Lennox ML193DF045P36B, ML193DF110P60C, ML193DF070P36B, ML193DF090P48C Unit Information

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Corp. 1026-L5

Service Literature

Revised 03-2014

ML193DF SERIES UNITS

ML193DF series units are high-efficiency gas furnaces manufactured with Lennox DuralokPlust aluminized steel clamshell-type heat exchangers, with a stainless steel con densing coil. ML193DF units are available in heating input capacities of 44,000 to 110,000 Btuh (13 to 32.2 kW) and cooling applications from 2 through 5 tons (7.0 through

17.6 kW). Refer to Engineering Handbook for proper siz ing.

Units are factory equipped for use with natural gas. A kit is available for conversion to LPG operation. All ML193DF units are equipped with a hot surface ignition system. The gas valve is redundant to assure safety shut-off as required by C.S.A.

The heat exchanger, burners and manifold assembly can be removed for inspection and service. The maintenance section gives a detailed description on how this is done.

ML193DF

All specifications are subject to change. Procedures out lined in this manual are presented as a recommendation only and do not supersede or replace local or state codes.

WARNING

Electric shock hazard. Can cause injury or death. Before attempting to perform any service or maintenance, turn the electrical power to unit OFF at discon nect switch(es). Unit may have multiple power supplies.

Table of Contents

Specifications 2.................................

Optional Accessories 3..........................

Blower Performance Data 4......................

I-Unit Components 6............................

II Placement and Installation 18....................

III-Start-Up 36...................................

IV-Heating System Service Checks 37..............

V-Typical Operating Conditions 39.................

VI-Maintenance 40...............................

VII-Wiring and Sequence of Operation 42...........

WARNING

Improper installation, adjustment, alteration, service or maintenance can cause property damage, person al injury or loss of life. Installation and service must be performed by a licensed professional HVAC in staller (or equivalent), service agency or the gas sup plier.

WARNING

Sharp edges. Be careful when servicing unit to avoid sharp edges which may result in personal injury.

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Litho U.S.A.

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SPECIFICATIONS

Gas Heating Performance

Model No. ML193DF045P36B ML193DF070P36B ML193DF090P48C ML193DF110P60C

AFUE 93% 93% 93% 93%

Input - Btuh 44,000 66,000 88,000 110,000

Output - Btuh 41,000 61,000 82,000 102,000

Temperature rise range - °F 25 - 55 50 - 80 40 - 70 50 - 80

Gas Manifold Pressure (in. w.g.)

3.5 / 10.0 3.5 / 10.0 3.5 / 10.0 3.5 / 10.0

Nat. Gas / LPG/Propane

High static - in. w.g. 0.50 0.50 0.50 0.50

Connections in.

Intake / Exhaust Pipe (PVC) 2 / 2 2 / 2 2 / 2 2 / 2

Gas pipe size IPS 1/2 1/2 1/2 1/2

Condensate Drain Trap (PVC pipe) - i.d. 1/2 1/2 1/2 1/2

with eld supplied (PVC coupling) - o.d. 3/4 3/4 3/4 3/4

Indoor Blower

Wheel nom. dia. x width - in. 10 x 8 10 x 8 10 x 10 11 ½ x 10

Motor output - hp 1/3 1/3 1/2 1

Tons of add-on cooling 2.5 - 3 2.5 - 3 3 - 4 4 - 5

Air Volume Range - cfm 605 - 1615 560 - 1550 920 - 2145 1210 - 2410

Electrical Data

Blower motor full load amps 6.1 6.1 8.2 11.5

Voltage 120 volts - 60 hertz - 1 phase

Maximum overcurrent protection 15 15 15 15

Shipping Data lbs. - 1 package 124 129 147 162

NOTE - Filters and provisions for mounting are not furnished and must be eld provided.

Annual Fuel Utilization Efciency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized

furnaces.

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OPTIONAL ACCESSORIES - MUST BE ORDERED EXTRA

“B” Width Models “C” Width Models

CABINET ACCESSORIES

Downow Combustible Flooring Base 11M60 11M61

CONDENSATE DRAIN KITS

Condensate Drain Heat Cable 6 ft. 26K68 26K68

24 ft. 26K69 26K69

50 ft. 26K70 26K70

Heat Cable Tape Fiberglass - 1/2 in. x 66 ft. 36G53 36G53

Aluminum foil - 2 in. x 60 ft. 16P89 16P89

Crawl Space Vent Drain Kit 51W18 51W18

CONTROLS

Twinning Kit 65W80 65W80

DOWNFLOW FILTER KITS

Downow Air Filter and Rack Kit 51W07 51W08

No. and Size of lter - in. (2) 20 x 20 x 1 (2) 20 x 20 x 1

NIGHT SERVICE KITS

Night Service Kit 51W03 51W03

TERMINATION KITS

See Installation Instructions for specic venting information.

Termination Kits Direct Vent Applications

Only

Termination Kits - Direct or Non-Direct vent

Roof Termination Flashing Kit - Direct or Non-Direct Vent Contains two ashings

Cleanable polyurethane frame type lter.

Kits contain enough parts for two, non−direct vent installations.

Non-direct vent only.

NOTE - Termination Kits 44W92, 44W93, 30G28, 81J20 are certied to ULC S636 standard for use in Canada only.

Concentric US - 2 in. 71M80 69M29

3 in. - - - 60L46

Canada - 2 in. 44W92 44W92

3 in. - - - 44W93

Flush-Mount 2, 2-1/2 or 3 in. 51W11 51W11

Wall - Close

Couple

Wall - Close

Couple WTK

US - 2 in. 22G44 - - -

3 in. 44J40 44J40

Canada - 2 in. 30G28 - - -

3 in. 81J20 81J20

Roof 2 in. 15F75 15F75

Wall Ring Kit 2 in. 15F74

44J41 44J41

15F74

High Altitude

Input

Pressure Switch Kit

4501 - 7500 ft. 7501 - 10,000 ft. 0 - 7500 ft. 0 - 7500 ft. 7501- 10,000 ft.

all models 74W90 74W91 69W73 73W81 73W37

GAS HEAT ACCESSORIES

Natural Gas to

LPG/Propane Kit

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LPG/Propane

to Natural Gas Kit

Natural Gas

High Altitude

Orice Kit

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BLOWER DATA

ML193DF045XP36B PERFORMANCE (Less Filter)

External

Static

Pressure

in. w.g.

0.00 1615 650 1385 555 1205 465 1045 390

0.10 1605 640 1375 545 1195 455 1035 380

0.20 1500 620 1340 525 1165 445 1015 370

0.30 1450 590 1290 490 1125 420 975 365

0.40 1350 560 1235 480 1090 405 920 345

0.50 1300 545 1170 450 1035 380 875 335

0.60 1195 500 1095 425 990 365 840 320

0.70 1140 485 1020 400 895 345 780 300

0.80 1025 450 920 370 840 330 695 275

0.90 945 435 800 335 700 295 605 250

ML193DF070XP36B PERFORMANCE (Less Filter)

External

Static

Pressure

in. w.g.

0.00 1505 660 1310 570 1090 455 940 390

0.10 1480 625 1295 550 1070 435 935 365

0.20 1405 585 1255 515 1055 425 930 350

0.30 1355 580 1225 475 1045 405 900 330

0.40 1305 540 1165 470 1010 385 890 325

0.50 1270 525 1110 425 975 370 835 305

0.60 1175 500 1080 415 925 345 815 290

0.70 1105 460 1000 395 855 320 745 270

0.80 1040 440 925 365 790 300 670 250

0.90 920 400 825 335 680 270 560 225

Air Volume / Watts at Various Blower Speeds

High

cfm Watts cfm Watts cfm Watts cfm Watts

Air Volume / Watts at Various Blower Speeds

High

cfm Watts cfm Watts cfm Watts cfm Watts

Medium-

High

Medium-

High

Medium-

Low

Medium-

Low

ML193DF090XP48C PERFORMANCE (Less Filter)

External

Static

Pressure

in. w.g.

0.00 2075 800 1890 720 1625 645 1375 535

0.10 1995 755 1830 680 1590 615 1350 515

0.20 1910 715 1775 645 1575 580 1340 500

0.30 1825 680 1705 610 1530 550 1325 485

0.40 1730 645 1620 580 1475 525 1285 460

0.50 1630 615 1530 545 1405 500 1240 440

0.60 1530 585 1450 525 1330 470 1175 420

0.70 1430 555 1340 485 1260 450 1095 390

0.80 1300 525 1245 465 1145 415 1015 370

0.90 1185 495 1110 430 1045 385 915 340

ML193DF110XP60C PERFORMANCE (Less Filter)

External

Static

Pressure

in. w.g.

0.00 2410 1390 2190 1080 1860 910 1560 735

0.10 2405 1385 2180 1070 1855 905 1555 730

0.20 2285 1345 2120 1030 1850 865 1540 720

0.30 2220 1315 2015 1005 1770 840 1535 705

0.40 2185 1295 1950 955 1750 815 1530 685

0.50 2045 1240 1830 925 1680 790 1500 660

0.60 1965 1220 1710 890 1575 755 1445 640

0.70 1820 1165 1610 850 1495 720 1370 615

0.80 1625 1155 1510 820 1400 695 1315 595

0.90 1455 1110 1390 790 1350 660 1210 565

Air Volume / Watts at Various Blower Speeds

High

cfm Watts cfm Watts cfm Watts cfm Watts

Air Volume / Watts at Various Blower Speeds

High

cfm Watts cfm Watts cfm Watts cfm Watts

Medium-

High

Medium-

High

Medium-

Low

Medium-

Low

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CONTROL BOX

(Includes integrated control,

transformer and door switch)

BLOWER MOTOR

BLOWER

ACCESS

PANEL

PARTS ARRANGEMENT

BAG ASSEMBLY

(hidden)

BURNER ACCESS

PANEL

COMBUSTION AIR INDUCER

BLOWER DECK

PRIMARY LIMIT

COLD END HEADER BOX

HEAT EXCHANGER

GAS VALVE

BURNER BOX ASSEMBLY

(includes sensor, rollout switches and ignitor)

FIGURE 1

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I-UNIT COMPONENTS

ML193DF unit components are shown in figure 1. The combustion air inducer, gas valve and burners can be ac cessed by removing the burner access panel. The blower and control box can be accessed by removing the blower access door.

A-Control Box Components (Figure 2)

Unit transformer (T1) and integrated ignition control (A92) are located in the control box. In addition, a door interlock switch (S51) is located in the control box.

ML193DF Control Box

INTEGRATED IGNITION

CONTROL

(A92)

DOOR INTERLOCK

SWITCH (S51)

WARNING

Shock hazard. Disconnect power before servicing. Control is not

field repairable. If control is inoperable, simply re place entire control.

Can cause injury or death. Unsafe operation will result if repair is attempted.

The ignition control system consists of an integrated con trol (figure 4) ignitor (figure 10) and sensor (figure 10). The integrated control and ignitor work in combination to en sure furnace ignition and ignitor durability. The integrated control, controls all maor furnace operations. The inte grated control also features two LED lights (DS1 red and DS2 green) for troubleshooting and two accessory termi nals rated at (1) one amp. The integrated control also fea tures a (3) amp fuse for overcurrent protection. Tables 1 and 2 show jack plug terminal designations. See table 3 for troubleshooting diagnostic codes. The 95 volt ignitor is made from a high strength, silicon nitride material that pro vides long life and trouble free maintenance. The inte grated control continuously monitors line voltage and maintains the ignitor power at a consistent level to provide proper lighting and maximum ignitor life.

TRANSFORMER

(T1)

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 volt age. When the blower door is removed the unit will shut down.

3. Integrated Ignition Control 100973 (A92)

TABLE 1

4-Pin Terminal Designation

PIN # FUNCTION

1 Combustion Air Inducer Line

Ignitor Line

Combustion Air Inducer Neutral

Ignitor Neutral

TABLE 2

12-Pin Terminal Designations

PIN # 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

CAUTION

Electrostatic discharge can affect elec tronic components. Take precautions to neutralize electrostatic charge by touching your hand and tools to metal prior to handling the control.

Electronic Ignition (See Figure 5)

On a call for heat the integrated control monitors the com bustion air inducer prove switch. The integrated control will not begin the heating cycle if the prove switch is closed (bypassed). Once the prove switch is determined to be open, the combustion air inducer is energized. When the differen

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tial in the prove switch is great enough, the prove switch closes and a 15-second pre-purge begins. If the prove switch is not proven within 2-1/2 minutes, the integrated control goes into Watchguard-Pressure Switch mode for a 5-minute re-set period. After the 15-second pre-purge period, the ignitor warms up for 20 seconds after which the gas valve opens for a 4-sec ond trial for ignition. The ignitor remains energized for the first 3 seconds during the 4 second trial. If ignition is not proved during the 4-second period, the integrated control will try four more times with an inter purge and warm-up time between trials of 35 seconds. After a total of five trials for ignition (including the initial trial), the integrated control goes into Watchguard-Flame Failure mode. After a 60-minute reset period, the integrated control will begin the ignition sequence again. The integrated control has an added feature of ignitor pow er regulation to maintain consistent lighting and longer igni tor life under all line voltage conditions.

Fan Control

The fan on time of 30 seconds is not adjustable. The fan off delay (amount of time that the blower operates after the heat demand has been satisfied) may be adjusted by changing the jumper position across the five pins on the integrated control. The unit is shipped with a factory fan off setting of 90 seconds. The fan off delay affects comfort and is adjustable to satisfy individual applications. Adjust the fan off delay to achieve a supply air temperature between 90° and 110°F at the moment that the blower is de-ener gized. Longer off delay settings provide lower return air temperatures; shorter settings provide higher return air temperatures. See figure 3.

FAN‐OFF TIME IN SECONDS

NO JUMPER

To adjust fan-off timing, reposition jumper across pins

to achieve desired setting.

FIGURE 3

LED 1

LED 2

INTEGRATED CONTROL

(Automatic Hot Surface Ignition System)

TERMINAL DESIGNATIONS

HUM LINE XFMR EAC COOL HEAT PARK FLAME NEUTRALS

3 AMP, 32 VAC FUSE

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)

BLOWER OFF

DELAY JUMPER

FIGURE 4

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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

FAST FLASH

SLOW FLASH ON

OFF SLOW FLASH

ALTERNATING

SLOW FLASH

SLOW FLASH OFF Flame sensed without gas valve energized.

ON SLOW FLASH Rollout switch open. OR: 12‐pin connector improperly attached.

SIMULTANEOUS

SLOW FLASH

SIMULTANEOUS

FAST FLASH

ALTERNATING

SLOW FLASH

Power on - Normal operation. Also signaled during cooling and continuous fan.

Normal operation - signaled when heating demand initiated at thermostat.

Primary or secondary limit switch open. Limit must close within 3 minutes or unit goes into 1 hour Watchguard.

Pressure prove switch open. OR: Blocked inlet/exhaust vent; OR: Pressure switch closed prior to activation of combustion air inducer.

Watchguard 1 hour -- burners failed to ignite or lost flame 5 times during single heating demand.

OFF

Circuit control failure or control wired incorrectly.

FAST FLASH SLOW FLASH Main power polarity reversed. Switch line and neutral.

SLOW FLASH FAST FLASH Low flame signal. Measures below 1.5 microamps. Replace flame sense rod.

ALTERNATING

FAST FLASH

ALTERNATING

FAST FLASH

Improper main ground. OR: Line voltage below 90 volts.

NOTE - Slow flash rate equals 1 Hz (one flash per second). Fast flash rate equals 3 Hz (three flashes per second). Minimum flame sense current = 0.5 microAmps.

*4 Sec.Trial

for Ign.

**Blower “On”

Delay

End of

Heat Demand

5 SEC

Post

Purge

Blower

Off

Time

OFF

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.

15 Sec.

Pre -Purge

20 sec.

Ignitor Warmup

FIGURE 5

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4. Integrated Ignition Control 103085 (A92)

WARNING

Shock hazard. Disconnect power before servicing. Control is not

field repairable. If control is inoperable, simply re place entire control.

Can cause injury or death. Unsafe operation will re sult if repair is attempted.

The hot surface ignition control system consisting of an in tegrated control (figure 6 with control terminal designations in tables 4 and 5), flame sensor and ignitor (figure 10). The integrated control and ignitor work in combination to en sure furnace ignition and ignitor durability. The integrated control, controls all major furnace operations. The inte grated control also features a RED LED for troubleshooting and two accessory terminals rated at (1) one amp. See table 6 for troubleshooting diagnostic codes. The 120 volt ignitor is made from a high strength, silicon nitride material that provides long life and trouble free maintenance.

Electronic Ignition (Figure 7)

On a call for heat the integrated control monitors the com bustion air inducer pressure switch. The control will not be gin the heating cycle if the pressure switch is closed (bypassed). Once the pressure switch is determined to be open, the combustion air inducer is energized. When the differential in the pressure switch is great enough, the pres sure switch closes and a 15-second pre-purge begins. If the pressure switch is not proven within 2-1/2 minutes, the integrated control goes into Watchguard-Pressure Switch mode for a 5-minute re-set period. After the 15-second pre-purge period, the ignitor warms up for 20 seconds after which the gas valve opens for a 4-sec ond trial for ignition. The ignitor remains energized for the first 3 seconds of the trial for ignition. If ignition is not proved during the trial for ignition, the integrated control will try four more times with an inter purge and warm-up time between trials of 30 seconds. After a total of five trials for ignition (in cluding the initial trial), the integrated control goes into Watchguard-Flame Failure mode. After a 60-minute reset period, the integrated control will begin the ignition se quence again.

TABLE 4

4-Pin Terminal Designation

PIN # FUNCTION

1 Combustion Air Inducer Line

Ignitor Line

Combustion Air Inducer Neutral

Ignitor Neutral

TABLE 5

12-Pin Terminal Designations

PIN # FUNCTION

1 High Limit Output

2 Sensor

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

TABLE 6

DIAGNOSTIC CODES

LED Status DESCRIPTION

LED Off

LED On Normal operation.

1 Flash

2 Flashes

3 Flashes

4 Flashes Primary limit switch open.

5 Flashes Rollout switch open.

6 Flashes Pressure switch cycle lockout.

7 Flashes Lockout, burners fail to light.

8 Flashes

9 Flashes Line voltage polarity incorrect.

Note - This control is equipped with a push button switch for diagnostic code recall. The control stores the last 5 fault codes in non-volatile memory. The most recent fault code is flashed first, the oldest fault code is flashed last. There is a 2 second pause between codes. When the push button switch is pressed for less than 5 seconds, the control will flash the stored fault codes when the switch is released. The fault code history may be cleared by pressing the push button switch for more than 5 seconds.

No power to control or control harware fault detected.

Flame present with gas vavle de-energized.

Pressure switch closed with combustion air inducer de-energized.

Pressure switch open with combus tion air inducer energized.

Lockout, buners lost flame too many times.

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LED

ЙЙЙЙЙЙЙЙЙ

INTEGRATED CONTROL

(Automatic Hot Surface Ignition System)

TERMINAL DESIGNATIONS

HUM LINE XFMR EAC COOL HEAT PARK CONT NEUTRALS

TWIN

Humidifier (120VAC) Input (120VAC) Transformer (120VAC) Indoor Air Qality Accessory Air Cleaner (120VAC) Blower - Cooling Speed (120VAC) Blower - Heating Speed (120VAC) Dead terminals to park alternate spd taps Continuous blower Neutral terminals (120VAC)

Twinning Terminal (24VAC)

TWIN

OFF

DEMAND

CAI IGNITOR GAS VALVE INDOOR BLOWER

*Blower on time will be 30 seconds after flame is sensed. Blower off time will depend on “OFF TIME” Setting.

PUSH BUTTON

Pre -Purge Ignitor Warm-up

FIGURE 6

ELECTRONIC IGNITION

351

Trial for

Ignition

FIGURE 7

Blower “On”*

Delay

5 SEC69

Post

Purge

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Fan Time Control

Heating Fan On Time

The fan on time of 30 seconds is not adjustable.

Heating Fan Off Time

Fan off time (time that the blower operates after the heat demand has been satisfied) can be adjusted by moving the jumper to a different setting. The unit is shipped with a fac tory fan off setting of 120 seconds. For customized comfort, monitor the supply air temperature once the heat demand is satisfied. Note the supply air temperature at the instant the blower is de-energized. Adjust the fan-off delay to achieve a supply air temperature between 90° - 110° at the instant the blower is de-ener gized. (Longer delay times allow for lower air temperature, shorter delay times allow for higher air temperature). See figure 8.

Cooling Fan On Time

The fan on time is 2 seconds and is not adjustable.

Cooling Fan Off Time

The control has a 60 second fan off delay after cooling de mand has been met. This delay is factory set and not ad justable.

Twinning 2 ML193DF Furnaces

Integrated control 103085 is equipped with a provision to ”twin” (interconnect) two(2) adjacent furnaces with a com mon plenum such that they operate as one (1) large unit.

When twinned, the circulating blower speeds are synchro nized between the furnaces. If either furnace has a need to run the blower, both furnaces will run the blower on the same speed. The cooling speed has highest priority, fol lowed by heating speed and fan speed.

Field installation of twinning consists of connecting wires between the ”C” and ”Twin” terminals of the two controls. The 24 VAC secondary of the two systems must be in phase. All thermostat connections are made to one control only. Figure 9 show wiring for two-stage and single stage thermostats.

The twinned furnace without thermostat connections is to have the call for heat supplied by an external 24VAC isola tion relay to prevent its rollout switch from being bypassed by the other twinned furnace. The coil of the isolation relay connects from the thermostat ”W” to 24 VAC common. The contacts of the relay connect ”R” to ”W” on the non-thermo stat twin.

HEAT FAN‐OFF TIME IN SECONDS

NO JUMPER

To adjust fan-off timing, reposition jumper across pins to

60 Second

off Time

120

180

achieve desired setting.

90 Second

off Time

120

180

120 Second

off Time

120

180

FIGURE 8

180 Second

off Time

120

180

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FIELD WIRING FOR TWINNING THE ML193DF

TWO-STAGE THERMOSTAT

Call For Cool

Call For Fan

Call For 1st Stage Heat

Call For 2nd

StageHeat

ISOLATION RELAY

TWIN

SINGLE STAGE THERMOSTAT

TWIN 1

Call For Cool

Call For Fan

Call For Heat

ISOLATION RELAY

TWIN 2

TWIN

TWIN 1

TWIN 2

FIGURE 9

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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 clam shell heat exchangers are located in the heating compart ment. The heating compartment can be accessed by re moving the burner access panel.

1. Ignitor (Figure 10)

ML193DF units use a mini-nitride ignitor made from a pro prietary ceramic material. Ignitor longevity is enhanced by controlling the voltage to the ignitor. Units equipped with control 103085 have a 120V ignitor. Units equipped with control 100973 have a 95V ignitor. See figure 11 and table 7 for resistance and voltage checks.

2. Flame Sensor (Figure 10)

A flame sensor is located on the left side of the burner sup port. The sensor is mounted on the bottom burner box plate and the tip protrudes into the flame envelope of the leftmost burner. The sensor can be removed for service with out 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.

NOTE - The ML193DF furnace contains electronic components that are polarity sensitive. Make sure that the furnace is wired correctly and is properly grounded.

3. Flame Rollout Switches (Figure 10)

Flame rollout switches S47 are SPST N.C. high tempera ture 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 (indi cating a blockage in the combustion passages), the flame rollout switch trips, and the ignition control immediately closes the gas valve. Switch S47 in all ML193DF units is factory preset to open at 250_F + a temperature rise. All flame rollout switches are manual reset.

12_F (121_C + 6.7_C) on

SENSOR

ML193DF Burner Box Assembly

IGNITOR

BURNERS

ROLLOUT SWITCHES

FRONT BURNER BOX PLATE

GAS VALVE

FIGURE 10

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IGNITOR CHECKS

TABLE 7

Control Ohms

103085

100973

39 to 70 24 to 47

Voltage +

120

10%

Multi−Meter

Test 1

(set to ohms)

Test 2

Check ignitor for correct resistance.

Seperate the 2-pin jack-plug near the manifold and check

resistance of ignitor at the plug. See table 7. If the

reading is correct, then the problem is with the wiring

between the jack-plug and the control. If reading is not

correct, the issue is the ignitor.

Integrated Control Detail

Test 1

Check ignitor circuit for correct resistance.

Remove 4-pin plug from control.

Check ohms reading across terminals 2 and 4.

See table 7. If value is correct, this is the only test

needed. If the reading on the meter is not correct, (0 or

infinity) then a second test is needed.

Multi−Meter

(set to ohms)

Test 2

Integrated Control DetailIntegrated Control Detail

Multi−Meter

(set to VAC)

Test 3

Integrated Control Detail

Test 3

Check ignitor for correct voltage

Insert meter probes into terminals 2 and 4 (use small

diameter probes in order not to damage plug).

Check voltage during 20 second ignitor warm up period. See

table 7. If voltage reads below these values, check for

correct supply voltage to furnace.

FIGURE 11

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4. Primary Limit Control (Figure 12)

Primary limit (S10) used on ML193DF 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 deenergizes the gas valve. The limit automatically resets when unit temperature returns to normal. The switch is fac tory set and cannot be adjusted. For limit replacement re move wires from limit terminals and rotate limit switch 90 degrees. Slowly remove from the vestibule panel. Install replacement limit with same care.

Primary Limit Location and Heat Exchanger

burner input. See table 8 for orifice size. The burner is sup ported 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 8

Gas Orifice Size

Unit Fuel Orifice Size

All Natural 0.0625

All L.P./Propane 0.034

Burner Detail Top Vie w

IGNITOR

Install limit face down

FIGURE 12

5. Heat Exchanger (Figure 12)

ML193DF units use an aluminized steel primary and stain less 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 burn er box. This air is mixed with gas in the burners. The gas / air mixture is then burned at the entrance of each clam shell. Combustion gases are then pulled through the pri mary and secondary heat exchangers and exhausted out the exhaust vent pipe.

6. Burners (Figure 13)

All units use inshot burners. Burners are factory set and do not require adjustment. Burners can be removed as an as sembly for service. Burner maintenance and service is de tailed in the MAINTENANCE section of this manual. Each burner uses an orifice which is precisely matched to the

SENSOR

ORIFICES

FIGURE 13

7. Gas Valve (GV1)

The ML193DF uses an internally redundant to valve to as sure 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

(under

barbed

fitting)

INLET

PRESSURE

PORT

Gas Valve

MANIFOLD

PRESSURE

OUTLET

PORT

FIGURE 14

Page 15

Page 16

8. Combustion Air Inducer (B6) & Cold End Header Box

Pressure Switch

All ML193DF units use a combustion air inducer to move air through the burners and heat exchanger during heating op eration. The blower uses a shaded pole 120VAC motor. The motor operates during all heating operation and is con trolled by burner ignition control A3. Blower operates con tinuously while there is a call for heat. The burner ignition control will not proceed with the ignition sequence until combustion air inducer operation is sensed by the proving switches.

The CAI 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 in ducer creates negative pressure at unit start up. The chan nel contains an orifice used to regulate flow created by the CAI. The box has pressure taps for the CAI pressure switch hoses. The pressure switch measure the pressure across the CAI 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 CAI to the box, must also be replaced.

TABLE 9

ML193DF Unit

C.A.I. Orifice Size

-045 0.618

-070 0.891

-090 1.031

-110 1.297

9. Combustion Air Pressure Switch (Figure 15)

ML193DF series units are equipped with a differential pres sure switch located on the cold end header box. The switches monitor across the CAI orifice to insure proper flow through the heat exchanger.

The switch is a SPST N.O. prove switch electrically con nected 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.

BRACKET

24VAC

TERMINALS

TAP

FIGURE 15

On start‐up, the switch senses that the combustion air in ducer is operating. It closes a circuit to the ignition control when the difference in pressure across the CAI orifice ex ceeds 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 ignition control. If the condensate line is blocked, wa ter 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 10.

Checks of pressure differential can aid in troubleshooting. When measuring the pressure differential, readings should be taken at the pressure switch. See figure 16. Lack of dif ferential usually indicates problems in the intake or exhaust piping, but may indicate problems in the heat exchanger, condensing coil, header boxes, combustion inducer or oth er components.

TABLE 10

Altitude ft

ML193DF

0 - 4500

4501 -

7500

7501 - 10000

Set Point SetPoint Set Point

-045

-070

-090

-110

-0.65 -0.60 -0.55

*Set point is factory set and non-adjustable

Page 16

Page 17

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. How ever the (+) port reads less negative pressure than the (-) port.

FIGURE 16

C-Blower Compartment

Blower motor (B3) and capacitor (C4), are located in the blower compartment. The blower compartment can be ac cessed by removing the blower access panel.

Blower Motor Housing

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 10.

5 - Remove thermostat demand and allow to cycle off.

6 - Remove manometer and tee's. Reinstall combustion air

sensing hoses to the pressure switch.

1.Blower Motor (B3) and Capacitor (C4)

All ML193DF units use single-phase direct-drive blower motors. All motors are 120V permanent split capacitor mo tors to ensure maximum efficiency. See SPECIFI CATIONS table at the front of this manual for more detail. See motor nameplate for capacitor ratings.

MOTOR

To Remove Blower From Unit: Disconnect Power, Remove Control

Box, Remove Bolts and Unplug Motor Wires From Control Board.

Then Slide Out Front of Unit.

FIGURE 17

BOLTS

CAPACITOR

Page 17

Page 18

II-PLACEMENT AND INSTALLATION

Pipe & Fittings Specifications

All pipe, fittings, primer and solvent cement must conform with American National Standard Institute and the Ameri can Society for Testing and Materials (ANSI/ASTM) stan dards. The solvent shall be free flowing and contain no lumps, undissolved particles or any foreign matter that ad versely affects the joint strength or chemical resistance of the cement. The cement shall show no gelation, stratifica tion, or separation that cannot be removed by stirring. Re fer to the table 11 below for approved piping and fitting ma terials.

CAUTION

Solvent cements for plastic pipe are flammable liq uids 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 ce ment with skin and eyes.

PIPING AND FITTINGS SPECIFICATIONS

Schedule 40 PVC (Pipe) D1785 Schedule 40 PVC (Cellular Core Pipe) F891

Schedule 40 PVC (Fittings) D2466

Schedule 40 CPVC (Pipe) F441

Schedule 40 CPVC (Fittings) F438

SDR-21 PVC or SDR-26 PVC (Pipe) D2241

SDR-21 CPVC or SDR-26 CPVC (Pipe) F442

Schedule 40 ABS Cellular Core DWV (Pipe) F628

Schedule 40 ABS (Pipe) D1527

Schedule 40 ABS (Fittings) D2468

ABS-DWV (Drain Waste & Vent) (Pipe & Fittings)

PVC-DWV (Drain Waste & Vent) Pipe & Fittings)

PRIMER & SOLVENT CEMENT

PVC & CPVC Primer F656 PVC Solvent Cement D2564

CPVC Solvent Cement F493

ABS Solvent Cement D2235

PVC/CPVC/ABS All Purpose Cement For Fittings & Pipe of the same material

ABS to PVC or CPVC Transition Solvent Cement

CANADA PIPE & FITTING & SOLVENT

CEMENT

PVC & CPVC Pipe and Fittings PVC & CPVC Solvent Cement

ABS to PVC or CPVC Transition Cement

POLYPROPYLENE VENTING SYSTEM

PolyPro by Duravent

TABLE 11

D2661

D2665

ASTM

SPECIFICATION

D2564, D2235, F493

D3138

MARKING

ULCS636

ULC-S636

IMPORTANT

ML193DF 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.

Use PVC primer and solvent cement or ABS solvent ce ment meeting ASTM specifications, refer to Table 11. 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.

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 in side 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) sys tem. In addition, the first three feet of vent pipe from the fur nace flue collar must be accessible for inspection.

Page 18

Page 19

Input Size

045

070

090

110

OUTDOOR TERMINATION USAGE*

TABLE 12

STANDARD CONCENTRIC

Flush

Vent Pipe

Dia. in.

Mount

Kit

51W11

(US)

51W12

2 inch 3 inch 2 inch

22G44 (US)

30G28 (CA)

(CA)

2-1/2

YES YES

YES YES YES

2 YES YES YES

2-1/2 YES YES

3 YES YES

Wall Kit Wall Ring Kit

44J40

(US)

81J20 (CA)

YES

15F74

YES

1-1/2 inch 2 inch 3 inch

Field

Fabricated

YES

YES YES YES

71M80

(US)

44W92

(CA)

YES

69M29

(US)

44W92

(CA)

60L46 (US)

44W93 (CA)

NOTE - Standard Terminations do not include any vent pipe or elbows external to the structure. Any vent pipe or elbows external to the structure must be included in total vent length calculations. See vent length tables.

* Kits must be properly installed according to kit instructions.

Requires field-provided outdoor 1-1/2” exhaust accelerator.

Concentric kits 71M80 and 44W92 include 1-1/2” outdoor accelerator, when used with 045 and 070 input models.

Flush mount kit 51W11 and 51W12 includes 1-1/2 in. outdoor exhaust accelerator, required when used with 045, 070 and 090 input models.

Termination kits 30G28, 44W92, 4493 and 81J20 are certified to ULC S636 for use in Canada only.

See table 17 for vent accelerator requirements.

Page 19

Page 20

Joint Cementing Procedure

Venting Practices

All cementing of joints should be done according to the specifications outlined in ASTM D 2855.

NOTE - A sheet metal screw may be used to secure the intake pipe to the connector, if desired. Use a drill or self tapping screw to make a pilot hole.

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.

6 - Promptly apply solvent cement to end of pipe and in

side socket surface of fitting. Cement should be ap plied lightly but uniformly to inside of socket. Take care to keep excess cement out of socket. Apply second coat to end of pipe.

NOTE - Time is critical at this stage. Do not allow prim er to dry before applying cement.

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 dur ing assembly (but not after pipe is fully inserted) to dis tribute cement evenly. DO NOT turn ABS or cellular core pipe.

NOTE - Assembly should be completed within 20 sec onds after last application of cement. Hammer blows should not be used when inserting pipe.

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.

Piping Suspension Guidelines

SCHEDULE 40

PVC - 5'

all other pipe* - 3'

* See table 11 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 outside

Wall

FIGURE 18

REPLACING FURNACE THAT

CHIMNEY

OR GAS

VENT

(Check sizing

for water

heater only)

FURNACE

(Replaced

by ML193)

If an ML193DF furnace replaces a furnace which was com monly vented with another gas appliance, the size of the ex isting 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.

WAS PART OF A COMMON

VENT SYSTEM

WATER

HEATER

OPENINGS

(To Adjacent

Room)

FIGURE 19

Page 20

Page 21

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 conden sate collection trap and lines.

Exhaust Piping (Figures 21 and 22)

Route piping to outside of structure. Continue with installa tion following instructions given in piping termination sec tion.

CAUTION

Do not discharge exhaust into an existing stack or stack that also serves another gas appliance. If verti cal discharge through an existing unused stack is re quired, 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 pres sure and must be completely sealed to prevent leak age of combustion products into the living space.

Vent Piping Guidelines

NOTE - Lennox has approved the use of DuraVent® manu factured vent pipe and terminations as an option to PVC. When using the PolyPro vent pipe requirements stated in the unit installation in struction – minimum & maximum vent lengths, termination clearances, etc. – apply and must be followed. Follow the instructions provided with PoyPro by DuraVent venting system for assembly or if requirements are more restrict ive. The PolyPro by Duravent venting system must also fol low the uninsulated and unconditioned space criteria listed in table 16.

by DuraVent venting system the

The ML193DF can be installed as either a Non-Direct Vent or a Direct Vent gas central furnace.

NOTE - In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged outdoors. In Non-Direct Vent installations, combustion air is taken from indoors or ventilated attic or crawlspace and flue gases are discharged outdoors.

Intake and exhaust pipe sizing -- Size pipe according to

tables 13 and 14. Count all elbows inside and outside the home. Table 13 lists the minimum vent pipe lengths per mitted. Table 14 lists the maximum pipe lengths permitted.

MINIMUM VENT PIPE LENGTHS

ML193DF

MODEL

045, 070, 090, 110

*Any approved termination may be added to the minimum length listed.

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 17.

In some applications which permit the use of several differ ent sizes of vent pipe, a combination vent pipe may be used. Contact Lennox' Application Department for assis tance in sizing vent pipe in these applications.

TABLE 13

MIN. VENT LENGTH*

15 ft. or

5 ft plus 2 elbows or

10 ft plus 1 elbow

IMPORTANT

Do not use screens or perforated metal in exhaust or intake terminations. Doing so will cause freeze-ups and may block the terminations.

Use the following steps to correctly size vent pipe diameter.

Page 21

Page 22

Piping Size Process

What is the

furnace capacity?

045, 070, 090 or

110?

Which style termination

being used?

Standard or concentric?

See table 12.

Which needs

most elbows?

Intake or

exhaust?

How many elbows? Count all elbows inside and outside house.

NOTE - It is acceptable to use any pipe size which fits within the guidelines allowed in table 14.

NOTE 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.

All horizontal runs of exhaust pipe must slope back

Desired pipe size?

2”, 2-1/2”, 3”

What is the altitude of the furnace installation?

Use table 14 or 15 to find max intake or exhaust pipe length. Includes all vent pipe and elbows inside and outside the house.

FIGURE 20

Page 22

Page 23

Maximum Allowable Intake or Exhaust Vent Length in Feet

TABLE 14

*Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Both Intake and Exhaust must be same pipe size. NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation.

Standard Termination at Elevation 0 - 10,000 ft.

Number

Of 90°

Elbows

Used

1 61 46 24

2 56 41 19 95 75 38 122 122 103 103

3 51 36 14 90 70 33 117 117 98 98

4 46 31

5 41 26 80 60 23 107 107 88 88

6 36 21 75 55 18 102 102 83 83

7 31 16 70 50 13 97 97 78 78

8 26 11 65 45

9 21

10 16 55 35 82 82 63 63

Number

Of 90°

Elbows

Used

1 53 38 22

2 48 33 17 85 65 34 106 106 99 99

3 43 28 12 80 60 29 101 101 94 94

4 38 23

5 33 18 70 50 19 91 91 84 84

6 28 13 65 45 14 86 86 79 79

7 23

8 18 55 35 76 76 69 69

9 13 50 30 71 71 64 64

10 n/a 45 25 66 66 59 59

045 070 090 110 045 070 090 110 045 070 090 110

2” Pipe 2-1/2” Pipe 3” Pipe

Model Model Model

100 80 43

85 65 28 112 112 93 93

n/a

Concentric Termination Elevation 0 - 10,000 ft.

2” Pipe 2-1/2” Pipe 3” Pipe

Model Model Model

n/a

60 40 87 87 68 68

90 70 39

75 55 24 96 96 89 89

60 40

n/a

127 127 108 108

92 92 73 73

111 111 104 104

81 81 74 74

Maximum Allowable Exhaust Vent Lengths With Furnace Installed in a Closet or Basement Using Ventilated

NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation.

Number

Of 90°

Elbows

Used

1 51 36 14

2 46 31 9 80 60 23 102 102 83 83

3 41 26 4 75 55 18 97 97 78 78

4 36 21

5 31 16 65 45 8 87 87 68 68

6 26 11 60 40 3 82 82 63 63

7 21 6 55 35

8 16 1 50 30 72 72 53 53

9 11

10 6 40 20 62 62 43 43

045 070 090 110 045 070 090 110 045 070 090 110

2” Pipe 2-1/2” Pipe 3” Pipe

Model Model Model

n/a

TABLE 15

Attic or Crawl Space For Intake Air in Feet

Standard Termination at Elevation 0 - 10,000 ft.

85 65 28

70 50 13 92 92 73 73

n/a

45 25 67 67 48 48

n/a

Page 23

107 107 88 88

77 77 58 58

Page 24

TYPICAL EXHAUST PIPE CONNECTIONS

Pipe size determined in table 14.

*2”

2”

DO NOT transition from smaller

to larger pipe size in horizontal

runs of exhaust pipe.

2”

3”

TRANSITION

* When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible.

NOTE − Exhaust pipe and intake pipe must be the same diameter.

FIGURE 21

TYPICAL INTAKE PIPE CONNECTIONS

2”

INTAKE

EXHAUST

TOP VIEW

Pipe size determined in table 14.

2”

3”

TRANSITION

*2”

* When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible.

NOTE − Intake pipe and exhaust pipe must be the same diameter.

FIGURE 22

Intake Piping

The ML193DF 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. Guidelines listed in Combustion, Dilution and Ventilation Air section must be followed.

2”

*2”

2”

TRANSITION

*2”

2”

3”

INTAKE

TOP VIEW

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 cement to secure the intake pipe to the inlet air

connector.

EXHAUST

Page 24

Page 25

2 - Route piping to outside of structure. Continue with

installation following instructions given in general guide lines for piping terminations and intake and ex haust piping terminations for direct vent sections. Re fer to table

14 for pipe sizes.

TYPICAL AIR INTAKE PIPE CONNECTIONS

NON−DIRECT VENT APPLICATIONS

AIR

INTAKE

SCREEN

(Provided)

(Inlet Air from Ventilated Attic and Outlet Air to Outside)

Roof T erminated

Exhaust Pipe

EQUIPMENT IN CONFINED SPACE

Ventilation Louvers

Inlet Air

(Minimum

12 in.(305mm) Abov

attic floor)

*Intake Debris

Screen

(Provided)

Furnace

* See table 15 for maximum vent lengths

NOTE-The inlet and outlet air openings shall each have a free area of at least one square inch per 4,000 Btu (645mm hour of the total input rating of all equipment in the enclosure.

per 1.17kW) per

FIGURE 24

NOTE - Air intake screen and elbow may be rotated, so that screen may be positioned to face forward or to either side.

FIGURE 23

Follow the next two steps when installing the unit in Non‐ Direct 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 23. 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 sideways.

2 - If intake air is drawn from a ventilated attic (figure 24)

or ventilated crawlspace (figure 25) the exhaust vent length must not exceed those listed in table 15. If 3” di ameter pipe is used, reduce to 2” diameter pipe at the termination point to accommodate the debris screen.

3 - Use cement to secure the intake pipe to the connector,

if desired.

CAUTION

If this unit is being installed in an application with combustion air coming in from a space serviced by an exhaust fan, power exhaust fan, or other device which may create a negative pressure in the space, take care when sizing the inlet air opening. The in let air opening must be sized to accommodate the maximum volume of exhausted air as well as the maximum volume of combustion air required for all gas appliances serviced by this space.

(Inlet Air from Ventilated Crawlspace and Outlet Air to Outside)

Roof T erminated

Exhaust Pipe

Ventilation

Louvers

(Crawl space)

(Field Provided)

EQUIPMENT IN CONFINED SPACE

Furnace

Coupling or 3 in. to 2 in.

Transition

12 in.(305mm)

*Intake Debris Screen Provided)

Inlet Air

(Minimum

Above crawl

space floor)

* See table 15 for maximum vent lengths

NOTE-The inlet and outlet air openings shall each have a free area of at least one square inch per 4,000 Btu (645mm hour of the total input rating of all equipment in the enclosure.

per 1.17kW) per

FIGURE 25

General Guidelines for Vent Terminations

In Non‐Direct Vent applications, combustion air is taken from indoors and the flue gases are discharged to the out doors. The ML193DF 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 out doors. The ML193DF 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 ab sence of local codes, refer to the current National Fuel Gas Code ANSI Z223-1/NFPA 54 in U.S.A., and current CSAB149 Natural Gas and Propane Installation Codes in Can ada for details.

Page 25

Page 26

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 accumula tion.

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 - See table 16 for maximum allowed exhaust pipe length without insulation in unconditioned space during winter design temperatures below 32°F (0°C). If required exhaust pipe should be insulated with 1/2” (13mm) Arma flex or equivalent. In extreme cold climate areas, 3/4” (19mm) Armaflex or equivalent may be necessary. Insula tion must be protected from deterioration. Armaflex with UV protection is permissable. Basements or other en

closed areas that are not exposed to the outdoor ambient temperature and are above 32 degrees F (0°C) are to be considered conditioned spaces.

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).

Maximum Allowable Exhaust Vent Pipe Length (in ft.) Without Insulation In Unconditioned Space For

TABLE 16

Winter Design Temperatures Single - Stage High Efficiency Furnace

Winter Design

Temperatures

(-18 to -29)

1Refer to 99% Minimum Design Temperature table provided in the current edition of the ASHRAE Fundamentals Handbook.

Poly-Propylene vent pipe (PP)

NOTE - Maximum uninsulated vent lengths listed may include the termination(vent pipe exterior to the structure) and cannot exceed 5 linear feet or the maximum allowable intake or exhaust vent length listed in table 14 or 15 which ever is less.

NOTE - If insulation is required in an unconditioned space, it must be located on the pipe closest to the furnace. See figure26.

32 to 21

(0 to -6)

20 to 1

(-7 to -17)

0 to -20

°F (°C)

Vent Pipe

Diameter

2 in. 26 24 44 41 44 44 24 24 N/A N/A

2-1/2 in. 18 N/A 32 N/A 50 N/A 58 N/A N/A N/A

3 in. 14 12 26 23 38 33 55 49 60 53

2 in 16 15 28 26 40 37 24 24 N/A N/A

2-1/2 in. 12 N/A 20 N/A 30 N/A 44 N/A N/A N/A

3 in. 9 8 16 14 26 23 32 28 40 35

2 in. 10 9 20 18 30 28 24 24 N/A N/A

2-1/2 in. 8 N/A 14 N/A 20 N/A 32 N/A N/A N/A

3 in. 4 3 10 8 16 14 26 23 30 26

045 070 090 110 135

PVC

PP PVC

Unit Input Size

PP PVC

Conditioned

Space

Conditioned

Space

FIGURE 26

Page 26

Pipe Insulation

Unconditioned

Space

Exhaust

Pipe

Intake

Pipe

Page 27

VENT TERMINATION CLEARANCES

FOR NON-DIRECT VENT INSTALLATIONS IN THE USA AND CANADA

INSIDE CORNER

DETAIL

Fixed

Closed

Operable

VENT TERMINAL

AIR SUPPLY INLET

US Installations

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

12 inches (305mm) or 12 in. (305mm)

above average snow accumulation.

4 feet (1.2 m) below or to side of opening;

1 foot (30cm) above opening

* 12”

* Equal to or greater than soffit depth.

horizontal distance of 2 feet (610 mm)

from the center line of the terminal

E =

F =

G =

H =

Clearance to unventilated soffit

Clearance to outside corner

Clearance to inside corner

Clearance to each side of center line ex

tended above meter / regulator assembly

I =

Clearance to service regulator

vent outlet

J =

Clearance to non-mechanical air

supply inlet to building or the com

bustion air inlet to any other ap

* Equal to or greater than soffit depth.

* No minimum to outside corner * No minimum to outside corner

3 feet (.9m) within a height 15 feet (4.5m)

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

pliance

K =

L =

Clearance to mechanical air sup

ply inlet

Clearance above paved sidewalk or

3 feet (.9m) above if within 10 feet

(3m) horizontally

7 feet (2.1m)†

paved driveway located on public property

M =

Clearance under veranda, porch, deck or balcony

In accordance with the current ANSI Z223.1/NFPA 54 Natural Fuel Gas Code

In 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.

*12 inches (305mm)‡

FIGURE 27

Fixed

Closed

AREA WHERE TERMINAL IS NOT PERMITTED

Canadian Installations

12 inches (305mm) or 12 in. (305mm)

above average snow accumulation.

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”

* Equal to or greater than soffit depth.

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

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 instal lation instructions.”

Page 27

Page 28

VENT TERMINATION CLEARANCES

FOR DIRECT VENT INSTALLATIONS IN THE USA AND CANADA

INSIDE CORNER

DETAIL

Fixed

Closed

Operable

VENT TERMINAL

AIR SUPPLY INLET

US Installations

A =

B =

Clearance above grade, veranda,

porch, deck or balcony

Clearance to window or

door that may be opened

12 inches (305mm) or 12 in. (305mm)

above average snow accumulation.

6 inches (152mm) for appliances <10,000

Btuh (3kw), 9 inches (228mm) for ap

pliances > 10,000 Btuh (3kw) and <50,000

Btuh (15 kw), 12 inches (305mm) for ap

pliances > 50,000 Btuh (15kw)

C =

Clearance to permanently

* 12”

closed window

D =

Vertical clearance to ventilated soffit

located above the terminal within a

* Equal to or greater than soffit depth

horizontal distance of 2 feet (610mm)

from the center line of the terminal

E =

F =

G =

H =

Clearance to unventilated soffit

Clearance to outside corner

Clearance to inside corner

Clearance to each side of center line ex

tended above meter / regulator assembly

I =

Clearance to service regulator

vent outlet

J =

Clearance to non-mechanical air

supply inlet to building or the com

bustion air inlet to any other ap

pliance

* Equal to or greater than soffit depth * Equal to or greater than soffit depth

* No minimum to outside corner

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

Btuh (3kw), 9 inches (228mm) for ap

pliances > 10,000 Btuh (3kw) and <50,000

Btuh (15 kw), 12 inches (305mm) for ap

pliances > 50,000 Btuh (15kw)

K =

L =

M =

In accordance with the current ANSI Z223.1/NFPA 54 Natural Fuel Gas Code

In 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.

Clearance to mechanical air sup

ply inlet

Clearance above paved sidewalk or

paved driveway located on public property

Clearance under veranda, porch, deck or balcony

3 feet (.9m) above if within 10 feet

(3m) horizontally

* 7 feet (2.1m)

*12 inches (305mm)‡

FIGURE 28

Fixed

Closed

AREA WHERE TERMINAL IS NOT PERMITTED

Canadian Installations

12 inches (305mm) or 12 in. (305mm)

above average snow accumulation.

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”

* Equal to or greater than soffit depth* Equal to or greater than soffit depth

* No minimum to outside corner

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

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)‡

Page 28

Page 29

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.

NOTE - Flue gas may be slightly acidic and may adversely affect some building materials. If any vent termination is used and the flue gasses may impinge on the building ma terial, a corrosion-resistant shield (minimum 24 inches square) should be used to protect the wall surface. If the optional tee is used, the protective shield is recommended. The shield should be constructed using wood, plastic, sheet metal or other suitable material. All seams, joints, cracks, etc. in the affected area should be sealed using an appropriate sealant. See figure 36.

Intake and exhaust pipes may be routed either horizontally through an outside wall or vertically through the roof. In at tic or closet installations, vertical termination through the roof is preferred. Figures 31 through 37 show typical ter minations.

1. Intake and exhaust terminations are not required to be in the same pressure zone. You may exit the intake on one side of the structure and the exhaust on another side (figure 29). You may exit the exhaust out the roof and the intake out the side of the structure (figure 30).

2. Intake and exhaust pipes should be placed as close together as possible at termination end (refer to il lustrations). Maximum separation is 3” (76mm) on roof terminations and 6” (152mm) on side wall termina tions.

NOTE - When venting in different pressure zones, the maximum separation requirement of intake and ex haust pipe DOES NOT apply.

3. On roof terminations, the intake piping should termi nate straight down using two 90° elbows (See figure

31).

4. Exhaust piping must terminate straight out or up as shown. A reducer may be required on the exhaust pip ing at the point where it exits the structure to improve the velocity of exhaust away from the intake piping. See table 17.

TABLE 17

EXHAUST PIPE TERMINATION SIZE REDUCTION

ML193

MODEL

*045 and *070

*090 2” (51mm)

110

*ML193DF-045, -070 and -090 units with the flush-mount termination must use the 1-1/2”accelerator supplied with the kit.

Exhaust Pipe Size

2” (51mm), 2-1/2” (64mm),

3” (76mm)

Termination

Pipe Size

1-1/2” (38mm)

2” (51mm)

5. On field-supplied terminations for side wall exit, ex haust 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 figure 36.

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 figure 36.

NOTE - Care must be taken to avoid recirculation of exhaust back into intake pipe.

Exiting Exhaust and Intake Vent

(different pressure zones)

Exhaust

Pipe

Furnace

Inlet Air

(Minimum 12 in.

305 MM) above

grade or snow

accumulation

FIGURE 29

Exiting Exhaust and Intake Vent

(different pressure zones)

Roof T

erminated

Exhaust Pipe

Inlet Air

Furnace

(Minimum 12 in.

305 MM) above

grade or snow

accumulation

FIGURE 30

Inches(mm)

8” (203mm) MIN

12” (305mm) ABOVE

AVERAGE SNOW

ACCUMULATION

3” (76mm) OR

2” (51mm) PVC

PROVIDE SUPPORT

FOR INTAKE AND

EXHAUST LINES

DIRECT VENT ROOF TERMINATION KIT

3”(76mm) MAX.

(15F75 or 44J41)

SIZE TERMINATION

PIPE PER TABLE 17.

UNCONDITIONED

ATTIC SPACE

1/2” (13mm) FOAM

INSULATION IN

UNCONDITIONED

SPACE

FIGURE 31

Page 29

Page 30

7. If intake and exhaust piping must be run up a side wall to position above snow accumulation or other ob structions, piping must be supported. At least one bracket must be used within 6” from the top of the el bow and then every 24” (610mm) as shown in figure 36, to prevent any movement in any direction. When exhaust and intake piping must be run up an outside wall, the exhaust piping must be terminated with pipe sized per table 17.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.

8. A multiple furnace installation may use a group of up to four terminations assembled together horizontally, as shown in figure 34.

1-1/2” (38mm) accelerator

provided on 71M80 & 44W92

12” (305mm)

Minimum

Above Average

Snow

Accumulation

kits for ML193DF045P36B- &

INTAKE

070P36B

FLASHING

(Not Furnished)

EXHAUST

VENT

INTAKE

AIR

Inches (mm)

optional intake elbow

OPTIONAL VENT TERMINATION FOR MULTIPLE UNIT

INSTALLATION OF DIRECT VENT WALL TERMINATION KIT

5”

(127mm)

18” MAX.

(457mm)

EXHAUST VENT

Side View

(30G28 or 81J20)

INTAKE

AIR

12”

(305mm)

5-1/2”

(140mm)

Front View

12” (305mm) Min.

above grade or

average snow ac

cumulation.

FIGURE 34

2” EXTENSION FOR 2” PVC PIPE1” EXTENSION FOR 3” PVC PIPE

4''

FURNACE EXHAUST

PIPE

SHEET METAL STRAP

(Clamp and sheet metal strap

must be field installed to support

CLAMP

DIRECT VENT CONCENTRIC ROOFTOP TERMINATION

71M80, 69M29 or 60L46 (US)

41W92 or 41W93 (Canada)

the weight of the termination kit.)

FIELD-PROVIDED

REDUCER MAY BE REQUIRED

TO ADAPT LARGER VENT

PIPE SIZE TO TERMINATION

FIGURE 32

1-1/2” (38mm) accelerator

FIELD-PROVIDED

REDUCER MAY BE

REQUIRED TO ADAPT

LARGER VENT PIPE

SIZE TO TERMINA

TION

EXHAUST

AIR

INTAKE

AIR

DIRECT VENT CONCENTRIC WALL TERMINATION

OUTSIDE

WALL

CLAMP

(Not Furnished)

71M80, 69M29 or 60L46 (US)

41W92 or 41W93 (Canada)

provided on 71M80 &

44W92 kits for

ML193DF045P36B- &

070P36B

INTAKE

AIR

EXHAUST

AIR

12” (305mm) Min.

INTAKE

AIR

above grade or

average snow ac

cumulation.

GRADE

FIGURE 33

FURNACE

INTAKE

PIPE

GLUE EXHAUST

END FLUSH INTO

TERMINATION

FLAT SIDE

1-1/2” ACCELERATOR

(all -45, -070 and -090 units)

FLUSH-MOUNT SIDE WALL TERMINATION

51W11 (US) or 51W12 (Canada)

FIGURE 35

Page 30

Page 31

NOTE − FIELD−PROVIDED

REQUIRED TO ADAPT

LARGER VENT PIPE SIZE

* WALL

SUPPORT

REDUCER MAY BE

TO TERMINATION

STRAIGHT

APPPLICATION

EXTENDED

APPLICATION

FIELD FABRICATED WALL TERMINATION

A− Minimum clearance

above grade or average

snow accumulation

B− Maximum horizontal separation between

intake and exhaust

C1 -Minimum from end of

exhaust to inlet of intake

C2 -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)

See venting table 14 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 within 6” (152 mm) from top of each pipe (intake and exhaust) to prevent movement in any direction.

Intake Elbow

2” (51mm)

Vent Pipe

12” (305 mm)

6” (152 mm)

3” (76mm)

Vent Pipe

12” (305 mm)

6” (152 mm)6” (152 mm)

8” (203 mm)8” (203 mm)

6” (152 mm)6” (152 mm)

20” (508 mm)

6” (152 mm)

ALTERNATE TERMINATIONS (TEE & FORTY−FIVE DEGREE ELBOWS ONLY)

2” (51MM)

12”

The exhaust termination tee should be connected to the 2” or 3” PVC flue pipe as shown in the illustration. Do not use an accelerator in applications that include an exhaust termination tee. The accelerator is not required.

As required. Flue gas may be acidic and may adversely affect some building materials. If a side wall vent

termination is used and flue gases will impinge on the building materials, a corrosion−resistant shield (24 inches square) should be used to protect the wall surface. If optional tee is used, the protective shield is recommended. The shield should be constructed using wood, sheet metal or other suitable material. All seams, joints, cracks, etc. in affected area, should be sealed using an appropriate sealant.

Exhaust pipe 45° elbow can be rotated to the side away from the combustion air inlet to direct exhaust away from adjacent property. The exhaust must never be directed toward the combustion air inlet.

Intake Elbow

Intake and Exhaust

Intake

Front View of

Exhaust

A− Clearance above

grade or average snow

accumulation

B− Horizontal

separation between

intake and exhaust

C− Minimum from

end of exhaust to

inlet of intake

D− Exhaust pipe length

E− Wall support distance

from top of each pipe

(intake/exhaust)

Vent Pipe

12” (305 mm) Min. 12” (305 mm) Min.

6” (152 mm) Min. 24” (610 mm) Max.

9” (227 mm) Min.

12” (305 mm) Min. 16” (405 mm) Max.

6” (152 mm) Max.

3” (76MM)

Vent Pipe

6” (152 mm) Min. 24” (610 mm) Max.

9” (227 mm) Min. 12” (305 mm) Min.

20” (508 mm) Max.

6” (152 mm) Max.

FIGURE 36

Page 31

Page 32

ML193DF DIRECT VENT APPLICATION

USING EXISTING CHIMNEY

8” - 12”

(203mm - 305mm)

Minimum 12” (305MM)

above chimney top

plate or average snow

accumulation

*SIZE TERMINATION PIPE PER TABLE 17.

NOTE - Do not discharge exhaust gases directly into any chimney or vent stack. If ver tical 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 illus trated. In any exterior portion of chimney, the exhaust vent must be insulated.

INTAKE PIPE

INSULATION (optional)

SHEET

METAL TOP

PLATE

INSULATE

TO FORM

SEAL

3” - 8” (76mm203mm)

STRAIGHT-CUT OR

ANGLE-CUT IN DIRECTION

OF ROOF SLOPE *

EXHAUST VENT

1/2” (13mm)

WEATHERPROOF

INSULATION

SHOULDER OF FITTINGS

PROVIDE SUPPORT

OF PIPE ON TOP PLATE

3” - 8” (76mm203mm)

ALTERNATE INTAKE PIPE

EXTERIOR

PORTION OF

CHIMNEY

FIGURE 37 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 pre ferred. Figures 38 through 39 show typical terminations.

1. Exhaust piping must terminate straight out or up as

shown. The termination pipe must be sized as listed in table 17.The specified pipe size ensures proper ve locity required to move the exhaust gases away from the building.

SIZE TERMINATION

PIPE PER TABLE

12” (305mm)

ABOVE AVE.

SNOW

ACCUMULATION

1/2” (13mm) FOAM

INSULATION

17.

2. On field supplied terminations for side wall exit, ex haust piping may extend a maximum of 12 inches (305mm) for 2” PVC and 20 inches (508mm) for 3” (76mm) PVC beyond the outside wall.

3. If exhaust piping must be run up a side wall to position above snow accumulation or other obstructions, pip ing must be supported every 24 inches (610mm). When exhaust piping must be run up an outside wall, any reduction in exhaust pipe size must be done after the final elbow.

4. Distance between exhaust pipe terminations on mul tiple furnaces must meet local codes.

ML193DF NON-DIRECT VENT APPLICATION

USING EXISTING CHIMNEY

SIZE TERMINATION

PIPE PER TABLE 17.

3” - 8”

(76mm-

Minimum 12” (305MM)

above chimney top

plate or average snow

accumulation

METAL TOP

INSULATE TO FORM

SEAL

203mm)

SHEET

PLATE

STRAIGHT-CUT OR

ANGLE-CUT IN DIRECTION

OF ROOF SLOPE

EXHAUST VENT

1/2” (13mm)

WEATHERPROOF

INSULATION

SHOULDER OF FITTINGS

PROVIDE SUPPORT

OF PIPE ON TOP PLATE

3” - 8”

(76mm-

203mm)

EXTERIOR

PORTION OF

CHIMNEY

FIGURE 39

3” (76mm) OR

2” (51mm) PVC

PROVIDE SUPPORT

FOR EXHAUST LINES

NON-DIRECT VENT ROOF TERMINATION KIT

(15F75 or 44J41)

FIGURE 38

UNCONDITIONED

ATTIC SPACE

Page 32

Page 33

Condensate Piping

This unit is designed for either right‐ or left‐side exit of con densate piping. Refer to figures 40 and 42 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

4 - Install drain trap using appropriate PVC fittings, glue

all joints. Glue the provided drain trap as shown in fig ures 46 and 47. Route the condensate line to an open drain.

5 - Figure 44 shows the furnace and evaporator coil using

a separate drain. If necessary, the condensate line from the furnace and evaporator coil can drain togeth er. See figures 45 and 43. The field provided vent must be a minimum 1” to a maximum 2” length above the condensate drain outlet connection.

NOTE - If necessary the condensate trap may be installed up to 5 feet away from the furnace. Piping from furnace must slope down a minimum of 1/4” per ft. toward trap.

NOTE - Appropriately sized tubing and barbed fitting may be used for condensate drain. Attach to the drain on the trap using a hose clamp. See figure 41.

Trap

(same on

right side)

1-1/2 in.

FIGURE 40

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.

2 - For furnaces with a 1/2” drain connection use a 3/8 al

len wrench and remove plug (figure 40) 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. For furnaces with a 3/4” drain connection use a large flat head screw driver or a 1/2” drive socket extension and remove plug. Install provided 3/4 NPT street elbow 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 figures 46 and 47.

Plug

(same on left

side)

Field Provided Drain Components

Elbow

Barbed Fitting

Tubing

Hose Clamp

FIGURE 41

6 - 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. Heat cable kit is avail able 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.

CAUTION

Do not use copper tubing or existing copper condensate lines for drain line.

Page 33

Page 34

CONDENSATE TRAP LOCATION

(shown with right side exit of condensation)

Trap can be installed a maxi mum of 5ft. from furnace (*PVC only)

Field Provided Vent

1” min. 2” max. above

condensate drain.

1” min.

2” max.

5’ max.

ML193DF with Evaporator Coil

Using a Separate Drain

Field Provided Vent

1” min. 2” max. above

condensate drain.

Condensate Drain

Connection

Evaporator Drain Line

(vent required)

to drain

*Piping from furnace must slope down a

minimum 1/4” per ft. toward trap

FIGURE 42

Condensate Trap With Optional Overflow Switch

From Evaporator Coil

Optional

Field Provided Vent

1” min. 2” max. above

condensate drain.

FurnaceCondensate

Drain

Connection

Drain

FIGURE 44

IMPORTANT

When combining the furnace and evaporator coil drains together, the A/C condensate drain outlet must be vented to relieve pressure in or der for the furnace pressure switch to operate properly.

ML193DF with Evaporator Coil Using a Common Drain

Field Provided Vent

1” min. 2” max. above

condensate drain.

Condensate Drain

Connection

FIGURE 43

Evaporator Drain Line

(vent required)

FIGURE 45

Page 34

Page 35

TRAP / DRAIN ASSEMBLY USING 1/2” PVC OR 3/4” PVC

COLD END HEADER BOX WITH 3/4” DRAIN CONNECTION

Optional Condensate Drain Connection

Adapter 3/4 inch slip X

3/4 inch mpt (not furnished)

90° Street Elbow 3/4 inch PVC (not furnished)

Condensate Drain

Connection In Unit

90° Street Elbow 3/4 inch PVC ( furnished)

Trap

OptionalDrainPipingFromTrap

Drain Assembly for 1/2 inch Drain Pipe

1/2 inch PVC Pipe

(Not Furnished)

90° Elbow

1/2 inch PVC

(Not Furnished)

Drain

Drain Assembly for 3/4 inch Drain Pipe

1 (25mm) Min. 2 (50 mm) Max. Above Top Of Condensate Drain Connection In Unit

Elbow 3/4 inch PVC

90°

(Not Furnished)

1/2 inch PVC Pipe

(Not Furnished)

Adapter 3/4 inch slip X

3/4 inch mpt (not furnished)

ent

5 Feet

Maximum

3/4 inch PVC Pipe

(Not Furnished)

Coupling 3/4 inch slip X slip

(Not Furnished)

Drain Trap

Assembly

(Furnished)

Condensate Drain

Connection In Un

90° Elbow

3/4 inch PVC

(Not Furnished)

Drain

DrainTrapAssembly

(Furnished)

(178)

Drain Trap

Clean Out

90° Elbow

3/4 inch PVC

(Not Furnished)

Coupling 3/4 inch slip X slip

Drain

DrainTrap Assembly with 1/2 inch Piping 1 (25 mm) Min. 2 (50 mm) Max. Above Top

Of Condensate Drain Connection In Unit

(Not Furnished)

Vent

1/2 inch

Condensate Drain

Connection In Unit

Drain

DrainTrap Assembly with 3/4 inch Piping

1 (25 mm) Min. 2 (50 mm) Max. Above Top Of Condensate Drain Connection In Unit

Vent

3/4 inch

Condensate Drain

Connection In Unit

Drain

FIGURE 46

Page 35

Page 36

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)

90° Street Elbow

1/2 inch PVC

(Not Furnished)

Condensate Drain

Connection In Unit

90° Street Elbow

1/2 inch PVC

(Furnished)

Trap

Optional Drain Piping From Trap

Drain Assembly for 1/2 inch Drain Pipe

1/2 inch PVC Pipe

(Not Furnished)

90° Elbow

1/2 inch PVC

(Not Furnished)

Drain

Drain Assembly for 3/4 inch Drain Pipe

1 (25 mm) Min. 2 (50 mm) Max. Above Top Of Condensate Drain Connection In Unit

90° Elbow 1/2 inch PVC

(Not Furnished)

1/2 inch PVC Pipe

(Not Furnished)

Adapter 1/2 inch slip X

1/2 inch mpt (Not Furnished)

Vent

5 Feet

Maximum

1/2 inch PVC Pipe

(Not Furnished)

Coupling 1/2 inch slip X slip

(Not Furnished)

Drain Trap

Assembly

(Furnished)

Condensate Drain

Connection In Unit

90° Elbow

3/4 inch PVC

(Not Furnished)

Drain

Drain Trap Assembly

(Furnished)

(178)

90° Elbow

3/4 inch PVC

(Not Furnished)

Coupling 3/4 inch slip X slip

Drain

Drain Trap Assembly with 1/2 inch Piping

1 (25 mm) Min. 2 (50 mm) Max. Above Top Of Condensate Drain Connection In Unit

(Not Furnished)

Vent

1/2 inch

Condensate Drain Connection In Unit

Drain

Drain Trap Clean Out

Drain Trap Assembly with 3/4 inch Piping

1 (25 mm) Min. 2 (50 mm) Max. Above Top Of Condensate Drain Connection In Unit

Vent

3/4 inch

Condensate Drain

Connection In Unit

Drain

FIGURE 47

Page 36

Page 37

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 as

sembly. 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 ML193DF is equipped with a gas con trol 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:

ML193DF units are equipped with a SureLight ignition sys tem. Do not

attempt to manually light burners on this fur nace. 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 op

eration.

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 de

mand.

5 - Wait for the combustion air inducer to stop. Set the

thermostat to initiate a heating demand and again al low the burners to fire for approximately 3 minutes.

6 - Adjust the thermostat to deactivate the heating de

mand and again wait for the combustion air inducer to stop. At this point, the trap should be primed with suffi cient water to ensure proper condensate drain opera tion.

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 48)

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 48. 7 - Wait five minutes to clear out any gas. If you then smell

gas, STOP! Immediately call your gas supplier from a neighbor's phone. Follow the gas supplier's instruc tions. If you do not smell gas go to next step.

8 - Move gas valve switch to ON. See figure 48.

MANIFOLD

PRESSURE

ADJUSTMENT

SCREW

(under

barbed

fitting)

INLET

PRESSURE

PORT

GAS VALVE SHOWN IN ON POSITION

MANIFOLD PRESSURE

OUTLET

FIGURE 48

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 techni cian 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 37

Page 38

IV-HEATING SYSTEM SERVICE CHECKS

A-C.S.A. Certification

All units are C.S.A. design certified without modifications. Refer to the ML193DF Operation and Installation Instruc tion Manual Information.

B-Gas Piping

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.

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

IMPORTANT

In case emergency shutdown is required, turn off the main shut‐off valve and disconnect the main power to unit. These controls should be properly labeled by the installer.

When pressure testing gas lines, the gas valve must be dis connected and isolated. Gas valves can be damaged if subjected to more than 0.5psig (14” W.C.). See figure 49.

MANUAL MAIN SHUT-OFF

VALVE WILL NOT HOLD

NORMAL TEST PRESSURE

1/8” N.P.T. PLUGGED TAP

CAP

FIGURE 49

When checking piping connections for gas leaks, use pre ferred means. Kitchen detergents can cause harmful cor rosion on various metals used in gas piping. Use of a spe cialty Gas Leak Detector is strongly recommended. It is

FURNACE

ISOLATE

GAS VALVE

D-Testing Gas Supply Pressure

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 48. Check gas line pressure with unit firing at maximum rate. Low pres sure may result in erratic operation or underfire. High pres sure can result in permanent damage to gas valve or over fire.

On multiple unit installations, each unit should be checked separately, with and without units operating. Supply pres sure must fall within range listed in table 19.

E-Check Manifold Pressure

After line pressure has been checked and adjusted, check manifold pressure. Move pressure gauge to outlet pres sure tap located on unit gas valve (GV1). Checks of manifold pressure are made as verification of proper regulator adjustment.

IMPORTANT

For safety, connect a shut‐off valve between the manometer and the gas tap to permit shut off of gas pressure to the manometer.

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 pres sure.

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

19.

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 38

Page 39

F- Proper Gas Flow (Approximate)

Gas Flow (Approximate)

TABLE 18

GAS METER CLOCKING CHART

Seconds for One Revolution

ML193

Unit

-045 80 160 200 400

-070 55 110 136 272

-090 41 82 102 204

-110 33 66 82 164

Natural-1000 btu/cu ft LP-2500 btu/cu ft

NOTE - To obtain accurate reading, shut off all other gas appliances connected to meter.

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

18. If manifold pressure matches table 19 and rate is incor rect, check gas orifices for proper size and restriction. Re move temporary gas meter if installed.

Manifold and Supply Pressure (Outlet) inches w.c.

At All Altitudes For -1 Through -6 Units

Fuel

Nat. Gas All sizes 3.5 4.5 13.0

L.P. Gas All sizes 10.0 11.0 13.0

Natural LP

1 cu ft

Dial

2 cu ft

Dial

TABLE 19

Model

Input Sizes

Manifold

Pressure in.wg.

1 cu ft

Dial

2 cu ft

DIAL

Supply

Pressure in.wg.

Min. Max.

G- Proper Combustion

Furnace should operate at least 15 minutes with correct manifold pressure and gas flow rate before checking com bustions. Take sample beyond the flue outlet and compare to table 20.

TABLE 20

ML193

Unit

CO2%

For Nat

CO2%

For L.P.

-045

-070

-090

7.2 - 7.9 8.6 - 9.3

-110

The carbon monoxide reading should not exceed 50 ppm.

H- High Altitude

NOTE - In Canada, certification for installations at eleva tions over 4500 feet (1372 m) is the jurisdiction of local au thorities.

ML193DF-1 through -6 units require no manifold pressure adjustments for operation at altitudes up to 10,000 feet (3048 m) above sea level. However, -7 units and later in stalled at altitude of 4501 - 10,000 feet (1373 to 3048m) re quire a pressure switch change which can be ordered sep arately and manifold de-rate. See table 19 or table 21 for manifold pressures at varying altitudes. Table 22 lists con version kit and pressure switch requirements at varying al titudes. The combustion air pressure switch is factory-set and re quires no adjustment.

TABLE 21

Manifold and Supply Line Pressure 0-10,000ft. For -7 Units and Later

Manifold Pressure in. wg.

ML193

Unit

All Sizes

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.

Gas

0-4500 ft. 4501-5500 ft. 5501-6500 ft.

Natural 3.5 3.3 3.2 3.1 3.5 4.5 13.0

LP/propane 10.0 9.4 9.1 8.9 10.0 11.0 13.0

6501 -

7500ft.

7501 - 10000ft.

Supply Line

0 - 10000 ft.

TABLE 22

Conversion Kit and Pressure Switch Requirements at Varying Altitudes

Natural to

ML193

Unit

-045

-070

-090

-110

* 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).

LP/Propane

0 - 7500 ft

(0 - 2286m)

*69W73 73W37 *73W81 93W87 93W88

High Altitude

Natural Burner Ori

fice Kit

7501 - 10,000 ft (2286 - 3038m)

LP/Propane to

Natural

0 - 7500 ft

(0 - 2286m)

High Altitude Pressure Switch

4501 - 7500 ft

(1373 - 2286m)

7501 -10,000 ft

(2286 - 3048m)

Pressure

in. w.g.

Page 39

Page 40

I-Flame Signal

A transducer (Part #78H5401 available from Lennox Re pair Parts) is required to measure flame signal if meter used will not read a low micro amp signal. Seefigure50. The transducer converts microamps to volts on a 1:1 con version. Flame signal is shown in table 23. A digital readout meter must be used. The transducer plugs into most me ters.

TABLE 23

Normal Flame Signal

Low Flame Signal

Drop Out Signal = 0.50 Microamps

To Measure Flame Signal:

1 - Set the volt meter to the DC voltage scale. Insert trans

ducer into the VDC and common inputs. Observe cor rect polarities. Failure to do so results in negative (-)

values. 2 - Turn off supply voltage to control. 3 - Disconnect ignition control flame sensor wire from the

flame sensor. 4 - Connect (-) lead of the transducer to flame sensor. 5 - Connect (+) lead of transducer to the ignition 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

(+) TO

IGNITION

CONTROL

SENSOR

WIRE

FIGURE 50

 1.50 Microamps

 1.40 Microamps

SET DIAL TO

MEASURE VDC

(+)

(-)

(-) TO

FLAME

SENSOR

TRANSDUCER PART #78H5401

RED COLLAR

INDICATES

POSITIVE

LEAD

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 sub

base fan switch. With fan switch in ON position, blower operates continuously. With fan switch in AUTO posi tion, 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 op eration 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 ra diant heat from the heat exchanger.

2 - Set thermostat for heat call. Unit must operate on sec

ond-stage heat.

3 - After plenum thermometers have reached their high

est 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, in crease blower speed to reduce temperature.

C-External Static Pressure

1 - Tap locations shown in figure 51. 2 - Punch a 1/4” diameter hole

in supply and return air ple nums. Insert manometer hose flush with inside edge of hole or insulation. Seal around the hose with perma gum. Connect the zero end of the manometer to the dis charge (supply) side of the system. On ducted sys tems, connect the other end of manometer to the return duct as above.

3 - With only the blower motor running and the evaporator

coil dry, observe the manometer reading. Adjust blow er motor speed to deliver the air desired according to the job requirements.

4 - External static pressure drop must not be more than

0.8” W.C. in the heating mode and must not exceed

1.0” W.C in the cooling mode.

5 - Seal the hole when the check is complete. 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.

STATIC PRESSURE TEST

filter

coil

FIGURE 50

Page 40

Page 41

VI-MAINTENANCE

Furnace

Cabinet Width

TABLE 24

Filter Size

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 opera tion, serious injury, death, or property damage. Before servicing, disconnect all electrical power to furnace. When servicing controls, label all wires prior to dis connecting. 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.

17-1/2”

21”

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 +

3 - Check amp-draw on the blower motor with blower ac

cess 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.

16 x 25 x 1 (1)

10%

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 inju ry 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 24 lists recommended filter sizes.

IMPORTANT

If a highefficiency filter is being installed as part of this system to ensure better indoor air quality, the fil ter must be properly sized. Highefficiency filters have a higher static pressure drop than standardef ficiency glass/foam filters. If the pressure drop is too great, system capacity and performance may be re duced. The pressure drop may also cause the limit to trip more frequently during the winter and the indoor coil to freeze in the summer, resulting in an increase in the number of service calls.

Before using any filter with this system, check the specifications provided by the filter manufacturer against the data given in the appropriate Lennox Product Specifications bulletin. Additional informa tion is provided in Service and Application Note ACC002 (August 2000).

Condensate Hose Screen (Figure 52)

Check the condensate hose screen for blockage and clean

if necessary. 1 - Turn off power to the unit. 2 - Remove hose from cold end header box. Twist and pull

screen to remove. 3 - Inspect screen and rinse with tap water if needed. 4 - Reinstall screen and turn on power to unit.

Condensate Hose Screen

Hose

FIGURE 52

Cleaning Heat Exchanger

If cleaning the heat exchanger becomes necessary, follow the below procedures and refer to figure 1 when disassem bling unit. Use papers or protective covering in front of fur nace while removing heat exchanger assembly.

1 - Turn off electrical and gas supplies to the furnace. 2 - Remove the furnace access panels. 3 - Disconnect the 2 wires from the gas valve. 4 - Remove gas supply line connected to gas valve. Re

move gas valve/manifold assembly.

5 - Remove sensor wire from sensor. Disconnect 2‐pin

plug from the ignitor.

Page 41

Page 42

6 - Disconnect wires from flame roll-out switches. 7 - Loosen clamps at vent elbow. Disconnect condensate

drain tubing from flue collar. and remove the vent el bow.

8 - Remove four burner box screws at the vestibule panel

and remove burner box. Set burner box assembly aside.

NOTE - If necessary, clean burners at this time. Follow procedures outlined in Burner Cleaning section.

9 - Mark and disconnect all combustion air pressure tub

ing from cold end header collector box.

10 - Mark and remove wires from pressure switches. Re

move pressure switches. Keep tubing attached to pressure switches.

11 - Disconnect the plug from the combustion air inducer.

Remove two screws which secure combustion air in ducer to collector box. Remove combustion air induc er assembly. Remove ground wire from vest panel.

12 - Remove electrical junction box from the side of the fur

nace.

13 - 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. 14 - Remove the primary limit from the vestibule panel. 15 - Remove two screws from the front cabinet flange at

the blower deck. Spread cabinet sides slightly to allow

clearance for removal of heat exchanger. 16 - Remove screws along vestibule sides and bottom

which secure vestibule panel and heat exchanger as

sembly to cabinet. Remove two screws from blower

rail which secure bottom heat exchanger flange. Re

move heat exchanger from furnace cabinet. 17 - Back wash heat exchanger with soapy water solution

or steam. If steam is used it must be below 275°F

(135°C) .

18 - Thoroughly rinse and drain the heat exchanger. Soap

solutions can be corrosive. Take care to rinse entire

assembly. 19 - Reinstall heat exchanger into cabinet making sure that

the clamshells of the heat exchanger assembly are

resting on the support located at the rear of the cabi

net. Remove the indoor blower to view this area

through the blower opening. 20 - Re‐secure the supporting screws along the vestibule

sides and bottom to the cabinet. Reinstall blower and

mounting screws. 21 - Reinstall cabinet screws on front flange at blower

deck. 22 - Reinstall the primary limit on the vestibule panel. 23 - Route heating component wiring through hole in blow

er deck and reinsert strain relief bushing. 24 - Reinstall electrical junction box. 25 - Reinstall the combustion air inducer. Reconnect the

combustion air inducer to the wire harness.

26 - Reinstall pressure switches and reconnect pressure

switch wiring.

27 - Carefully connect combustion air pressure switch hos

ing from pressure switches to proper stubs on cold end

header collector box. 28 - Reinstall condensate trap. 29 - Reconnect exhaust piping and exhaust drain tubing. 30 - Reinstall burner box assembly in vestibule area. 31 - Reconnect flame roll-out switch wires. 32 - Reconnect sensor wire and reconnect 2-pin plug from

ignitor. 33 - Secure burner box assembly to vestibule panel using

four existing screws. Make sure burners line up in

center of burner ports.

34 - Reinstall gas valve manifold assembly. Reconnect

gas supply line to gas valve. 35 - Reconnect 2 wires to gas valve. 36 - Replace the blower compartment access panel. 37 - Refer to instruction on verifying gas and electrical con

nections when re-establishing supplies. 38 - Follow lighting instructions to light and operate fur

nace for 5 minutes to ensure that heat exchanger is

clean and dry and that furnace is operating properly. 39 - Replace heating compartment access panel.

Cleaning the Burner Assembly

1 - Turn off electrical and gas power supplies to furnace.

Remove upper and lower furnace access panels. 2 - Disconnect the 2-pin plug from the gas valve. 3 - Remove the burner box cover. 4 - Disconnect the gas supply line from the gas valve. Re

move gas valve/manifold assembly. 5 - Mark and disconnect sensor wire from the sensor. Dis

connect 2‐pin plug from the ignitor at the burner box. 6 - Remove four screws which secure burner box assem

bly to vest panel. Remove burner box from the unit. 7 - Use the soft brush attachment on a vacuum cleaner to

gently clean the face of the burners. Visually inspect

the inside of the burners and crossovers for any block

age caused by foreign matter. Remove any blockage. 8 - Reconnect the sensor wire and reconnect the 2-pin

plug to the ignitor wiring harness. 9 - Reinstall the burner box assembly using the existing

four screws. Make sure that the burners line up in the

center of the burner ports. 10 - Reinstall the gas valve manifold assembly. Reconnect

the gas supply line to the gas valve. Reinstall the burn

er box cover. 11 - Reconnect 2-pin plug to gas valve. 12 - Replace the blower compartment access panel. 13 - Refer to instruction on verifying gas and electrical con

nections when re-establishing supplies. 14 - Follow lighting instructions to light and operate fur

nace for 5 minutes to ensure that heat exchanger is

clean and dry and that furnace is operating properly. 15 - Replace heating compartment access panel.

Page 42

Page 43

VII-WIRING DIAGRAM AND SEQUENCE OF OPERATION

ML193DF With Integrated Control 100973

1 - When there is a call for heat, W1 of the thermostat en

ergizes 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 contol (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 30-second delay, the integrated control (A92)

energizes indoor blower B3.

8 - When heat demand is satisfied, W1 of the indoor ther

mostat 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 in door blower B3 completes a selected OFF time delay.

Page 43

Page 44

Sequence of Operation Flow Chart - Integrated Control 100973

HEATING SEQUENCE OF OPERATION

NORMAL HEATING MODE

POWER ON

CONTROL SELF-CHECK OKAY?

YES

IS POLARITY CORRECT?

YES

IS THERE A PROPER GROUND?

YES

IS VOLTAGE

ABOVE 90 VOLTS?

YES

ROLLOUT SWITCH CLOSED?

YES

ABNORMAL HEATING MODE

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

(RESET CONTROL BY TURNING MAIN POWER OFF.)

HEATING UNTIL VOLTAGE RISES ABOVE 95 VOLTS.

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES

AND POWER IS RESET OR T'STAT IS INTERRUPTED

INDOOR BLOWER DELAY OFF.

LED #1 ON LED #2 ON

POLARITY REVERSED.

LED #1 -- FAST FLASH

LED #2 -- SLOW FLASH

IMPROPER GROUND. LED #1 -- ALTERNATING FAST FLASH LED #2 -- ALTERNATING FAST FLASH

LEDs SIGNAL FAST ALTERNATING FLASH.

CONTROL WILL NOT RESPOND TO A CALL FOR

INDOOR BLOWER ON.

LED #1 -- ON. LED #2 -- SLOW FLASH.

FOR MINIMUM OF 1 SECOND.

(Flame sensed without gas valve energized)

BURNER OFF?

YES

NORMAL OPERATION:

LED #1 -- SLOW FLASH LED #2 -- SLOW FLASH

YES

THERMOSTAT CALLS FOR HEAT:

LED #1 -- FAST FLASH LED #2 -- FAST FLASH

YES

PRIMARY LIMIT SWITCH. CLOSED?

YES

IS COMBUSTION AIR

PRESSURE SWITCH OPEN?

YES

IS COMBUSTION AIR INDUCER

ENERGIZED?

YES

HAS COMBUSTION AIR PRESSURE

SWITCH CLOSED IN 2.5 MINUTES?

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON HEATING SPEED.

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?

LED #1 -- SLOW FLASH

LED #2 -- OFF

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER ON

LED #1 SLOW FLASH RATE

LED #2 -- ON

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.)

YES

CONTINUED NEXT

PAGE

Page 44

Page 45

HEATING SEQUENCE CONTINUED

NORMAL HEATING MODE ABNORMAL HEATING MODE

15‐SECOND COMBUSTION AIR INDUCER PREPURGE

INITIATED BY CLOSED PRESSURE SWITCH.

YES

IGNITOR WARM‐UP -- 20 SECONDS.

YES

4‐SECOND TRIAL FOR IGNITION.

GAS VALVE OPENS. IGNITOR ENERGIZED FOR

FIRST 3 SECONDS OF THE TRIAL.

YES

FLAME STABILIZATION PERIOD.

4 SECONDS

FLAME RECTIFICATION CURRENT

CHECK. CAN FLAME BE PROVEN WITHIN

4 SECONDS AFTER GAS VALVE OPENS?

(0.5 microamps)

YES

FLAME PRESENT?

YES

FLAME SIGNAL 1.5 MICROAMPS OR GREATER?

YES

INDOOR BLOWER ON

AFTER 30-SECOND DELAY

YES

PRIMARY AND SECONDARY LIMIT

SWITCHES CLOSED?

YES

IS VOLTAGE ABOVE 90 VOLTS?

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

HAS CONTROL FAILED TO SENSE FLAME FOR

FIVE CONSECUTIVE TRIES DURING A SINGLE

WATCHGUARD MODE. GAS VALVE OFF.

LEDs SIGNAL WATCHGUARD FAILURE CODE.

IS 60‐MINUTE RESET PERIOD COMPLETE?

(Does not affect operation of control)

LED #1 -- SLOW FLASH

COMBUSTION AIR INDUCER DE-ENERGIZED.

INDOOR BLOWER ON UNTIL SWITCH CLOSES.

LED #1 -- SLOW FLASH. LED #2 -- ON.

HAS PRIMARY / SECONDARY

INDOOR BLOWER OFF.

HEAT DEMAND?

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY

HAS CONTROL RESET IGNITION

SEQUENCE FOUR TIMES?

LOW FLAME SIGNAL

LED #2 -- FAST FLASH

GAS VALVE DE-ENERGIZED.

IS LIMIT SWITCH CLOSED?

YES

LIMIT RESET TIME

EXCEEDED 3 MINUTES?

LEDS SIGNAL

LIMIT SWITCH WATCHGUARD

MODE. GAS VALVE, COMB. AIR

INDUCER AND INDOOR BLOW

ER OFF. LEDs SIGNAL LIMIT

SWITCH OPEN UNTIL MAIN

YES

ALTERNATING

FAST FLASH UNTIL

VOLTAGE IS ABOVE

95 VOLTS, THEN

RESTARTS HEATING

SEQUENCE.

YES

POWER IS

INTERRUPTED OR

T'STAT IS CYCLED

OFF/ON FOR 1 SEC.

MINIMUM. 60-MIN UTE WATCHGUARD PERIOD STARTS AT

TIME LIMIT CLOSES.

IS 60-MIN. PERIOD

COMPLETE?

ROLLOUT SWITCH CLOSED?

YES

COMBUSTION AIR PRESSURE

SWITCH CLOSED?

YES

THERMOSTAT DEMAND SATISFIED.

YES

LED #1 & #2 SIMULTANEOUS SLOW FLASHES.

YES

COMB. AIR INDUCER CONTINUES 5‐SECOND

POST PURGE AFTER T'STAT DEMAND IS SATISFIED.

INDOOR AIR BLOWER COMPLETES SELECTED “OFF”

DELAY BEFORE SHUTTING OFF.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESET

THERMOSTAT IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.

HAS PRESSURE SWITCH OPENED 5

TIMES IN THE SAME HEAT DEMAND?

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?

5‐MINUTE PRESSURE SWITCH

WATCHGUARD MODE.

GAS VALVE POWER OFF.

COMBUSTION AIR INDUCER POWER ON.

INDOOR BLOWER ON

LED #1 -- ON. LED #2 -- SLOW FLASH.

AND MAIN POWER IS INTERRUPTED OR

Page 45

YES

WATCHGUARD

1 HR

PRESSURE

SWITCH

MODE

Page 46

COOLING SEQUENCE OF OPERATION

NORMAL COOLING MODE ABNORMAL COOLING MODE

POWER ON

IGNITION CONTROL MAIN POWER ON.

CONTROL SELF DIAGNOSTIC CHECK.

IS CONTROL OPERATING NORMALLY?

YES

IS THERE A PROPER GROUND?

YES

IS POLARITY CORRECT?

YES

IS VOLTAGE

ABOVE 90 VOLTS?

YES

ROLLOUT SWITCH MONITORED CONTINUOUSLY.

IS ROLLOUT SWITCH CLOSED?

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH NORMAL DELAY.

SIGNAL CIRCUIT CONTROL FAILURE AT LED.

INTERRUPT MAIN POWER TO RESET CONTROL.

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.

LED SIGNALS LOW VOLTAGE. CONTROL WILL

CONTINUE TO CALL FOR COOLING

IN THIS CONDITION.

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.

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 46

Page 47

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).

THERMOSTAT CALLS FOR COOLING.

YES

SYSTEM FAN SWITCHED TO COOL SPEED.

EAC TERM. REMAINS ON.

THERMOSTAT OPENS.

MANUAL FAN SELECTION MADE AT THERMOSTAT.

CONTROL (G) ENERGIZES SYSTEM FAN AT HEAT

SPEED. EAC TERM. ENERGIZED.

HUM TERM. ENERGIZES

WITH COMB. AIR INDUCER.

YES

SYSTEM FAN REMAINS ON

HEATING SPEED.

THERMOSTAT OPENS.

HUM TERM. DE-ENERGIZES

WITH COMB. AIR INDUCER

SYSTEM FAN REMAINS ON

HEATING SPEED.

Page 47

Page 48

ML193DF With Integrated Control 103085

1 - When there is a call for heat, W1 of the thermostat en

ergizes 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

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 30-second delay, the integrated control (A92)

energizes indoor blower B3.

8 - When heat demand is satisfied, W1 of the indoor ther

Page 48

Page 49

Sequence of Operation Flow Chart - Integrated Control 103085

HEATING SEQUENCE OF OPERATION

NORMAL HEATING MODE

POWER ON

CONTROL SELF-CHECK OKAY?

YES

IS POLARITY CORRECT?

YES

IS THERE A PROPER GROUND?

YES

IS VOLTAGE

ABOVE 90 VOLTS?

YES

ROLLOUT SWITCH CLOSED?

YES

ABNORMAL HEATING MODE

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER DELAY OFF.

LED: OFF

POLARITY REVERSED.

LED: 9 FLASHES

IMPROPER GROUND.

LED: OFF

CONTROL WILL NOT RESPOND TO CALL FOR HEAT

UNTIL PROPER GROUND.

LED: ON STEADY

IGNITOR WILL GLOW DIMLY BUT WILL NOT LIGHT

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON.

LED: 5 FLASHES

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES

AND POWER IS RESET OR T'STAT IS INTERRUPTED

FOR MINIMUM OF 1 SECOND.

BURNER OFF?

(Contiuous Flame Check)

YES

NORMAL OPERATION:

LED: STEADY ON

YES

THERMOSTAT CALLS FOR

HEAT:

LED: STEADY ON

YES

PRIMARY AND SECONDARY LIMIT SWITCH.

CLOSED?

YES

IS COMBUSTION AIR

PRESSURE SWITCH OPEN?

YES

IS COMBUSTION AIR INDUCER

ENERGIZED?

YES

HAS COMBUSTION AIR PRESSURE

SWITCH CLOSED IN 2.5 MINUTES?

YES

CONTINUED NEXT

PAGE

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON HEATING SPEED.

COMBUSTION AIR INDUCER OFF.

PRESSURE SWITCH IS IN WATCHGUARD MODE.

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY.

IS 5‐MINUTE RESET PERIOD COMPLETE?

LED: 1 FLASH

INDOOR BLOWER ON

LED: 4 FLASHES

GAS VALVE OFF.

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH

DELAY.

LED: 2 FLASHES

(Sequence holds until pressure switch

opens or thermostat resets control.)

LED: 3 FLASHES

YES

Page 49

Page 50

HEATING SEQUENCE CONTINUED

NORMAL HEATING MODE ABNORMAL HEATING MODE

15‐SECOND COMBUSTION AIR INDUCER PREPURGE

INITIATED BY CLOSED PRESSURE SWITCH.

YES

IGNITOR WARM‐UP -- 20 SECONDS.

YES

4‐SECOND TRIAL FOR IGNITION.

GAS VALVE OPENS.

YES

FLAME STABILIZATION PERIOD.

4 SECONDS

FLAME RECTIFICATION CURRENT

CHECK. CAN FLAME BE PROVEN WITHIN

4 SECONDS AFTER GAS VALVE OPENS?

YES

FLAME PRESENT?

YES

IS VOLTAGE ABOVE 90 VOLTS?

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

HAS CONTROL FAILED TO SENSE FLAME FOR

FIVE CONSECUTIVE TRIES DURING A SINGLE

WATCHGUARD MODE. GAS VALVE OFF.

LED: 7 FLASHES WATCHGUARD FAILURE CODE.

IS 60‐MINUTE RESET PERIOD COMPLETE?

INDOOR BLOWER OFF.

HEAT DEMAND?

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY

HAS CONTROL RESET IGNITION

SEQUENCE FOUR TIMES?

LED: ON STEADY

UNTIL VOLTAGE IS

ABOVE 95 VOLTS,

THEN RESTARTS

HEATING

SEQUENCE.

YES

FLAME SIGNAL 1.5 MICROAMPS OR GREATER?

YES

INDOOR BLOWER ON

AFTER 30-SECOND DELAY

YES

PRIMARY AND SECONDARY LIMIT

SWITCHES CLOSED?

YES

ROLLOUT SWITCH CLOSED?

YES

COMBUSTION AIR PRESSURE

SWITCH CLOSED?

YES

THERMOSTAT DEMAND SATISFIED.

YES

LED: ON STEADY

YES

COMB. AIR INDUCER CONTINUES 15‐SECOND

POST PURGE AFTER T'STAT DEMAND IS SATISFIED.

INDOOR AIR BLOWER COMPLETES SELECTED “OFF”

DELAY BEFORE SHUTTING OFF.

COMBUSTION AIR INDUCER DE-ENERGIZED.

INDOOR BLOWER ON UNTIL SWITCH CLOSES.

LOW FLAME SIGNAL

(Does not affect operation of control)

LED: ON STEADY

GAS VALVE DE-ENERGIZED.

LED: 4 FLASHES

IS LIMIT SWITCH CLOSED?

5 MINUTE WATCHGUARD MODE.

HAS LIMIT SWITCHED CLOSED

AFTER 5 MINUTES?

GAS VALVE POWER OFF.

COMBUSTION AIR INDUCER POWER ON AFTER 15

SECOND DELAY. INDOOR BLOWER ON

LED: 5 FLASHES

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESET

AND MAIN POWER IS INTERRUPTED OR

THERMOSTAT IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.

HAS PRESSURE SWITCH OPENED 5

TIMES IN THE SAME HEAT DEMAND?

GAS VALVE DE-ENERGIZED.

COMBUSTION AIR INDUCER ON.

INDOOR BLOWER OFF WITH DELAY

LED: 6 FLASHES 5 MINUTE PRESSURE

SWITCH WATCHGUARD MODE.

YES

WATCHGUARD

1 HR

PRESSURE

SWITCH

MODE

Page 50

Page 51

COOLING SEQUENCE OF OPERATION

NORMAL COOLING MODE ABNORMAL COOLING MODE

POWER ON

IGNITION CONTROL MAIN POWER ON. LED: ON STEADY

CONTROL SELF DIAGNOSTIC CHECK.

IS CONTROL OPERATING NORMALLY?

YES

IS THERE A PROPER GROUND?

YES

IS POLARITY CORRECT?

YES

IS VOLTAGE

ABOVE 90 VOLTS?

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH NORMAL DELAY.

INTERRUPT MAIN POWER TO RESET CONTROL.

CONTROL WILL CONTINUE TO CALL FOR COOLING

CONTROL WILL CONTINUE TO CALL FOR

COOLING IN THIS CONDITION.

LED: OFF

LED: ON STEADY

IN THIS CONDITION.

LED: 9 FLASHES

IN THIS CONDITION.

LED: ON STEADY.

REMAINS UNCHANGED THROUGHOUT COOLING CYCLE.

THERMOSTAT CALLS FOR COOLING.

COMPRESSOR CONTACTOR AND SYSTEM FAN

ENERGIZED WITH 2‐SECOND DELAY

(COOLING SPEED). EAC TERM. ENERGIZED.

SYSTEM FAN AND EAC TERM. OFF

LED: ON STEADY.

THERMOSTAT OPENS.

COMPRESSOR OFF.

WITH 60‐SECOND DELAY.

CONTINUOUS FAN SEQUENCE OF OPERATION

MANUAL FAN SELECTION MADE AT THERMOSTAT.

CONTROL (G) ENERGIZES SYSTEM FAN ON CONTINUOUS

BLOWER SPEED. EAC TERMINAL IS ENERGIZED.

THERMOSTAT CALLS FOR HEAT (W).

THERMOSTAT CALLS FOR COOLING.

YES

SYSTEM FAN SWITCHED TO COOL SPEED.

EAC TERM. REMAINS ON.

LED: ON STEADY

HUM TERM. ENERGIZES

WITH COMB. AIR INDUCER.

YES

SYSTEM FAN SWITCHES TO

HEATING SPEED.

THERMOSTAT OPENS.

MANUAL FAN SELECTION MADE AT THERMOSTAT.

CONTROL (G) ENERGIZES SYSTEM FAN ON

CONTINUOUS BLOWER SPEED.

HUM TERM. DE-ENERGIZES WITH COMB. AIR INDUCER

SYSTEM FAN SWITCHES TO

CONTINUOUS BLOWER SPEED

Page 51

Lennox ML193DF045P36B, ML193DF110P60C, ML193DF070P36B, ML193DF090P48C Unit Information

Specifications and Main Features

Frequently Asked Questions

User Manual