ml193 service manual - Heating and Air Parts

ml193 service manual - Heating and Air Parts
Corp. 1025−L5
Service Literature
ML193UH
ML193UH SERIES UNITS
ML193UH series units are high−efficiency gas furnaces
manufactured with Lennox DuralokPlust aluminized
steel clamshell−type heat exchangers, with a stainless steel
condensing coil. ML193UH units are available in heating
input capacities of 44,000 to 132,000 Btuh (13 to 38.6 kW)
and cooling applications from 2 through 5 tons (7.0 through
17.6 kW). Refer to Engineering Handbook for proper sizing.
Units are factory equipped for use with natural gas. A kit is
available for conversion to LPG operation. All ML193UH
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 outlined
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 disconnect switch(es). Unit may have multiple
power supplies.
Table of Contents
WARNING
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Optional Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . 3
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 installer (or
equivalent), service agency or the gas supplier.
Blower Performance Data . . . . . . . . . . . . . . . . . . . . . . 4
I−Unit Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
II Placement and Installation . . . . . . . . . . . . . . . . . . . . 14
III−Start−Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
IV−Heating System Service Checks . . . . . . . . . . . . . . 36
WARNING
V−Typical Operating Conditions . . . . . . . . . . . . . . . . . . 38
VI−Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Sharp edges.
Be careful when servicing unit to avoid sharp edges
which may result in personal injury.
VII−Sequence of Operation and Flow Charts . . . . . . . 41
VIII−Integrated Control Troubleshooting . . . . . . . . . . . 46
Page 1
© 2010 Lennox Industries Inc.
Litho U.S.A.
SPECIFICATIONS
Gas
Heating
Performance
Model No. ML193UH045P36B ML193UH070P24B ML193UH070P36B ML193UH090P36C
1
AFUE
93%
93%
93%
93%
Input - Btuh
44,000
66,000
66,000
88,000
Output - Btuh
42,000
62,000
62,000
83,000
Temperature rise range - °F
25 - 55
50 - 80
40 - 70
50 - 80
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
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
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
Connections
in.
with field supplied (PVC coupling) - o.d.
Indoor
Blower
Wheel nom. dia. x width - in.
Motor output - hp
Electrical
Data
3/4
3/4
3/4
3/4
10 x 8
10 x 8
10 x 8
10 x 8
1/3
1/5
1/3
1/3
Tons of add-on cooling
2.5 - 3
1.5 - 2
2.5 - 3
2-3
Air Volume Range - cfm
700 - 1600
390 - 1140
660 - 1615
695 - 1620
Voltage
120 volts - 60 hertz - 1 phase
Blower motor full load amps
6.1
3.1
6.1
6.1
Maximum overcurrent protection
15
15
15
15
122
125
127
143
Shipping Data
lbs. - 1 package
NOTE - Filters and provisions for mounting are not furnished and must be field provided.
1
Annual Fuel Utilization Efficiency 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. ML193UH090P48C ML193UH110P48C ML193UH110P60C ML193UH135P60D
1
AFUE
93%
93%
93%
Input - Btuh
88,000
110,000
110,000
132,000
Output - Btuh
83,000
103,000
103,000
123,000
Temperature rise range - °F
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
Connections
in.
93%
40 - 70
50 - 80
40 - 70
45 - 75
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
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 field supplied (PVC coupling) - o.d.
3/4
3/4
3/4
3/4
10 x 10
10 x 10
11 ½ x 10
11 ½ x 10
Indoor
Blower
Wheel nom. dia. x width - in.
Motor output - hp
Electrical
Data
1/2
1/2
1
1
Tons of add-on cooling
3-4
3-4
4-5
4-5
Air Volume Range - cfm
900 - 2025
850 - 2030
1210 - 2525
1340 - 2800
Voltage
Blower motor full load amps
Maximum overcurrent protection
Shipping Data
lbs. - 1 package
120 volts - 60 hertz - 1 phase
8.2
8.2
11.5
11.5
15
15
15
15
146
155
161
178
NOTE - Filters and provisions for mounting are not furnished and must be field provided.
1
Annual Fuel Utilization Efficiency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized
furnaces.
Page 2
OPTIONAL ACCESSORIES - MUST BE ORDERED EXTRA
“B” Width
Models
“C” Width
Models
“D” Width
Models
Horizontal Suspension Kit - Horizontal only
Return Air Base - Upflow only
51W10
50W98
51W10
50W99
51W10
51W00
Condensate Drain Heat Cable
26K68
26K69
26K70
36G53
16P89
51W18
26K68
26K69
26K70
36G53
16P89
51W18
26K68
26K69
26K70
36G53
16P89
51W18
65W80
65W80
65W80
87L96 - 18 x 25 x 1
44J22
66K63
16 x 25 x 1
87L97 - 20 x 25 x 1
44J22
66K63
16 x 25 x 1
87L98 - 25 x 25 x 1
44J22
66K63
16 x 25 x 1
51W03
51W03
51W03
71M80
--44W92
--51W11
22G44
44J40
30G28
81J20
15F75
15F74
69M29
60L46
44W92
44W93
51W11
--44J40
--81J20
15F75
3
15F74
--60L46
--44W93
51W11
--44J40
--81J20
-----
44J41
44J41
44J41
CABINET ACCESSORIES
CONDENSATE DRAIN KITS
6 ft.
24 ft.
50 ft.
Fiberglass - 1/2 in. x 66 ft.
Aluminum foil - 2 in. x 60 ft.
Heat Cable Tape
Crawl Space Vent Drain Kit
CONTROLS
Twinning Kit
FILTER KITS
Air Filter and
Rack Kit
1
Horizontal (end)
Side Return
NIGHT SERVICE KITS
Size of filter - in.
Single
Ten Pack
Size of filter - in.
Night Service Kit
TERMINATION KITS
See Installation Instructions for specific venting information.
Termination Kits Concentric
US - 2 in.
Direct Vent
3 in.
Applications Only
Canada - 2 in.
3 in.
Flush-Mount
2, 2-1/2 or 3 in.
Wall - Close
US - 2 in.
Couple
3 in.
Wall - Close
Canada - 2 in.
Couple WTK
3 in.
Roof
2 in.
Termination Kits Direct or NonWall Ring Kit
2 in.
Direct vent
Roof Termination Flashing Kit - Direct or
2 in.
Non-Direct Vent (2 flashings)
Cleanable polyurethane frame type filter.
Kits contain enough parts for two, non−direct vent installations.
3
Non−direct vent only.
NOTE - Termination Kits 44W92, 44W93, 30G28, 81J20 are certified to ULC S636 standard for use in Canada only.
1
2
GAS HEAT ACCESSORIES
Input
all models
High Altitude
Pressure Switch Kit
4501 - 7500 ft.
74W90
Natural Gas to
LPG/Propane Kit
LPG/Propane
to Natural Gas Kit
0 - 7500 ft.
69W73
0 - 7500 ft.
73W81
7501 - 10,000 ft.
74W91
Natural Gas
High Altitude
Orifice Kit
7501- 10,000 ft.
73W37
INSTALLATION CLEARANCES - INCHES (MM)
Sides
Rear
Top/Plenum
Front
Front (service/alcove)
Floor
0 inches (0 mm)
0 inches (0 mm)
1 inch (25 mm)
0 inches (0 mm)
24 inches (610 mm)
2
Combustible
1
NOTE − Air for combustion must conform to the methods outlined in the National Fuel Gas Code (NFPA 54/ANSI−Z223.1)
or the National Standard of Canada CAN/CSA−B149.1 Natural Gas and Propane Installation Code”.
NOTE − In the U.S. flue sizing must conform to the methods outlined in the current National Fuel Gas Code (NFPA 54/
ANSI−Z223.1) or applicable provisions of local building codes. In Canada flue sizing must conform to the methods
outlined in National Standard of Canada CAN/CSA−B149.1.
1
Allow proper clearances to accommodate condensate trap and vent pipe installation.
2
Do not install the furnace directly on carpeting, tile, or other combustible materials other than wood flooring.
Page 3
BLOWER DATA
ML193UH045P36B PERFORMANCE (Less Filter)
Air Volume / Watts at Various Blower Speeds
External
MediumMediumStatic
High
Low
High
Low
Pressure
in. w.g. cfm Watts cfm Watts cfm Watts cfm Watts
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1600
1600
1550
1480
1425
1355
1320
1225
1135
1025
700
685
650
625
590
565
545
500
480
445
1370
1355
1330
1295
1280
1190
1165
1110
1050
950
590
565
540
515
490
460
435
425
395
360
1160
1155
1150
1140
1105
1085
1030
975
920
800
475 1005 400
465 1015 390
445 1000 380
430 975 365
415 975 350
395 940 335
375 900 315
355 855 310
330 780 280
295 700 255
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
ML193UH070P24B PERFORMANCE (Less Filter)
Air Volume / Watts at Various Blower Speeds
External
MediumMediumStatic
High
Low
High
Low
Pressure
in. w.g. cfm Watts cfm Watts cfm Watts cfm Watts
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1140
1135
1125
1090
1065
1020
945
910
790
735
455
445
430
415
405
390
365
350
325
310
920
900
895
870
870
825
780
740
670
575
365
360
350
340
325
315
300
295
275
255
765
765
755
725
715
675
640
585
510
460
295
290
285
280
270
260
250
240
225
220
710
690
680
660
635
605
555
505
455
390
1615
1565
1535
1440
1405
1340
1255
1165
1060
955
680
660
630
600
570
535
500
475
455
425
1355
1365
1340
1300
1255
1200
1125
1080
990
895
570
545
525
500
470
445
420
395
365
345
1140
1150
1150
1110
1075
1045
995
935
870
750
480
465
440
420
400
380
355
335
315
285
1030
1020
1025
1000
975
945
875
820
750
660
1620
1610
1565
1525
1485
1431
1365
1295
1200
1060
745
720
695
665
635
600
570
535
505
460
1340
1335
1335
1300
1295
1260
1210
1155
1065
955
620
595
565
555
520
495
475
445
415
375
1130
1135
1145
1135
1110
1090
1035
995
930
820
500
490
465
455
435
405
390
365
340
305
965
975
970
970
960
940
900
860
745
695
405
395
385
370
355
345
330
305
270
260
ML193UH090P48C PERFORMANCE (Less Filter)
Air Volume / Watts at Various Blower Speeds
External
MediumMediumStatic
High
Low
High
Low
Pressure
in. w.g. cfm Watts cfm Watts cfm Watts cfm Watts
265
255
255
250
245
235
225
220
205
195
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
ML193UH070P36B PERFORMANCE (Less Filter)
Air Volume / Watts at Various Blower Speeds
External
MediumMediumStatic
High
Low
High
Low
Pressure
in. w.g. cfm Watts cfm Watts cfm Watts cfm Watts
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
ML193UH090P36C PERFORMANCE (Less Filter)
Air Volume / Watts at Various Blower Speeds
External
MediumMediumStatic
High
Low
High
Low
Pressure
in. w.g. cfm Watts cfm Watts cfm Watts cfm Watts
2025
1995
1925
1850
1790
1700
1610
1540
1415
1270
900
880
835
795
760
725
690
645
615
565
1690
1705
1675
1640
1575
1540
1455
1365
1265
1165
780
760
715
680
645
625
580
550
510
470
1395
1390
1405
1400
1395
1350
1295
1225
1125
1060
645
635
605
580
560
535
505
480
445
420
1200
1205
1205
1170
1170
1140
1100
1030
980
900
540
525
505
490
475
450
430
405
385
350
ML193UH110P48C PERFORMANCE (Less Filter)
Air Volume / Watts at Various Blower Speeds
External
MediumMediumStatic
High
Low
High
Low
Pressure
in. w.g. cfm Watts cfm Watts cfm Watts cfm Watts
400
385
375
350
345
330
310
290
265
245
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
Page 4
2030
1950
1935
1885
1830
1750
1660
1540
1420
1290
905
865
840
810
780
740
695
665
615
575
1750
1755
1675
1660
1585
1565
1485
1380
1290
1175
805
770
735
685
645
630
585
555
520
470
1425
1430
1455
1410
1385
1320
1280
1230
1140
1045
665
630
610
585
570
535
505
485
445
410
1225
1215
1230
1200
1190
1165
1105
1060
945
850
530
515
505
485
470
455
425
405
375
350
BLOWER DATA
ML193UH110P60C PERFORMANCE (Less Filter)
Air Volume / Watts at Different Blower Speeds
External Bottom Return Air, Side Return Air with Optional Return Single Side Return Air − Air volumes in bold require field
Static Air Base, Return Air from Both Sides or Return Air from fabricated transition to accommodate 20 x 25 x 1 in. air filter
in order to maintain proper air velocity.
Pressure Bottom and One Side.
High
Medium-High Medium-Low
Low
High
Medium-High Medium-Low
Low
in. w.g.
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00
2525 1560 2175 1165 1820 905 1465 725 2520 1545 2135 1150 1750 905 1445 720
0.10
2585 1545 2200 1135 1860 900 1475 710 2555 1545 2135 1115 1775 890 1470 715
0.20
2515 1505 2150 1110 1840 890 1490 705 2465 1480 2105 1085 1775 875 1465 705
0.30
2445 1445 2135 1065 1790 870 1500 690 2370 1430 2045 1055 1750 855 1460 690
0.40
2340 1385 2065 1035 1770 845 1500 675 2275 1375 1990 1010 1730 830 1460 680
0.50
2230 1350 1985 985 1755 810 1470 665 2185 1345 1930 970 1690 800 1460 655
0.60
2130 1295 1920 950 1685 785 1425 640 2060 1290 1850 935 1650 780 1420 635
0.70
2030 1250 1815 905 1640 760 1405 625 1930 1230 1760 900 1580 750 1355 610
0.80
1920 1190 1735 865 1560 725 1350 605 1825 1180 1660 855 1505 710 1290 585
0.90
1735
1135
1620
830
1450
685
1270
575
1665
1130
1520
810
1415
675
1210
560
ML193UH135P60D PERFORMANCE (Less Filter)
Air Volume / Watts at Different Blower Speeds
External Bottom Return Air, Side Return Air with Optional Return Single Side Return Air − Air volumes in bold require field
Static Air Base, Return Air from Both Sides or Return Air from fabricated transition to accommodate 20 x 25 x 1 in. air filter
in order to maintain proper air velocity.
Pressure Bottom and One Side.
High
Medium-High Medium-Low
Low
High
Medium-High Medium-Low
Low
in. w.g.
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00
2800 1715 2155 1160 1730 900 1375 695 2720 1685 2110 1135 1670 905 1355 705
0.10
2770 1665 2170 1145 1740 895 1415 700 2660 1650 2110 1115 1725 895 1390 700
0.20
2690 1635 2150 1110 1770 890 1450 700 2600 1585 2125 1090 1750 885 1450 695
0.30
2590 1560 2140 1080 1785 870 1455 695 2535 1525 2075 1065 1750 865 1465 685
0.40
2500 1535 2105 1055 1785 855 1475 690 2400 1490 2055 1030 1715 845 1460 680
0.50
2420 1465 2050 1025 1770 835 1465 665 2335 1420 2000 1005 1725 825 1455 660
0.60
2330 1410 2015 995 1720 810 1460 655 2270 1385 1950 970 1720 800 1445 650
0.70
2225 1370 1965 960 1690 785 1450 650 2175 1335 1895 950 1665 780 1430 635
0.80
2150 1335 1875 925 1655 755 1435 630 2075 1295 1840 910 1605 745 1400 620
0.90
2025
1290
1830
890
1575
720
1375
605
Page 5
1975
1255
1755
875
1540
725
1340
590
ML193UH PARTS IDENTIFICATION
FLEXIBLE NO−HUB
EXHAUST COLLAR
MANIFOLD
BURNER BOX
ASSEMBLY
GAS VALVE
TOP CAP
DuralokPlus TM
HEAT EXCHANGER
ASSEMBLY
FLUE COLLAR
COMBUSTION AIR
INDUCER
BURNER
ACCESS
PANEL
CABINET
PRIMARY LIMIT
COMBUSTION
AIR PRESSURE
SWITCH
SIGHT
GLASS
BLOWER
ACCESS
DOOR
BLOWER
ASSEMBLY
COLD END
HEADER BOX
CONTROL BOX
(includes integrated itegrated control, transformer and interlock switch)
FIGURE 1
Page 6
BAG ASSEMBLIES
(shipping location)
I−UNIT COMPONENTS
ML193UH unit components are shown in figure 1. The
combustion air inducer, gas valve and burners can be accessed 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.
ML193UH Control Box
integrated control also features two LED lights (DS1 red
and DS2 green) for troubleshooting and two accessory
terminals rated at (1) one amp. The integrated control also
features a (3) amp fuse for overcurrent protection. Tables 1
and 2 show jack plug terminal designations. See table 3 for
troubleshooting diagnostic codes. The mini−nitride ignitor
is made from a non−porous, high strength proprietary ceramic material that provides long life and trouble free
maintenance. The integrated control continuously monitors line voltage and maintains the ignitor power at a consistent level to provide proper lighting and maximum ignitor life.
TRANSFORMER
(T1)
TABLE 1
4−Pin Terminal Designation
PIN #
DOOR INTERLOCK
SWITCH (S51)
FUNCTION
1
Combustion Air Inducer Line
2
3
4
Ignitor Line
Combustion Air Inducer Neutral
Ignitor Neutral
TABLE 2
PIN #
INTEGRATED IGNITION
CONTROL
(A92)
FIGURE 2
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 voltage. When the blower door is removed the unit will shut
down.
3. Integrated Ignition Control (A92)
WARNING
Shock hazard.
Disconnect power before servicing. Control is not
field repairable. If control is inoperable, simply replace entire control.
Can cause injury or death. Unsafe operation will
result if repair is attempted.
12−Pin Terminal Designations
FUNCTION
1
High Limit Output
2
Not Used
3
24V Line
4
Not Used
5
Rollout Switch Out
6
24V Neutral
7
High Limit Input
8
Ground
9
Gas 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 combustion 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 differential 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.
The ignition control system consists of an integrated control (figure 4) ignitor (figure 6) and flame sensor (figure 6).
The integrated control and ignitor work in combination to
ensure furnace ignition and ignitor durability. The integrated control, controls all major furnace operations. The
Page 7
After the 15−second pre−purge period, the ignitor warms up
for 20 seconds during which the gas valve opens at 19 seconds 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 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 power regulation to maintain consistent lighting and longer ignitor life under all line voltage conditions.
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−energized. Longer off delay settings provide lower return air
temperatures; shorter settings provide higher return air
temperatures. See figure 3.
FAN-OFF TIME IN SECONDS
NO JUMPER
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
To adjust fan−off timing, reposition jumper across pins
to achieve desired setting.
FIGURE 3
INTEGRATED CONTROL
(Automatic Hot Surface Ignition System)
HUM
LINE
XFMR
EAC
COOL
HEAT
PARK
FLAME
NEUTRALS
TERMINAL DESIGNATIONS
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
LED 1
LED 2
BLOWER OFF
DELAY JUMPER
FIGURE 4
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
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
ON
SLOW FLASH
ON
ON
Primary or secondary limit switch open. Limit must close within 3 minutes or unit
goes into 1 hour Watchguard.
Flame sensed without gas valve energized.
Rollout switch open. OR: 12-pin connector improperly attached.
Circuit board failure or control wired incorrectly.
ON
OFF
OFF
ON
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.
ÉÉ
ÉÉ
ÉÉ ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉ
ON
OFF
15 Sec.
Pre −Purge
20 sec.
Ignitor Warmup
*4
Sec.Trial
for Ign.
**Blower On"
Delay
End of
Heat Demand
5 SEC
Post
Purge
Blower
Off
Time
DEMAND
CAI
IGNITOR
GAS VALVE
INDOOR BLOWER
*Ignitor will energize the first 3 seconds of the 4 second trial for ignition
**Blower on time will be 45 seconds after gas valve is energized. Blower off time will depend on OFF TIME" Setting.
FIGURE 5
Page 9
NOTE − The ML193UH furnace contains electronic
components that are polarity sensitive. Make sure that
the furnace is wired correctly and is properly grounded.
B−Heating Components
Combustion air inducer (B6), primary limit control (S10),
SureLight ignitor, burners, flame rollout switch (S47), gas
valve (GV1), combustion air prove switch (S18), and clamshell heat exchangers are located in the heating compartment. The heating compartment can be accessed by removing the burner access panel.
1. Ignitor (Figure 6)
ML193UH units use a mini−nitride ignitor made from a proprietary ceramic material. Ignitor longevity is enhanced by
controlling the voltage to the ignitor. Due to this feature of
the integrated control, voltage cannot be measured. To
check ignitor, measure its resistance. A value of 50 to 450
ohms indicates a good ignitor.
3. Flame Rollout Switches (Figure 6)
Flame rollout switches S47 are SPST N.C. high temperature
limits located on the top left and bottom right of the front buner
box plate. S47 is wired to the burner ignition control A92.
When either of the switches sense flame rollout (indicating a blockage in the combustion passages), the flame
rollout switch trips, and the ignition control immediately
closes the gas valve. Switch S47 in all ML193UH units is
factory preset to open at 210_F + 12_F (99_C + 6.7_C) on a
temperature rise. All flame rollout switches are manual reset.
2. Flame Sensor (Figure 6)
A flame sensor is located on the left side of the burner support. The sensor is mounted on the front burner box plate
and the tip protrudes into the flame envelope 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 ignition control allows the gas valve
to remain open as long as flame signal is sensed.
ML193UH Burner Box Assembly
BURNERS
FRONT BURNER BOX PLATE
ROLLOUT SWITCHES
IGNITOR
FLAME SENSOR
ORIFICES
GAS VALVE
FIGURE 6
Page 10
4. Primary Limit Control (Figure 7)
Primary limit (S10) used on ML193UH units is located in the
heating vestibule panel. When excess heat is sensed in the
heat exchanger, the limit will open. Once the limit opens, the
furnace control energizes the supply air blower and de−energizes the gas valve. The limit automatically resets when
unit temperature returns to normal. The switch is factory
set and cannot be adjusted. For limit replacement remove
wires from limit terminals, remove mounting screws, rotate
limit switch 90 degrees and slowly remove from the vestibule panel. Install replacement limit with same care.
an orifice which is precisely matched to the burner input.
See table 4 for orifice size. The burner is supported by the
orifice and will easily slide off for service. A flame retention
ring in the end of each burner maintains correct flame length
and shape and keeps the flame from lifting off the burner head.
TABLE 4
Gas Orifice Size
Unit
Fuel
Orifice Size
All
Natural
0.0625
All
L.P./Propane
0.0340
Primary Limit Location and Heat Exchanger
Burner Detail Top View
IGNITOR
FLAME SENSOR
ORIFICES
FIGURE 8
7. Gas Valve (GV1)
Install limit face down
FIGURE 7
5. Heat Exchanger (Figure 7)
ML193UH units use an aluminized steel primary and
stainless steel secondary heat exchanger assembly.
Heat is transferred to the air stream from all surfaces of
the heat exchanger. The shape of the heat exchanger ensures maximum efficiency.
The combustion air inducer pulls fresh air through the burner box. This air is mixed with gas in the burners. The gas /
air mixture is then burned at the entrance of each clamshell. Combustion gases are then pulled through the primary
and secondary heat exchangers and exhausted out the exhaust vent pipe.
The ML193UH uses an internally redundant valve to assure
safety shut-off. If the gas valve must be replaced, the same
type valve must be used.
24VAC terminals and gas control switch are located on
top of the valve. All terminals on the gas valve are connected to wires from the ignition control. 24V applied to the
terminals opens the valve.
Inlet and outlet pressure taps are located on the valve. A
manifold adjustment screw is also located on the valve. An
LPG changeover kit is available.
MANIFOLD
PRESSURE
ADJUSTMENT
SCREW
Gas Valve
MANIFOLD
PRESSURE
OUTLET
PORT
6. Burners (Figure 8)
All units use inshot burners. Burners are factory set and do not
require adjustment. Burners can be removed as an assembly
for service. Burner maintenance and service is detailed in the
MAINTENANCE section of this manual. Each burner uses
Page 11
INLET
PRESSURE
PORT
FIGURE 9
8. Combustion Air Inducer (B6)
& Cold End Header Box
Pressure Switch
All ML193UH units use a combustion air inducer to move
air through the burners and heat exchanger during heating operation. The blower uses a shaded pole 120VAC
motor. The motor operates during all heating operation and
is controlled by integrated control A3. Blower operates continuously while there is a call for heat. The integrated control will not proceed with the ignition sequence until combustion air inducer operation is sensed by the proving switches.
The combustion air inducer is installed on the cold end
header box. The cold end header box is a single piece
made of hard plastic. The box has an internal channel
where the combustion air inducer creates negative pressure at unit start up. The channel contains an orifice used
to regulate flow created by the combustion air inducer.
The box has pressure taps for the combustion air inducer
pressure switch hoses. The pressure switch measures
the pressure across the combustion air inducer orifice or
difference in the channel and the box. If replacement is
necessary the gaskets used to seal the box to the
vestibule panel and the combustion air inducer to the
box, must also be replaced.
TABLE 5
ML193UH Unit
Combustion Air Inducer
Orifice Size
−045
0.563
−070
0.844
−090
1.00
−110
1.22
−135
1.30
FIGURE 10
On start-up, the switch monitors whether the combustion air
inducer is operating. It closes a circuit to the integrated
control when the difference in pressure across the combustion air inducer orifice exceeds a non−adjustable factory
setting. If the switch does not successfully sense the required differential, the switch cannot close and the furnace cannot operate. If the flue or air inlet become obstructed during operation, the switch senses a loss of
pressure differential and opens the circuit to the integrated
control. If the condensate line is blocked, water will back up
into the header box and reduce the pressure differential
across the switch. The prove switch opens if the differential
drops below the set point. See table 6.
Checks of pressure differential can aid in troubleshooting.
When measuring the pressure differential, readings should be
taken at the pressure switch. See figure 11. Lack of differential
usually indicates problems in the intake or exhaust piping, but
may indicate problems in the heat exchanger, condensing coil, header boxes, combustion inducer or other
components.
TABLE 6
9. Combustion Air Pressure Switch
(Figure 10)
Unit
ML193UH series units are equipped with a differential
pressure switch located on the cold end header box. The
switch monitors across the combustion air inducer orifice to insure proper flow through the heat exchanger.
The switch is a SPST N.O. prove switch electrically connected to the integrated control. The purpose of the switch is
to prevent burner operation if the combustion air inducer is not
moving enough air for proper combustion.
−045
−070
−090
−110
−135
Altitude ft.
0 − 4500
4501 − 7500
7501 − 10000
Set Point w.c. Set Point w.c Set Point w.c.
−0.65
−0.60
*Set point is factory set and non−adjustable
Page 12
−0.055
Measuring Pressure Differential
RED TUBING
NEGATIVE
BLACK TUBING
POSITIVE
1 − Remove thermostat demand and allow unit to
cycle off.
2 − Install a tee in the negative (−) line (red tubing) and a
tee in the positive (+) line (black tubing) running from
the pressure switch to the cold end header box.
3 − Install a manometer with hose from the negative (−)
side of the manometer to the tee installed in the
negative (−) line and with hose from the positive (+)
side of the manometer to the tee in the positive (+)
line.
NOTE − Both sides of the cold end header box are negative. However the (+) port reads less negative pressure
than the (−) port.
4 − Operate unit and observe manometer reading.
Readings will change as heat exchanger warms.
a. Take one reading immediately after start-up.
b. Take a second reading after unit has reached
steady state (approximately 5 minutes). This will be
the pressure differential.
The pressure differential should be greater
than those listed in table 6.
5 − Remove thermostat demand and allow to cycle off.
6 − Remove manometer and tee’s. Reinstall combustion
air sensing hoses to the pressure switch.
FIGURE 11
C− Blower Compartment
1. Blower Motor (B3) and Capacitor (C4)
Blower motor (B3) and capacitor (C4), are located in the
blower compartment. The blower compartment can be accessed by removing the blower access panel.
All ML193UH units use single−phase direct−drive blower motors. All motors are 120V permanent split capacitor motors
to ensure maximum efficiency. See SPECIFICATIONS table
at the front of this manual for more detail. See motor nameplate for capacitor ratings.
Blower Motor Housing
BOLTS
MOTOR
CAPACITOR
To Remove Blower From Unit: Disconnect Power, Remove Control
Box, Remove Bolts and Unplug Motor Wires From Control. Then
Slide Out Front of Unit.
FIGURE 12
Page 13
II−PLACEMENT AND INSTALLATION
Combustion, Dilution & Ventilation Air
If the ML193UH is installed as a Non−Direct Vent Furnace, follow the guidelines in this section.
NOTE − In Non−Direct Vent installations, combustion air
is taken from indoors and flue gases are discharged out−
doors.
In the past, there was no problem in bringing in sufficient
outdoor air for combustion. Infiltration provided all the air
that was needed. In today’s homes, tight construction
practices make it necessary to bring in air from outside
for combustion. Take into account that exhaust fans, appliance vents, chimneys, and fireplaces force additional
air that could be used for combustion out of the house.
Unless outside air is brought into the house for combustion, negative pressure (outside pressure is greater than
inside pressure) will build to the point that a downdraft
can occur in the furnace vent pipe or chimney. As a result,
combustion gases enter the living space creating a potentially dangerous situation.
In the absence of local codes concerning air for combus−
tion and ventilation, use the guidelines and procedures in
this section to install ML193UH furnaces to ensure efficient and safe operation. You must consider combustion
air needs and requirements for exhaust vents and gas
piping. A portion of this information has been reprinted
with permission from the National Fuel Gas Code (ANSI−
Z223.1/NFPA 54). This reprinted material is not the complete and official position of the ANSI on the referenced
subject, which is represented only by the standard in its
entirety.
In Canada, refer to the CSA B149 installation codes.
CAUTION
Do not install the furnace in a corrosive or contaminated atmosphere. Meet all combustion and ventilation air requirements, as well as all local codes.
All gas-fired appliances require air for the combustion process. If sufficient combustion air is not available, the furnace or other appliance will operate inefficiently and unsafely. Enough air must be provided to meet the needs of all
fuel−burning appliances and appliances such as exhaust
fans which force air out of the house. When fireplaces, exhaust fans, or clothes dryers are used at the same time as
the furnace, much more air is required to ensure proper
combustion and to prevent a downdraft. Insufficient air
causes incomplete combustion which can result in carbon
monoxide.
In addition to providing combustion air, fresh outdoor air dilutes contaminants in the indoor air. These contaminants
may include bleaches, adhesives, detergents, solvents
and other contaminants which can corrode furnace components.
The requirements for providing air for combustion and ventilation depend largely on whether the furnace is installed in
an unconfined or a confined space.
Unconfined Space
An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the combined input rating of all appliances installed in that space.
This space also includes adjacent rooms which are not
separated by a door. Though an area may appear to be unconfined, it might be necessary to bring in outdoor air for
combustion if the structure does not provide enough air by
infiltration. If the furnace is located in a building of tight
construction with weather stripping and caulking around
the windows and doors, follow the procedures in the Air
from Outside section.
Confined Space
A confined space is an area with a volume less than 50 cubic
feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the com−
bined input rating of all appliances installed in that space. This
definition includes furnace closets or small equipment rooms.
When the furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside the space containing the furnace, the return air must be handled by ducts
which are sealed to the furnace casing and which terminate
outside the space containing the furnace. This is especially
important when the furnace is mounted on a platform in a
confined space such as a closet or small equipment room.
Even a small leak around the base of the unit at the platform
or at the return air duct connection can cause a potentially
dangerous negative pressure condition. Air for combustion
and ventilation can be brought into the confined space either from inside the building or from outside.
Air from Inside
If the confined space that houses the furnace adjoins a
space categorized as unconfined, air can be brought in by
providing two permanent openings between the two
spaces. Each opening must have a minimum free area of 1
square inch (645 mm2) per 1,000 Btu (.29 kW) per hour of
total input rating of all gas−fired equipment in the confined
space. Each opening must be at least 100 square inches
(64516 mm2). One opening shall be within 12 inches (305
mm) of the top of the enclosure and one opening within 12
inches (305 mm) of the bottom. See figure 13.
Page 14
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM INSIDE
ROOF TERMINATED
EXHAUST PIPE
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
OPENINGS
(To Adjacent
Unconfined
Space)
ML193UH
NOTE − Each opening shall have a free area of at least one square inch
per 1,000 Btu (645mm2 per .29kW) per hour of the total input rating of
all equipment in the enclosure, but not less than 100 square inches
(64516mm. 2).
FIGURE 13
Air from Outside
If air from outside is brought in for combustion and ventilation, the confined space shall be provided with two permanent openings. One opening shall be within 12" (305mm)
of the top of the enclosure and one within 12" (305mm) of
the bottom. These openings must communicate directly
or by ducts with the outdoors or spaces (crawl or attic) that
freely communicate with the outdoors or indirectly
through vertical ducts. Each opening shall have a minimum free area of 1 square inch per 4,000 Btu (645mm2
per 1.17kW) per hour of total input rating of all equipment
in the enclosure. When communicating with the outdoors
through horizontal ducts, each opening shall have a minimum free area of 1 square inch per 2,000 Btu (645mm2
per .59kW) per total input rating of all equipment in the enclosure (See figure 14).
If air from outside is brought in for combustion and ventilation, the confined space must have two permanent openings. One opening shall be within 12 inches (305 mm) of
the top of the enclosure and one opening within 12 inches
(305 mm) of the bottom. These openings must communicate directly or by ducts with the outdoors or spaces (crawl
or attic) that freely communicate with the outdoors or indirectly through vertical ducts. Each opening shall have a
minimum free area of 1 square inch (645 mm2) per 4,000
Btu (1.17 kW) per hour of total input rating of all equipment
in the enclosure. See figures 14 and 15. When
communicating with the outdoors through horizontal
ducts, each opening shall have a minimum free area of 1
square inch (645 mm2) per 2,000 Btu (.56 kW) per total input rating of all equipment in the enclosure. See figure 16.
When ducts are used, they shall be of the same cross−sectional area as the free area of the openings to which they
connect. The minimum dimension of rectangular air ducts
shall be no less than 3 inches (75 mm). In calculating free
area, the blocking effect of louvers, grilles, or screens
must be considered. If the design and free area of protective covering is not known for calculating the size opening
required, it may be assumed that wood louvers will have
20 to 25 percent free area and metal louvers and grilles
will have 60 to 75 percent free area. Louvers and grilles
must be fixed in the open position or interlocked with the
equipment so that they are opened automatically during
equipment operation.
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM OUTSIDE
(All Air Through Ventilated Attic)
ROOF TERMINATED
EXHAUST PIPE
OUTLET
AIR
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM OUTSIDE
(Inlet Air from Crawl Space and Outlet Air to Ventilated Attic)
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
VENTILATION LOUVERS
(Each end of attic)
ROOF TERMINATED
EXHAUST PIPE
FURNACE
INLET AIR
(Ends 12" above
bottom)
NOTE−The inlet and outlet air openings shall each have a free area of
at least one square inch per 4,000 Btu (645mm2 per 1.17kW) per hour
of the total input rating of all equipment in the enclosure.
FIGURE 15
OUTLET
AIR
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
VENTILATION LOUVERS
(Each end of attic)
FURNACE
INLET
AIR
VENTILATION
LOUVERS
(For unheated
crawl space)
NOTE−The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm2 per 1.17kW) per
hour of the total input rating of all equipment in the enclosure.
FIGURE 14
Page 15
Use PVC primer and solvent cement or ABS solvent cement
meeting ASTM specifications, refer to Table 7. As an alternate, use all purpose cement, to bond ABS, PVC, or CPVC
pipe when using fittings and pipe made of the same materials. Use transition solvent cement when bonding ABS to either PVC or CPVC.
TABLE 7
PIPING AND FITTINGS SPECIFICATIONS
EQUIPMENT IN CONFINED SPACE −
ALL AIR FROM OUTSIDE
ROOF TERMINATED
EXHAUST PIPE
OUTLET AIR
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
FURNACE
INLET AIR
Schedule 40 PVC (Pipe)
Schedule 40 PVC (Cellular Core Pipe)
D1785
F891
Schedule 40 PVC (Fittings)
D2466
Schedule 40 CPVC (Pipe)
F441
Schedule 40 CPVC (Fittings)
SDR−21 PVC or SDR−26 PVC (Pipe)
SDR−21 CPVC or SDR−26 CPVC (Pipe)
NOTE−Each air duct opening shall have a free area of at least one
square inch per 2,000 Btu (645mm2 per .59kW) per hour of the total
input rating of all equipment in the enclosure. If the equipment room
is located against an outside wall and the air openings communicate directly with the outdoors, each opening shall have a free area
of at least 1 square inch per 4,000 Btu (645mm 2 per 1.17kW) per
hour of the total input rating of all other equipment in the enclosure.
Schedule 40 ABS Cellular Core DWV (Pipe)
FIGURE 16
F628
D1527
Schedule 40 ABS (Fittings)
D2468
ABS−DWV (Drain Waste & Vent)
(Pipe & Fittings)
D2661
PVC−DWV (Drain Waste & Vent)
Pipe & Fittings)
D2665
PRIMER & SOLVENT CEMENT
IMPORTANT
F442
Schedule 40 ABS (Pipe)
Pipe & Fittings Specifications
All pipe, fittings, primer and solvent cement must conform
with American National Standard Institute and the American Society for Testing and Materials (ANSI/ASTM) standards. The solvent shall be free flowing and contain no
lumps, undissolved particles or any foreign matter that adversely affects the joint strength or chemical resistance of
the cement. The cement shall show no gelation, stratification, or separation that cannot be removed by stirring. Refer to the table 7 below for approved piping and fitting materials.
F438
D2241
PVC & CPVC Primer
PVC Solvent Cement
CPVC Solvent Cement
ABS Solvent Cement
ASTM
SPECIFICATION
F656
D2564
F493
D2235
PVC/CPVC/ABS All Purpose Cement For
Fittings & Pipe of the same material
D2564, D2235, F493
ABS to PVC or CPVC Transition Solvent
Cement
D3138
CANADA PIPE & FITTING & SOLVENT
CEMENT
PVC & CPVC Pipe and Fittings
PVC & CPVC Solvent Cement
MARKING
ULCS636
ABS to PVC or CPVC Transition Cement
ML193UH exhaust and intake connections are made
of PVC. Use PVC primer and solvent cement when
using PVC vent pipe. When using ABS vent pipe, use
transitional solvent cement to make connections to
the PVC fittings in the unit.
CAUTION
Solvent cements for plastic pipe are flammable liquids and should be kept away from all sources of
ignition. Do not use excessive amounts of solvent
cement when making joints. Good ventilation should
be maintained to reduce fire hazard and to minimize
breathing of solvent vapors. Avoid contact of cement
with skin and eyes.
Low temperature solvent cement is recommended during
cooler weather. Metal or plastic strapping may be used for
vent pipe hangers. Uniformly apply a liberal coat of PVC
primer for PVC or use a clean dry cloth for ABS to clean inside socket surface of fitting and male end of pipe to depth
of fitting socket.
Canadian Applications Only − Pipe, fittings, primer
and solvent cement used to vent (exhaust) this appliance must be certified to ULC S636 and supplied by a
single manufacturer as part of an approved vent (exhaust) system. When bonding the vent system to the furnace, use ULC S636 approved One−Step Transition Cement to bond the pipe to the flue collar, or to bond the 90°
elbow or reducing 90° elbow to the flue collar. In addition, the first three feet of vent pipe from the furnace flue
collar must be accessible for inspection.
Page 16
TABLE 8
OUTDOOR TERMINATION KITS USAGE
STANDARD
ML193
UNIT
045
070
090
110
135
VENT
PIPE
DIA.
(in.)
CONCENTRIC
Outdoor Exhaust Accelerator
(Dia. X
Length)
Outdoor Exhaust Accelerator
(Dia. X
Length)
2" Wall Plate
Kit
3" Wall Plate
Kit
2" Wall
Ring Kit
FlushMount
Kit
1−1/2"
Concentric
Kit
2" Concentric Kit
3" Concentric Kit
1−1/2" X 12"
2" X 12"
22G44
or 30G28
44J40
or 81J20
15F74
51W11**
71M80
or
44W92
69M29
or
44W92
60L46
or 44W93
2
YES
YES
YES*
YES
YES
YES
2−1/2
YES
YES
YES*
YES
YES
YES
3
YES
YES
YES*
YES
YES
YES
2
YES
YES
YES*
YES
YES
YES
2−1/2
YES
YES
YES*
YES
YES
YES
3
YES
YES
YES*
YES
YES
YES
2
YES
YES
YES
YES
YES
YES
2−1/2
YES
YES
YES
YES
YES
YES
3
YES
YES
YES
YES
YES
YES
2
YES
YES
YES
YES
YES
YES
2−1/2
YES
YES
YES
YES
YES
YES
3
YES
YES
YES
YES
YES
YES
3
YES
YES
YES
*Requires field−provided and installed 1−1/2" exhaust accelerator.
** Kit 51W11 is provided with a 1−1/2" accelerator which must be used for all ML193UH−045, −070 and −090 installations.
Termination kits 44W92, 44W93, 30G28 and 81J20 approved for use in Canadian installations to meet CSAB149.
The 44W92 Concentric kit is provided with a 1−1/2" accelerator which must be installed on the exhaust outlet when this kit is used with the ML193UH045P36B,
ML193UH070P24B and ML193UH070P36B furnaces.
Joint Cementing Procedure
All cementing of joints should be done according to the
specifications outlined in ASTM D 2855.
DANGER
DANGER OF EXPLOSION!
Fumes from PVC glue may ignite during system
check. Allow fumes to dissipate for at least 5 minutes
before placing unit into operation.
1 − Measure and cut vent pipe to desired length.
2 − Debur and chamfer end of pipe, removing any ridges
or rough edges. If end is not chamfered, edge of pipe
may remove cement from fitting socket and result in a
leaking joint.
3 − Clean and dry surfaces to be joined.
4 − Test fit joint and mark depth of fitting on outside of pipe.
5 − Uniformly apply a liberal coat of PVC primer for PVC or
use a clean dry cloth for ABS to clean inside socket
surface of fitting and male end of pipe to depth of fitting
socket.
NOTE − Time is critical at this stage. Do not allow primer to dry before applying cement.
6 − Promptly apply solvent cement to end of pipe and inside socket surface of fitting. Cement should be applied lightly but uniformly to inside of socket. Take
care to keep excess cement out of socket. Apply second coat to end of pipe.
7 − Immediately after applying last coat of cement to pipe,
and while both inside socket surface and end of pipe
are wet with cement, forcefully insert end of pipe into
socket until it bottoms out. Turn PVC pipe 1/4 turn during assembly (but not after pipe is fully inserted) to distribute cement evenly. DO NOT turn ABS or cellular
core pipe.
NOTE − Assembly should be completed within 20 seconds after last application of cement. Hammer blows
should not be used when inserting pipe.
Page 17
8 − After assembly, wipe excess cement from pipe at end
of fitting socket. A properly made joint will show a
bead around its entire perimeter. Any gaps may indicate an improper assembly due to insufficient solvent.
9 − Handle joints carefully until completely set.
REPLACING FURNACE THAT WAS
PART OF A COMMON VENT SYSTEM
CHIMNEY
OR GAS
VENT
(Check sizing
for water
heater only)
Venting Practices
FURNACE
(Replaced
by ML193)
WATER
HEATER
Piping Suspension Guidelines
OPENINGS
(To Adjacent
Room)
SCHEDULE 40
PVC − 5’
all other pipe* − 3’
If an ML193UH furnace replaces a furnace which
was commonly vented with another gas appliance,
the size of the existing vent pipe for that gas appliance must be checked. Without the heat of the
original furnace flue products, the existing vent pipe
is probably oversized for the single water heater or
other appliance. The vent should be checked for
proper draw with the remaining appliance.
* See table 7 for allowable pipe.
NOTE − Isolate piping at the point where it exits the outside wall or
roof in order to prevent transmission of vibration to the structure.
Wall Thickness Guidelines
24" maximum
3/4" minimum
inside
Wall
FIGURE 18
Exhaust Piping (Figures 21 and 22)
outside
Route piping to outside of structure. Continue with installation following instructions given in piping termination section.
CAUTION
insulation
(if required)
FIGURE 17
1
In areas where piping penetrates joists or interior
walls, hole must be large enough to allow clearance on
all sides of pipe through center of hole using a hanger.
2. When furnace is installed in a residence where unit is
shut down for an extended period of time, such as a
vacation home, make provisions for draining condensate collection trap and lines.
Do not discharge exhaust into an existing stack or
stack that also serves another gas appliance. If vertical discharge through an existing unused stack is required, insert PVC pipe inside the stack until the end
is even with the top or outlet end of the metal stack.
CAUTION
The exhaust vent pipe operates under positive pressure and must be completely sealed to prevent leakage of combustion products into the living space.
Page 18
Use the following steps to correctly size vent pipe diameter.
Vent Piping Guidelines
The ML193UH can be installed as either a Non−Direct
Vent or a Direct Vent gas central furnace.
NOTE − In Non-Direct Vent installations, combustion air is
taken from indoors and flue gases are discharged outdoors.
In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged outdoors.
Intake and exhaust pipe sizing −− Size pipe according to
tables 9 and 10. Table 9 lists the minimum vent pipe lengths
permitted. Table 10 lists the maximum pipe lengths permitted.
Regardless of the diameter of pipe used, the standard roof
and wall terminations described in section Exhaust Piping
Terminations should be used. Exhaust vent termination
pipe is sized to optimize the velocity of the exhaust gas as
it exits the termination. Refer to table 11.
In some applications which permit the use of several different sizes of vent pipe, a combination vent pipe may be
used. Contact Lennox’ Application Department for assistance in sizing vent pipe in these applications.
NOTE − The exhaust collar on all models is sized to accommodate 2" Schedule 40 vent pipe. When vent pipe
which is larger than 2" must be used in an upflow application, a transition must be applied at the exhaust collar in
order to properly step to the larger diameter vent pipe.
Contact the Application Department for more information
concerning sizing of vent systems which include multiple
pipe sizes.
1
2
Furnace capacity?
045, 070,
090, 110
or 135 btuh
Which termination?
Standard or
Concentric?
See table 8
3
Which needs
most elbows?
4
How many?
Intake or
exhaust
Exhaust Pipe
12" Min.
5
Desired pipe size?
6
What is the altitude?
7
Use table 5 to find
max. pipe length.
2", 2 1/2", 3"
12" max
of straight pipe
Horizontal Application
NOTE − All horizontal runs of exhaust pipe must slope back toward unit. A minimum of 1/4" (6mm) drop for each 12" (305mm)
of horizontal run is mandatory for drainage.
NOTE − Exhaust pipe MUST be glued to furnace exhaust fittings.
NOTE − Exhaust piping should be checked carefully to make
sure there are no sags or low spots.
FIGURE 19
TABLE 9
MINIMUM VENT PIPE LENGTHS
ML193UH
MODEL
FIGURE 20
MIN. VENT LENGTH*
15 ft. or
5 ft plus 2 elbows or
10 ft plus 1 elbow
135**
*Any approved termination may be added to the minimum length listed.
**ML193UH135P60D must have 3" to 2" reducing ell (supplied or field replacement Canadian kit) installed directly into unit flue collar.
IMPORTANT
045, 070, 090, 110
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze−ups
and may block the terminations.
Page 19
TABLE 10
Maximum Allowable Vent Length in Feet
Standard Termination at Elevation 0 − 10,000 ft.
Pipe
Size
Number
Of 90°
Ebows
Used
Model
1
2
3
4
5
6
7
8
9
10
2"
045
81
76
71
66
61
56
51
46
41
36
070
66
61
56
51
46
41
36
31
26
21
Pipe
Size
Number
Of 90°
Ebows
Used
Model
1
2
3
4
5
6
7
8
9
10
090
44
39
34
29
24
19
14
n/a
2−1/2"
110
24
19
14
135
045
070
090
110
135
115
100
68
43
110
95
63
38
105
90
58
33
100
85
53
28
95
80
48
23
n/a
n/a
90
75
43
18
85
70
38
13
n/a
80
65
33
75
60
28
n/a
70
55
23
Concentric Termination Elevation 0 − 10,000 ft.
2"
045
73
68
63
58
53
48
43
38
33
28
070
58
53
48
43
38
33
28
23
18
13
090
42
37
32
27
22
17
12
n/a
3"
045
137
132
127
122
117
112
107
102
97
92
070
137
132
127
122
117
112
107
102
97
92
2−1/2"
110
22
17
12
135
n/a
n/a
045
105
100
95
90
85
80
75
70
65
60
070
90
85
80
75
70
65
60
55
50
45
Page 20
090
64
59
54
49
44
39
34
29
24
19
090
118
113
108
103
98
93
88
83
78
73
110
118
113
108
103
98
93
88
83
78
73
135
114
109
104
99
94
89
84
79
74
69
110
114
109
104
99
94
89
84
79
74
69
135
105
100
95
90
85
80
75
70
65
60
3"
110
39
34
29
24
19
14
n/a
135
n/a
045
121
116
111
106
101
96
91
86
81
76
070
121
116
111
106
101
96
91
86
81
76
090
114
109
104
99
94
89
84
79
74
69
TYPICAL EXHAUST PIPE CONNECTIONS AND CONDENSATE TRAP INSTALLATION
IN UPFLOW DIRECT OR NON−DIRECT VENT APPLICATIONS
Pipe size determined in table 10
2”
2”
2”
3”
or
TRANSITION
2”
2”
EXHAUST
2”
TRAP
DO NOT transition
from smaller to larger
pipe in horizontal runs
of exhaust pipe.
Use only the
factory−supplied trap.
Trap can be installed
on either side of
cabinet within 5 ft. of
the furnace.
FIGURE 21
TYPICAL EXHAUST PIPE CONNECTIONS AND CONDENSATE TRAP INSTALLATION
IN HORIZONTAL DIRECT OR NON−DIRECT VENT APPLICATIONS
(RIGHT HAND DISCHARGE SHOWN)
12" max.
45°
MAX
45°
MAX
3”
2”
TRANSITION
2”
or
2”
2”
2”
2”
2”
SIDE VIEW
EXHAUST
DO NOT transition
from smaller to larger
pipe in horizontal runs
of exhaust pipe.
Use only the factory−supplied
trap. Trap can be installed
within 5 ft. of the furnace and
MUST be installed on left side
for left−hand discharge.
FIGURE 22
Page 21
TYPICAL AIR INTAKE PIPE CONNECTIONS IN UPFLOW
DIRECT VENT APPLICATIONS
Pipe size determined in table 10
3”
2”
TRANSITION
AIR INTAKE
*2”
2”
2”
2”
or
TRAP
2”
Use only the factory−supplied
trap. Trap can be installed on
either side of cabinet within 5
ft. of the furnace.
FIGURE 23
TYPICAL AIR INTAKE PIPE CONNECTIONS IN HORIZONTAL DIRECT VENT APPLICATIONS
(RIGHT HAND DISCHARGE SHOWN)
3”
2”
2”
or
TRANSITION
2”
2”
2”
2”
AIR INTAKE
Use only the factory−supplied trap.
Trap can be installed within 5 ft. of the
furnace and MUST be installed on left
side for left−hand discharge.
FIGURE 24
Page 22
2”
Intake Piping
The ML193UH furnace may be installed in either direct
vent or non−direct vent applications. In non−direct vent
applications, when intake air will be drawn into the furnace
from the surrounding space, the indoor air quality must be
considered and guidelines listed in Combustion, Dilution
and Ventilation Air section must be followed.
Follow the next two steps when installing the unit in Direct
Vent applications, where combustion air is taken from
outdoors and flue gases are discharged outdoors. The
provided air intake screen must not be used in direct
vent applications (outdoors).
1 − Use transition solvent cement or a sheet metal screw
to secure the intake pipe to the inlet air connector.
2 − Route piping to outside of structure. Continue with
installation following instructions given in general
guide lines for piping terminations and intake and exhaust piping terminations for direct vent sections. Refer to table 10 for pipe sizes.
TYPICAL AIR INTAKE PIPE CONNECTIONS
UPFLOW NON−DIRECT
VENT APPLICATIONS
INTAKE
DEBRIS
SCREEN
(Provided)
TYPICAL AIR INTAKE PIPE CONNECTIONS
HORIZONTAL NON−DIRECT VENT APPLICATIONS
(Horizontal Right−Hand Air Discharge Application Shown)
PVC pipe
coupling
OR
INTAKE
DEBRIS
SCREEN
(Provided)
NOTE − Debris screen may be positioned straight out
(preferred) or with an elbow rotated to face down.
FIGURE 26
Follow the next two steps when installing the unit in NonDirect Vent applications where combustion air is taken
from indoors and flue gases are discharged outdoors.
1 − Use field−provided materials and the factory−provided
air intake screen to route the intake piping as shown in
figure 25 or 26. Maintain a minimum clearance of 3"
(76mm) around the air intake opening. The air intake
opening (with the protective screen) should always be
directed forward or to either side in the upflow position,
and either straight out or downward in the horizontal
position.
The air intake piping must not terminate too close
to the flooring or a platform. Ensure that the intake
air inlet will not be obstructed by loose insulation
or other items that may clog the debris screen.
2 − Use a sheet metal screw to secure the intake pipe to
the connector, if desired.
NOTE − Debris screen and elbow may be rotated, so that
screen may be positioned to face forward or to either side.
FIGURE 25
Page 23
General Guidelines for Vent Terminations
In Non-Direct Vent applications, combustion air is taken
from indoors and the flue gases are discharged to the outdoors. The ML193UH is then classified as a non-direct
vent, Category IV gas furnace.
In Direct Vent applications, combustion air is taken from
outdoors and the flue gases are discharged to the outdoors. The ML193UH is then classified as a direct vent,
Category IV gas furnace.
In both Non-Direct Vent and Direct Vent applications, the
vent termination is limited by local building codes. In the
absence of local codes, refer to the current National Fuel
Gas Code ANSI Z223−1/NFPA 54 in U.S.A., and current
CSA−B149 Natural Gas and Propane Installation Codes in
Canada for details.
Position termination according to location given in figure 27
or 28. In addition, position termination so it is free from any
obstructions and 12" above the average snow accumulation.
At vent termination, care must be taken to maintain
protective coatings over building materials (prolonged
exposure to exhaust condensate can destroy protective
coatings). It is recommended that the exhaust outlet not be
located within 6 feet (1.8m) of a condensing unit because
the condensate can damage the painted coating.
NOTE − If winter design temperature is below 32°F (0°C),
exhaust piping should be insulated with 1/2" (13mm), Armaflex or equivalent when run through unheated space.
Do not leave any surface area of exhaust pipe open to outside air; exterior exhaust pipe should be insulated with
1/2" (13mm) Armaflex or equivalent. In extreme cold climate areas, 3/4" (19mm) Armaflex or equivalent may be
necessary. Insulation on outside runs of exhaust pipe
must be painted or wrapped to protect insulation from deterioration. Exhaust pipe insulation may not be necessary
in some specific applications.
NOTE − During extremely cold temperatures, below
approximately 20°F (6.7°C), units with long runs of vent
pipe through unconditioned space, even when insulated,
may form ice in the exhaust termination that prevents the
unit from operating properly. Longer run times of at least 5
minutes will alleviate most icing problems. Also, a heating
cable may be installed on exhaust piping and termination
to prevent freeze−ups. Heating cable installation kit is
available from Lennox. See Condensate Piping section
for part numbers.
IMPORTANT
Do not use screens or perforated metal in exhaust
terminations. Doing so will cause freeze−ups and
may block the terminations.
IMPORTANT
For Canadian Installations Only:
In accordance to CSA International B149 installation
codes, the minimum allowed distance between the
combustion air intake inlet and the exhaust outlet of
other appliances shall not be less than 12 inches
(305mm).
Page 24
VENT TERMINATION CLEARANCES
FOR NON−DIRECT VENT INSTALLATIONS IN THE USA AND CANADA
INSIDE CORNER
DETAIL
G
H
A
D
E
B
L
Fixed
Closed
Operable
F
B
B
C
Operable
Fixed
Closed
I
M
B
K
J
A
B
VENT TERMINAL
A=
Clearance above grade, veranda,
porch, deck or balcony
B=
Clearance to window or
door that may be opened
C=
Clearance to permanently
closed window
D=
Vertical clearance to ventilated soffit
located above the terminal within a
horizontal distance of 2 feet (mm)
from the center line of the terminal
E=
F=
G=
Clearance to unventilated soffit
Clearance to outside corner
Clearance to inside corner
H=
Clearance to each side of center line extended above meter / regulator assembly
I=
Clearance to service regulator
vent outlet
Clearance to non−mechanical air
supply inlet to building or the combustion air inlet to any other appliance
J=
K=
Clearance to mechanical air supply inlet
L=
Clearance above paved sidewalk or
paved driveway located on public property
M=
1 In
2 In
Clearance under veranda, porch,
deck or balcony
AIR SUPPLY INLET
AREA WHERE TERMINAL
IS NOT PERMITTED
US Installations1
Canadian Installations2
12 inches (305mm) or 12 in. 305mm)
above average snow accumulation.
12 inches (305mm) or 12 in. 305mm)
above average snow accumulation.
4 feet (1.2 m) below or to side of opening;
1 foot (30 cm) above opening
6 inches (152mm) for appliances <10,000
Btuh (3kw), 12 inches (305mm) for
appliances > 10,000 Btuh (3kw) and
<100,000 Btuh (30kw), 36 inches (.9m)
for appliances > 100,000 Btuh (30kw)
* 12"
* 12"
* Equal to or greater than soffit depth.
* Equal to or greater than soffit depth.
* Equal to or greater than soffit depth.
* No minimum to outside corner
* 3 feet (.9m)
* Equal to or greater than soffit depth.
* No minimum to outside corner
* 3 feet (.9m)
* 3 feet (.9m) within a height 15 feet (4.5m) 3 feet (.9m) within a height 15 feet (4.5m)
above the meter / regulator assembly
above the meter / regulator assembly
* 3 feet (.9m)
4 feet (1.2 m) below or to side of opening;
1 foot (30 cm) above opening
3 feet (.9m) above if within 10 feet
(3m) horizontally
7 feet (2.1m)
*12 inches (305mm)
accordance with the current ANSI Z223.1/NFPA 54 Natural Fuel Gas Code
accordance with the current CSA B149.1, Natural Gas and Propane Installation Code
A vent shall not terminate directly above a sidewalk or paved driveway that is located
between two single family dwellings and serves both dwellings.
Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two
sides beneath the floor. Lennox recommends avoiding this location if possible.
FIGURE 27
Page 25
3 feet (.9m)
6 inches (152mm) for appliances <10,000
Btuh (3kw), 12 inches (305mm) for
appliances > 10,000 Btuh (3kw) and
<100,000 Btuh (30kw), 36 inches (.9m)
for appliances > 100,000 Btuh (30kw)
6 feet (1.8m)
7 feet (2.1m)
12 inches (305mm)
*For clearances not specified in ANSI Z223.1/NFPA 54 or CSA B149.1,
clearance will be in accordance with local installation codes and the requirements of the gas supplier and these installation instructions."
VENT TERMINATION CLEARANCES
FOR DIRECT VENT INSTALLATIONS IN THE USA AND CANADA
INSIDE CORNER
DETAIL
G
H
A
D
E
B
L
Fixed
Closed
Operable
F
B
B
C
I
Fixed
Closed
Operable
M
B
K
J
A
B
VENT TERMINAL
A=
Clearance above grade, veranda,
porch, deck or balcony
B=
Clearance to window or
door that may be opened
C=
Clearance to permanently
closed window
D=
Vertical clearance to ventilated soffit
located above the terminal within a
horizontal distance of 2 feet (mm)
from the center line of the terminal
E=
Clearance to unventilated soffit
F=
Clearance to outside corner
G=
Clearance to inside corner
H=
Clearance to each side of center line extended above meter / regulator assembly
I=
Clearance to service regulator
vent outlet
Clearance to non−mechanical air
supply inlet to building or the combustion air inlet to any other appliance
J=
K=
Clearance to mechanical air supply inlet
L=
Clearance above paved sidewalk or
paved driveway located on public property
M=
1 In
2 In
Clearance under veranda, porch,
deck or balcony
AIR SUPPLY INLET
AREA WHERE TERMINAL
IS NOT PERMITTED
US Installations1
Canadian Installations2
12 inches (305mm) or 12 in. 305mm)
above average snow accumulation.
12 inches (305mm) or 12 in. 305mm)
above average snow accumulation.
6 inches (152mm) for appliances <10,000 6 inches (152mm) for appliances <10,000
Btuh (3kw), 9 inches (mm) for appliances
Btuh (3kw), 12 inches (305mm) for
> 10,000 Btuh (3kw) and <50,000 Btuh
appliances > 10,000 Btuh (3kw) and
(15 kw), 12 inches (305mm) for ap<100,000 Btuh (30kw), 36 inches (.9m)
pliances > 50,000 Btuh (15kw)
for appliances > 100,000 Btuh (30kw)
* 12"
* Equal to or greater than soffit depth
* Equal to or greater than soffit depth
* No minimum to outside corner
* 3 feet (.9m)
3 feet (.9m) within a height 15 feet (4.5m)
above the meter / regulator assembly
* 3 feet (.9m)
* 12"
* Equal to or greater than soffit depth
* Equal to or greater than soffit depth
* No minimum to outside corner
* 3 feet (.9m)
3 feet (.9m) within a height 15 feet (4.5m)
above the meter / regulator assembly
3 feet (.9m)
6 inches (152mm) for appliances <10,000 6 inches (152mm) for appliances <10,000
Btuh (3kw), 12 inches (305mm) for
Btuh (3kw), 9 inches (mm) for appliances
> 10,000 Btuh (3kw) and <50,000 Btuh
appliances > 10,000 Btuh (3kw) and
<100,000 Btuh (30kw), 36 inches (.9m)
(15 kw), 12 inches (305mm) for appliances > 50,000 Btuh (15kw)
for appliances > 100,000 Btuh (30kw)
3 feet (.9m) above if within 10 feet
6 feet (1.8m)
(3m) horizontally
7 feet (2.1m)
* 7 feet (2.1m)
*12 inches (305mm)
accordance with the current ANSI Z223.1/NFPA 54 Natural Fuel Gas Code
accordance with the current CSA B149.1, Natural Gas and Propane Installation Code
A vent shall not terminate directly above a sidewalk or paved driveway that is located
between two single family dwellings and serves both dwellings.
*For clearances not specified in ANSI Z223.1/NFPA 54 or CSA B149.1, clearance will be in accordance with local installation codes and the requirements
of the gas supplier and these installation instructions."
Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two
sides beneath the floor. Lennox recommends avoiding this location if possible.
FIGURE 28
Page 26
12 inches (305mm)
Details of Intake and Exhaust Piping Terminations for
Direct Vent Installations
NOTE − In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged to outdoors.
Intake and exhaust pipes may be routed either horizontally
through an outside wall or vertically through the roof. In attic
or closet installations, vertical termination through the roof
is preferred. Figures 29 through 40 show typical terminations.
1. Exhaust and intake exits must be in same pressure
zone. Do not exit one through the roof and one on the
side. Also, do not exit the intake on one side and the
exhaust on another side of the house or structure.
2. Intake and exhaust pipes should be placed as close
together as possible at termination end (refer to illustrations). Maximum separation is 3" (76mm) on roof
terminations and 6" (152mm) on side wall terminations.
3. On roof terminations, the intake piping should terminate straight down using two 90° elbows (See figure
29).
4. Exhaust piping must terminate straight out or up as
shown. A reducer may be required on the exhaust piping at the point where it exits the structure to improve
the velocity of exhaust away from the intake piping.
See table 11.
TABLE 11
FIELD SUPPLIED WALL TERMINATION OR
(15F74) WALL RING TERMINATION KIT
NOTE − FIELD PROVIDED
REDUCER MAY BE
REQUIRED TO ADAPT
LARGER VENT PIPE SIZE
TO TERMINATION
SIZE TERMINATION
PER TABLE 11
D
B
C
1/2" (13mm) ARMAFLEX INSULATION
IN UNCONDITIONED SPACE
*045 and 070
*090
110
135
2" (51mm), 2−1/2" (64mm),
3" (76mm)
3" (76mm)
B
A
C
1−1/2" (38mm)
2" (51mm)
2" (51mm)
2" (51mm)
*ML193UH−045, −070 and −090 units with the flush mount
termination must use the 1 1/2"accelerator supplied with the
kit.
NOTE − Care must be taken to avoid recirculation of exhaust back into intake pipe.
Inches(mm)
3"(76mm) MAX.
A−Minimum clearance
above grade or average
snow accumulation
B−Maximum horizontal
separation between
intake and exhaust
UNCONDITIONED
ATTIC SPACE
1/2" (13mm) FOAM
INSULATION IN
UNCONDITIONED
SPACE
12" (305mm) ABOVE
AVERAGE SNOW
ACCUMULATION
EXTENDED
APPLICATION
See venting table 10 for maximum venting lengths with this
arrangement.
* Use wall support every 24" (610 mm). Use two wall supports if
extension is greater than 24" (610 mm) but less than 48" (1219 mm).
NOTE − One wall support must be 6" (152 mm) from top of each pipe
(intake and exhaust)
SIZE TERMINATION
PIPE PER TABLE 11.
8" (203mm) MIN
D
E
* WALL
SUPPORT
Termination
Pipe Size
Exhaust Pipe Size
STRAIGHT
APPPLICATION
A
EXHAUST PIPE TERMINATION SIZE REDUCTION
ML193UH
MODEL
1/2" (13mm) ARMAFLEX
INSULATION IN UNCONDITIONED SPACE
C−Minimum from
end of exhaust to
inlet of intake
D−Maximum exhaust
pipe length
E−Maximum wall support
distance from top of each
pipe (intake/exhaust)
3" (76mm) OR
2" (51mm) PVC
PROVIDE SUPPORT
FOR INTAKE AND
EXHAUST LINES
2" (51mm)
Vent Pipe
3" (76mm)
Vent Pipe
12" (508MM)
12" (508MM)
6" (152MM)
6" (152MM)
8" (203MM)
8" (203MM)
12" (305MM)
20" (508MM)
6" (152MM)
6" (152MM)
FIGURE 30
DIRECT VENT ROOF TERMINATION KIT
(15F75 or 44J41)
FIGURE 29
Page 27
5. On field supplied terminations for side wall exit, exhaust piping may extend a maximum of 12 inches
(305mm) for 2" PVC and 20 inches (508mm) for 3"
(76mm) PVC beyond the outside wall. Intake piping
should be as short as possible. See figures 30 and 31.
6. On field supplied terminations, a minimum distance
between the end of the exhaust pipe and the end of
the intake pipe without a termination elbow is 8" and a
minimum distance of 6" with a termination elbow. See
figures 30 and 31.
7. If intake and exhaust piping must be run up a side wall
to position above snow accumulation or other obstructions, piping must be supported every 24"
(610mm) as shown in figures 30 and 31. In addition,
close coupled wall termination kits must be extended
for use in this application. See figures 38 and 39.
When exhaust and intake piping must be run up an
outside wall, the exhaust piping must be terminated
with pipe sized per table 11.The intake piping may be
equipped with a 90° elbow turndown. Using turndown
will add 5 feet (1.5m) to the equivalent length of the
pipe.
FIELD SUPPLIED WALL TERMINATION OR
(15F74) WALL RING TERMINATION KIT
With INTAKE ELBOW
NOTE − FIELD PROVIDED
REDUCER MAY BE
REQUIRED TO ADAPT
LARGER VENT PIPE SIZE
TO TERMINATION
1/2" (13mm) ARMAFLEX
INSULATION IN UNCONDITIONED SPACE
SIZE TERMINATION
PER TABLE 11
D
B
C
A
STRAIGHT
APPPLICATION
1/2" (13mm) ARMAFLEX INSULATION
IN UNCONDITIONED SPACE
D
E
* WALL
SUPPORT
8. A multiple furnace installation may use a group of up to
four terminations assembled together horizontally, as
shown in figure 35.
B
A
EXTENDED
APPLICATION
C
2" EXTENSION
FOR 2" PVC PIPE
1" EXTENSION
FOR 3" PVC PIPE
See venting table 10 for maximum venting lengths with this
arrangement.
* Use wall support every 24" (610 mm). Use two wall supports if
extension is greater than 24" (610 mm) but less than 48" (1219 mm).
NOTE − One wall support must be 6" (152 mm) from top of each pipe
(intake and exhaust)
A−Minimum clearance
above grade or average
snow accumulation
B−Maximum horizontal
separation between
intake and exhaust
C−Minimum from
end of exhaust to
inlet of intake
D−Maximum exhaust
pipe length
2" (51mm)
Vent Pipe
3" (76mm)
Vent Pipe
12" (508MM)
12" (508MM)
6" (152MM)
6" (152MM)
6" (152MM)
E−Maximum wall support
distance from top of each
pipe (intake/exhaust)
4’’
FURNACE
INTAKE PIPE
GLUE EXHAUST
END FLUSH INTO
TERMINATION
FLAT SIDE
1−1/2" ACCELERATOR
(all −45, −070 and −090 units)
6" (152MM)
12" (305MM)
20" (508MM)
6" (152MM)
6" (152MM)
FURNACE
EXHAUST
PIPE
FLUSH−MOUNT SIDE WALL TERMINATION
51W11
FIGURE 32
FIGURE 31
Page 28
1 1/2" (38mm) accelerator
provided on 71M80 & 44W92
kits for ML193UH045P24B,
070P24B & 070P36B
EXHAUST
VENT
12” (305mm)
Minimum
Above Average
Snow
Accumulation
SIZE
TERMINATION
PIPE PER
TABLE 11.
INTAKE
AIR
FLASHING
(Not Furnished)
INTAKE
AIR
EXHAUST VENT
Front View
Top View
1/2" (13mm) Foam Insulation
in Unconditioned Space
SHEET METAL STRAP
(Clamp and sheet metal strap
must be field installed to support
the weight of the termination kit.)
CLAMP
FIELD−
PROVIDED
REDUCER MAY
BE REQUIRED
TO ADAPT
LARGER VENT
PIPE SIZE TO
TERMINATION
FIELD−PROVIDED
REDUCER MAY BE REQUIRED
TO ADAPT LARGER VENT
PIPE SIZE TO TERMINATION
FIGURE 36
1−1/2" (38mm) accelerator
provided on 71M80 & 44W92
kits for ML193UH045P24B,
070P24B & 070P36B
INTAKE
AIR
EXHAUST
VENT
6 (152mm) MIN.
DIRECT VENT WALL TERMINATION KIT
(30G28 or 81J20)
FIGURE 33
OUTSIDE
WALL
INTAKE AIR
OUTSIDE WALL
DIRECT VENT CONCENTRIC ROOFTOP TERMINATION
71M80, 69M29 or 60L46 (US)
41W92 or 41W93 (Canada)
FIELD−PROVIDED
REDUCER MAY BE REQUIRED
TO ADAPT LARGER VENT
PIPE SIZE TO TERMINATION
EXHAUST VENT
EXHAUST VENT
Front View
SIZE
TERMINATION
PIPE PER
TABLE 11.
INTAKE
AIR
EXHAUST
VENT
Top View
INTAKE
AIR
INTAKE 12" (305mm) Min.
above grade or
AIR
CLAMP
(Not Furnished)
1/2" (13mm) Foam Insulation
in Unconditioned Space
average snow
accumulation.
FIELD−
PROVIDED
REDUCER MAY
BE REQUIRED
TO ADAPT
LARGER VENT
PIPE SIZE TO
TERMINATION
GRADE
DIRECT VENT CONCENTRIC WALL TERMINATION
71M80, 69M29 or 60L46 (US)
41W92 or 41W93 (Canada)
FIGURE 34
EXHAUST VENT
INTAKE AIR
8" (206mm) MIN.
OUTSIDE WALL
EXHAUST
VENT
12"
(305mm)
5−1/2"
(140mm)
5"
(127mm)
DIRECT VENT WALL TERMINATION KIT
(22G44 or 44J40)
FIGURE 37
INTAKE
AIR
18" MAX.
(457mm)
Front View
EXHAUST VENT
Inches (mm)
12" (305mm) Min.
above grade or
average snow
INTAKE accumulation.
AIR
optional intake elbow
Side View
OPTIONAL VENT TERMINATION FOR MULTIPLE UNIT
INSTALLATION OF DIRECT VENT WALL TERMINATION KIT
(22G44, 44J40, 30G28 or 81J20)
FIGURE 35
Page 29
WALL TERMINATION KITS (CLOSE−COUPLE)
EXTENDED VENT FOR GRADE CLEARANCE
2 inch (51 mm) 22G44 (US)
3 inch (76 mm) 44J40 (US)
If intake and exhaust pipe is less than 12 in. (305 mm)
above snow accumulation or other obstructions, field−
fabricated piping must be installed.
WALL SUPPORT*
FIELD−PROVIDED
REDUCER MAY BE REQUIRED TO ADAPT
LARGER VENT PIPE SIZE TO TERMINATION
8” (203 mm) Min. for 2” (51 mm) & 3” (76 mm) DIA. pipe
between the end of the exhaust pipe and intake pipe
12” (305 mm) Max. for 2” (51 mm) Dia. Exhaust
20” (508 mm) Max. for 3” (76 mm) Dia. Exhaust
12”
(305 mm)
EXHAUST
AIR
6” (152 mm)
Maximum
1/2” (13 mm)
FOAM INSULATION
(Field−Furnished)
INTAKE
AIR
INTAKE
AIR
EXHAUST
AIR
5” (127 mm)
8” (203 mm) Min.
12” (305 mm) Minimum
Above Grade or Average
Snow Accumulation
ÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉ
GRADE
12” (305 mm) Max. for 2” (51 mm) Dia. Exhaust
20” (508 mm) Max. for 3” (76 mm) Dia. Exhaust
12” (305 mm) Minimum
Above Grade or Average
Snow Accumulation
ÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉ
5−1/2”
(140 mm)
GRADE
*Use wall support every 24" (610). Use two supports if
extension is greater than 24" but less than 48".
FIGURE 38
WALL TERMINATION KITS (CLOSE−COUPLE)
EXTENDED VENT FOR GRADE CLEARANCE
2 inch (51 mm) 30G28 (WTK Canada)
3 inch (76 mm) 81J20 (WTK Canada)
See Installation Instructions for additional information.
If intake and exhaust pipe is less than 12 in. (305 mm)
above snow accumulation or other obstructions, field−
fabricated piping must be installed.
WALL SUPPORT*
FIELD−PROVIDED
REDUCER MAY BE REQUIRED TO ADAPT
LARGER VENT PIPE SIZE TO TERMINATION
12” (305 mm) Max. for 2” (51 mm) Dia. Exhaust
20” (508 mm) Max. for 3” (76 mm) Dia. Exhaust
12”
(305 mm)
EXHAUST
AIR
6” (152 mm)
Maximum
1/2” (13 mm)
FOAM INSULATION
(Field−Furnished)
INTAKE
AIR
6” (152 mm)
Minimum
INTAKE
AIR
EXHAUST
AIR
5” (127 mm)
6” (152 mm)
Minimum
12” (305 mm) Minimum
Above Grade or Average
Snow Accumulation
12” (305 mm) Minimum
Above Grade or Average
Snow Accumulation
ÉÉÉÉÉÉÉÉÉÉÉÉ ÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉ ÉÉÉÉÉÉÉÉÉÉÉÉ
GRADE
12” (305 mm) Max. for 2” (51 mm) Dia. Exhaust
20” (508 mm) Max. for 3” (76 mm) Dia. Exhaust
*Use wall support every 24" (610). Use two supports if
extension is greater than 24" but less than 48".
FIGURE 39
Page 30
5−1/2”
(140 mm)
GRADE
ML193UH DIRECT VENT APPLICATION
USING EXISTING CHIMNEY
3"−8"
(76mm−203mm)
8" − 12"
(203mm − 305mm)
Minimum 12" (305MM)
above chimney top
plate or average snow
accumulation
12" (305mm) MAX. for 2" (51mm)
20" (508mm) MAX. for 3" (76mm)
1/2" (13mm) ARMAFLEX
INSULATION IN
UNCONDITIONED SPACE
STRAIGHT−CUT OR
ANGLE−CUT IN DIRECTION
OF ROOF SLOPE *
FIELD−PROVIDED
REDUCER MAY
BE REQUIRED TO
ADAPT LARGER
VENT PIPE SIZE
TO TERMINATION
SIZE TERMINATION
PIPE PER TABLE 11.
EXHAUST VENT
1/2" (13mm)
WEATHERPROOF
INSULATION
SHOULDER OF FITTINGS
PROVIDE SUPPORT
OF PIPE ON TOP PLATE
INTAKE PIPE
INSULATION (optional)
SHEET
METAL TOP
PLATE
3" − 8"
(76mm−
203mm)
12" MIN.
(305mm)
Above Grade or
average snow
accumulation
NON−DIRECT VENT FIELD SUPPLIED WALL TERMINATION OR
(15F74) WALL TERMINATION KIT
EXTERIOR
PORTION OF
CHIMNEY
*SIZE TERMINATION
PIPE PER TABLE 11.
NOTE − Do not discharge exhaust gases directly into any chimney or vent stack. If vertical discharge through an existing unused chimney or stack is required, insert piping
inside chimney until the pipe open end is above top of chimney and terminate as illustrated. In any exterior portion of chimney, the exhaust vent must be insulated.
FIGURE 40
Details of Exhaust Piping Terminations for Non-Direct
Vent Applications
Exhaust pipes may be routed either horizontally through an
outside wall or vertically through the roof. In attic or closet
installations, vertical termination through the roof is preferred. Figures 41 through 44 show typical terminations.
1. Exhaust piping must terminate straight out or up as
shown. The termination pipe must be sized as listed in
table 11.The specified pipe size ensures proper
velocity required to move the exhaust gases away
from the building.
2. On field supplied terminations for side wall exit, exhaust piping may extend a maximum of 12 inches
(305mm) for 2" PVC and 20 inches (508mm) for 3"
(76mm) PVC beyond the outside wall. See figure 42.
FIGURE 42
3. If exhaust piping must be run up a side wall to position
above snow accumulation or other obstructions, piping must be supported every 24 inches (610mm) as
shown in figure 43. When exhaust piping must be run
up an outside wall, any reduction in exhaust pipe size
must be done after the final elbow.
12" (305mm) MAX. for 2" (51mm)
20" (508mm) MAX. for 3" (76mm)
UNCONDITIONED
SPACE
6" (152mm)
Max
*WALL SUPPORT
OUTSIDE WALL
FIELD−PROVIDED
REDUCER MAY BE
REQUIRED TO
ADAPT LARGER
VENT PIPE SIZE TO
TERMINATION
SIZE TERMINATION
PIPE PER
TABLE 11.
12" (305mm)
ABOVE GRADE OR
AVERAGE SNOW
ACCUMULATION
1/2" (13mm) FOAM
INSULATION IN
UNCONDITIONED
SPACE
1/2" (13mm) FOAM
INSULATION
NON−DIRECT VENT FIELD SUPPLIED WALL TERMINATION
EXTENDED OR (15F74) WALL TERMINATION VENT PIPE
EXTENDED
*Use wall support every 24" (610). Use two supports if extension is
greater than 24" but less than 48".
SIZE TERMINATION
PIPE PER TABLE
11.
FIGURE 43
1/2" (13mm) FOAM
INSULATION
3" (76mm) OR
2" (51mm) PVC
PVC REDUCER
ALTERNATE
INTAKE PIPE
INSULATE
TO FORM
SEAL
12" (305mm)
ABOVE AVE.
SNOW
ACCUMULATION
1/2" (13mm)
ARMAFLEX
INSULATION
UNCONDITIONED
ATTIC SPACE
PROVIDE SUPPORT
FOR EXHAUST LINES
NON−DIRECT VENT ROOF TERMINATION KIT
(15F75 or 44J41)
FIGURE 41
Page 31
1 − Determine which side condensate piping will exit the
unit, location of trap, field−provided fittings and length of
PVC pipe required to reach available drain.
ML193UH NON−DIRECT VENT APPLICATION
USING EXISTING CHIMNEY
SIZE TERMINATION
PIPE PER TABLE 11.
STRAIGHT−CUT OR
ANGLE−CUT IN DIRECTION
OF ROOF SLOPE
2 − Remove plug (figure 45) from the cold end header box
at the appropriate location on the side of the unit. Install
field−provided 1/2 NPT male fitting into cold end header box. Use Teflon tape or appropriate pipe dope.
3 − Install the cap over the clean out opening at the base of
the trap. Secure with clamp. See figure 49.
4 − Install drain trap using appropriate PVC fittings, glue
all joints. Glue the provided drain trap as shown in figure 49. Route the condensate line to an open drain.
Condensate line must maintain a 1/4" downward slope
from the furnace to the drain.
EXHAUST VENT
1/2" (13mm)
WEATHERPROOF
INSULATION
Minimum 12" (305MM)
above chimney top
plate or average snow
accumulation
SHOULDER OF FITTINGS
PROVIDE SUPPORT
OF PIPE ON TOP PLATE
SHEET
METAL TOP
PLATE
INSULATE
TO FORM
SEAL
EXTERIOR
PORTION OF
CHIMNEY
CAUTION
NOTE − Do not discharge exhaust gases directly into any chimney or vent stack. If vertical discharge through an existing unused chimney or stack is required, insert piping
inside chimney until the pipe open end is above top of chimney and terminate as illustrated. In any exterior portion of chimney, the exhaust vent must be insulated.
FIGURE 44
Condensate Piping
This unit is designed for either right- or left-side exit of condensate piping in upflow applications. In horizontal applications, the condensate trap must extend below the unit. An
8" service clearance is required for the condensate trap.
Refer to figure 45 for condensate trap locations.
NOTE − If necessary the condensate trap may be installed
up to 5´ away from the furnace. Use PVC pipe to connect
trap to furnace condensate outlet. Piping from furnace
must slope down a minimum of 1/4" per ft. toward trap.
CONDENSATE TRAP AND PLUG LOCATIONS
(Unit shown in upflow position)
Do not use copper tubing or existing copper condensate lines for drain line.
5 − If unit will be started immediately upon completion of
installation, prime trap per procedure outlined in Unit
Start−Up section.
Condensate line must slope downward away from the
trap to drain. If drain level is above condensate trap,
condensate pump must be used. Condensate drain
line should be routed within the conditioned space to
avoid freezing of condensate and blockage of drain
line. If this is not possible, a heat cable kit may be used
on the condensate trap and line. Heating cable kit is
available from Lennox in various lengths; 6 ft. (1.8m) −
kit no. 26K68; 24 ft. (7.3m) − kit no. 26K69; and 50 ft.
(15.2m) − kit no. 26K70.
Trap
(same on
right side)
CONDENSATE TRAP LOCATIONS
(Unit shown in upflow position with remote trap)
Field−Provided Vent
Min. 1" Above Condensate
Drain Connection
1−1/2 in.
Plug
(same on left side)
1" Min.
5’ max.
*PVC Pipe Only
Trap can be installed a
maximum 5’ from furnace.
NOTE − In upflow applications where side return
air filter is installed on same side as the condensate trap, filter rack must be installed beyond
condensate trap or trap must be re−located to
avoid interference.
FIGURE 45
To Drain
*Piping from furnace must slope down a minimum
of 1/4" per ft. toward trap.
FIGURE 46
Page 32
CAUTION
A separate drain line must be run to the drain from
the condensate trap. DO NOT connect the condensate trap drain into the drain line from the evaporator
coil.
ML193UH with Cooling Coil
Condensate trap and
evaporator coil must
drain separately as
shown.
Field−Provided
Vent
Drain
FIGURE 47
CONDENSATE TRAP LOCATIONS
(Unit shown in horizontal right−hand discharge position)
Field−Provided Vent
Must Not Interfere With
Service To The Unit
4−1/2"
Min.
5’ max.
*PVC Pipe Only
to drain
*Piping from furnace must slope down a minimum of 1/4" per ft. toward trap.
FIGURE 48
Page 33
TRAP / DRAIN ASSEMBLY USING 1/2" PVC OR 3/4" PVC
OPTIONAL Condensate Drain Connection
Adapter 1/2 inch slip X
1/2 inch mpt (Not Furnished)
Adapter 1/2 inch slip X
1/2 inch mpt (Not Furnished)
90° Street Elbow
1/2 inch PVC
(Not Furnished)
1 (25) Minimum
Vent
5 Feet
Maximum
Above Top of Condensate Drain
Connection In Unit
90° Elbow 1/2 inch PVC
(Not Furnished)
Condensate Drain
Connection In Unit
OPTIONAL Drain Piping
1/2 inch PVC Pipe
(Not Furnished)
1/2 inch PVC Pipe
(Not Furnished)
Coupling 1/2 inch slip X slip
(Not Furnished)
Drain Assembly for 1/2 inch Drain Pipe
1/2 inch PVC Pipe
(Not Furnished)
90° Street Elbow
1/2 inch PVC
(Not Furnished)
To
Drain
Condensate Drain
Connection In Unit
To
Drain
Drain Trap
Assembly
(Furnished)
90° Elbow
1/2 inch PVC
(Not Furnished)
Drain Assembly for 3/4 inch Drain Pipe
Drain Trap
Clean Out
90° Elbow
3/4 inch PVC
(Not Furnished)
To
Drain
90° Elbow
3/4 inch PVC
(Not Furnished)
To Coupling 3/4 inch slip X slip
Drain
(Not Furnished)
Drain Trap Assembly with 1/2 inch Piping
Drain Trap Assembly with 3/4 inch Piping
1 inch (25mm) Minimum Above Top of
Condensate Drain Connection In Unit
1 inch (25mm) Minimum Above Top of
Condensate Drain Connection In Unit
Vent
Drain Trap Assembly
(Furnished)
Vent
7
(178)
Condensate Drain
Connection In Unit
Condensate Drain
Connection In Unit
To
Drain
To
Drain
FIGURE 49
Page 34
III−START-UP
A−Preliminary and Seasonal Checks
1 − Inspect electrical wiring, both field and factory installed
for loose connections. Tighten as required.
2 − Check voltage at disconnect switch. Voltage must be within range listed on the nameplate. If not, consult the power
company and have voltage condition corrected before starting unit.
3 − Inspect condition of condensate traps and drain assembly. Disassemble and clean seasonally.
B−Heating Start-Up
BEFORE LIGHTING the unit, smell all around the furnace area for gas. Be sure to smell next to the floor because some gas is heavier than air and will settle on the
floor.
The gas valve on the ML193UH is equipped with a gas
control switch. Use only your hand to move the switch.
Never use tools. If the the switch will not move by hand,
replace the valve. Do not try to repair it. Force or attempted repair may result in a fire or explosion.
Placing the furnace into operation:
ML193UH units are equipped with a SureLight ignition
system. Do not attempt to manually light burners on this
furnace. Each time the thermostat calls for heat, the
burners will automatically light The ignitor does not get
hot when there is no call for heat on units with SureLightt
ignition system.
Priming Condensate Trap
The condensate trap should be primed with water prior to
start−up to ensure proper condensate drainage. Either
pour 10 fl. oz. (300 ml) of water into the trap, or follow
these steps to prime the trap:
1 − Follow the lighting instructions to place the unit into operation.
2 − Set the thermostat to initiate a heating demand.
3 − Allow the burners to fire for approximately 3 minutes.
4 − Adjust the thermostat to deactivate the heating demand.
5 − Wait for the combustion air inducer to stop. Set the
thermostat to initiate a heating demand and again allow the burners to fire for approximately 3 minutes.
6 − Adjust the thermostat to deactivate the heating demand and again wait for the combustion air inducer to
stop. At this point, the trap should be primed with sufficient water to ensure proper condensate drain operation.
WARNING
If you do not follow these instructions exactly, a fire
or explosion may result causing property damage,
personal injury or death.
Gas Valve Operation (Figure 50)
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. See figure 50.
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 instructions. If you do not smell gas go to next step.
8 − Move gas valve switch to ON. See figure 50.
MANIFOLD
PRESSURE
ADJUSTMENT
SCREW
MANIFOLD
PRESSURE
OUTLET
INLET
PRESSURE
PORT
GAS VALVE SHOWN IN ON POSITION
FIGURE 50
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 your service technician or 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.
5 − Replace the upper access panel.
Failure To Operate
If the unit fails to operate, check the following:
1 − Is the thermostat calling for heat?
2 − Are access panels securely in place?
3 − Is the main disconnect switch closed?
4 − Is there a blown fuse or tripped breaker?
5 − Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit control to shut the unit off.
6 − Is gas turned on at the meter?
7 − Is the manual main shut-off valve open?
8 − Is the internal manual shut-off valve open?
9 − Is the unit ignition system in lockout? If the unit locks out
again, inspect the unit for blockages.
Page 35
IV−HEATING SYSTEM SERVICE CHECKS
A−C.S.A. Certification
D−Testing Gas Supply Pressure
Gas Flow (Approximate)
All units are C.S.A. design certified without modifications.
Refer to the ML193UH Operation and Installation Instruction Manual Information.
TABLE 12
GAS METER CLOCKING CHART
Seconds for One Revolution
Natural
LP
ML193
Unit
1 cu ft
2 cu ft
1 cu ft
2 cu ft
Dial
Dial
Dial
DIAL
−045
80
160
200
400
−070
55
110
136
272
−090
41
82
102
204
−110
33
66
82
164
−135
27
54
68
136
B−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. The flexible connector can then
be added between the black iron pipe and the gas
supply line.
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
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.
When pressure testing gas lines, the gas valve must be disconnected and isolated. Gas valves can be damaged if
subjected to more than 0.5psig (14" W.C.). See figure 51.
1/8" N.P.T. PLUGGED TAP
LP−2500 btu/cu ft
Furnace should operate at least 5 minutes before checking gas flow. Determine time in seconds for two revolutions of gas through the meter. (Two revolutions assures a
more accurate time.) Divide by two and compare to time
in table 12 below. If manifold pressure matches table 13
and rate is incorrect, check gas orifices for proper size and
restriction. Remove temporary gas meter if installed.
NOTE − To obtain accurate reading, shut off all other gas
appliances connected to meter.
IMPORTANT
MANUAL MAIN SHUT−OFF
VALVE WILL NOT HOLD
NORMAL TEST PRESSURE
Natural−1000 btu/cu ft
FURNACE
Supply Pressure Measurement
When testing supply gas pressure, use the 1/8" N.P.T.
plugged tap or pressure post located on the gas valve to
facilitate test gauge connection. See figure 50. Check gas
line pressure with unit firing at maximum rate. Low pressure may result in erratic operation or underfire. High pressure can result in permanent damage to gas valve or overfire.
On multiple unit installations, each unit should be checked
separately, with and without units operating. Supply pressure must fall within range listed in table 13.
ISOLATE
GAS VALVE
Manifold Pressure Measurement
CAP
FIGURE 51
When checking piping connections for gas leaks, use preferred means. Kitchen detergents can cause harmful corrosion 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.
WARNING
Do not use matches, candles, flame or any other
source of ignition to check for gas leaks.
1 − Remove the threaded plug from the outlet side of the
gas valve and install a field−provided barbed fitting.
Connect to a manometer to measure manifold pressure.
2 − Start unit and allow 5 minutes for unit to reach steady
state.
3 − While waiting for the unit to stabilize, observe the
flame. Flame should be stable and should not lift from
burner. Natural gas should burn blue.
4 − After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in table
13.
NOTE − Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to remove
barbed fitting and replace threaded plug.
Page 36
TABLE 13
Supply Line and Manifold Pressure (inches w.c.)
Unit
Fuel
Manifold Pressure
Line
Pressure
All
Nat. Gas
3.5
4.5 − 10.4
All
L.P. Gas
10.0
11.0 − 13.0
F−High Altitude
NOTE − A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit
installation instruction for the conversion procedure.
E−Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking combustion. Take combustion sample beyond the flue outlet
and compare to the tables below.
TABLE 14
ML193
CO2% For Nat CO2% For L.P.
Unit
−045
−070
−090
7.2 − 7.9
8.6 − 9.3
−110
−135
NOTE − In Canada, certification for installations at elevations over 4500 feet (1372 m) is the jurisdiction of local authorities.
ML193UH units require no manifold pressure adjustments
for operation at altitudes up to 10,000 feet (3048 m) above
sea level. Units installed at altitude of 4501 − 10,000 feet
(1373 to 3048m) require a pressure switch change which
can be ordered separately. Table 15 lists conversion kit and
pressure switch requirements at varying altitudes.
The combustion air pressure switch is factory−set and requires no adjustment.
NOTE − A natural to LP/propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit
installation instruction for the conversion procedure.
The maximum carbon monoxide reading should not exceed 50 ppm.
TABLE 15
Conversion Kit and Pressure Switch Requirements at Varying Altitudes
ML193
Unit
Natural to
LP/Propane
High Altitude
Natural Burner
Orifice Kit
LP/Propane to
Natural
0 − 7500 ft
(0 − 2286m)
7501 − 10,000 ft
(2286 − 3038m)
0 − 7500 ft
(0 − 2286m)
4501 − 7500 ft
(1373 − 2286m)
7501 −10,000 ft
(2286 − 3048m)
*69W73
73W37
*73W81
74W90
74W91
High Altitude Pressure Switch
−045
−070
−090
−110
−135
* Conversion requires installation of a gas valve manifold spring which is provided with the gas conversion kit.
Pressure switch is factory set. No adjustment necessary. All models use the factory−installed pressure switch from 0−4500 feet (0−1370 m).
Page 37
G−Flame Signal
A transducer (Part #78H5401 available from Lennox Repair
Parts) is required to measure flame signal if meter used will not
read a low micro amp signal. Seefigure52. The transducer
converts microamps to volts on a 1:1 conversion. Flame signal
is shown in table 16. A digital readout meter must be used.
The transducer plugs into most meters.
TABLE 16
Normal Flame Signal
1.50 Microamps
Low Flame Signal
1.40 Microamps
Drop Out Signal
= 0.50 Microamps
To Measure Flame Signal:
1 − Set the volt meter to the DC voltage scale. Insert
transducer into the VDC and common inputs. Observe correct polarities. Failure to do so results in
negative (−) values.
2 − Turn off supply voltage to control.
3 − Disconnect integrated control flame sensor wire from
the flame sensor.
4 − Connect (−) lead of the transducer to flame sensor.
5 − Connect (+) lead of transducer to the integrated control
sensor wire.
6 − Turn supply voltage on and close thermostat contacts to
cycle system.
7 − When main burners are in operation for two minutes, take
reading. Remember 1 DC volt = 1 DC microamp.
NOTE−MUST USE DIGITAL METER
SET DIAL TO
MEASURE VDC
(+)
(+) TO
INTEGRATED
CONTROL
SENSOR
WIRE
(−)
(−) TO
FLAME
SENSOR
TRANSDUCER
PART #78H5401
RED COLLAR
INDICATES
POSITIVE
LEAD
FIGURE 52
V−TYPICAL OPERATING CHARACTERISTICS
A−Blower Operation and Adjustment
1 − Blower operation is dependent on thermostat control
system.
2 − Generally, blower operation is set at thermostat subbase 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
Temperature rise depends on unit input, 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.
To Measure Temperature Rise:
1 − Place plenum thermometers in the supply and return air
plenums. Locate supply air thermometer in the first horizontal run of the plenum where it will not pick up radiant
heat from the heat exchanger.
2 − Set thermostat for heat call.
3 − After plenum thermometers have reached their highest and steadiest readings, subtract the two readings.
The difference should be in the range listed on the unit
rating plate. If the temperature is too low, decrease
blower speed. If temperature is too high, first check the
firing rate. Provided the firing rate is acceptable, increase blower speed to reduce temperature.
To change existing heat tap, turn off power then switch out
speed tap with tap connected to "PARK" . See unit diagram
for blower motor tap colors for each speed.
C−External Static Pressure
1 − Tap locations shown in figure 53.
STATIC PRESSURE TEST
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 perma−
gum. Connect the zero end
FIGURE 53
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 blower motor speed to deliver the air desired according to
the job requirements.
4 − External static pressure drop must not be more than
0.5" W.C. in the heating mode and must not exceed
0.6" W.C in the cooling mode.
5 − Seal the hole when the check is complete.
Page 38
VI−MAINTENANCE
WARNING
ELECTRICAL SHOCK, FIRE,
OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly could result
in dangerous operation, serious injury, death or
property damage.
Improper servicing could result in dangerous operation, serious injury, death, or property damage.
Before servicing, disconnect all electrical power to
furnace.
When servicing controls, label all wires prior to disconnecting. Take care to reconnect wires correctly.
Verify proper operation after servicing.
At the beginning of each heating season, system should be
checked as follows by a qualified service technician:
Blower
Check the blower wheel for debris and clean if necessary.
The blower motors are prelubricated for extended bearing
life. No further lubrication is needed.
WARNING
The blower access panel must be securely in place
when the blower and burners are operating. Gas
fumes, which could contain carbon monoxide, can
be drawn into living space resulting in personal injury or death.
Filters
All air filters are installed external to the unit. Filters should
be inspected monthly. Clean or replace the filters when
necessary to ensure proper furnace operation. Table 17
lists recommended filter sizes.
TABLE 17
Filter Size
Furnace
Cabinet Width
Side Return
Bottom Return
17−1/2"
16 X 25 X 1 (1)
16 X 25 X 1 (1)
21"
16 X 25 X 1 (1)
20 X 25 X 1 (1)
24−1/2"
16 X 25 X 1 (2)
24 X 25 X 1 (1)
Exhaust and air intake pipes
Check the exhaust and air intake pipes and all connections
for tightness and to make sure there is no blockage.
NOTE − After any heavy snow, ice or frozen fog event the
furnace vent pipes may become restricted. Always check
the vent system and remove any snow or ice that may be
obstructing the plastic intake or exhaust pipes.
Electrical
1 − Check all wiring for loose connections.
2 − Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 120VAC + 10%
3 − Check amp−draw on the blower motor with blower access panel in place.
Motor Nameplate__________Actual__________
Winterizing and Condensate Trap Care
1 − Turn off power to the furnace.
2 − Have a shallow pan ready to empty condensate water.
3 − Remove the clean out cap from the condensate trap
and empty water. Inspect the trap then reinstall the
clean out cap.
Cleaning Heat Exchanger
If cleaning the heat exchanger becomes necessary, follow
the below procedures and refer to figure 1 when disassembling unit. Use papers or protective covering in front of furnace while removing heat exchanger assembly.
1 − Turn off electrical and gas supplies to the furnace.
2 − Remove the burner access panel.
3 − Mark all gas valve wires and disconnect them from
valve.
4 − Remove gas supply line connected to gas valve.
5 − Remove sensor wire from flame sensor. Disconnect
2-pin plug from the ignitor.
6 − Disconnect wires from flame roll−out switches.
7 − Remove four burner assembly screws at the vestibule
panel and remove gas valve /manifold and burner box
as a single unit.
NOTE − If necessary, clean burners at this time. Follow
procedures outlined in Burner Cleaning section.
9 − Remove the clean−out cap on trap and drain. Replace
cap.
10 − Disconnect condensate drain line from the condensate trap. Remove condensate trap (it may be necessary to cut drain pipe). Remove the 1/2" NPT fitting
from the cold end header box. Disconnect drain tubes
from cold end header collector box.
11 − Disconnect condensate drain tubes from flue collar.
Remove screws that secures flue collar in place. Remove flue collar. It may be necessary to cut the exiting
exhaust pipe for removal of the fitting.
12 − Loosen two clamps from flexible no−hub exhaust collar.
13 − Disconnect the 2-pin plug from the combustion air inducer. Remove screws which secure combustion air
inducer to collector box. Remove combustion air inducer assembly. Remove ground wire.
14 − Mark and disconnect all combustion air pressure tubing from cold end header collector box.
15 − Mark and remove wires from pressure switch. Remove pressure switch. Keep tubing attached to pressure switch.
16 − Remove electrical junction box from the side of the furnace.
17 − Remove blower access panel.
18 − Mark and disconnect any remaining wiring to heating
compartment components. Disengage strain relief
bushing and pull wiring and bushing through the hole in
the blower deck.
19 − Remove the primary limit from the vestibule panel.
Page 39
20 − Remove top cap screws to allow top cap to be tilted upward to allow clearance for removing heat exchanger.
21 − Remove two screws from the front cabinet flange at
the blower deck. Spread cabinet sides slightly to allow
clearance for removal of heat exchanger.
22 − Remove screws along vestibule sides and bottom
which secure vestibule panel and heat exchanger assembly to cabinet. Remove two screws from blower
rails which secure bottom heat exchanger flange. Remove heat exchanger from furnace cabinet.
23 − Back wash heat exchanger with soapy water solution
or steam. If steam is used it must be below 275°F
(135°C) .
24 − Thoroughly rinse and drain the heat exchanger. Soap
solutions can be corrosive. Take care to rinse entire
assembly.
25 − Reinstall heat exchanger into cabinet making sure that
the rear baffle of the heat exchanger assembly is
nested under the support located at the rear of the
cabinet. Remove the indoor blower to view this area
through the blower opening.
26 − Re-secure the supporting screws along the vestibule
sides.
27 − Reinstall blower assembly and reinstall two screws
through rails.
28 − Reinstall cabinet screws on front flange at blower
deck.
29 − Reinstall screws securing top cap.
30 − Reinstall the primary limit on the vestibule panel.
31 − Route heating component wiring through hole in blower deck and reinsert strain relief bushing.
32 − Reinstall pressure switch and reconnect pressure
switch wiring.
33 − Carefully connect combustion air pressure switch
hosing from pressure switch to proper stubs on cold
end header collector box.
34 − Reinstall 1/2" NPT (if removed) in the cold end header
box. Reconnect drain tubing to collector box.
35 − Reinstall condensate trap pipe. Reconnect condensate drain line to the condensate trap.
36 − Reinstall electrical junction box.
37− Reinstall the combustion air inducer and flexible no
hub connector. Reconnect the 2−pin plug to the wire
harness.
39 − Reconnect drain tubes between flue collar and cold
end header box.
40 − Secure burner assembly to vestibule panel using four
existing screws. Burners are self aligning to center
of clam shells.
41 − Reconnect gas supply line to gas valve.
42 − Reconnect flame roll−out switch wires.
43 − Reconnect sensor wire and reconnect 2−pin plug from
ignitor.
44 − Reconnect wires to gas valve.
45 − Replace the blower compartment access panel.
46 − Refer to instruction on verifying gas and electrical connections when re−establishing supplies.
47 − Follow lighting instructions to light and operate furnace for 5 minutes to ensure that heat exchanger is
clean and dry and that furnace is operating properly.
48 − Replace heating compartment access panel.
Cleaning the Burner Assembly
1 − Turn off gas and electrical power to the furnace. Remove heating compartment access panel.
2 − Disconnect the gas supply line from the gas valve.
3 − Disconnect and label wires from gas valve.
4 − Disconnect ignitor wiring at 2 circuit plug.
5 − Disconnect and label wires from rollout switch.
6 − Disconnect and label flame sensor wire.
7 − Disconnect and label ground wire from burner/manifold assembly.
8 − Remove four screws that secures burner/manifold assembly to vestibule. Remove the assembly and make
note not to allow ignitor plate to dislodge from the assembly.
9 − Gently clean the face of the burners using the soft
brush attachment on a vacuum cleaner. Visually inspect the inside of the burners and crossovers for any
blockage caused by foreign matter. Remove any
blockage
10 − Reinstall the burner/manifold assembly using the existing four screws. Burners are self aligning to center of clam shells.
11 − Reconnect ground wire.
12 − Reconnect flame sensor wire.
13 − Reconnect rollout switch wires.
14 − Reconnect ignitor wires.
15 − Reconnect gas valve wires.
16 − Reconnect gas supply line to gas valve.
17 − Refer to instructions on verifying gas and electrical
connections when re−establishing supplies.
18 − Follow instructions to place furnace in operation. Run
furnace 5 minutes to ensure burners are clean and operating correctly.
19 − Replace heating compartment access panel.
Page 40
VII−WIRING DIAGRAM AND SEQUENCE OF OPERATION
1 − When there is a call for heat, W1 of the thermostat energizes W of the furnace control with 24VAC.
2 − S10 primary limit switch and S47 rollout switch are
closed. Call for heat can continue.
3 − The integrated control (A92) energizes combustion air
inducer B6. Combustion air inducer runs until S18
combustion air prove switch closes (switch must close
within 2−1/2 minutes or control goes into 5 minute
Watchguard Pressure Switch delay). Once S18
closes, a 15−second pre−purge follows.
4 − The integrated control (A92) energizes ignitor. A
20−second warm−up period begins.
5 − Gas valve opens for a 4−second trial for ignition
6 − Flame is sensed, gas valve remains open for the heat
call.
7 − After 45−second delay, the integrated control (A92) energizes indoor blower B3.
8 − When heat demand is satisfied, W1 of the indoor thermostat de−energizes W of the integrated control which
de−energizes the gas valve. Combustion air inducer
B6 continues a 5−second post−purge period, and indoor blower B3 completes a selected OFF time delay.
Page 41
Sequence of Operation Flow Chart
HEATING SEQUENCE OF OPERATION
ABNORMAL HEATING MODE
NORMAL HEATING MODE
POWER ON
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER DELAY OFF.
LED #1 ON
LED #2 ON
(RESET CONTROL BY TURNING MAIN POWER OFF.)
NO
CONTROL SELF−CHECK OKAY?
YES
NO
POLARITY REVERSED.
LED #1 −− FAST FLASH
LED #2 −− SLOW FLASH
NO
IMPROPER GROUND.
LED #1 −− ALTERNATING FAST FLASH
LED #2 −− ALTERNATING FAST FLASH
IS POLARITY CORRECT?
YES
IS THERE A PROPER GROUND?
YES
NO
LEDs SIGNAL FAST ALTERNATING FLASH.
CONTROL WILL NOT RESPOND TO A CALL FOR
HEATING UNTIL VOLTAGE RISES ABOVE 95 VOLTS.
IS VOLTAGE
ABOVE 90 VOLTS?
YES
ROLLOUT SWITCH CLOSED?
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER ON.
LED #1 −− ON. LED #2 −− SLOW FLASH.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES
AND POWER IS RESET OR T’STAT IS INTERRUPTED
FOR MINIMUM OF 1 SECOND.
NO
YES
BURNER OFF?
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER ON HEATING SPEED.
LED #1 −− SLOW FLASH
LED #2 −− OFF
NO
(Flame sensed without gas valve energized)
YES
NO
NORMAL OPERATION:
LED #1 −− SLOW FLASH
LED #2 −− SLOW FLASH
YES
THERMOSTAT CALLS FOR HEAT:
LED #1 −− FAST FLASH
LED #2 −− FAST FLASH
NO
YES
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER ON
LED #1 SLOW FLASH RATE
LED #2 −− ON
PRIMARY LIMIT SWITCH. CLOSED?
YES
NO
IS COMBUSTION AIR
PRESSURE SWITCH OPEN?
YES
GAS VALVE OFF.
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY.
LED #1 OFF
LED #2 SLOW FLASH
(Sequence holds until pressure switch
opens or thermostat resets control.)
IS COMBUSTION AIR INDUCER
ENERGIZED?
YES
HAS COMBUSTION AIR PRESSURE
SWITCH CLOSED IN 2.5 MINUTES?
NO
YES
CONTINUED NEXT PAGE
Page 42
PRESSURE SWITCH IS IN WATCHGUARD MODE.
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY.
LED #1 −− OFF. LED #2 −− SLOW FLASH.
IS 5-MINUTE RESET PERIOD COMPLETE?
YES
HEATING SEQUENCE CONTINUED
NORMAL HEATING MODE
ABNORMAL HEATING MODE
15-SECOND COMBUSTION AIR INDUCER PREPURGE
INITIATED BY CLOSED PRESSURE SWITCH.
YES
NO
IS VOLTAGE ABOVE 90 VOLTS?
IGNITOR WARM-UP −− 20 SECONDS.
YES
NO
YES
4-SECOND TRIAL FOR IGNITION.
GAS VALVE OPENS. IGNITOR ENERGIZED FOR
FIRST 3 SECONDS OF THE TRIAL.
YES
FLAME STABILIZATION PERIOD.
4 SECONDS
LEDS SIGNAL
ALTERNATING
FAST FLASH UNTIL
VOLTAGE IS ABOVE
95 VOLTS, THEN
RESTARTS HEATING
SEQUENCE.
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER OFF.
NO HAS CONTROL FAILED TO SENSE FLAME FOR
FIVE CONSECUTIVE TRIES DURING A SINGLE
HEAT DEMAND?
FLAME RECTIFICATION CURRENT
CHECK. CAN FLAME BE PROVEN WITHIN
4 SECONDS AFTER GAS VALVE OPENS?
(0.5 microamps)
NO
YES
WATCHGUARD MODE. GAS VALVE OFF.
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY
LEDs SIGNAL WATCHGUARD FAILURE CODE.
IS 60-MINUTE RESET PERIOD COMPLETE?
YES
YES
NO
NO
HAS CONTROL RESET IGNITION
SEQUENCE FOUR TIMES?
FLAME PRESENT?
YES
YES
LIMIT SWITCH WATCHGUARD
MODE. GAS VALVE, COMB. AIR
INDUCER AND INDOOR BLOWER OFF. LEDs SIGNAL LIMIT
SWITCH OPEN UNTIL MAIN
POWER IS
INTERRUPTED OR
GAS VALVE DE−ENERGIZED.
T’STAT IS CYCLED
COMBUSTION AIR INDUCER DE−ENERGIZED.
OFF/ON FOR 1 SEC.
NO INDOOR BLOWER ON UNTIL SWITCH CLOSES.
MINIMUM. 60−MINUTE
LED #1 −− SLOW FLASH. LED #2 −− ON.
WATCHGUARD PEIS LIMIT SWITCH CLOSED?
RIOD STARTS AT
YES
TIME LIMIT CLOSES.
IS 60−MIN. PERIOD
YES
HAS PRIMARY / SECONDARY
COMPLETE?
LIMIT RESET TIME
NO
FLAME SIGNAL 1.5 MICROAMPS OR GREATER?
YES
INDOOR BLOWER ON
AFTER 30−SECOND DELAY
YES
PRIMARY AND SECONDARY LIMIT
SWITCHES CLOSED?
YES
LOW FLAME SIGNAL
(Does not affect operation of control)
LED #1 −− SLOW FLASH
LED #2 −− FAST FLASH
EXCEEDED 3 MINUTES?
NO
ROLLOUT SWITCH CLOSED?
YES
COMBUSTION AIR PRESSURE
SWITCH CLOSED?
YES
THERMOSTAT DEMAND SATISFIED.
YES
LED #1 & #2 SIMULTANEOUS SLOW FLASHES.
NO
NO
GAS VALVE POWER OFF.
COMBUSTION AIR INDUCER POWER ON.
INDOOR BLOWER ON
LED #1 −− ON. LED #2 −− SLOW FLASH.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESET
AND MAIN POWER IS INTERRUPTED OR
THERMOSTAT IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.
GAS VALVE DE−ENERGIZED.
COMBUSTION AIR INDUCER ON.
INDOOR BLOWER OFF WITH DELAY
LED #1 −− OFF. LED #2 −− SLOW FLASH.
HAS CAB SWITCH CLOSED IN 2.5 MINUTES?
NO
YES
5-MINUTE PRESSURE SWITCH
WATCHGUARD MODE.
COMB. AIR INDUCER CONTINUES 5-SECOND
POST PURGE AFTER T’STAT DEMAND IS SATISFIED.
INDOOR AIR BLOWER COMPLETES SELECTED OFF"
DELAY BEFORE SHUTTING OFF.
Page 43
YES
COOLING SEQUENCE OF OPERATION
NORMAL COOLING MODE
ABNORMAL COOLING MODE
POWER ON
IGNITION CONTROL MAIN POWER ON.
NO
CONTROL SELF DIAGNOSTIC CHECK.
IS CONTROL OPERATING NORMALLY?
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.
INTERRUPT MAIN POWER TO RESET CONTROL.
YES
NO
IS THERE A PROPER GROUND?
YES
NO
IS POLARITY CORRECT?
YES
SIGNAL IMPROPER GROUND AT LED.
CONTROL WILL CONTINUE TO CALL FOR COOLING
IN THIS CONDITION.
SIGNAL POLARITY REVERSED AT LED. CONTROL
WILL CONTINUE TO CALL FOR COOLING IN THIS
CONDITION.
NO
LED SIGNALS LOW VOLTAGE. CONTROL WILL
CONTINUE TO CALL FOR COOLING
IN THIS CONDITION.
IS VOLTAGE
ABOVE 90 VOLTS?
YES
NO
ROLLOUT SWITCH MONITORED CONTINUOUSLY.
IS ROLLOUT SWITCH CLOSED?
YES
LED: SLOW FLASH RATE REMAINS UNCHANGED
THROUGHOUT COOLING CYCLE.
THERMOSTAT CALLS FOR COOLING.
COMPRESSOR CONTACTOR AND SYSTEM FAN
ENERGIZED WITH 2-SECOND DELAY
(COOLING SPEED). EAC TERM. ENERGIZED.
THERMOSTAT OPENS.
COMPRESSOR OFF.
SYSTEM FAN AND EAC TERM. OFF
WITH 45-SECOND DELAY.
Page 44
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER ON.
SIGNAL ROLL-OUT SWITCH OPEN AT LED.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES
AND MAIN POWER IS INTERRUPTED OR THERMOSTAT
IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.
CONTINUOUS HEAT SPEED FAN SEQUENCE OF OPERATION
LED: SLOW FLASH RATE REMAINS
UNCHANGED THROUGHOUT SEQUENCE.
MANUAL FAN SELECTION MADE AT THERMOSTAT.
CONTROL (G) ENERGIZES SYSTEM FAN AT HEAT
SPEED. EAC TERMINAL IS ENERGIZED.
THERMOSTAT CALLS FOR HEAT (W).
YES
NO
THERMOSTAT CALLS FOR COOLING.
YES
SYSTEM FAN SWITCHED TO COOL SPEED.
EAC TERM. REMAINS ON.
NO
HUM TERM. ENERGIZES
WITH COMB. AIR INDUCER.
SYSTEM FAN REMAINS ON
HEATING SPEED.
THERMOSTAT OPENS.
HUM TERM. DE−ENERGIZES
WITH COMB. AIR INDUCER
THERMOSTAT OPENS.
MANUAL FAN SELECTION MADE AT THERMOSTAT.
CONTROL (G) ENERGIZES SYSTEM FAN AT HEAT
SPEED. EAC TERM. ENERGIZED.
Page 45
SYSTEM FAN REMAINS ON
HEATING SPEED.
VIII−Integrated Control Troubleshooting Chart
UPON INITIAL POWER UP, REMOVE ALL THERMOSTAT DEMANDS TO THE UNIT
PROBLEM: 1 UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE
Condition
Possible Cause
1.1
1.1.1
− Both diagnostic lights fail to light up. Main voltage 120V not supplied to unit.
LED#1−Off
LED#2−Off
ACTION 1 − Check for correct wiring of 120V to
power make up box and transformer.
ACTION 2 − Check 24V wiring to control.
1.1.3
Blown fuse
ACTION 1 − Replace fuse.
ACTION 2 − If fuse still blows, check for short.
1.1.4
Door interlock switch failure.
ACTION 1 − Check that door switch is activated
when door is closed.
ACTION 2 − Check wire connections to switch, replace loose connectors.
ACTION 3 − Check continuity of switch in closed
position. Replace if defective.
1.1.5
Transformer Failure.
ACTION 1 − Check that transformer output is
24V. Replace if defective.
Failed control.
− Diagnostic lights flash the roll−out .
code.
LED#1−On,
LED#2−Slow Flash
1.3
− Both diagnostic lights the polarity
code.
1.2.1
Roll−out switch open.
LED#1−Slow Flash
LED#2−Slow Flash
ACTION 1 − If all the above items have been
checked, replace control.
ACTION 1 − Manually reset the roll−out switch
by pushing the top button.
ACTION 2 − Determine the cause of the roll−out
switch activation before leaving furnace.
1.2.2
Roll−out switch failure.
ACTION 1 − Check continuity across roll−out
switch. Replace roll−out switch if switch is reset
but does not have continuity.
1.2.3
Miswiring or improper connections at
roll−out switch.
ACTION 1 − Check wiring connections to switch.
1.2.4
12 pin connector failure
ACTION 1 − Check 12−pin connector for proper
connection to control.
ACTION 2 − Check continuity of the multi plug
pin.
1.3.1
120V main power polarity reversed.
ACTION 1 − Check the 120V has line and neutral
correctly input into control.
ACTION 2 − Reverse the line and neutral at the
120V field connection.
1.4.1
Open combustion air inducer motor
circuit.
ACTION 1 − Check for 120V to combustion air
inducer. If no power, check wire and connections.
1.4.2
Failed combustion air inducer motor.
ACTION 1 − If power is present at blower, replace
blower.
LED#1−Fast Flash,
LED#2−Slow Flash.
1.4
ACTION 1 − Check 120V main voltage.
Determine cause of main power failure.
1.1.2
Miswiring of furnace or improper connections.
1.1.6
1.2
Corrective Action / Comments
Page 46
PROBLEM 1: UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE
Condition
Possible Cause
Corrective Action / Comments
1.5
− Diagnostic lights flash the improper
main ground.
1.5.1
Improper ground to the unit.
ACTION 1 − Check that the unit is properly
ground.
ACTION 2 − Install a proper main ground to the
unit
1.5.2
4−Pin connector is improperly attached to the circuit board.
ACTION 1 − Check 4−pin connector for proper
installation. Correctly insert connector into control.
1.5.3
Line voltage is below 90V
ACTION 1 − Check that the line voltage is correct.
Determine cause of voltage drop and supply correct voltage to the control.
LED#1−Alternating Fast Flash*
LED#2−Alternating Fast Flash*
PROBLEM 2: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOES NOT
ENERGIZE
Condition
2.1
− Unit operates with a cooling or continuous fan demand.
− Combustion air inducer will not start
with a Heating demand.
− Diagnostic lights flash the limit failure
mode.
LED#1−Slow Flash,
LED#2−On
2.2
− Unit operates with a cooling and continuous fan demand.
− Combustion air inducer will not start
with a Heating demand.
− Diagnostic lights flash the pressure
switch failure code.
LED#1−Off,
LED#2−Slow Flash
Possible Cause
Corrective Action / Comments
2.1.1
Primary or secondary (if equipped )
limit open.
ACTION 1 − Check continuity across switch(es).
Switches reset automatically upon cool down.
ACTION 2 − Check for restrictions on blower inlet
air (including filter) and outlet air. Determine
cause for limit activation before placing unit back
in operation.
2.1.2
Miswiring of furnace or improper connections at limit switch(es).
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
2.2.1
Miswiring of furnace or improper connections to combustion air inducer.
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
2.2.2
Pressure switch stuck closed.
ACTION 1 − Check that the pressure switch is
open without the combustion air inducer operating. Replace if defective.
Page 47
PROBLEM 2: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR INDUCER DOES
NOT ENERGIZE (CONT.).
Condition
2.3
− Unit operates with a cooling and continuous fan demand.
− Combustion air inducer will not start
with a Heating demand.
− Diagnostic lights flash the pressure
switch failure code 2.5 minutes after
heating demand.
LED#1−Off,
LED#2−Slow Flash
Possible Cause
Corrective Action/Comments
2.3.1
Miswiring of furnace or improper connections to combustion air inducer.
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
2.3.2
Combustion air inducer failure.
ACTION 1 − If there is 120V to combustion air inducer and it does not operate, replace combustion air inducer.
PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR INDUCER
ENERGIZES, IGNITOR IS NOT ENERGIZED.
Condition
Possible Cause
Corrective Action/Comments
3.1
− Unit operates with a cooling and
continuous fan demand.
− Combustion air inducer energizes
with a heating demand.
− Diagnostic lights flash the pressure
switch failure code 2.5 minutes after
heating demand.
3.1.1
Pressure switch does not close due
to incorrect routing of the pressure
switch lines.
ACTION 1 − Check that the pressure switch lines
are correctly routed. Correctly route pressure
switch lines.
3.1.2
Pressure switch does not close due
to obstructions in the pressure lines.
ACTION 1 − Remove any obstructions from the
the pressure lines and/or taps.
3.1.3
Pressure switch lines damaged
ACTION 1 − Check pressure switch lines for
leaks. Replace any broken lines.
3.1.4
Condensate in pressure switch line.
ACTION 1 − Check pressure switch lines for condensate. Remove condensate from lines.
3.1.5
Pressure switch does not close due
to a low differential pressure across
the pressure switch.
ACTION 1 − Check the differential pressure
across the pressure switch. This pressure
should exceed the set point listed on the
switch.
ACTION 2 − Check for restricted inlet vent. Remove all blockage.
ACTION 3 − Check for proper vent sizing and
run length.
3.1.6
Wrong pressure switch installed in the
unit, or pressure switch is out of calibration.
ACTION 1 − Check that the proper pressure
switch is installed in the unit. Replace pressure
switch if necessary.
3.1.7
Miswiring of furnace or improper connections at pressure switch.
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
3.1.8
Pressure switch failure.
ACTION 1 − If all the above modes of failure have
been checked, the pressure switch may have
failed. Replace pressure switch and determine if
unit will operate.
LED#1−Off
LED#2−Slow Flash
Page 48
PROBLEM 4: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER
ENERGIZES, IGNITOR IS ENERGIZED.
Condition
4.1
− Unit operates with a cooling and
continuous fan demand.
− Combustion air inducer energizes
with Heating demand.
− Ignitor is energized but unit fails to
light.
LED#1−Alternating Slow Flash
LED#2−Alternating Slow Flash
Possible Cause
Corrective Action/Comments
4.1.1
Check that gas is being supplied to
the unit.
ACTION 1 − Check line pressure at the gas valve.
Pressure should not exceed 13" WC for both natural and propane. Line pressure should read a
minimum 4.5" WC for natural and 11.0"WC for
propane.
4.1.2
Miswiring of gas valve or loose connections at multi−pin control amp
plugs or valve.
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
4.1.3
Defective gas valve or ignition control.
ACTION 1 − Check that 24V is supplied to the gas
valve approximately 35 seconds after heat demand is initiated.
ACTION 2 − Replace the valve if 24V is supplied
but valve does not open.
ACTION 3 − Replace the control if 24V is not supplied to valve.
PROBLEM 5: BURNERS LIGHT WITH A HEATING DEMAND BUT UNIT SHUTS DOWN
PREMATURELY
Condition
5.1
− Burners fire with a heating demand.
− Burners light but unit shuts off prior
to satisfying T−stat demand.
− Diagnostic lights flash the pressure
switch code.
LED#1−Off
LED#2−Slow Flash
5.2
− Combustion air inducer energizes
with a heating demand.
− Burners light but fail to stay lit.
− After 5 tries the control diagnostics
flash the watchguard burners failed to
ignite code.
LED#1−Alternating Slow Flash
LED#2−Alternating Slow Flash
Possible Cause
Corrective Action/Comments
5.1.1
Low pressure differential at the pressure switch.
ACTION 1 − Check for restricted intake/exhaust
vent. Remove all blockage.
ACTION 2: Check for proper vent sizing. See
installation instructions.
5.1.2
Wrong concentric vent kit used for
terminating the unit.
ACTION 1 − Check vent termination kit installed.
See Placement and Installation section.
5.1.3
Condensate drain line is not draining
properly.
ACTION 1 − Check condensate line for proper
vent slope, and any blockage. Condensate
should flow freely during operation of furnace.
Repair or replace any improperly installed condensate lines.
5.2.1
Sensor or sense wire is improperly
installed.
ACTION 1 − Check that sensor is properly located and that the sense wire is properly attached to both the sensor and the control.
5.2.2
Sensor or sense wire is broken.
ACTION 1 − Check for a broken sensor.
ACTION 2 − Test continuity across the sense
wire. If wire or sensor are damaged replace the
component.
5.2.3
Sensor or sensor wire is grounded to
the unit.
ACTION 1 − Check for resistance between the
sensor rod and the unit ground.
ACTION 2 − Check for resistance between the
sensor wire and the unit ground.
ACTION 3 − Correct any shorts found in circuit.
5.2.4
Control does not sense flame.
ACTION 1 − Check the microamp signal from
the burner flame. If the microamp signal is below normal, check the sense rod for proper
location or contamination.
ACTION 2 − Replace, clean, or relocate flame
sense rod. If rod is to be cleaned, use steel
wool or replace sensor. DO NOT CLEAN ROD
WITH SAND PAPER. SAND PAPER WILL
CONTRIBUTE TO THE CONTAMINATION
PROBLEM. NOTE: Do not attempt to bend
sense rod.
Page 49
PROBLEM 5: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN
PREMATURELY (CONT.)
Condition
Possible Cause
Corrective Action/Comments
5.3.1
Unit is firing above 100% of the
nameplate input.
ACTION 1 − Check that the manifold pressure
matches value listed on nameplate. See installation instructions for proper procedure.
ACTION 2 − Verify that the installed orifice size
match the size listed on the nameplate or installation instructions.
ACTION 3 − Check gas valve sensing hose to insure no leaks are present.
ACTION 4 − Check the input rate to verify rate
matches value listed on nameplate.
5.3.2
Gas orifices leak at the manifold connection.
ACTION 1 − Tighten orifice until leak is sealed.
NOTE: Be careful not to strip orifice threads.
ACTION 2 − Check for gas leakage at the
threaded orifice connection. Use approved method for leak detection (see unit instructions).
5.3.3
Air leakage at the connections between the primary heat exchanger,
secondary heat exchanger, and combustion air blower.
ACTION 1 − Check for air leakage at all joints in
the heat exchanger assembly. Condition will
cause high CO2 with high CO.
ACTION 2 − Seal leakage if possible, replace
heat exchanger if necessary, tag and return heat
exchanger to proper Lennox personnel.
5.3.4
Insufficient flow through the heat exchanger caused by a sooted or restricted heat exchanger.
ACTION 1 − Check for sooting deposits or other
restrictions in the heat exchanger assembly.
Clean assembly as outlined in instruction manual.
ACTION 2 − Check for proper combustion.
5.3.5
Burners are not properly located in
the burner box.
ACTION 1 − Check that the burners are firing into
the center of the heat exchanger openings. Correct the location of the burners if necessary.
5.4
− Combustion air inducer energizes
with a heating demand.
− Burners light roughly and the unit
fails to stay lit.
− Diagnostic lights flash watchguard
flame failure.
5.4.1
Recirculation of flue gases. This condition causes rough ignitions and operation. Problem is characterized by
nuisance flame failures.
ACTION 1 − Check for proper flow of exhaust
gases away from intake vent. Remove any obstacles in front of the intake and exhaust vent
which would cause recirculation.
ACTION 2 − Check for correct intake and exhaust
vent installation. See instructions
5.4.2
Improper burner cross−overs
ACTION 1 − Remove burner and inspect the
cross−overs for burrs, or any restriction or if
crossover is warped. Remove restriction or replace burners.
LED#1−Alternating Slow Flash
LED#2−Alternating Slow Flash
5.4.3
Pressure Switch opens 5 times during
a single demand
ACTION 1 − Inspect vent pipe installation and for
any restriction. Remove restriction.
ACTION 2 − Check pressure switch reliability.
5.3
− Combustion air inducer energizes
with a heating demand.
− Burners light.
− Roll−out switch trips during the
heating demand.
− Diagnostic lights flash roll−out failure.
LED#1−On
LED#2−Slow Flash
Page 50
PROBLEM 6: CONTROL SIGNALS LOW FLAME SENSE DURING HEATING MODE
Condition
Possible Cause
Corrective Action/Comments
6.0
− Unit operates correctly but the diagnostic lights flash low flame sense
code.
6.1.1
Sensor rod is improperly located on
the burner.
ACTION 1 − Check the sensor rod for proper location on the burner. Properly locate the sensor rod
or replace if rod cannot be located correctly.
6.1.2
Sensor rod is contaminated.
ACTION 1 − Check sensor rod for contamination
or coated surface. Clean the sensor rod with steel
wool or replace sensor. DO NOT USE SAND PAPER TO CLEAN ROD. SAND PAPER WILL
CONTRIBUTE TO THE CONTAMINATION
PROBLEM.
LED#1−Slow Flash
LED#2−Fast Flash
PROBLEM 7: INDOOR BLOWER FAILS TO OPERATE IN COOLING, HEATING, OR CONTINUOUS
FAN MODE
Condition
7.0
− Indoor blower fails to operate in
continuous fan, cooling, or heating
mode.
Possible Cause
Corrective Action/Comments
7.1.1
Miswiring of furnace or improper connections at control or indoor blower
motor.
ACTION 1− Correct wiring and/or replace any
loose connections. Check for correct wiring and
loose connections.
7.1.2
120V is not being supplied to the indoor air blower or blower motor failure.
7.1.3
Defective control
7.1.4
Defective run capacitor
ACTION 1 − Check for 120V at the various calls
for indoor blower by energizing "Y", "G", and "W"
individually on the low voltage terminal strip. Note
that when "W’ is energized, the blower is delayed
45 seconds. If there is 120V to each motor tap but
the blower does not operate, replace the motor.
ACTION 1 − If there is not 120V when "Y", "G", or
"W" is energized, replace the control.
ACTION 1 − Replace capacitor
PROBLEM 8: RF STATIC DURING TIME FOR IGNITION
Condition
Possible Cause
Corrective Action/Comments
8.0
− AM radio interference.
8.1.2
Ignitor operation
ACTION 1 − Call Technical Support, Dallas.
Page 51
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