terminal. Unused taps must be secured on
dummy terminals labeled ”PARK. To change out existing
speed tap, turn off power and switch out speed tap with tap
connected to “PARK”. See blower speed tap table on unit
diagram for motor tap colors for each speed.