Lennox ML193DF045P36B Installation and operation manual

Page 1 ©2014 Lennox Industries Inc.
Litho U.S.A.
Corp. 1026-L5 ML193DF
Service Literature Revised 03-2014
ML193DF SERIES UNITS
ML193DF series units are high-efficiency gas furnaces
manufactured with Lennox DuralokPlustaluminized steel
clamshell-type heat exchangers, with a stainless steel con
densing coil. ML193DF units are available in heating input
capacities of 44,000 to 110,000 Btuh (13 to 32.2 kW) and
cooling applications from 2 through 5 tons (7.0 through
17.6 kW). Refer to Engineering Handbook for proper siz
ing.
Units are factory equipped for use with natural gas. A kit is
available for conversion to LPG operation. All ML193DF
units are equipped with a hot surface ignition system. The
gas valve is redundant to assure safety shut-off as required
by C.S.A.
The heat exchanger, burners and manifold assembly can
be removed for inspection and service. The maintenance
section gives a detailed description on how this is done.
All specifications are subject to change. Procedures out
lined in this manual are presented as a recommendation
only and do not supersede or replace local or state codes.
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.
Table of Contents
Specifications 2.................................
Optional Accessories 3..........................
Blower Performance Data 4......................
I-Unit Components 6............................
II Placement and Installation 18....................
III-Start-Up 36...................................
IV-Heating System Service Checks 37..............
V-Typical Operating Conditions 39.................
VI-Maintenance 40...............................
VII-Wiring and Sequence of Operation 42...........
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
Sharp edges.
Be careful when servicing unit to avoid sharp edges
which may result in personal injury.

Page 2
SPECIFICATIONS
Gas
Heating
Performance
Model No. ML193DF045P36B ML193DF070P36B ML193DF090P48C ML193DF110P60C
1AFUE 93% 93% 93% 93%
Input - Btuh 44,000 66,000 88,000 110,000
Output - Btuh 41,000 61,000 82,000 102,000
Temperature rise range - °F 25 - 55 50 - 80 40 - 70 50 - 80
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
3.5 / 10.0 3.5 / 10.0 3.5 / 10.0 3.5 / 10.0
High static - in. w.g. 0.50 0.50 0.50 0.50
Connections
in.
Intake / Exhaust Pipe (PVC) 2 / 2 2 / 2 2 / 2 2 / 2
Gas pipe size IPS 1/2 1/2 1/2 1/2
Condensate Drain Trap (PVC pipe) - i.d. 1/2 1/2 1/2 1/2
with eld supplied (PVC coupling) - o.d. 3/4 3/4 3/4 3/4
Indoor
Blower
Wheel nom. dia. x width - in. 10 x 8 10 x 8 10 x 10 11 ½ x 10
Motor output - hp 1/3 1/3 1/2 1
Tons of add-on cooling 2.5 - 3 2.5 - 3 3 - 4 4 - 5
Air Volume Range - cfm 605 - 1615 560 - 1550 920 - 2145 1210 - 2410
Electrical
Data
Voltage 120 volts - 60 hertz - 1 phase
Blower motor full load amps 6.1 6.1 8.2 11.5
Maximum overcurrent protection 15 15 15 15
Shipping Data lbs. - 1 package 124 129 147 162
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.

Page 3
OPTIONAL ACCESSORIES - MUST BE ORDERED EXTRA
“B” Width Models “C” Width Models
CABINET ACCESSORIES
Downow Combustible Flooring Base 11M60 11M61
CONDENSATE DRAIN KITS
Condensate Drain Heat Cable 6 ft. 26K68 26K68
24 ft. 26K69 26K69
50 ft. 26K70 26K70
Heat Cable Tape Fiberglass - 1/2 in. x 66 ft. 36G53 36G53
Aluminum foil - 2 in. x 60 ft. 16P89 16P89
Crawl Space Vent Drain Kit 51W18 51W18
CONTROLS
Twinning Kit 65W80 65W80
DOWNFLOW FILTER KITS
Downow Air Filter and Rack Kit 51W07 51W08
No. and Size of lter - in. (2) 20 x 20 x 1 (2) 20 x 20 x 1
NIGHT SERVICE KITS
Night Service Kit 51W03 51W03
TERMINATION KITS
See Installation Instructions for specic venting information.
Termination Kits -
Direct Vent Applications
Only
Concentric US - 2 in. 71M80 69M29
3 in. - - - 60L46
Canada - 2 in. 44W92 44W92
3 in. - - - 44W93
Flush-Mount 2, 2-1/2 or 3 in. 51W11 51W11
Wall - Close
Couple
US - 2 in. 22G44 - - -
3 in. 44J40 44J40
Wall - Close
Couple WTK
Canada - 2 in. 30G28 - - -
3 in. 81J20 81J20
Termination Kits -
Direct or Non-Direct vent
Roof 2 in. 15F75 15F75
Wall Ring Kit 2 in. 15F74 315F74
Roof Termination Flashing Kit - Direct or Non-Direct Vent -
Contains two ashings
44J41 44J41
1 Cleanable polyurethane frame type lter.
2 Kits contain enough parts for two, non−direct vent installations.
3 Non-direct vent only.
NOTE - Termination Kits 44W92, 44W93, 30G28, 81J20 are certied to ULC S636 standard for use in Canada only.
GAS HEAT ACCESSORIES
Input
High Altitude
Pressure Switch Kit
Natural Gas to
LPG/Propane Kit
LPG/Propane
to Natural Gas Kit
Natural Gas
High Altitude
Orice Kit
4501 - 7500 ft. 7501 - 10,000 ft. 0 - 7500 ft. 0 - 7500 ft. 7501- 10,000 ft.
all models 74W90 74W91 69W73 73W81 73W37

Page 4
BLOWER DATA
ML193DF070XP36B PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High Medium-
High
Medium-
Low Low
cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1505 660 1310 570 1090 455 940 390
0.10 1480 625 1295 550 1070 435 935 365
0.20 1405 585 1255 515 1055 425 930 350
0.30 1355 580 1225 475 1045 405 900 330
0.40 1305 540 1165 470 1010 385 890 325
0.50 1270 525 1110 425 975 370 835 305
0.60 1175 500 1080 415 925 345 815 290
0.70 1105 460 1000 395 855 320 745 270
0.80 1040 440 925 365 790 300 670 250
0.90 920 400 825 335 680 270 560 225
ML193DF110XP60C PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High Medium-
High
Medium-
Low Low
cfm Watts cfm Watts cfm Watts cfm Watts
0.00 2410 1390 2190 1080 1860 910 1560 735
0.10 2405 1385 2180 1070 1855 905 1555 730
0.20 2285 1345 2120 1030 1850 865 1540 720
0.30 2220 1315 2015 1005 1770 840 1535 705
0.40 2185 1295 1950 955 1750 815 1530 685
0.50 2045 1240 1830 925 1680 790 1500 660
0.60 1965 1220 1710 890 1575 755 1445 640
0.70 1820 1165 1610 850 1495 720 1370 615
0.80 1625 1155 1510 820 1400 695 1315 595
0.90 1455 1110 1390 790 1350 660 1210 565
ML193DF045XP36B PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High Medium-
High
Medium-
Low Low
cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1615 650 1385 555 1205 465 1045 390
0.10 1605 640 1375 545 1195 455 1035 380
0.20 1500 620 1340 525 1165 445 1015 370
0.30 1450 590 1290 490 1125 420 975 365
0.40 1350 560 1235 480 1090 405 920 345
0.50 1300 545 1170 450 1035 380 875 335
0.60 1195 500 1095 425 990 365 840 320
0.70 1140 485 1020 400 895 345 780 300
0.80 1025 450 920 370 840 330 695 275
0.90 945 435 800 335 700 295 605 250
ML193DF090XP48C PERFORMANCE (Less Filter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Various Blower Speeds
High Medium-
High
Medium-
Low Low
cfm Watts cfm Watts cfm Watts cfm Watts
0.00 2075 800 1890 720 1625 645 1375 535
0.10 1995 755 1830 680 1590 615 1350 515
0.20 1910 715 1775 645 1575 580 1340 500
0.30 1825 680 1705 610 1530 550 1325 485
0.40 1730 645 1620 580 1475 525 1285 460
0.50 1630 615 1530 545 1405 500 1240 440
0.60 1530 585 1450 525 1330 470 1175 420
0.70 1430 555 1340 485 1260 450 1095 390
0.80 1300 525 1245 465 1145 415 1015 370
0.90 1185 495 1110 430 1045 385 915 340

Page 5
FIGURE 1
CONTROL BOX
(Includes integrated control,
transformer and door switch)
BAG ASSEMBLY
BLOWER MOTOR
(hidden)
BLOWER
ACCESS
PANEL
BURNER
ACCESS
PANEL
COMBUSTION
AIR INDUCER
BURNER BOX ASSEMBLY
(includes sensor, rollout switches and ignitor)
GAS VALVE
BLOWER DECK
HEAT EXCHANGER
COLD END HEADER BOX
PRIMARY LIMIT
PARTS ARRANGEMENT

Page 6
I-UNIT COMPONENTS
ML193DF unit components are shown in figure 1. The
combustion air inducer, gas valve and burners can be ac
cessed by removing the burner access panel. The blower
and control box can be accessed by removing the blower
access door.
A-Control Box Components (Figure 2)
Unit transformer (T1) and integrated ignition control (A92)
are located in the control box. In addition, a door interlock
switch (S51) is located in the control box.
FIGURE 2
DOOR INTERLOCK
SWITCH (S51)
INTEGRATED IGNITION
CONTROL
(A92)
TRANSFORMER
(T1)
ML193DF Control Box
1. Transformer (T1)
A transformer located in the control box provides power to
the low voltage section of the unit. The transformers on all
models are rated at 40VA with a 120V primary and 24V
secondary.
2. Door Interlock Switch (S51)
A door interlock switch rated 14A at 120VAC is located on
the control box. The switch is wired in series with line volt
age. When the blower door is removed the unit will shut
down.
3. Integrated Ignition Control 100973 (A92)
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.
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
result if repair is attempted.
The ignition control system consists of an integrated con
trol (figure 4) ignitor (figure 10) and sensor (figure 10). The
integrated control and ignitor work in combination to en
sure furnace ignition and ignitor durability. The integrated
control, controls all maor furnace operations. The inte
grated control also features two LED lights (DS1 red and
DS2 green) for troubleshooting and two accessory termi
nals rated at (1) one amp. The integrated control also fea
tures a (3) amp fuse for overcurrent protection. Tables 1
and 2 show jack plug terminal designations. See table 3 for
troubleshooting diagnostic codes. The 95 volt ignitor is
made from a high strength, silicon nitride material that pro
vides long life and trouble free maintenance. The inte
grated control continuously monitors line voltage and
maintains the ignitor power at a consistent level to provide
proper lighting and maximum ignitor life.
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
Electronic Ignition (See Figure 5)
On a call for heat the integrated control monitors the com
bustion air inducer prove switch. The integrated control will
not begin the heating cycle if the prove switch is closed (by-
passed). Once the prove switch is determined to be open,
the combustion air inducer is energized. When the differen

Page 7
tial in the prove switch is great enough, the prove switch
closes and a 15-second pre-purge begins. If the prove
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 after which the gas valve opens for a 4-sec
ond 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 integrated control
will try four more times with an inter purge and warm-up
time between trials of 35 seconds. After a total of five trials
for ignition (including the initial trial), the integrated control
goes into Watchguard-Flame Failure mode. After a
60-minute reset period, the integrated control will begin the
ignition sequence again.
The integrated control has an added feature of ignitor pow
er regulation to maintain consistent lighting and longer igni
tor life under all line voltage conditions.
Fan Control
The fan on time of 30 seconds is not adjustable. The fan off
delay (amount of time that the blower operates after the
heat demand has been satisfied) may be adjusted by
changing the jumper position across the five pins on the
integrated control. The unit is shipped with a factory fan off
setting of 90 seconds. The fan off delay affects comfort and
is adjustable to satisfy individual applications. Adjust the
fan off delay to achieve a supply air temperature between
90° and 110°F at the moment that the blower is de-ener
gized. Longer off delay settings provide lower return air
temperatures; shorter settings provide higher return air
temperatures. See figure 3.
FIGURE 3
FAN‐OFF TIME IN SECONDS
To adjust fan-off timing, reposition jumper across pins
to achieve desired setting.
NO JUMPER
FIGURE 4
INTEGRATED CONTROL
(Automatic Hot Surface Ignition System)
TERMINAL DESIGNATIONS
HUM
LINE
XFMR
EAC
COOL
HEAT
PARK
FLAME
NEUTRALS
Humidifier (120VAC)
Input (120VAC)
Transformer (120VAC)
Electronic Air Cleaner (120VAC)
Blower - Cooling Speed (120VAC)
Blower - Heating Speed (120VAC)
Dead terminals to park alternate spd taps
Flame sensor
Neutral terminals (120VAC)
3 AMP, 32 VAC FUSE
BLOWER OFF
DELAY JUMPER
LED 1 LED 2

Page 8
The integrated control is equipped with two LED lights for troubleshooting. The diagnostic codes are listed below in table 3.
TABLE 3
DIAGNOSTIC CODES
Make sure to Identify LED'S Correctly.
LED #1 (Red) LED #2 (Green) DESCRIPTION
SIMULTANEOUS
SLOW FLASH
SIMULTANEOUS
SLOW FLASH
Power on - Normal operation.
Also signaled during cooling and continuous fan.
SIMULTANEOUS
FAST FLASH
SIMULTANEOUS
FAST FLASH Normal operation - signaled when heating demand initiated at thermostat.
SLOW FLASH ON Primary or secondary limit switch open. Limit must close within 3 minutes or unit
goes into 1 hour Watchguard.
OFF SLOW FLASH
Pressure prove switch open.
OR: Blocked inlet/exhaust vent;
OR: Pressure switch closed prior to activation of combustion air inducer.
ALTERNATING
SLOW FLASH
ALTERNATING
SLOW FLASH
Watchguard 1 hour -- burners failed to ignite or lost flame 5 times during single
heating demand.
SLOW FLASH OFF Flame sensed without gas valve energized.
ON SLOW FLASH Rollout switch open. OR: 12‐pin connector improperly attached.
ON
ON
OFF
ON
OFF
ON
Circuit control failure or control wired incorrectly.
FAST FLASH SLOW FLASH Main power polarity reversed. Switch line and neutral.
SLOW FLASH FAST FLASH Low flame signal. Measures below 1.5 microamps. Replace flame sense rod.
ALTERNATING
FAST FLASH
ALTERNATING
FAST FLASH
Improper main ground.
OR: Line voltage below 90 volts.
NOTE - Slow flash rate equals 1 Hz (one flash per second). Fast flash rate equals 3 Hz (three flashes per second).
Minimum flame sense current = 0.5 microAmps.
FIGURE 5
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉ
É
É
DEMAND
CAI
GAS VALVE
ON
OFF
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
É
É
ÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉ
IGNITOR
15 Sec.
Pre -Purge
20 sec.
Ignitor Warmup
*4 Sec.Trial
for Ign.
Post
Purge
5 SEC
**Blower on time will be 45 seconds after gas valve is energized. Blower off time will depend on “OFF TIME” Setting.
INDOOR BLOWER
ÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉ
**Blower “On”
Delay
End of
Heat Demand Blower
Off
Time
*Ignitor will energize the first 3 seconds of the 4 second trial for ignition

Page 9
4. Integrated Ignition Control 103085 (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 6 with control terminal designations
in tables 4 and 5), flame sensor and ignitor (figure 10). 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 troubleshooting
and two accessory terminals rated at (1) one amp. See
table 6 for troubleshooting diagnostic codes. The 120 volt
ignitor is made from a high strength, silicon nitride material
that provides long life and trouble free maintenance.
Electronic Ignition (Figure 7)
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 after which the gas valve opens for a 4-sec
ond trial for ignition. The ignitor remains energized for the
first 3 seconds of the trial for ignition. If ignition is not proved
during the trial for ignition, the integrated control will try four
more times with an inter purge and warm-up time between
trials of 30 seconds. After a total of five trials for ignition (in
cluding the initial trial), the integrated control goes into
Watchguard-Flame Failure mode. After a 60-minute reset
period, the integrated control will begin the ignition se
quence again.
TABLE 4
4-Pin Terminal Designation
PIN # FUNCTION
1Combustion Air Inducer Line
2Ignitor Line
3Combustion Air Inducer Neutral
4Ignitor Neutral
TABLE 5
12-Pin Terminal Designations
PIN # FUNCTION
1High Limit Output
2 Sensor
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 6
DIAGNOSTIC CODES
LED Status DESCRIPTION
LED Off No power to control or control harware
fault detected.
LED On Normal operation.
1 Flash Flame present with gas vavle
de-energized.
2 Flashes Pressure switch closed with combustion
air inducer de-energized.
3 Flashes Pressure switch open with combus
tion air inducer energized.
4 Flashes Primary limit switch open.
5 Flashes Rollout switch open.
6 Flashes Pressure switch cycle lockout.
7 Flashes Lockout, burners fail to light.
8 Flashes Lockout, buners lost flame too many
times.
9 Flashes Line voltage polarity incorrect.
Note - This control is equipped with a push button switch for
diagnostic code recall. The control stores the last 5 fault
codes in non-volatile memory. The most recent fault code
is flashed first, the oldest fault code is flashed last. There is
a 2 second pause between codes. When the push button
switch is pressed for less than 5 seconds, the control will
flash the stored fault codes when the switch is released.
The fault code history may be cleared by pressing the push
button switch for more than 5 seconds.

Page 10
FIGURE 6
INTEGRATED CONTROL
(Automatic Hot Surface Ignition System)
TERMINAL DESIGNATIONS
HUM
LINE
XFMR
EAC
COOL
HEAT
PARK
CONT
NEUTRALS
Humidifier (120VAC)
Input (120VAC)
Transformer (120VAC)
Indoor Air Qality Accessory Air Cleaner (120VAC)
Blower - Cooling Speed (120VAC)
Blower - Heating Speed (120VAC)
Dead terminals to park alternate spd taps
Continuous blower
Neutral terminals (120VAC)
PUSH BUTTON
LED
TWIN
TWIN Twinning Terminal (24VAC)
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉ
DEMAND
CAI
GAS VALVE
15
ON
OFF
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉ
39
ÉÉÉÉÉÉÉÉÉÉ
IGNITOR
351
Pre -Purge Ignitor Warm-up Trial for
Ignition Post
Purge
5 SEC69
*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 7