Lennox 070XP36B, 045XP36B, 110XP48C, 110XP60C, 135XP60D Unit Information

...

Corp. 1035-L7

Service Literature

Revised 03-2014

ML195UH SERIES UNITS

ML195UH series units are high-efficiency gas furnaces manufactured with Lennox DuralokPlust aluminized steel clamshell-type heat exchangers, with a stainless steel con densing coil. ML195UH units are available in heating input capacities of 44,000 to 132,000 Btuh (13 to 38.6 kW) and cooling applications from 2 through 5 tons (7.0 through

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

Units are factory equipped for use with natural gas. A kit is available for conversion to LPG operation. All ML195UH 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.

ML195UH

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 7............................

II Placement and Installation 20....................

III-Start-Up 45...................................

IV-Heating System Service Checks 46..............

V-Typical Operating Conditions 48.................

VI-Maintenance 49...............................

VII-Sequence of Operation 52.....................

WARNING

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

WARNING

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

Page 1

Litho U.S.A.

SPECIFICATIONS

Gas Heating Performance

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

Gas Manifold Pressure (in. w.g.)

Nat. Gas / LPG/Propane

High static - in. w.g. 0.5 0.5 0.5 0.5

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 furnished 90° street elbow 1/2 slip x 1/2 Mipt 1/2 slip x 1/2 Mipt 1/2 slip x 1/2 Mipt 1/2 slip x 1/2 Mipt

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

Indoor

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

Blower

Tons of add-on cooling 2.5 - 3 2 - 3 2.5 - 3 2 - 3

Air Volume Range - cfm 390 - 1140 700 - 1605 650 - 1585 655 - 1630

Electrical Data

Blower motor full load amps 3.1 6.1 6.1 6.1

Maximum overcurrent protection 12 12 12 12

Shipping Data lbs. - 1 package 119 121 129 144

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.

Model No. ML195UH

045XP24B

AFUE 95% 95% 95% 95%

ML195UH

045XP36B

ML195UH

070XP36B

ML195UH

090XP36C

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

Output - Btuh 41,000 42,000 64,000 85,000

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

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

Voltage 120 volts - 60 hertz - 1 phase

SPECIFICATIONS

Gas Heating Performance

Temperature rise range - °F 40 - 70 50 - 80 40 - 70 45 - 75

Gas Manifold Pressure (in. w.g.)

Nat. Gas / LPG/Propane

High static - in. w.g. 0.5 0.5 0.5 0.5

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 furnished 90° street elbow 1/2 slip x 1/2 Mipt 1/2 slip x 1/2 Mipt 1/2 slip x 1/2 Mipt 1/2 slip x 1/2 Mipt

with eld supplied (PVC coupling) - o.d. 3/4 3/4 1 1

Indoor

Wheel nom. dia. x width - in. 10 x 10 10 x 10 11-1/2 x 10 11-1/2 x 10

Blower

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

Air Volume Range - cfm 900 - 2140 715 - 2000 1250 - 2485 1145 - 2595

Electrical Data

Blower motor full load amps 8.2 8.2 11.5 11.5

Maximum overcurrent protection 12 12 15 15

Shipping Data lbs. - 1 package 149 159 164 177

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.

Model No. ML195UH

090XP48C

AFUE 95% 95% 95% 95%

ML195UH

110XP48C

ML195UH

110XP60C

Input - Btuh 88,000 110,000 110,000 132,000

Output - Btuh 85,000 105,000 106,000 126,000

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

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

Voltage 120 volts - 60 hertz - 1 phase

Page 2

ML195UH

135XP60D

OPTIONAL ACCESSORIES - MUST BE ORDERED EXTRA

“B” Width Models “C” Width Models “D” Width Models

CABINET ACCESSORIES

Horizontal Suspension Kit - Horizontal only 51W10 51W10 51W10 Return Air Base - Upow only 50W98 50W99 51W00

CONDENSATE DRAIN KITS

Condensate Drain Heat Cable 6 ft. 26K68 26K68 26K68

24 ft. 26K69 26K69 26K69 50 ft. 26K70 26K70 26K70

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

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

Crawl Space Vent Drain Kit 51W18 51W18 51W18

FILTER KITS

Air Filter and

Rack Kit

NIGHT SERVICE KIT

Night Service Kit 51W03 51W03 51W03

Safety Service Kit 89W20 89W20 89W20

TERMINATION KITS

See Installation Instructions for specic venting information.

Termination Kits Direct Vent

Applications Only

Termination Kits Direct or NonDirect vent

Roof Termination Flashing Kit - Direct or Non-

Direct Vent (2 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.

Horizontal (end) Size of lter - in. 87L96 - 18 x 25 x 1 87L97 - 20 x 25 x 1 87L98 - 25 x 25 x 1

Side Return Single 44J22 44J22 44J22

Ten Pack 66K63 66K63 66K63

Size of lter - in. 16 x 25 x 1 16 x 25 x 1 16 x 25 x 1

Concentric US - 2 in. 71M80 69M29 - - -

3 in. - - - 60L46 60L46

Canada - 2 in. 44W92 44W92 - - -

3 in. - - - 44W93 44W93

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

Wall - Close

Couple

Wall - Close

Couple WTK

US - 2 in. 22G44 - - - - - -

3 in. 44J40 44J40 44J40

Canada - 2 in. 30G28 - - - - - -

3 in. 81J20 81J20 81J20

Roof 2 in. 15F75 15F75 - - -

Wall Ring Kit 2 in. 15F74

15F74 - - -

2 in. 44J41 44J41 44J41

GAS HEAT ACCESSORIES

High Altitude

Input

045 No Change 80W60 69W73 73W81 73W37 68W68 070 80W66 80W59 69W73 73W81 73W37 68W68 090 80W65 80W59 69W73 73W81 73W37 68W68 110 80W66 80W59 69W73 73W81 73W37 68W68 135 80W65 80W59 69W73 73W81 73W37 68W68

Pressure Switch Kit

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

Natural Gas to

LPG/Propane Kit

Page 3

LPG/Propane

to Natural Gas Kit

Natural Gas

High Altitude

Orice Kit

LPG/Propane

High Altitude

Orice Kit

BLOWER DATA

ML195UH045XP24B PERFORMANCE (Less Filter)

External

Static

Pressure

in. w.g.

0.00 1140 455 920 365 765 295 710 265

0.10 1135 445 900 360 765 290 690 255

0.20 1125 430 895 350 755 285 680 255

0.30 1090 415 870 340 725 280 660 250

0.40 1065 405 870 325 715 270 635 245

0.50 1020 390 825 315 675 260 605 235

0.60 945 365 780 300 640 250 555 225

0.70 910 350 740 295 585 240 505 220

0.80 790 325 670 275 510 225 455 205

0.90 735 310 575 255 460 220 390 195

ML195UH045XP36B PERFORMANCE (Less Filter)

External

Static

Pressure

in. w.g.

0.00 1605 700 1370 590 1160 475 1010 400

0.10 1600 680 1355 565 1155 465 1015 390

0.20 1550 645 1330 540 1150 445 1000 380

0.30 1480 620 1295 520 1140 430 975 365

0.40 1425 590 1280 490 1105 415 975 345

0.50 1355 565 1190 460 1085 395 940 335

0.60 1320 545 1165 435 1030 380 900 315

0.70 1225 500 1110 425 980 355 855 310

0.80 1135 480 1050 395 920 330 780 280

0.90 1025 445 950 360 795 295 700 255

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 Low

ML195UH090XP36C PERFORMANCE (Less Filter)

External

Static

Pressure

in. w.g.

0.00 1630 715 1345 590 1090 475 885 385

0.10 1615 700 1320 580 1070 465 890 380

0.20 1580 675 1305 570 1070 455 890 370

0.30 1525 620 1295 535 1060 435 890 360

0.40 1480 615 1275 515 1055 430 885 350

0.50 1415 565 1220 485 1030 410 860 330

0.60 1350 535 1175 450 1005 390 835 310

0.70 1260 505 1115 415 955 360 785 290

0.80 1190 480 1010 380 880 325 740 285

0.90 1060 435 930 360 795 295 655 250

ML195UH090XP48C PERFORMANCE (Less Filter)

External

Static

Pressure

in. w.g.

0.00 2140 880 1895 780 1590 645 1350 550

0.10 2110 850 1880 760 1585 635 1360 545

0.20 2060 810 1840 725 1580 620 1360 520

0.30 1990 765 1805 690 1550 585 1365 500

0.40 1925 750 1755 655 1510 545 1330 470

0.50 1830 700 1675 610 1460 525 1285 450

0.60 1720 645 1610 575 1390 480 1230 415

0.70 1600 615 1520 535 1300 465 1165 390

0.80 1455 560 1410 500 1200 430 1035 365

0.90 1300 515 1305 465 1100 390 901 320

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 Low

ML195UH070XP36B PERFORMANCE (Less Filter)

External

Static

Pressure

in. w.g.

0.00 1585 685 1340 585 1095 480 880 380

0.10 1560 665 1320 565 1085 470 885 375

0.20 1515 630 1300 540 1080 460 880 370

0.30 1465 590 1275 520 1065 440 890 360

0.40 1410 570 1235 490 1050 420 875 350

0.50 1345 540 1195 470 1020 400 840 335

0.60 1275 510 1140 440 975 365 830 315

0.70 1195 485 1090 410 930 355 780 290

0.80 1105 460 995 380 850 325 730 275

0.90 985 420 890 345 770 300 650 255

Air Volume / Watts at Various Blower Speeds

High

cfm Watts cfm Watts cfm Watts cfm Watts

Medium-

High

Medium-Low Low

Page 4

ML195UH110XP48C PERFORMANCE (Less Filter)

External

Static

Pressure

in. w.g.

0.00 2000 910 1675 765 1360 635 1185 525

0.10 1980 895 1650 745 1370 610 1180 505

0.20 1935 855 1600 710 1400 590 1170 485

0.30 1875 830 1560 680 1370 570 1160 490

0.40 1800 785 1490 655 1325 545 1120 455

0.50 1725 720 1400 610 1295 515 1080 435

0.60 1630 685 1335 585 1185 480 1030 410

0.70 1530 665 1290 525 1100 435 940 385

0.80 1410 610 1190 485 985 400 790 365

0.90 1245 560 1000 430 925 380 715 315

Air Volume / Watts at Various Blower Speeds

High

cfm Watts cfm Watts cfm Watts cfm Watts

Medium-

High

Medium-Low Low

BLOWER DATA

ML195UH110XP60C PERFORMANCE (Less Filter)

Air Volume / Watts at Different Blower Speeds

External

Static

Pressure

in. w.g.

0.00 2485 1515 2090 1070 1835 865 1380 660 2400 1475 2100 1075 1755 870 1320 655

0.10 2460 1475 2075 1040 1810 835 1390 650 2370 1440 2090 1060 1735 850 1330 645

0.20 2405 1445 2040 995 1790 820 1405 650 2320 1405 2060 1050 1720 835 1340 650

0.30 2335 1375 1990 980 1760 790 1460 635 2235 1350 2040 1030 1725 825 1350 645

0.40 2215 1355 1935 940 1740 775 1410 630 2165 1330 1975 970 1700 815 1330 632

0.50 2185 1310 1865 895 1680 750 1410 625 2040

0.60 2060 1270 1805 870 1630 720 1405 610 1960 1260 1845 910 1635 770 1340 620

0.70 1945 1235 1700 840 1605 700 1380 590 1865 1215 1750 890 1575 730 1295 600

0.80 1845 1210 1605 810 1505 670 1305 570 1715 1175 1590 840 1505 710 1280 590

0.90 1730 1150 1570 790 1470 660 1250 540 1630 1135 1490 685 1460 685 1235 565

ML195UH135XP60D PERFORMANCE (Less Filter)

External

Static

Pressure

in. w.g.

0.00 2595 1515 2245 2015 1780 890 1365 700 2540 1500 2185 1095 1715 880 1350 700

0.10 2570 1490 2235 1095 1765 875 1370 665 2525 1480 2165 1085 1725 870 1335 675

0.20 2440 1465 2135 1075 1745 865 1395 660 2440 1445 2120 1090 1725 865 1345 675

0.30 2340 1405 2075 1060 1755 845 1365 660 2345 1400 2060 1060 1715 850 1345 670

0.40 2255 1370 1995 1005 1680 825 1370 660 2220 1345 1955 1015 1685 820 1370 660

0.50 2095 1320 1915 960 1650 805 1335 650 2100

0.60 1995 1270 1840 935 1595 775 1320 630 2005 1285 1780 945 1605 790 1285 635

0.70 1900 1225 1755 905 1540 755 1270 615 1845 1235 1700 910 1510 740 1225 610

0.80 1740 1180 1650 875 1430 725 1190 590 1745 1185 1645 880 1450 720 1175 595

0.90 1580 1140 1535 840 1350 695 1145 570 1655 1160 1545 840 1380 705 1135 575

Bottom Return Air, Side Return Air with Optional Return Air Base, Return Air from Both Sides or Return Air from Bottom and One Side.

High Medium-High Medium-Low Low High Medium-High Medium-Low Low

cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts

Air Volume / Watts at Different Blower Speeds Bottom Return Air, Side Return Air with Optional Return Air Base, Return Air from Both Sides or Return Air from Bottom and One Side.

High Medium-High Medium-Low Low High Medium-High Medium-Low Low

cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts

Single Side Return Air − Air volumes in bold require eld fabricated transition to accommodate 20 x 25 x 1 in. air lter in order to maintain proper air velocity.

1290 1920 945 1700 790 1325 620

Single Side Return Air − Air volumes in bold require eld fabricated transition to accommodate 20 x 25 x 1 in. air lter in order to maintain proper air velocity.

1310 1895 985 1620 805 1320 650

Page 5

MANIFOLD

GAS VALVE

COMBUSTION AIR

INDUCER

BURNER ACCESS

PANEL

ROLLOUT

SWITCHES

ML195UH PARTS IDENTIFICATION

FLEXIBLE NO-HUB EXHAUST COLLAR

BURNER BOX

ASSEMBLY

DuralokPlus

HEAT EXCHANGER

ASSEMBLY

TOP CAP

SIGHT

GLASS

BLOWER

ACCESS

DOOR

COMBUSTION

AIR PRESSURE

SWITCH

COLD END

HEADER BOX

PRIMARY LIMIT

BLOWER

ASSEMBLY

CONTROL BOX

(includes integrated control, transformer and interlock switch)

FIGURE 1

CABINET

BAG ASSEMBLIES

(shipping location)

Page 6

I-UNIT COMPONENTS

ML195UH 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.

ML195UH Control Box

TRANSFORMER

(T1)

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 flame sensor (figure

10). The integrated control and ignitor work in combination to ensure furnace ignition and ignitor durability. The inte grated control, controls all major furnace operations. The integrated control also features two LED lights (DS1 red and DS2 green) for troubleshooting and two accessory ter minals rated at (1) one amp. The integrated control also features a (3) amp fuse for overcurrent protection. Tables 1 and 2 show jack plug terminal designations. See table 3 for troubleshooting diagnostic codes. The 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.

INTEGRATED IGNITION

CONTROL

(A92)

FIGURE 2

1. Transformer (T1)

A transformer located in the control box provides power to the low voltage section of the unit. The transformers on all models are rated at 40VA with a 120V primary and 24V secondary.

2. Door Interlock Switch (S51)

A door interlock switch rated 14A at 120VAC is located on the control box. The switch is wired in series with line 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

Page 7

tial in the prove switch is great enough, the prove switch closes and a 15-second pre-purge begins. If the prove switch is not proven within 2-1/2 minutes, the integrated control goes into Watchguard-Pressure Switch mode for a 5-minute re-set period. After the 15-second pre-purge period, the ignitor warms up for 20 seconds after which the gas valve opens at 19 sec onds for a 4-second trial for ignition. The ignitor remains energized for the first 3 seconds during the 4 second trial. If ignition is not proved during the 4-second period, the inte grated control will try four more times with an inter purge and warm-up time between trials of 35 seconds. After a to tal of five trials for ignition (including the initial trial), the inte grated control goes into Watchguard-Flame Failure mode. After a 60-minute reset period, the integrated control will begin the ignition sequence again. 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

Page 8

The integrated control is equipped with two LED lights for troubleshooting. The diagnostic codes are listed below in table 3.

ЙЙЙЙЙЙЙЙЙ

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 board 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.

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 30 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

Page 9

4. Integrated Ignition Control 103085 (A92)

WARNING

Shock hazard. Disconnect power before servicing. Control is not

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

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

The hot surface ignition control system consisting of an in tegrated control (figure 6 with control terminal designations in tables 4 and 5), flame sensor and ignitor (figure 10). The integrated control and ignitor work in combination to en sure furnace ignition and ignitor durability. The integrated control, controls all major furnace operations. The inte grated control also features a RED LED for troubleshooting and two accessory terminals rated at (1) one amp. See table 6 for troubleshooting diagnostic codes. The 120V ig nitor 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 4 second 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 (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.

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.

Page 10

LED

ЙЙЙЙЙЙЙЙЙЙЙЙЙЙЙЙЙЙЙЙЙЙЙЙ

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

Page 11

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 ML195UH 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

Page 12

TWO-STAGE THERMOSTAT

FIELD WIRING FOR TWINNING THE ML195UH

TWIN

SINGLE STAGE THERMOSTAT

TWIN

Call For Cool

Call For Fan

Call For 1st

Stage Heat

Call For 2nd

StageHeat

ISOLATION RELAY

TWIN

TWIN 1

Call For Cool

Call For Fan

Call For Heat

ISOLATION RELAY

TWIN 2

TWIN

TWIN 1

TWIN 2

FRONT BURNER BOX PLATE

ROLLOUT SWITCHES

FLAME SENSOR

FIGURE 9

ML195UH Burner Box Assembly

BURNERS

IGNITOR

ORIFICES

GAS VALVE

FIGURE 10

Page 13

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. Flame Rollout Switches (Figure 10)

Burner Detail Top View

IGNITOR

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 ML195UH units is factory preset to open at 210_F +

12_F (99_C + 6.7_C) on a temperature rise. All flame rollout switches are manual re set.

2. Primary Limit Control (Figure 12)

Primary limit (S10) used on ML195UH 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, remove mounting screws, rotate limit switch 90 degrees and slowly remove from the vestibule panel. Install replacement limit with same care.

3. Burners (Figure 11)

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 burner input. See table 7 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.

FLAME SENSOR

ORIFICES

FIGURE 11

4. Heat Exchanger (Figure 12)

ML195UH 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.

Primary Limit Location and Heat Exchanger

TABLE 7

Gas Orifice Size

Unit Fuel Orifice Size

All Natural 0.063

All L.P./Propane 0.0340

Install limit face down

FIGURE 12

5. Gas Valve (GV1)

The ML195UH uses an internally redundant valve to as sure safety shut‐off. If the gas valve must be replaced, the same type valve must be used.

Page 14

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

INLET

PRESSURE

PORT

Gas Valve

MANIFOLD

PRESSURE

OUTLET

PORT

FIGURE 13

6. Flame Sensor (Figure 10)

A flame sensor is located on the left side of the burner sup port. The sensor is mounted on the front 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 ML195UH furnace contains electronic components that are polarity sensitive. Make sure that the furnace is wired correctly and is properly grounded.

A microamp DC meter is needed to check the flame signal on the integrated control.

Flame (microamp) signal is an electrical current which passes from the integrated control to the sensor during unit operation. Current passes from the sensor through the flame to ground to complete a safety circuit.

To Measure Flame Signal - Integrated Control:

Use a digital readout meter capable of reading DC micro amps. See figure 14 for flame signal check.

1 - Set the meter to the DC amps scale. 2 - Turn off supply voltage to control. 3 - Disconnect integrated control flame sensor wire from

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

7. Ignitor (Figure 10)

ML195UH 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 15 and table 8 for resistance and voltage checks.

Page 15

Flame Signal In Microamps

Normal Low Drop Out

 1.5

0.5 - 1.4

 0.4

Measuring Flame Signal

Flame Sensor

Wire

Remove sensor wire from integrated control and connect alligator clip(-) to flame sensor lead.

Intergrated Control

Multi−Meter

Set Dial to Ohms

Flame Sensor

Terminal

(+)

To Flame

Terminal

(+) To Control

Sensor Terminal

Remove sensor wire from integrated control and connect alligator clip(+) to terminal on control.

FIGURE 14

Page 16

Check ignitor circuit for correct resistance.

Test 1

Remove 4-pin plug from control.

Check ohms reading across terminals 2 and 4.

See table 8. 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 1

IGNITOR CHECKS

TABLE 8

Control Ohms

103085

100973

39 to 70 24 to 47

Voltage +

120

10%

Check ignitor for correct resistance.

Test 2

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

resistance of ignitor at the plug. See table 8. 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.

Test 2

Multi−Meter

(set to ohms)

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 8. If voltage reads below these values, check for

correct supply voltage to furnace.

Integrated Control Detail

Multi−Meter

(set to VAC)

Test 3

Integrated Control Detail

FIGURE 15

Page 17

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

All ML195UH units use a combustion air inducer to move air through the burners and heat exchanger during heating operation. The blower uses a shaded pole 120VAC motor. The motor operates during all heating operation and is con trolled by integrated control A3. Blower operates continu ously while there is a call for heat. The integrated control will not proceed with the ignition sequence until combus tion air inducer operation is sensed by the proving switches.

The combustion air inducer is installed on the cold end header box. The cold end header box is a single piece made of hard plastic. The box has an internal channel where the combustion air inducer creates negative pres sure at unit start up. The channel contains an orifice used to regulate flow created by the combustion air inducer. The box has pressure taps for the combustion air inducer pres sure switch hoses. The pressure switch measures the pressure across the combustion air inducer orifice or differ ence in the channel and the box. If replacement is neces

sary the gaskets used to seal the box to the vestibule panel and the combustion air inducer to the box, must also be replaced.

TABLE 9

Unit

-045 0.618”

-070 0.810”

-090 0.973”

-110 1.040”

-135 1.235”

Combustion Air Inducer

Orifice Size

9. Combustion Air Pressure Switch (Figure 16)

ML195UH series units are equipped with a differential pressure switch located on the cold end header box. The switch monitors across the combustion air inducer orifice to insure proper flow through the heat exchanger.

The switch is a SPST N.O. prove switch electrically 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.

Pressure Switch

FIGURE 16

On start‐up, the switch monitors whether the combustion air inducer is operating. It closes a circuit to the integrated control when the difference in pressure across the com bustion air inducer orifice exceeds a non-adjustable factory setting. If the switch does not successfully sense the re quired 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 dif ferential and opens the circuit to the integrated control. If the condensate line is blocked, water will back up into the header box and reduce the pressure differential across the switch. The prove switch opens if the differential drops be low 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 17. 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.

Unit

-045 -0.65 -0.65 -0.60

-070 -0.90 -0.85 -0.65

-090 -0.90 -0.80 -0.65

-110 -0.90 -0.85 -0.65

-135 -0.90 -0.80 -0.65

*Set point is factory set and non-adjustable

0 - 4500 4501 - 7500 7501 - 10000

Set Point

“w.c.

Set Point “w.c

Set Point

“w.c.

Page 18

Red Tubing

(negative -)

To Cold End Header Box

Measuring Pressure Differential

Black Tubing

(positive +)

To Cold End Header Box

Field Provided Tubing

To Pressure Switch

“+”

High

“-”

Low

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 nega tive. However the (+) port reads less negative pressure than the (-) port.

FIGURE 17

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 combus

tion air sensing hoses to the pressure switch.

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

All ML195UH 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.

BOLTS

CAPACITOR

To Remove Blower From Unit: Disconnect Power, Remove Control

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

Slide Out Front of Unit.

FIGURE 18

MOTOR

Page 19

II-PLACEMENT AND INSTALLATION

Combustion, Dilution & Ventilation Air

If the ML195UH is installed as a Non-Direct Vent Fur nace, follow the guidelines in this section.

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

In the past, there was no problem in bringing in sufficient outdoor air for combustion. Infiltration provided all the air that was needed. In today's homes, tight construction prac tices make it necessary to bring in air from outside for com bustion. Take into account that exhaust fans, appliance vents, chimneys, and fireplaces force additional air that could be used for combustion out of the house. Unless out side air is brought into the house for combustion, negative pressure (outside pressure is greater than inside pressure) will build to the point that a downdraft can occur in the fur nace vent pipe or chimney. As a result, combustion gases enter the living space creating a potentially dangerous situ ation.

In the absence of local codes concerning air for combustion and ventilation, use the guidelines and procedures in this section to install ML195UH furnaces to ensure efficient and safe operation. You must consider combustion air needs and requirements for exhaust vents and gas piping. A portion of this information has been reprinted with per mission from the National Fuel Gas Code (ANSIZ223.1/NFPA 54). This reprinted material is not the com plete and official position of the ANSI on the referenced subject, which is represented only by the standard in its en tirety.

In Canada, refer to the CSA B149 installation codes.

CAUTION

Do not install the furnace in a corrosive or contami nated atmosphere. Meet all combustion and ventila tion air requirements, as well as all local codes.

All gas‐fired appliances require air for the combustion pro cess. If sufficient combustion air is not available, the fur nace or other appliance will operate inefficiently and un safely. Enough air must be provided to meet the needs of all fuel-burning appliances and appliances such as ex haust fans which force air out of the house. When fire

places, exhaust fans, or clothes dryers are used at the same time as the furnace, much more air is required to en sure proper combustion and to prevent a downdraft. Insuf ficient air causes incomplete combustion which can result in carbon monoxide.

In addition to providing combustion air, fresh outdoor air di lutes contaminants in the indoor air. These contaminants may include bleaches, adhesives, detergents, solvents and other contaminants which can corrode furnace compo nents.

The requirements for providing air for combustion and ven tilation depend largely on whether the furnace is installed in an unconfined or a confined space.

Unconfined Space

An unconfined space is an area such as a basement or large equipment room with a volume greater than 50 cubic feet (1.42 m bined input rating of all appliances installed in that space. This space also includes adjacent rooms which are not separated by a door. Though an area may appear to be un confined, it might be necessary to bring in outdoor air for combustion if the structure does not provide enough air by infiltration. If the furnace is located in a building of tight construction with weather stripping and caulking around the windows and doors, follow the procedures in the Air from Outside section.

Confined Space

A confined space is an area with a volume less than 50 cu bic feet (1.42 m com-bined input rating of all appliances installed in that space. This definition includes furnace closets or small equipment rooms.

When the furnace is installed so that supply ducts carry air circulated by the furnace to areas outside the space con taining the furnace, the return air must be handled by ducts which are sealed to the furnace casing and which terminate outside the space containing the furnace. This is especially important when the furnace is mounted on a platform in a confined space such as a closet or small equipment room. Even a small leak around the base of the unit at the platform or at the return air duct connection can cause a potentially dangerous negative pressure condition. Air for combustion and ventilation can be brought into the confined space ei ther from inside the building or from outside.

) per 1,000 Btu (.29 kW) per hour of the com

) per 1,000 Btu (.29 kW) per hour of the

Page 20

Air from Inside

If the confined space that houses the furnace adjoins a space categorized as unconfined, air can be brought in by providing two permanent openings between the two spaces. Each opening must have a minimum free area of 1 square inch (645 mm

) per 1,000 Btu (.29 kW) per hour of total input rating of all gas-fired equipment in the confined space. Each opening must be at least 100 square inches (64516 mm

). One opening shall be within 12 inches (305 mm) of the top of the enclosure and one opening within 12 inches (305 mm) of the bottom. See figure 19.

EQUIPMENT IN CONFINED SPACE - ALL AIR FROM INSIDE

ROOF TERMINATED

EXHAUST PIPE

OPENINGS

SIDE WALL

TERMINATED

EXHAUST PIPE

(ALTERNATE

LOCATION)

NOTE - Each opening shall have a free area of at least one square inch per 1,000 Btu (645mm all equipment in the enclosure, but not less than 100 square inches (64516mm.

2).

ML195UH

per .29kW) per hour of the total input rating of

(To Adjacent

Unconfined

Space)

FIGURE 19

Air from Outside

If air from outside is brought in for combustion and ventila tion, the confined space shall be provided with two perma nent openings. One opening shall be within 12” (305mm) of the top of the enclosure and one within 12” (305mm) of the bottom. These openings must communicate directly or by ducts with the outdoors or spaces (crawl or attic) that freely communicate with the outdoors or indirectly through verti cal ducts. Each opening shall have a minimum free area of

1 square inch per 4,000 Btu (645mm

per 1.17kW) per hour of total input rating of all equipment in the enclosure. When communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of 1 square

inch per 2,000 Btu (645mm

per .59kW) per total input rat

ing of all equipment in the enclosure (See figure 20).

EQUIPMENT IN CONFINED SPACE - ALL AIR FROM OUTSIDE

(Inlet Air from Crawl Space and Outlet Air to Ventilated Attic)

VENTILATION LOUVERS

OUTLET

AIR

(Each end of attic)

VENTILATION

LOUVERS

(For unheated

crawl space)

per 1.17kW) per

ROOF TERMINATED

EXHAUST PIPE

SIDE WALL

TERMINATED

EXHAUST PIPE

(ALTERNATE

LOCATION)

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.

FURNACE

INLET

AIR

FIGURE 20

If air from outside is brought in for combustion and ventila tion, the confined space must have two permanent open ings. One opening shall be within 12 inches (305 mm) of the top of the enclosure and one opening within 12 inches (305 mm) of the bottom. These openings must communicate di rectly or by ducts with the outdoors or spaces (crawl or at tic) that freely communicate with the outdoors or indirectly through vertical ducts. Each opening shall have a minimum

free area of 1 square inch (645 mm

) per 4,000 Btu (1.17 kW) per hour of total input rating of all equipment in the en closure. See figures 20 and 21. When communicating with the outdoors through horizontal ducts, each opening shall

have a minimum free area of 1 square inch (645 mm

) per

2,000 Btu (.56 kW) per total input rating of all equipment in the enclosure. See figure 22.

When ducts are used, they shall be of the same cross-sec tional area as the free area of the openings to which they connect. The minimum dimension of rectangular air ducts shall be no less than 3 inches (75 mm). In calculating free area, the blocking effect of louvers, grilles, or screens must be considered. If the design and free area of protective cov ering is not known for calculating the size opening required, it may be assumed that wood louvers will have 20 to 25 per cent free area and metal louvers and grilles will have 60 to 75 percent free area. Louvers and grilles must be fixed in the open position or interlocked with the equipment so that they are opened automatically during equipment opera tion.

Page 21

EQUIPMENT IN CONFINED SPACE - ALL AIR FROM OUTSIDE

ROOF TERMINATED

EXHAUST PIPE

(All Air Through Ventilated Attic)

VENTILATION LOUVERS

(Each end of attic)

OUTLET

AIR

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.

SIDE WALL

TERMINATED

EXHAUST PIPE

(ALTERNATE

LOCATION)

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

FURNACE

INLET AIR

(Ends 12” above

bottom)

per 1.17kW) per hour

FIGURE 21

EQUIPMENT IN CONFINED SPACE -

ALL AIR FROM OUTSIDE

ROOF TERMINATED

EXHAUST PIPE

OUTLET AIR

SIDE WALL

TERMINATED

EXHAUST PIPE

(ALTERNATE

LOCATION)

NOTE-Each air duct opening shall have a free area of at least one square inch per 2,000 Btu (645mm input rating of all equipment in the enclosure. If the equipment room is located against an outside wall and the air openings communi cate directly with the outdoors, each opening shall have a free area of at least 1 square inch per 4,000 Btu (645mm hour of the total input rating of all other equipment in the enclosure.

FURNACE

INLET AIR

per .59kW) per hour of the total

per 1.17kW) per

FIGURE 22

PIPING AND FITTINGS SPECIFICATIONS

TABLE 11

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

D2661

D2665

ASTM

SPECIFICATION

D2564, D2235, F493

D3138

MARKING

ULCS636

ULC-S636

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.

IMPORTANT

ML195UH 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.

Page 22

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.

TABLE 12

OUTDOOR TERMINATION USAGE*

STANDARD KITS CONCENTRIC KITS

Vent

Input Size

Pipe

Dia. in.

045

2-1/2

070

2-1/2

090

2-1/2

2 YES YES YES

110

2-1/2 YES YES

3 YES YES

135 3 YES

Flush Mount

Kit

2 inch 3 inch 2 inch

51W11

(US)

51W12

22G44 (US)

30G28 (CA)

(CA)

YES YES

YES YES YES

Wall Kit Wall Ring Kit

44J40

(US)

81J20 (CA)

YES

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.

1-1/2 inch 2 inch 3 inch

15F74

YES

Field

Fabricated

YES

YES 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 uses with 045 and 070 input models.

Flush mount kits 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.

2 - Debur and chamfer end of pipe, removing any ridges

Joint Cementing Procedure

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 in take pipe to the connector, if desired. Use a drill or self tap ping screw to make a pilot hole.

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

DANGER

DANGER OF EXPLOSION!

Fumes from PVC glue may ignite during system check. Allow fumes to dissipate for at least 5 minutes

surface of fitting and male end of pipe to depth of fitting

socket.

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

before placing unit into operation.

1 - Measure and cut vent pipe to desired length.

Page 23

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.

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.

Venting Practices

Piping Suspension Guidelines

SCHEDULE 40

PVC - 5'

all other pipe* - 3'

2. 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.

3. 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.

CHIMNEY

OR GAS

VENT

(Check sizing

for water

heater only)

FURNACE

(Replaced

by ML195)

REPLACING FURNACE THAT

WAS PART OF A COMMON

VENT SYSTEM

WATER

HEATER

OPENINGS

(To Adjacent

Room)

If an ML195UH furnace replaces a furnace which was commonly vented with another gas appliance, the size of the existing vent pipe for that gas ap pliance must be checked. Without the heat of the original furnace flue products, the existing vent pipe is probably oversized for the single water heater or other appliance. The vent should be checked for proper draw with the remaining appliance.

* See table 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

insulation

(if required)

FIGURE 23

FIGURE 24

Exhaust Piping (Figures 27 and 28)

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.

Page 24

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.

The ML195UH can be installed as either a Non-Direct Vent or a Direct Vent gas central furnace.

NOTE - In Non‐Direct Vent installations, combustion air is taken from indoors and flue gases are discharged out doors. In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged outdoors.

Intake and exhaust pipe sizing -- Size pipe according to

tables 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.

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.

NOTE - The exhaust collar on all models is sized to accom modate 2” Schedule 40 vent pipe. In horizontal applica tions, any transition to exhaust pipe larger than 2” must be made in vertical runs of the pipe. Therefore a 2” elbow must be added before the pipe is transitioned to any size larger than 2”. This elbow must be added to the elbow count used to determine acceptable vent lengths. Contact the Applica tion Department for more information concerning sizing of vent systems which include multiple pipe sizes.

by DuraVent venting system the

MINIMUM VENT PIPE LENGTHS

TABLE 13

ML195UH

MODEL

045, 070, 090, 110

135

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

MIN. VENT LENGTH*

15 ft. or

5 ft plus 2 elbows or

10 ft plus 1 elbow

Use the following steps to correctly size vent pipe diameter.

Piping Size Process

What is the

furnace capacity?

045, 070, 090,

110 or 135?

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.

Desired pipe size?

2”, 2-1/2”, 3”

What is the altitude of the furnace installation?

Exhaust Pipe

Horizontal

Gas Furnace

NOTE - All horizontal runs of exhaust pipe must slope back to ward 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.

12” max

of straight pip

FIGURE 25

12” Min.

Page 25

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 26

IMPORTANT

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

Maximum Allowable Vent Length in Feet

TABLE 14

NOTE - 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 - 4500 ft

Number Of

90° Elbows

Used

1 81 66 44 24

2 76 61 39 19 110 110 88 53 133 132 113 113 109

3 71 56 34 14 105 105 83 48 128 127 108 108 104

4 66 51 29

5 61 46 24 95 95 73 38 118 117 98 98 94

6 56 41 19 90 90 68 33 113 112 93 93 89

7 51 36 14 85 85 63 28 108 107 88 88 84

8 46 31

9 41 26 75 75 53 18 98 97 78 78 74

10 36 21 70 70 48 13 93 92 73 73 69

Number Of 90° Elbows

Used

1 81 66 44

2 76 61 39 110 110 88 53 133 132 113 113 109

3 71 56 34 105 105 83 48 128 127 108 108 104

4 66 51 29 100 100 78 43 123 122 103 103 99

5 61 46 24 95 95 73 38 118 117 98 98 94

6 56 41 19 90 90 68 33 113 112 93 93 89

7 51 36 14 85 85 63 28 108 107 88 88 84

8 46 31

9 41 26 75 75 53 18 98 97 78 78 74

10 36 21 70 70 48 13 93 92 73 73 69

045 070 090 110 135 045 070 090 110 135 045 070 090 110 135

2” Pipe 2-1/2” Pipe 3” Pipe

Model Model Model

115 115 93 58

100 100 78 43 123 122 103 103 99

n/a

80 80 58 23 103 102 83 83 79

n/a

Standard Termination Elevation 4500 - 10,000 ft

2” Pipe 2-1/2” Pipe 3” Pipe

Model Model Model

115 115 93 58

n/a n/a

80 80 58 23 103 102 83 83 79

n/a

138 137 118 118 114

Page 26

Maximum Allowable Vent Length in Feet

TABLE 14 Continued

Concentric Termination at Elevation 0 - 4500 ft

Number Of 90° Elbows

Used

045 070 090 110 135 045 070 090 110 135 045 070 090 110 135

1 73 58 42 22

2 68 53 37 17 100 100 84 49 116 116 109 109 100

3 63 48 32 12 95 95 79 44 111 111 104 104 95

4 58 43 27

5 53 38 22 85 85 69 34 101 101 94 94 85

6 48 33 17 80 80 64 29 96 96 89 89 80

7 43 28 12 75 75 59 24 91 91 84 84 75

8 38 23

9 33 18 65 65 49 14 81 81 74 74 65

10 28 13 60 60 44 n/a 76 76 69 69 60

Number Of 90° Elbows

Used

045 070 090 110 135 045 070 090 110 135 045 070 090 110 135

1 73 58 42

2 68 53 37 100 100 84 49 116 116 109 109 100

3 63 48 32 95 95 79 44 111 111 104 104 95

4 58 43 27 90 90 74 39 106 106 99 99 90

5 53 38 22 85 85 69 34 101 101 94 94 85

6 48 33 17 80 80 64 29 96 96 89 89 80

7 43 28 12 75 75 59 24 91 91 84 84 75

8 38 23

9 33 18 65 65 49 14 81 81 74 74 65

10 28 13 60 60 44 n/a 76 76 69 69 60

2” Pipe 2-1/2” Pipe 3” Pipe

Model Model Model

105 105 89 54

90 90 74 39 106 106 99 99 90

n/a

70 70 54 19 86 86 79 79 70

n/a

Concentric Termination Elevation 4501 - 10,000 ft

2” Pipe 2-1/2” Pipe 3” Pipe

Model Model Model

105 105 89 54

n/a n/a

70 70 54 19 86 86 79 79 70

n/a

121 121 114 114 105

Page 27

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

TABLE 15

Attic or Crawl Space For Intake Air in Feet

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 - 4500 ft

Number Of 90° Elbows

Used

1 71 56 34 14

2 66 51 29 9 95 95 73 38 113 112 93 93 89

3 61 46 24 4 90 90 68 33 108 107 88 88 84

4 56 41 19

5 51 36 14 80 80 58 23 108 97 78 78 74

6 46 31 9 75 75 53 18 93 92 73 73 89

7 41 26 4 70 70 48 13 88 87 68 68 64

8 36 21

9 31 16 60 60 38 3 78 77 58 58 54

10 26 11 55 55 33 n/a 73 72 53 53 49

Number Of 90° Elbows

Used

1 71 56 34

2 66 51 29 95 95 73 38 113 112 93 93 89

3 61 46 24 90 90 68 33 108 107 88 88 84

4 56 41 19 85 85 63 28 103 102 83 83 79

5 51 36 14 80 80 58 23 98 97 78 78 74

6 46 31 9 75 75 53 18 93 92 73 73 69

7 41 26 4 70 70 48 13 88 87 68 68 64

8 36 21

9 31 16 60 60 38 3 78 77 58 58 54

10 26 11 55 55 33 n/a 73 72 53 53 49

045 070 090 110 135 045 070 090 110 135 045 070 090 110 135

2” Pipe 2-1/2” Pipe 3” Pipe

Model Model Model

100 100 78 43

85 85 63 28 103 102 83 83 79

n/a

65 65 43 8 83 82 63 63 59

n/a

Standard Termination Elevation 4500 - 10,000 ft

2” Pipe 2-1/2” Pipe 3” Pipe

Model Model Model

100 100 78 43

n/a n/a

65 65 43 8 83 82 63 63 59

n/a

128 117 98 98 94

118 117 98 98 94

Page 28

TYPICAL EXHAUST

PIPE CONNECTIONS IN UPFLOW DIRECT OR

NON-DIRECT VENT APPLICATIONS

Pipe size determined in table 14

2”

EXHAUST

2”

3”

TRANSITION

DO NOT transition

from smaller to larger

pipe in horizontal runs

of exhaust pipe.

* 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 27

TYPICAL EXHAUST PIPE CONNECTIONS IN HORIZONTAL DIRECT OR

NON-DIRECT VENT APPLICATIONS

(RIGHT HAND DISCHARGE SHOWN)

*2”

12” max.

3”

TRANSITION

*2”

2”

EXHAUST

2”

DO NOT transition

from smaller to larger

pipe in horizontal runs

of exhaust pipe.

* 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 28

45°

MAX

45°

MAX

SIDE VIEW

Page 29

TYPICAL AIR INTAKE

PIPE CONNECTIONS IN UPFLOW DIRECT VENT

APPLICATIONS

AIR INTAKE

2”

3”

TRANSITION

*2”

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

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

2”

FIGURE 29

Pipe size determined in table 14

TYPICAL AIR INTAKE

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

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

PIPE CONNECTIONS IN HORIZONTAL DIRECT VENT APPLICATIONS

(RIGHT HAND DISCHARGE SHOWN)

3”

TRANSITION

*2”

2”

AIR INTAKE

2”

FIGURE 30

Page 30

Intake Piping

The ML195UH furnace may be installed in either direct vent or non-direct vent applications. In non-direct vent

applications, when intake air will be drawn into the furnace from the surrounding space, the indoor air quality must be considered and guidelines listed in Combustion, Dilution and Ventilation Air section must be followed.

Follow the next two steps when installing the unit in Direct Vent applications, where combustion air is taken from outdoors and flue gases are discharged outdoors. The

provided air intake screen must not be used in direct vent applications (outdoors).

1 - Use transition solvent cement or a sheet metal screw

to secure the intake pipe to the inlet air connector.

2 - Route piping to outside of structure. Continue with

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

14 for pipe sizes.

TYPICAL AIR INTAKE PIPE CONNECTIONS

HORIZONTAL NON−DIRECT VENT APPLICATIONS

(Horizontal Right−Hand Air Discharge Application Shown)

PVC pipe

coupling

INTAKE DEBRIS

SCREEN

(Provided)

NOTE - Debris screen may be positioned straight out (preferred) or with an elbow rotated to face down.

TYPICAL AIR INTAKE PIPE CONNECTIONS

UPFLOW NON−DIRECT

VENT APPLICATIONS

INTAKE DEBRIS

SCREEN

(Provided)

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

FIGURE 31

FIGURE 32

Follow the next three 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 31 or 32. Maintain a minimum clearance of 3” (76mm) around the air intake opening. The air intake opening (with the protective screen) should always be directed forward or to either side in the upflow position, and either straight out or downward in the horizontal position.

The air intake piping must not terminate too close to the flooring or a platform. Ensure that the intake air inlet will not be obstructed by loose insulation or other items that may clog the debris screen.

2 - If intake air is drawn from a ventilated attic (figure 33)

or ventilated crawlspace (figure 34) 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 a sheet metal screw to secure the intake pipe to

the connector, if desired.

Page 31

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 Attic and Outlet Air to Outside)

Roof T erminated

Exhaust Pipe

* 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.

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

Roof T erminated

Exhaust Pipe

EQUIPMENT IN CONFINED SPACE

Ventilation Louvers

12 in.(305mm) Abov

*Intake Debris

Screen

(Provided)

Furnace

per 1.17kW) per

FIGURE 33

EQUIPMENT IN CONFINED SPACE

Inlet Air

(Minimum attic floor)

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 ML195UH 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 ML195UH 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.

Position termination according to location given in figure 36 or 37. 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.

Inlet Air

(Minimum

Ventilation

Louvers

(Crawl space)

Coupling or 3 in. to 2 in.

Transition

(Field Provided)

Furnace

12 in.(305mm)

Above crawl

space floor)

*Intake Debris Screen Provided)

* 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.

FIGURE 34

per 1.17kW) per

IMPORTANT

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

IMPORTANT

For Canadian Installations Only: In accordance to CSA International B149 installation codes, the minimum allowed distance between the combustion air intake inlet and the exhaust outlet of other appliances shall not be less than 12 inches (305mm).

Page 32

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

32 to 21

(0 to -6)

°F (°C)

Vent Pipe

Diameter

045 070 090 110 135

PVC2PP PVC2PP PVC

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

Unit Input Size

PP PVC

PP PVC2PP

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

20 to 1

(-7 to -17)

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

0 to -20

(-18 to -29)

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

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 figure35.

Conditioned

Space

Conditioned

Space

FIGURE 35

Pipe Insulation

Unconditioned

Space

Exhaust

Pipe

Intake

Pipe

Page 33

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 36

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 34

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

closed window

Vertical clearance to ventilated soffit

D =

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 =

Clearance to mechanical air sup

ply inlet

Clearance above paved sidewalk or

L =

paved driveway located on public property

Clearance under veranda, porch, deck or balcony

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.

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

(3m) horizontally

* 7 feet (2.1m)

*12 inches (305mm)‡

* 12”

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)‡

FIGURE 37

Page 35

Details of Intake and Exhaust Piping Terminations for Direct Vent Installations

NOTE - In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged to outdoors.

Intake and exhaust pipes may be routed either horizontally through an outside wall or vertically through the roof. In at tic or closet installations, vertical termination through the roof is preferred. Figures 38 through 45 show typical terminations.

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 39). You may exit the exhaust out the roof and the intake out the side of the structure (figure 40).

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

38).

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

ML195UH

MODEL

*045 and 070

*090 2” (51mm)

110 2” (51mm) 135

Exhaust Pipe Size

2” (51mm), 2-1/2” (64mm),

3” (76mm)

Termination

Pipe Size

1-1/2” (38mm)

2” (51mm)

*ML195UH-045, -070 and -090 units with the flush mount termination must use the 1 1/2”accelerator supplied with the kit.

NOTE - Care must be taken to avoid recirculation of ex haust back into intake pipe.

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

Exiting Exhaust and Intake Vent

(differen pressure zones)

Exhaust

Pipe

Exiting Exhaust and Intake Vent

(different pressure zones)

Roof T

erminated

Exhaust Pipe

3”(76mm) MAX.

(15F75 or 44J41)

FIGURE 38

Furnace

FIGURE 39

SIZE TERMINATION

PIPE PER TABLE 17.

UNCONDITIONED

ATTIC SPACE

1/2” (13mm) FOAM

INSULATION IN

UNCONDITIONED

SPACE

Inlet Air (Minimum 12 in. 305 MM) above

grade or snow

accumulation

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 46.

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 46.

Page 36

Inlet Air

Furnace

(Minimum 12 in.

305 MM) above

grade or snow

accumulation

FIGURE 40

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 46, 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 44.

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

FURNACE

4''

EXHAUST

PIPE

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 41

1 1/2” (38mm) accelerator

EXHAUST

12” (305mm)

Minimum

Above Average

Snow

Accumulation

VENT

provided on 71M80 & 44W92

kits for EL296UHV045P24B,

070P24B & 070P36B

INTAKE

AIR

FLASHING

(Not Furnished)

SHEET METAL STRAP

(Clamp and sheet metal strap must be field installed to support the weight of the termination kit.)

CLAMP

FIELD-PROVIDED

REDUCER MAY BE REQUIRED

TO ADAPT LARGER VENT

PIPE SIZE TO TERMINATION

DIRECT VENT CONCENTRIC ROOFTOP TERMINATION

71M80, 69M29 or 60L46 (US)

44W92 or 44W93 (Canada)

FIGURE 42

EXHAUST

VENT

5”

(127MM)

5-1/2”

(140mm)

12”

(305MM)

INTAKE

AIR

18” MAX. (457MM)

Front View

EXHAUST VENT

12” (305MM) Min.

above grade or

Inches (MM)

INTAKE

average snow

accumulation.

AIR

optional intake elbow

Side View

OPTIONAL VENT TERMINATION FOR MULTIPLE UNIT

INSTALLATION OF DIRECT VENT WALL TERMINATION KIT

(30G28 or 81J20)

FIGURE 44

ML195UH DIRECT VENT APPLICATION

USING EXISTING CHIMNEY

STRAIGHT-CUT OR

3”-8”

(76mm-203mm)

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

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

FIELD-PROVIDED

REDUCER MAY BE REQUIRED

TO ADAPT LARGER VENT

PIPE SIZE TO TERMINATION

OUTSIDE

WALL

EXHAUST

VENT

INTAKE

AIR

CLAMP

(Not Furnished)

DIRECT VENT CONCENTRIC WALL TERMINATION

71M80, 69M29 or 60L46 (US)

44W92 or 44W93 (Canada)

FIGURE 43

1-1/2” (38mm) accelerator

provided on 71M80 & 44W92

kits for EL296UHV045P24B,

070P24B & 070P36B

INTAKE

AIR

EXHAUST

VENT

AIR

12” (305mm) Min.

above grade or

average snow

accumulation.

INTAKE

GRADE

FIGURE 45

Page 37

NOTE − FIELD−PROVIDED

REDUCER MAY BE

REQUIRED TO ADAPT

LARGER VENT PIPE SIZE

* WALL

SUPPORT

TO TERMINATION

Intake Elbow

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.

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”

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

Intake Elbow

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.

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.

Front View of

Intake and Exhaust

Intake

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 46

Page 38

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 47 through 48 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 velocity required to move the exhaust gases away from the building.

ML195UH NON-DIRECT VENT APPLICATION

USING EXISTING CHIMNEY

SIZE TERMINATION

PIPE PER TABLE 17.

Minimum 12” (305MM)

above chimney top

plate or average snow

accumulation

SHEET

METAL TOP

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

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.

SIZE TERMINATION

12” (305mm)

ABOVE AVE.

SNOW

ACCUMULATION

3” (76mm) OR

2” (51mm) PVC

PROVIDE SUPPORT

FOR EXHAUST LINES

NON-DIRECT VENT ROOF TERMINATION KIT

1/2” (13mm) FOAM

INSULATION

(15F75 or 44J41)

PIPE PER TABLE

17.

UNCONDITIONED

ATTIC SPACE

FIGURE 47

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.

INSULATE TO FORM

SEAL

EXTERIOR

PORTION OF

CHIMNEY

FIGURE 48

Condensate Piping

This unit is designed for either right‐ or left‐side exit of con densate piping in upflow applications. In horizontal applica tions, the condensate trap must extend below the unit. An 8” service clearance is required for the condensate trap. Refer to figures 49 and 51 for condensate trap locations. Figure 58 shows trap assembly using 1/2” PVC or 3/4” PVC.

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.

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 49) 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

Page 39

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 figure 57 or 58.

4 - Install drain trap using appropriate PVC fittings, glue

all joints. Glue the provided drain trap as shown in fig ures 57 and 58. Route the condensate line to an open drain. Condensate line must maintain a 1/4” down

ward slope from the furnace to the drain.

CONDENSATE TRAP AND PLUG LOCATIONS

(Unit shown in upflow position)

Trap

(same on

right side)

1-1/2 in.

Plug

(same on left side)

NOTE - In upflow applications where side return air filter is installed on same side as the conden sate trap, filter rack must be installed beyond condensate trap or trap must be re-located to avoid interference.

FIGURE 49

5 - Figures 52 and 54 show the furnace and evaporator

coil using a separate drain. If necessary the conden sate line from the furnace and evaporator coil can drain together. See figures 53, 55 and 56. Upflow furnace (figure 55) - In upflow furnace applica tions the field provided vent must be a minimum 1” to a maximum 2” length above the condensate drain outlet connection. Any length above 2” may result in a flooded heat exchanger if the combined primary drain line were to become restricted. Horizontal furnace (figure 56) - In horizontal furnace applications the field provided vent must be a mini mum 4” to a maximum 5” length above the condensate drain outlet connection. Any length above 5” may re sult in a flooded heat exchanger if the combined pri mary drain line were to become restricted.

NOTE - In horizontal applications it is recommended to install a secondary drain pan underneath the unit and trap assembly.

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 50.

Field Provided Drain Components

Elbow

Barbed Fitting

Tubing

Hose Clamp

FIGURE 50

CAUTION

Do not use copper tubing or existing copper conden sate lines for drain line.

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. Heating cable kit is available from Lennox in various lengths; 6 ft. (1.8m) kit no. 26K68; 24 ft. (7.3m) - kit no. 26K69; and 50 ft. (15.2m) - kit no. 26K70.

CONDENSATE TRAP LOCATIONS

(Unit shown in upflow position with remote trap)

FieldProvidedVent

Min.1” AboveCondensate

Drain

Connection

1”

Min.

2”Max.

*5’ max.

PVCPipeOnly

To Drain

*Piping from furnace must slope down a minimum of 1/4” per ft. toward trap.

FIGURE 51

Page 40

ML195UH With Evaporator Coil Using A Separate Drain

Field Provided Vent (1” min. 2” max. above condensate connec tion)

Condensate

Connection

Drain

Evaporator drain

line required

Condensate Trap With Optional Overflow Switch

From Evaporator Coil

Horizontal Furnace 4”Min.to 5”Max.above

condensate drain connection)

FurnaceCondensate

DrainConnection

Optional

Drain Pan

FIGURE 52

FIGURE 53

ML195UH with Evaporatoir Coil Using a Separate Drain

(Unit shown in horizontal left-hand discharge position)

Evaporator

Coil

4”min

5”max

5’ max.

PVC Pipe Only

Condensate

DrainConnection

Piping from furnace and evaporator coil must slope down a minimum 1/4” per ft. toward trap

FIGURE 54

Field Provided Vent (4” min. to 5” max. above condensate connection)

Page 41

ML195UH with Evaporator Coil Using a Common Drain

(1”min. to 2” Max.above

condensate drain connection)

Condensate

Connection

Drain

FIGURE 55

IMPORTANT

Evaporator drain

line required

ML195UH with Evaporator Coil Using a Common Drain

(Unit shown in horizontal left−hand discharge position)

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.

Drain

Pan

Evaporator

Coil

(4”min. to 5” Max.above

condensate drain connection)

4”min

5”max

5’ max.

PVC Pipe Only

CondensateDrain

Connection

Piping from furnace and evaporator coil must slope down a minimum 1/4” per ft. toward trap

FIGURE 56

Page 42

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 (25 mm) 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 Unit

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 57

Page 43

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

COLD END HEADER BOX WITH 1/2” DRAIN CONNECTION

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 58

Page 44

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 ML195UH 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:

ML195UH 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 59)

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 59. 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 59.

MANIFOLD PRESSURE

ADJUSTMENT

SCREW

INLET

PRESSURE

PORT

GAS VALVE SHOWN IN ON POSITION

MANIFOLD

PRESSURE

OUTLET

FIGURE 59

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 45

IV-HEATING SYSTEM SERVICE CHECKS

D-Testing Gas Supply Pressure

A-C.S.A. Certification

All units are C.S.A. design certified without modifications. Refer to the ML195UH Operation and Installation Instruc tion Manual Information.

B-Gas Piping

CAUTION

If a flexible gas connector is required or allowed by the authority that has jurisdiction, black iron pipe shall be installed at the gas valve and extend outside the furnace cabinet. The flexible connector can then be added between the black iron pipe and the gas supply line.

Gas supply piping should not allow more than 0.5”W.C. drop in pressure between gas meter and unit. Supply gas pipe must not be smaller than unit gas connection.

Compounds used on gas piping threaded joints should be resistant to action of liquefied petroleum gases.

C-Testing Gas Piping

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 60.

MANUAL MAIN SHUT-OFF

VALVE WILL NOT HOLD

NORMAL TEST PRESSURE

1/8” N.P.T. PLUGGED TAP

FIGURE 60

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 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.

CAP

FURNACE

ISOLATE

GAS VALVE

Gas Flow (Approximate)

TABLE 18

GAS METER CLOCKING CHART

Seconds for One Revolution

ML195

Unit

-045 80 160 200 400

-070 55 110 136 272

-090 41 82 102 204

-110 33 66 82 164

-135 27 54 68 136

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

Furnace should operate at least 5 minutes before checking gas flow. Determine time in seconds for two revolutions of gas through the meter. (Two revolutions assures a more accurate time.) Divide by two and compare to time in table 18 below. If manifold pressure matches table 19 and rate is incorrect, check gas orifices for proper size and restriction. Remove temporary gas meter if installed.

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

Supply Pressure Measurement

When testing supply gas pressure, use the 1/8” N.P.T. plugged tap or pressure post located on the gas valve to facilitate test gauge connection. See figure 59. 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.

Manifold Pressure Measurement

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.

Natural LP

1 cu ft

Dial

2 cu ft

Dial

1 cu ft

Dial

2 cu ft

DIAL

Page 46

TABLE 19

Supply Line and Manifold Pressure (inches w.c.) At

All Altitudes For -1 Through -5 Units

Unit Fuel

All Nat. Gas 3.5 4.5 - 13.0

All L.P. Gas 10.0 11.0 - 13.0

Manifold Pres

sure

Line

Pressure

NOTE - A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruction for the conversion procedure.

E-Proper Combustion

Furnace should operate minimum 15 minutes with correct manifold pressure and gas flow rate before checking com bustion. Take combustion sample beyond the flue outlet and compare to the tables below.

TABLE 20

ML195

Unit

-045

-070

-090

-110

-135

The maximum carbon monoxide reading should not exceed 50 ppm.

CO2%

For Nat

CO2%

7.2 - 8.2 8.6 - 9.6

For L.P.

F-High Altitude

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

ML195UH-1 through -5 units require no manifold pressure adjustments for operation at altitudes up to 10,000 feet (3048 m) above sea level. However, -6 units and later installed at altitude of 4501 - 10,000 feet (1373 to 3048m) require a pressure switch change which can be ordered separately and a manifold pressure de-rate. See table 19 or table 21 for manifold pressuers at varying altitudes. Table 22 lists conversion kit and pressure switch require ments at varying altitudes.

The combustion air pressure switch is factory-set and re quires no adjustment.

TABLE 21

Manifold and Supply Line Pressure 0-10,000ft. For -6 Units and Later

ML195

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. 6501 - 7500ft. 7501 - 10000ft.

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

Manifold Pressure in. wg.

Supply Line Pressure

in. w.g.

0 - 10000 ft.

TABLE 22

Conversion Kit and Pressure Switch Requirements at Varying Altitudes

* 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).

ML195

Unit

-045

Natural to

LP/Propane

0 - 7500 ft

(0 - 2286m)

High Altitude

Natural Burner

Orifice Kit

7501 - 10,000 ft

(2286 - 3038m)

High Altitude

LP/Propane Burner

Orifice Kit

7501 - 10,000 ft

(2286 - 3038m)

High Altitude Pressure Switch

4501 - 7500 ft

(1373 - 2286m)

7501 -10,000 ft (2286 - 3048m)

No Change 93W87

-070 93W93 93W86

-090 93W92 93W86

*69W73 73W37 *68W68

-110 93W93 93W86

-135 93W92 93W86

Page 47

G- Proper Ground and Voltage

A poorly grounded furnace can contribute to premature ig nitor failure. Use the following procedure to check for ground and voltage to the integrated control.

1 - Measure the AC voltage between Line Neutral (spade

terminals) and “C” terminal (low voltage terminal block) on the integrated control. See figure 61. A wide variation in the voltage between Line Neutral and “C” as a function of load indicates a poor or partial ground. Compare the readings to the table below. If the read ings exceed the maximum shown in table 1, make re pairs before operating the furnace.

2 - In addition, measure the AC voltage from Line Hot to

Line Neutral (spade terminals) on the integrated con trol. See figure 62. This voltage should be in the range of 97 to 132 Vac

TABLE 23

Furnace Status

Power On Furnace Idle 0.3 2

CAI / Ignitor Energized 0.75 5

Indoor Blower Energized Less than 2 10

Measurement VAC

Expected Maximum

CHECK VOLTAGE BETWEEN LINE HOT

AND LINE NEUTRAL

AN2

AN1

GREEN

RED

CHECK VOLTAGE BETWEEN LINE NEU

TRAL AND LOW VOLTAGE “C” TERMINAL

AN2

AN1

GREEN

RED

FIGURE 61

FIGURE 62

V-TYPICAL OPERATING CHARACTERISTICS

A-Blower Operation and Adjustment

NOTE- The following is a generalized procedure and does not apply to all thermostat controls.

1 - Blower operation is dependent on thermostat control

system.

2 - Generally, blower operation is set at thermostat sub

base fan switch. With fan switch in ON position, blower operates continuously. With fan switch in AUTO 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 (Figure 63)

Temperature rise for EL195UH units depends on unit input, blower speed, blower horsepower and static pressure as marked on the unit rating plate. The blower speed must be set for unit operation within the range of “TEMP. RISE °F” listed on the unit rating plate.

Page 48

TEMPERATURE RISE

Supply Duct Temperature ________

Return Duct Temperature

_____

Temperature Rise = ________

SUPPLY

AIR

EXTERNAL STATIC PRESSURE Supply Duct Static ________

Return Duct Static + _____

Total Duct Static = ________ (dry coil)

Supply Air

Duct Static

Temperature s

RETURN AIR

FIGURE 63

C-External Static Pressure

1 - Tap locations shown in figure . 2 - Punch a 1/4” diameter hole in supply and return air ple

nums. See figure 64. Insert manometer hose flush with inside edge of hole or insulation. Seal around the hose with permagum. Connect the zero end of the manome ter to the discharge (supply) side of the system. On ducted systems, connect the other end of manometer to the return duct as above.

3 - With only the blower motor running and the evaporator

coil dry, observe the manometer reading. Adjust blow er motor speed to deliver the air desired according to the job requirements. For heating speed external static pressure drop must not be more than 0.5” W.C. For cooling speed external static pressure drop must not be more than 0.8” W.C.

4 - Seal the hole when the check is complete.

Return Air

FIGURE 64

D-Blower Speed Taps

Blower speed tap changes are made on the integrated con trol. See figure 4. The heating tap is connected to the “HEAT” terminal and the cooling tap is connected to the “COOL” terminal. On all units the continuous blower tap is connected to the “FAN” terminal. Unused taps must be se cured on two dummy terminals labeled ”PARK. To change out existing speed tap, turn off power and switch out speed tap with tap connected to “PARK”. See blower speed tap table on unit diagram for motor tap colors for each speed.

VI-MAINTENANCE

WARNING

ELECTRICAL SHOCK, FIRE,

OR EXPLOSION HAZARD.

Failure to follow safety warnings exactly could result in dangerous operation, serious injury, death or property damage. Improper servicing could result in dangerous 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:

Page 49

Blower

Check the blower wheel for debris and clean if necessary. The blower motors are prelubricated for extended bearing life. No further lubrication is needed.

WARNING

The blower access panel must be securely in place when the blower and burners are operating. Gas fumes, which could contain carbon monoxide, can be drawn into living space resulting in personal 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).

TABLE 24

Furnace

Cabinet Width

17-1/2” 16 X 25 X 1 (1) 16 X 25 X 1 (1)

21” 16 X 25 X 1 (1) 20 X 25 X 1 (1)

24-1/2” 16 X 25 X 1 (2) 24 X 25 X 1 (1)

Exhaust and air intake pipes

Check the exhaust and air intake pipes and all connections for tightness and to make sure there is no blockage.

NOTE - After any heavy snow, ice or frozen fog event the furnace vent pipes may become restricted. Always check the vent system and remove any snow or ice that may be obstructing the plastic intake or exhaust pipes.

Electrical

1 - Check all wiring for loose connections. 2 - Check for the correct voltage at the furnace (furnace

operating). Correct voltage is 120VAC +

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

cess panel in place. Motor Nameplate__________Actual__________

Side Return Bottom Return

Filter Size

10%

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.

Condensate Hose Screens (Figure 65)

Check the condensate hose screens for blockage and

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

pull screens to remove. 3 - Inspect screens and rinse with tap water if needed. 4 - Reinstall screens, reconnect hoses and turn on power

to unit.

Condensate Hose Screens

Hose

FIGURE 65

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 burner access panel. 3 - Mark all gas valve wires and disconnect them from

valve. 4 - Remove gas supply line connected to gas valve. 5 - Remove sensor wire from flame sensor. Disconnect

2‐pin plug from the ignitor. 6 - Disconnect wires from flame roll-out switches. 7 - Remove four burner assembly screws at the vestibule

panel and remove gas valve /manifold and burner box

as a single unit.

NOTE - If necessary, clean burners at this time. Follow

procedures outlined in Burner Cleaning section.

9 - Remove the clean-out cap on trap and drain. Replace

cap. 10 - Disconnect condensate drain line from the conden

sate trap. Remove condensate trap (it may be neces

sary to cut drain pipe). Remove the 1/2” NPT fitting

from the cold end header box. Disconnect drain tubes

from cold end header collector box. 11 - Disconnect condensate drain tubes from flue collar.

Remove screws that secures flue collar in place. Re

move flue collar. It may be necessary to cut the exiting

exhaust pipe for removal of the fitting. 12 - Loosen two clamps from flexible no-hub exhaust col

lar.

Hose

Page 50

13 - Disconnect the 2‐pin plug from the combustion air in

ducer. Remove screws which secure combustion air inducer to collector box. Remove combustion air in ducer assembly. Remove ground wire.

14 - Mark and disconnect all combustion air pressure tub

ing from cold end header collector box.

15 - Mark and remove wires from pressure switch. Re

move pressure switch. Keep tubing attached to pres sure switch.

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

nace.

17 - Remove blower access panel.

18 - Mark and disconnect any remaining wiring to heating

compartment components. Disengage strain relief bushing and pull wiring and bushing through the hole in the blower deck.

19 - Remove the primary limit from the vestibule panel.

20 - Remove top cap screws to allow top cap to be tilted up

ward to allow clearance for removing heat exchanger.

21 - Remove two screws from the front cabinet flange at

the blower deck. Spread cabinet sides slightly to allow clearance for removal of heat exchanger.

22 - Remove screws along vestibule sides and bottom

which secure vestibule panel and heat exchanger as sembly to cabinet. Remove two screws from blower rails which secure bottom heat exchanger flange. Re move heat exchanger from furnace cabinet.

23 - Back wash heat exchanger with soapy water solution

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

(135°C) .

24 - Thoroughly rinse and drain the heat exchanger. Soap

solutions can be corrosive. Take care to rinse entire assembly.

25 - Reinstall heat exchanger into cabinet making sure that

the rear baffle of the heat exchanger assembly is nested under the support located at the rear of the cabinet. Remove the indoor blower to view this area through the blower opening.

26 - Re‐secure the supporting screws along the vestibule

sides.

27 - Reinstall blower assembly and reinstall two screws

through rails.

28 - Reinstall cabinet screws on front flange at blower

deck.

29 - Reinstall screws securing top cap.

30 - Reinstall the primary limit on the vestibule panel.

31 - Route heating component wiring through hole in blow

er deck and reinsert strain relief bushing.

32 - Reinstall pressure switch and reconnect pressure

switch wiring.

33 - Carefully connect combustion air pressure switch hos

ing from pressure switch to proper stubs on cold end header collector box.

34 - Reinstall 1/2” NPT (if removed) in the cold end header

box. Reconnect drain tubing to collector box.

35 - Reinstall condensate trap pipe. Reconnect conden

sate drain line to the condensate trap. 36 - Reinstall electrical junction box. 37- Reinstall the combustion air inducer and flexible no

hub connector. Reconnect the 2-pin plug to the wire

harness. 39 - Reconnect drain tubes between flue collar and cold

end header box. 40 - Secure burner assembly to vestibule panel using four

existing screws. Burners are self aligning to center

of clam shells.

41 - Reconnect gas supply line to gas valve. 42 - Reconnect flame roll-out switch wires. 43 - Reconnect sensor wire and reconnect 2-pin plug from

ignitor. 44 - Reconnect wires to gas valve. 45 - Replace the blower compartment access panel. 46 - Refer to instruction on verifying gas and electrical con

nections when re-establishing supplies. 47 - 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. 48 - Replace heating compartment access panel.

Cleaning the Burner Assembly

1 - Turn off gas and electrical power to the furnace. Re

move heating compartment access panel. 2 - Disconnect the gas supply line from the gas valve. 3 - Disconnect and label wires from gas valve. 4 - Disconnect ignitor wiring at 2 circuit plug. 5 - Disconnect and label wires from rollout switch. 6 - Disconnect and label flame sensor wire. 7 - Disconnect and label ground wire from burner/man

ifold assembly. 8 - Remove four screws that secures burner/manifold as

sembly to vestibule. Remove the assembly and make

note not to allow ignitor plate to dislodge from the as

sembly. 9 - Gently clean the face of the burners using the soft

brush attachment on a vacuum cleaner. Visually in

spect the inside of the burners and crossovers for any

blockage caused by foreign matter. Remove any

blockage 10 - Reinstall the burner/manifold assembly using the ex

isting four screws. Burners are self aligning to cen

ter of clam shells.

11 - Reconnect ground wire. 12 - Reconnect flame sensor wire. 13 - Reconnect rollout switch wires. 14 - Reconnect ignitor wires. 15 - Reconnect gas valve wires. 16 - Reconnect gas supply line to gas valve. 17 - Refer to instructions on verifying gas and electrical

connections when re-establishing supplies. 18 - Follow instructions to place furnace in operation. Run

furnace 5 minutes to ensure burners are clean and op

erating correctly. 19 - Replace heating compartment access panel.

Page 51

VII-WIRING DIAGRAM AND SEQUENCE OF OPERATION

ML195UH 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 control (A92) energizes combustion air

inducer B6. Combustion air inducer runs until S18 combustion air prove switch closes (switch must close within 2-1/2 minutes or control goes into 5 minute Watchguard Pressure Switch delay). Once S18 closes, a 15-second pre-purge follows.

4 - The integrated control (A92) energizes ignitor. A

20-second warm-up period begins.

5 - Gas valve opens for a 4-second trial for ignition

6 - Flame is sensed, gas valve remains open for the heat

call.

7 - After 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 52

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)

PRIMARY LIMIT SWITCH. CLOSED?

HAS COMBUSTION AIR PRESSURE

SWITCH CLOSED IN 2.5 MINUTES?

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

IS COMBUSTION AIR

PRESSURE SWITCH OPEN?

YES

IS COMBUSTION AIR INDUCER

ENERGIZED?

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 53

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 54

YES

WATCHGUARD

1 HR

PRESSURE

SWITCH

MODE

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 BOARD FAILURE AT LED.

INTERRUPT MAIN POWER TO RESET CONTROL.

AND MAIN POWER IS INTERRUPTED OR THERMOSTAT

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

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 55

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 56

ML195UH 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 57

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.

CONTROL WILL NOT RESPOND TO CALL FOR HEAT

IGNITOR WILL GLOW DIMLY BUT WILL NOT LIGHT

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: OFF

POLARITY REVERSED.

LED: 9 FLASHES

IMPROPER GROUND.

LED: OFF

UNTIL PROPER GROUND.

LED: ON STEADY

INDOOR BLOWER ON.

LED: 5 FLASHES

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 58

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 59

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 1‐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 60

Lennox 070XP36B, 045XP36B, 110XP48C, 110XP60C, 135XP60D Unit Information

Specifications and Main Features

Frequently Asked Questions

User Manual