Lennox G71MPP Unit Information

Page 1

Corp. 0804−L2

G71MPP

Service Literature

Revised 05−05−2008

G71MPP SERIES UNITS

G71MPP series units are high−efficiency multi−position (upflow, downflow, horizontal right and left) gas furnaces equipped with variable capacity gas valve, variable speed combustion air inducer and variable speed indoor blower motor. All models are designed only for direct vent (dual pipe) venting system. G71MPP units are available in heating capacities from 66,000 to 132,000 Btuh (19.3 to 38.6 kW) and cooling applications from 2 to 5 tons (7.0 kW to

17.5 kW). Refer to Engineering Handbook for proper sizing.

Units are factory equipped for use with natural gas. Kits are available for conversion to LPG operation. G71MPP model units are equipped with the Lennox SureLight

®

variable capacity integrated control. All G71MPP units meet the California Nitrogen Oxides (NO

x

) Standards and California Sea-

sonal Efficiency requirements.

All specifications in this manual are subject to change. Procedures outlined in this manual are presented as a recommendation only and do not supersede or replace local or state codes. In the absence of local or state codes, the guidelines and procedures outlined in this manual (except where noted) are recommendations only and do not constitute code.

TABLE OF CONTENTS

Specifications Page 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

Blower Data Page 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I Unit Components Page 16. . . . . . . . . . . . . . . . . . . . . . .

Control Box 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blower Compartment 28. . . . . . . . . . . . . . . . . . . . . . . . .

Heating Components 30. . . . . . . . . . . . . . . . . . . . . . . . .

II Installation Page 36. . . . . . . . . . . . . . . . . . . . . . . . . . . .

III Start Up Page 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IV Heating System Service Checks Page 48. . . . . . . . .

V Typical Operating Characteristics Page 51. . . . . . . . .

VI Maintenance Page 52. . . . . . . . . . . . . . . . . . . . . . . . . .

VII Wiring and Sequence of Operation Page 54. . . . . .

VIII Field Wiring Page 61. . . . . . . . . . . . . . . . . . . . . . . . .

WARNING

Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal injury or loss of life. Installation and service must be performed by a licensed professional installer (or equivalent), service agency or the gas supplier.

WARNING

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

WARNING

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

Page 2

SPECIFICATIONS

Gas Heating Performance

ModelNo. G71MPP

−36B−070

G71MPP

−36C−090

G71MPP

−60C−090

G71MPP

−60C−110

G71MPP

−60D−135

Maximum

Input− Btuh 66,000 88,000 88,000 110,000 132,000

Output− Btuh 60,000 81,000 81,000 103,000 123,000

Temperature rise range − _F 50 − 80 60 − 90 50 − 80 50 − 80 55 − 85

Gas Manifold Pressure (in. w.g.)

Natural Gas / LPG/Propane

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

Minimum

Input − Btuh 26,000 35,000 35,000 44,000 53,000

Output − Btuh 25,000 34,000 34,000 42,000 51,000

Temperature rise range − _F 40 − 70 40 − 70 40 − 70 40 − 70 40 − 70

Gas Manifold Pressure (in. w.g.)

Natural Gas / LPG/Propane

0.7 / 2.0 0.7 / 2.0 0.7 / 2.0 0.7 / 2.0 0.7 / 2.0

1

AFUE 95.0% 95.0% 95.0% 95.0% 95.0%

Highstatic(CSA)− in.w.g. .80 .80 .80 .80 .80

Connections in.

Intake / Exhaust Pipe (PVC) 2 / 2 2 / 2 2 / 2 2 / 2 3 / 3

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

with field supplied (PVC coupling) − o.d. 3/4 3/4 3/4 3/4 3/4

hose with hose clamp − i.d. x o.d. 1 x 1−1/4 1 x 1 1/4 1 x 1 1/4 1 x 1 1/4 1 x 1 1/4

GaspipesizeIPS 1/2 1/2 1/2 1/2 1/2

Indoor Blower

Wheelnominaldiameter xwidth −in. 10 x 8 10 x 10 11−1/2 x 10 11−1/2 x 10 11−1/2 x 10

Motoroutput − hp 1/2 1/2 1 1 1

Tons ofadd−oncooling 2 − 3.5 2 − 3.5 3.5 − 5 3.5 − 5 3.5 − 5

Air volume range − cfm

250 −1395 250 − 1395

450 − 2215 450 − 2210 450 − 2190

ShippingData lbs. − 1 package 149 160 171 184 206

Electricalcharacteristics 120 volts − 60 hertz − 1 phase (less than 12 amps)

NOTE − Filters and provisions for mounting are not furnished and must be field provided.

1

Annual Fuel Utilization Efficiency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non−weatherized furnaces.

Page 3

OPTIONAL ACCESSORIES

B" Width Models C" Width Models D" Width Models

FILTER KITS

1

Air Filter and

Rack Kit

Horizontal (end) Size of filter − 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 filter − in. 16 x 25 x 1 16 x 25 x 1 16 x 25 x 1

EZ Filter Base

Catalog No. − Ship. Wt. − lbs. 73P56 − 7 73P57 − 8 73P58 − 10

Size of field provided filter − in. 16 x 25 x 1 20 x 25 x 1 24 x 24 x 1

CABINET ACCESSORIES

Down−Flow Additive Base 11M60 11M61 11M62

Horizontal Support Frame Kit 56J18 56J18 56J18

Return Air Base 98M60 98M58 98M59

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

Condensate Trap Alternate Location Kit − Up−Flow Only 76M20 76M20 76M20

CONTROLS

ComfortSenset 7000 Thermostat Y0349 Y0349 Y0349

TERMINATION KITS − See Installation Instructions for specific venting information.

Termination Kits Concentric

2 in. 71M80 69M29 − − −

3 in. − − − 60L46 60L46

Wall − Close Couple

2 in. 22G44 − − − − − −

3 in. 44J40 44J40 44J40

Close Couple 2 in. 30G28 − − − − − −

3 in. 81J20 81J20 81J20

Wall − Wall Ring Kit 2 in. 15F74 15F74 − − −

Roof 2 in. 15F75 15F75 − − −

Roof Termination Flashing Kit − Contains two flashings. 44J41 44J41 44J41

1

Cleanable polyurethane frame type filter.

GAS HEAT ACCESSORIES

Input

High Altitude Pressure Switch Kit LPG/Propane Kit LPG/Propane to Natural Gas Kit

7501−10,000 ft. 0−10,000 ft. 0−10,000 ft.

−070 36W77 33W41 33W42

−090 40W05 33W41 33W42

−110 40W06 33W41 33W42

−135 40W07 33W41 33W42

Page 4

TABLE 1 G71MPP−36B−070 BLOWER PERFORMANCE (less filter) 0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE

Heating Adjust CFM Selections

Heating Input Range and Blower Volume − CFM

40% 50% 60% 70% 80% 90% 100%

Increase (+15%) Heat CFM 535 610 690 770 870 975 1075

Increase (+7.5%) Heat CFM 505 575 645 720 810 905 1000

Default Heat CFM 480 545 610 675 760 845 930

Decrease (–7.5% ) Heat CFM 460 520 580 640 715 790 870

Decrease (–15% ) Heat CFM 440 490 540 590 655 715 780

COOLING BLOWER PERFORMANCE

Cooling Adjust CFM

Selections

Blower Speed Selections

First Stage Cool Speed − cfm Second Stage Cool Speed − cfm

Low

Medium−

Low

Medium

High

(Default)

Low

Medium−

Low

Medium

High

(Default)

Increase (+10%) Cool CFM 730 815 865 935 1015 1190 1280 1395

Default Cool CFM 680 755 795 855 930 1065 1155 1270

Decrease (–10%) Cool CFM 625 695 730 775 830 950 1010 1105

The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 250 cfm. The following control board configurations are available. See Installation Instructions for details and DIP switch settings. Heat Mode (Heating Blower Performance Table): With a single−stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey−shaded columns). With two−stage thermostat there are two modes available. Traditional two−stage mode − W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70% and 100% grey−shaded columns only). Variable Rate Capacity Mode − furnace automatically adjusts firing rate based on first− and second−stage cycle times. (all columns) Cool Mode (Cooling Blower Performance table):

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 250 cfm.

G71MPP−36B−070 BLOWER MOTOR WATTS − COOLING

Blower Speed

Options

Motor Watts @ Various External Static Pressures − in. wg.

First Stage Second Stage

0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Increase (+10%) Cool CFM

Low 55 70 90 110 130 145 160 175 190 135 155 175 200 220 245 270 295 320

Medium−Low 75 90 110 130 150 170 190 205 220 185 215 250 285 315 345 370 395 420

Medium−High 85 100 120 145 165 185 205 225 250 235 265 300 335 370 400 425 455 480

High 105 125 150 170 190 210 235 255 280 315 340 370 395 440 480 510 540 570

Default Cool CFM

Low 45 60 80 95 115 130 145 160 175 100 120 140 165 190 215 235 255 275

Medium−Low 60 75 95 110 130 145 165 180 200 140 165 190 220 245 265 290 315 340

Medium−High 65 85 105 125 140 155 175 195 215 175 200 230 260 285 310 340 365 390

High 85 100 120 140 160 180 200 220 240 230 260 295 325 360 390 410 435 455

Decrease (–10%) Cool CFM

Low 40 55 70 85 100 120 130 145 160 75 90 110 125 150 175 190 210 225

Medium−Low 45 60 80 95 115 135 145 160 175 95 120 150 175 200 220 240 260 285

Medium−High 50 65 85 105 125 145 160 175 190 125 150 175 195 220 240 265 290 320

High 60 75 95 115 135 150 170 190 215 165 190 215 245 265 485 315 340 370

Page 5

TABLE 2 G71MPP−36C−090 BLOWER PERFORMANCE (less filter) 0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE

Heating Adjust CFM Selections

Heating Input Range and Blower Volume − CFM

40% 50% 60% 70% 80% 90% 100%

Increase (+15%) Heat CFM 650 740 825 910 1005 1100 1200

Increase (+7.5%) Heat CFM 620 695 775 850 940 1025 1115

Default Heat CFM 590 655 725 790 870 950 1030

Decrease (–7.5% ) Heat CFM 555 615 680 740 815 890 965

Decrease (–15% ) Heat CFM 525 575 630 680 745 805 870

COOLING BLOWER PERFORMANCE

Cooling Adjust CFM

Selections

Blower Speed Selections

First Stage Cool Speed − cfm Second Stage Cool Speed − cfm

Low

Medium−

Low

Medium

High

(Default)

Low

Medium−

Low

Medium

High

(Default)

Increase (+10%) Cool CFM 705 790 845 920 1020 1185 1275 1395

Default Cool CFM 650 730 770 830 905 1060 1145 1270

Decrease (–10%) Cool CFM 600 670 705 750 800 925 1010 1100

The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 250 cfm. The following control board configurations are available. See Installation Instructions for details and DIP switch settings. Heat Mode (Heating Blower Performance Table): With a single−stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey−shaded columns). With two−stage thermostat there are two modes available. Traditional two−stage mode − W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70% and 100% grey−shaded columns only). Variable Rate Capacity Mode − furnace automatically adjusts firing rate based on first− and second−stage cycle times. (all columns) Cool Mode (Cooling Blower Performance table):

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 250 cfm.

G71MPP−36C−090 BLOWER MOTOR WATTS − COOLING

Blower Speed

Options

Motor Watts @ Various External Static Pressures − in. wg.

First Stage Second Stage

0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Increase (+10%) Cool CFM

Low 35 50 70 90 105 125 140 160 175 85 110 135 160 185 205 235 265 295

Medium−Low 45 60 80 100 125 150 170 185 205 125 155 185 220 245 275 305 330 360

Medium−High 60 75 95 110 135 160 180 200 220 165 195 230 265 300 330 355 380 410

High 65 85 110 135 160 180 205 225 245 210 245 285 325 360 390 425 460 495

Default Cool CFM

Low 35 45 60 75 95 115 130 145 160 60 80 110 135 155 175 195 215 235

Medium−Low 40 55 70 90 110 130 150 165 185 105 125 145 170 200 225 250 270 295

Medium−High 45 60 80 95 115 135 155 175 195 11 5 140 175 205 235 265 290 315 335

High 50 65 85 105 130 155 180 200 220 155 185 220 255 285 315 345 380 415

Decrease (–10%) Cool CFM

Low 30 40 55 75 90 105 120 135 150 55 65 85 105 125 150 170 190 210

Medium−Low 40 50 65 80 100 120 130 145 160 65 90 120 145 165 185 205 225 250

Medium−High 40 55 70 90 105 125 140 160 180 85 105 135 165 185 210 235 260 285

High 45 60 75 90 115 135 155 170 190 105 125 150 175 210 240 275 305 335

Page 6

TABLE 3

G71MPP−60C−090 BLOWER PERFORMANCE (less filter)

Bottom Return Air, Return Air from Both Sides or Return Air from Bottom and One Side

0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE

Heating Adjust CFM Selections

Heating Input Range and Blower Volume − CFM

40% 50% 60% 70% 80% 90% 100%

Increase (+15%) Heat CFM 665 800 935 1070 1205 1335 1470

Increase (+7.5%) Heat CFM 600 730 860 990 111 0 1235 1355

Default Heat CFM 615 715 820 920 1035 1150 1265

Decrease (–7.5% ) Heat CFM 520 630 740 850 960 1070 1180

Decrease (–15% ) Heat CFM 465 565 665 765 870 970 1075

COOLING BLOWER PERFORMANCE

Cooling Adjust CFM

Selections

Blower Speed Selections

First Stage Cool Speed − cfm Second Stage Cool Speed − cfm

Low

Medium−

Low

Medium

High

(Default)

Low

Medium−

Low

Medium

High

(Default)

Increase (+10%) Cool CFM 1105 1185 1355 1545 1605 1710 1925 2165

Default Cool CFM 995 1080 1205 1345 1440 1560 1755 1960

Decrease (–10%) Cool CFM 890 960 1090 1215 1275 1380 1590 1755

The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 450 cfm. The following control board configurations are available. See Installation Instructions for details and DIP switch settings. Heat Mode (Heating Blower Performance Table): With a single−stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey−shaded columns). With two−stage thermostat there are two modes available. Traditional two−stage mode − W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70% and 100% grey−shaded columns only). Variable Rate Capacity Mode − furnace automatically adjusts firing rate based on first− and second−stage cycle times. (all columns) Cool Mode (Cooling Blower Performance table):

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 450 cfm.

G71MPP−60C−090 BLOWER MOTOR WATTS − COOLING Bottom Return Air, Return Air from Both Sides or Return Air from Bottom and One Side

Blower Speed

Options

Motor Watts @ Various External Static Pressures − in. wg.

First Stage Second Stage

0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Increase (+10%) Cool CFM

Low 115 135 160 185 205 230 255 275 300 305 340 375 410 440 475 505 535 565

Medium−Low 145 165 190 215 240 265 285 305 325 355 390 430 470 510 550 580 610 635

Medium−High 170 200 240 275 305 335 370 400 430 510 555 600 645 690 730 765 795 830

High 265 295 330 365 400 435 465 500 535 725 780 835 895 935 975 1005 1035 1065

Default Cool CFM

Low 90 110 130 155 175 195 215 235 255 220 250 285 320 350 385 415 450 485

Medium−Low 110 130 155 180 200 220 245 265 285 270 305 345 385 420 455 485 515 545

Medium−High 145 165 190 215 245 270 295 320 340 390 425 465 500 540 580 610 640 670

High 180 205 240 270 300 330 365 395 430 540 580 625 670 710 755 795 830 870

Decrease (–10%) Cool CFM

Low 70 85 105 125 145 165 185 205 225 160 190 220 255 275 300 330 360 390

Medium−Low 80 100 120 140 165 190 210 225 245 195 225 260 295 325 350 385 415 450

Medium−High 110 130 160 185 205 225 250 275 300 295 330 365 400 430 460 495 535 570

High 155 175 195 220 245 270 295 315 340 400 435 470 510 545 585 610 640 665

Page 7

TABLE 4

G71MPP−60C−090 BLOWER PERFORMANCE (less filter) −− Single Side Return Air

(Air volumes in bold require field fabricated transition to accommodate 20 x 25 x 1 in. cleanable air filter

in order to maintain proper air velocity across the filter.)

0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE

Heating Adjust CFM Selections

Heating Input Range and Blower Volume − CFM

40% 50% 60% 70% 80% 90% 100% Increase (+15%) Heat CFM 655 790 920 1050 1180 1310 1440

Increase (+7.5%) Heat CFM 605 725 850 970 1090 1205 1325

Default Heat CFM 555 675 790 905 1015 1125 1235

Decrease (–7.5% ) Heat CFM 515 625 730 835 940 1045 1150

Decrease (–15% ) Heat CFM 465 565 665 765 860 960 1055

COOLING BLOWER PERFORMANCE

Cooling Adjust CFM

Selections

Blower Speed Selections

First Stage Cool Speed − cfm Second Stage Cool Speed − cfm

Low

Medium−

Low

Medium

High

(Default)

Low

Medium−

Low

Medium

High

(Default)

Increase (+10%) Cool CFM 1080 1160 1315 1490 1575 1690 1895 2135

Default Cool CFM 985 1060 1185 1330 1405 1530 1735 1935

Decrease (–10%) Cool CFM 865 930 1065 1185 1250 1355 1560 1735

The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 450 cfm. The following control board configurations are available. See Installation Instructions for details and DIP switch settings. Heat Mode (Heating Blower Performance Table): With a single−stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey−shaded columns). With two−stage thermostat there are two modes available. Traditional two−stage mode − W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70% and 100% grey−shaded columns only). Variable Rate Capacity Mode − furnace automatically adjusts firing rate based on first− and second−stage cycle times. (all columns) Cool Mode (Cooling Blower Performance table):

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 450 cfm.

G71MPP−60C−090 BLOWER MOTOR WATTS − COOLING

Blower Speed

Options

Motor Watts @ Various External Static Pressures − in. wg.

First Stage Second Stage

0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Increase (+10%) Cool CFM

Low 110 130 155 180 205 225 245 270 290 285 320 355 390 430 465 500 535 565

Medium−Low 125 150 175 205 225 250 275 300 325 355 390 430 470 500 530 570 605 645

Medium−High 170 195 230 260 290 325 355 385 415 515 550 590 625 670 710 750 795 840

High 240 275 315 355 380 405 445 485 525 740 785 835 885 920 955 990 1020 1050

Default Cool CFM

Low 85 100 125 145 170 200 215 235 255 200 230 270 310 340 370 400 430 460

Medium−Low 105 125 150 170 195 220 240 260 280 260 295 330 365 400 440 470 500 530

Medium−High 135 160 185 215 240 270 290 315 335 410 440 470 500 540 580 610 640 670

High 170 200 235 265 305 340 365 390 415 550 585 620 655 695 740 780 825 865

Decrease (–10%) Cool CFM

Low 65 80 100 120 140 160 180 205 225 180 215 245 265 290 320 345 375 445

Medium−Low 75 90 110 130 155 180 200 220 245 220 250 275 305 335 370 400 430 510

Medium−High 100 120 150 175 200 220 245 265 290 320 350 385 415 445 485 520 560 635

High 135 160 185 215 240 265 290 315 335 435 465 495 540 585 610 640 665 765

Page 8

TABLE 5

G71MPP−60C−090 BLOWER PERFORMANCE (less filter) −− Side Return Air with Optional RAB Return Air Base

0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE

Heating Adjust CFM Selections

Heating Input Range and Blower Volume − CFM

40% 50% 60% 70% 80% 90% 100%

Increase (+15%) Heat CFM 645 770 895 1020 1155 1290 1425

Increase (+7.5%) Heat CFM 595 710 825 945 1070 1195 1315

Default Heat CFM 545 660 775 890 1005 1115 1225

Decrease (–7.5% ) Heat CFM 505 605 710 810 920 1030 1140

Decrease (–15% ) Heat CFM 455 555 650 750 845 945 1045

COOLING BLOWER PERFORMANCE

Cooling Adjust CFM

Selections

Blower Speed Selections

First Stage Cool Speed − cfm Second Stage Cool Speed − cfm

Low

Medium−

Low

Medium

High

(Default)

Low

Medium−

Low

Medium

High

(Default)

Increase (+10%) Cool CFM 1060 1135 1285 1455 1525 1655 1860 2100

Default Cool CFM 960 1035 1165 1310 1385 1500 1695 1905

Decrease (–10%) Cool CFM 865 920 1050 1165 1240 1320 1510 1695

The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 450 cfm. The following control board configurations are available. See Installation Instructions for details and DIP switch settings. Heat Mode (Heating Blower Performance Table): With a single−stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey−shaded columns). With two−stage thermostat there are two modes available. Traditional two−stage mode − W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70% and 100% grey−shaded columns only). Variable Rate Capacity Mode − furnace automatically adjusts firing rate based on first− and second−stage cycle times. (all columns) Cool Mode (Cooling Blower Performance table):

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 450 cfm.

G71MPP−60C−090 BLOWER MOTOR WATTS − COOLING Side Return Air with Optional RAB Return Air Base

Blower Speed

Options

Motor Watts @ Various External Static Pressures − in. wg.

First Stage Second Stage

0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Increase (+10%) Cool CFM

Low 110 130 150 175 195 215 240 265 290 275 305 340 380 410 440 470 505 540

Medium−Low 130 155 175 200 220 245 265 290 315 360 390 420 455 485 515 550 590 625

Medium−High 160 190 220 255 280 305 335 360 390 490 530 570 610 645 680 715 750 785

High 220 255 295 330 365 400 430 460 490 695 750 805 855 895 935 965 995 1025

Default Cool CFM

Low 80 95 120 140 165 190 210 235 255 190 225 265 305 330 355 390 420 455

Medium−Low 100 120 140 165 190 215 235 255 275 265 295 325 355 390 420 455 495 530

Medium−High 140 160 185 205 235 260 285 305 325 375 410 440 475 500 530 570 610 650

High 180 205 240 270 300 325 350 380 405 520 560 605 645 685 720 760 805 845

Decrease (–10%) Cool CFM

Low 70 85 105 125 140 160 180 200 220 155 175 200 225 255 290 315 340 365

Medium−Low 80 95 115 135 155 175 200 220 245 185 210 235 260 295 325 355 385 415

Medium−High 105 125 150 175 200 220 240 265 290 255 290 330 365 400 430 460 490 520

High 135 160 185 215 235 260 285 305 330 370 400 440 475 505 530 565 600 635

Page 9

TABLE 6

G71MPP−60C−110 BLOWER PERFORMANCE (less filter)

Bottom Return Air, Return Air from Both Sides or Return Air from Bottom and One Side

0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE

Heating Adjust CFM Selections

Heating Input Range and Blower Volume − CFM

40% 50% 60% 70% 80% 90% 100%

Increase (+15%) Heat CFM 890 1050 1215 1375 1535 1695 1855

Increase (+7.5%) Heat CFM 845 975 1125 1275 1430 1585 1740

Default Heat CFM 800 960 1075 1190 1335 1480 1625

Decrease (–7.5% ) Heat CFM 735 860 990 1120 1250 1380 1510

Decrease (–15% ) Heat CFM 670 790 910 1030 1145 1260 1375

COOLING BLOWER PERFORMANCE

Cooling Adjust CFM

Selections

Blower Speed Selections

First Stage Cool Speed − cfm Second Stage Cool Speed − cfm

Low

Medium−

Low

Medium

High

(Default)

Low

Medium−

Low

Medium

High

(Default)

Increase (+10%) Cool CFM 945 1020 1160 1300 1625 1745 1990 2210

Default Cool CFM 840 910 1055 1180 1465 1580 1790 1995

Decrease (–10%) Cool CFM 740 800 920 1045 1290 1405 1605 1790

The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 450 cfm. The following control board configurations are available. See Installation Instructions for details and DIP switch settings. Heat Mode (Heating Blower Performance Table): With a single−stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey−shaded columns). With two−stage thermostat there are two modes available. Traditional two−stage mode − W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70% and 100% grey−shaded columns only). Variable Rate Capacity Mode − furnace automatically adjusts firing rate based on first− and second−stage cycle times. (all columns) Cool Mode (Cooling Blower Performance table):

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 450 cfm.

G71MPP−60C−110 BLOWER MOTOR WATTS − COOLING Bottom Return Air, Return Air from Both Sides or Return Air from Bottom and One Side

Blower Speed

Options

Motor Watts @ Various External Static Pressures − in. wg.

First Stage Second Stage

0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Increase (+10%) Cool CFM

Low 75 90 115 135 160 180 200 220 240 280 315 350 390 430 475 510 550 585

Medium−Low 90 105 130 150 175 200 220 245 270 340 380 425 465 505 545 575 610 645

Medium−High 120 140 170 195 225 250 275 300 330 510 545 585 620 675 735 770 805 840

High 160 185 210 235 265 290 325 360 395 710 755 805 855 905 950 980 1010 1035

Default Cool CFM

Low 55 70 90 110 135 155 175 195 215 205 235 275 310 345 380 415 450 485

Medium−Low 75 90 105 125 150 170 190 215 235 250 285 325 360 400 440 470 505 540

Medium−High 95 115 135 160 190 220 240 265 285 375 410 445 485 530 575 605 635 670

High 125 150 175 200 225 255 280 305 335 510 550 595 640 685 725 770 815 860

Decrease (–10%) Cool CFM

Low 45 60 80 100 115 125 145 160 180 155 180 210 240 270 295 325 355 385

Medium−Low 55 70 85 105 125 150 165 185 200 185 215 245 280 315 345 380 415 450

Medium−High 70 85 105 125 150 170 195 215 235 265 300 345 385 425 465 500 535 570

High 95 110 135 160 190 220 240 260 280 375 415 455 495 535 575 615 650 690

Page 10

TABLE 7

G71MPP−60C−110 BLOWER PERFORMANCE (less filter) −− Single Side Return Air

(Air volumes in bold require field fabricated transition to accommodate 20 x 25 x 1 in. cleanable air filter

in order to maintain proper air velocity across the filter.)

0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE

Heating Adjust CFM Selections

Heating Input Range and Blower Volume − CFM

40% 50% 60% 70% 80% 90% 100% Increase (+15%) Heat CFM 870 1030 1185 1345 1490 1630 1775

Increase (+7.5%) Heat CFM 815 955 1095 1240 1380 1525 1670

Default Heat CFM 765 900 1035 1170 1305 1435 1570

Decrease (−7.5% ) Heat CFM 715 840 965 1090 1210 1330 1450

Decrease (−15% ) Heat CFM 650 765 880 995 1110 1225 1335

COOLING BLOWER PERFORMANCE

Cooling Adjust CFM

Selections

Blower Speed Selections

First Stage Cool Speed − cfm Second Stage Cool Speed − cfm

Low

Medium−

Low

Medium

High

(Default)

Low

Medium−

Low

Medium

High

(Default)

Increase (+10%) Cool CFM 935 1025 1155 1285 1585 1700 1905 2135

Default Cool CFM 840 915 1050 1175 1435 1535 1740 1930

Decrease (–10%) Cool CFM 750 800 925 1050 1280 1385 1570 1755

The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 450 cfm. The following control board configurations are available. See Installation Instructions for details and DIP switch settings. Heat Mode (Heating Blower Performance Table): With a single−stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey−shaded columns). With two−stage thermostat there are two modes available. Traditional two−stage mode − W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70% and 100% grey−shaded columns only). Variable Rate Capacity Mode − furnace automatically adjusts firing rate based on first− and second−stage cycle times. (all columns) Cool Mode (Cooling Blower Performance table):

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 450 cfm.

G71MPP−60C−110 BLOWER MOTOR WATTS − COOLING

Blower Speed

Options

Motor Watts @ Various External Static Pressures − in. wg.

First Stage Second Stage

0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Increase (+10%) Cool CFM

Low 70 90 11 0 130 150 165 185 210 230 255 295 345 390 430 470 510 545 585

Medium−Low 85 105 125 150 170 190 215 235 255 340 375 415 455 490 525 570 615 660

Medium−High 115 135 160 185 210 230 255 285 310 455 500 555 610 655 695 750 800 850

High 155 175 195 220 250 285 310 335 360 650 710 770 835 880 920 960 995 1035

Default Cool CFM

Low 60 75 90 110 125 145 165 185 205 195 230 270 305 345 380 415 455 490

Medium−Low 70 85 105 125 140 160 180 200 220 225 265 315 360 400 440 475 515 555

Medium−High 95 110 130 150 175 200 225 245 265 365 400 445 485 525 565 610 650 690

High 115 135 165 190 215 235 260 285 310 495 535 580 625 675 725 770 815 860

Decrease (–10%) Cool CFM

Low 45 60 80 100 11 0 125 140 155 170 155 180 205 235 270 305 340 370 400

Medium−Low 50 65 85 100 120 135 155 175 195 170 200 240 275 315 355 390 420 455

Medium−High 75 90 105 120 140 160 185 210 235 250 290 330 375 410 445 485 525 570

High 95 110 135 155 175 200 225 250 270 365 405 450 490 535 575 615 655 690

Page 11

TABLE 8

G71MPP−60C−110 BLOWER PERFORMANCE (less filter) −− Side Return Air with Optional RAB Return Air Base

0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE

Heating Adjust CFM Selections

Heating Input Range and Blower Volume − CFM

40% 50% 60% 70% 80% 90% 100%

Increase (+15%) Heat CFM 865 1020 1175 1330 1485 1635 1785

Increase (+7.5%) Heat CFM 805 950 1095 1240 1385 1535 1680

Default Heat CFM 760 895 1030 1165 1300 1435 1570

Decrease (–7.5% ) Heat CFM 710 835 960 1090 1210 1335 1460

Decrease (–15% ) Heat CFM 645 765 880 1000 1110 1220 1335

COOLING BLOWER PERFORMANCE

Cooling Adjust CFM

Selections

Blower Speed Selections

First Stage Cool Speed − cfm Second Stage Cool Speed − cfm

Low

Medium−

Low

Medium

High

(Default)

Low

Medium−

Low

Medium

High

(Default)

Increase (+10%) Cool CFM 1085 1155 1310 1475 1555 1685 1895 2130

Default Cool CFM 955 1050 1185 1335 1415 1540 1735 1930

Decrease (–10%) Cool CFM 850 920 1070 1195 1245 1350 1545 1725

The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 450 cfm. The following control board configurations are available. See Installation Instructions for details and DIP switch settings. Heat Mode (Heating Blower Performance Table): With a single−stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey−shaded columns). With two−stage thermostat there are two modes available. Traditional two−stage mode − W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70% and 100% grey−shaded columns only). Variable Rate Capacity Mode − furnace automatically adjusts firing rate based on first− and second−stage cycle times. (all columns) Cool Mode (Cooling Blower Performance table):

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 450 cfm.

G71MPP−60C−110 BLOWER MOTOR WATTS − COOLING − Side Return Air with Optional RAB Return Air Base

Blower Speed

Options

Motor Watts @ Various External Static Pressures − in. wg.

First Stage Second Stage

0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Increase (+10%) Cool CFM

Low 105 125 150 175 200 220 245 265 290 250 285 320 360 395 435 470 500 535

Medium−Low 130 150 175 200 220 240 270 295 320 335 365 405 445 480 515 550 590 630

Medium−High 165 190 220 250 275 305 335 370 400 470 505 545 585 630 670 710 755 800

High 205 240 285 330 360 390 420 450 485 655 695 745 790 840 885 925 965 1005

Default Cool CFM

Low 75 90 11 5 135 160 185 205 225 250 190 220 255 290 325 360 395 430 460

Medium−Low 100 120 145 165 185 205 230 255 280 250 285 325 360 390 420 455 485 520

Medium−High 135 155 175 200 230 260 280 305 330 355 395 435 475 510 545 580 620 660

High 170 195 225 255 290 320 350 375 405 475 515 565 610 655 705 745 785 825

Decrease (–10%) Cool CFM

Low 55 70 90 110 135 155 175 195 220 150 170 200 225 255 285 315 340 370

Medium−Low 65 80 105 130 150 170 195 215 240 165 195 230 265 300 330 360 390 420

Medium−High 100 125 150 180 200 220 240 260 280 240 280 320 360 400 435 470 505 540

High 140 160 180 200 230 260 285 305 330 350 385 420 455 500 540 575 610 645

Page 12

TABLE 9

G71MPP−60D−135 BLOWER PERFORMANCE (less filter)

Bottom Return Air, Return Air from Both Sides or Return Air from Bottom and One Side

0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE

Heating Adjust CFM Selections

Heating Input Range and Blower Volume − CFM

40% 50% 60% 70% 80% 90% 100%

Increase (+15%) Heat CFM 1045 1220 1390 1565 1725 1885 2045

Increase (+7.5%) Heat CFM 975 1130 1290 1450 1600 1750 1900

Default Heat CFM 900 1045 1195 1340 1495 1650 1805

Decrease (–7.5% ) Heat CFM 840 975 1110 1250 1390 1535 1675

Decrease (–15% ) Heat CFM 760 890 1020 1145 1275 1405 1535

COOLING BLOWER PERFORMANCE

Cooling Adjust CFM

Selections

Blower Speed Selections

First Stage Cool Speed − cfm Second Stage Cool Speed − cfm

Low

Medium−

Low

Medium

High

(Default)

Low

Medium−

Low

Medium

High

(Default)

Increase (+10%) Cool CFM 1135 1205 1365 1540 1615 1730 1945 2190

Default Cool CFM 1025 1105 1235 1390 1455 1580 1780 1985

Decrease (–10%) Cool CFM 915 985 1115 1235 1305 1400 1600 1780

The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 450 cfm. The following control board configurations are available. See Installation Instructions for details and DIP switch settings. Heat Mode (Heating Blower Performance Table): With a single−stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey−shaded columns). With two−stage thermostat there are two modes available. Traditional two−stage mode − W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70% and 100% grey−shaded columns only). Variable Rate Capacity Mode − furnace automatically adjusts firing rate based on first− and second−stage cycle times. (all columns) Cool Mode (Cooling Blower Performance table):

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 450 cfm.

G71MPP−60D−135 BLOWER MOTOR WATTS − COOLING Bottom Return Air, Return Air from Both Sides or Return Air from Bottom and One Side

Blower Speed

Options

Motor Watts @ Various External Static Pressures − in. wg.

First Stage Second Stage

0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Increase (+10%) Cool CFM

Low 95 120 145 170 190 215 240 265 290 250 285 320 360 390 420 450 485 515

Medium−Low 115 135 160 185 210 235 260 290 315 290 330 375 420 455 490 525 565 605

Medium−High 145 175 215 250 275 300 330 355 385 425 465 505 550 590 635 670 710 750

High 205 240 280 320 350 380 410 445 480 615 655 700 745 800 855 900 940 980

Default Cool CFM

Low 80 95 115 135 160 190 210 230 255 185 215 245 280 310 335 370 400 430

Medium−Low 90 115 140 165 190 215 230 250 265 230 260 295 335 370 405 435 470 500

Medium−High 130 150 170 195 225 255 275 300 320 315 355 400 445 480 515 555 590 625

High 150 180 220 255 285 315 345 375 405 445 485 530 580 625 670 705 740 775

Decrease (–10%) Cool CFM

Low 65 80 100 120 140 160 180 195 215 145 170 195 225 250 280 305 330 355

Medium−Low 70 90 110 130 155 175 200 220 240 160 190 225 255 285 315 345 380 415

Medium−High 95 120 145 170 190 215 235 250 270 245 280 315 355 385 415 445 480 515

High 135 155 175 200 220 245 270 300 325 325 365 405 445 485 520 550 580 610

Page 13

TABLE 10

G71MPP−60D−135 BLOWER PERFORMANCE (less filter) −− Single Side Return Air

(Air volumes in bold require field fabricated transition to accommodate 20 x 25 x 1 in. cleanable air filter

in order to maintain proper air velocity across the filter.)

0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE

Heating Adjust CFM Selections

Heating Input Range and Blower Volume − CFM

40% 50% 60% 70% 80% 90% 100% Increase (+15%) Heat CFM 995 1160 1325 1490 1640 1790 1940

Increase (+7.5%) Heat CFM 930 1075 1225 1370 1520 1670 1825

Default Heat CFM 865 1005 1145 1280 1425 1570 1715

Decrease (–7.5% ) Heat CFM 805 930 1060 1185 1325 1470 1610

Decrease (–15% ) Heat CFM 735 850 970 1090 1215 1345 1470

COOLING BLOWER PERFORMANCE

Cooling Adjust CFM

Selections

Blower Speed Selections

First Stage Cool Speed − cfm Second Stage Cool Speed − cfm

Low

Medium−

Low

Medium

High

(Default)

Low

Medium−

Low

Medium

High

(Default)

Increase (+10%) Cool CFM 1105 1180 1330 1500 1585 1705 1905 2130

Default Cool CFM 990 1075 1210 1355 1430 1545 1765 1975

Decrease (–10%) Cool CFM 890 950 1085 1210 1275 1370 1565 1755

The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 450 cfm. The following control board configurations are available. See Installation Instructions for details and DIP switch settings. Heat Mode (Heating Blower Performance Table): With a single−stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey−shaded columns). With two−stage thermostat there are two modes available. Traditional two−stage mode − W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70% and 100% grey−shaded columns only). Variable Rate Capacity Mode − furnace automatically adjusts firing rate based on first− and second−stage cycle times. (all columns) Cool Mode (Cooling Blower Performance table):

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 450 cfm.

G71MPP−60D−135 BLOWER MOTOR WATTS − COOLING

Blower Speed

Options

Motor Watts @ Various External Static Pressures − in. wg.

First Stage Second Stage

0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Increase (+10%) Cool CFM

Low 90 110 140 170 195 220 240 265 290 230 265 310 355 390 425 460 490 525

Medium−Low 105 130 165 195 215 235 260 290 315 285 330 380 430 455 485 525 565 605

Medium−High 150 175 205 235 270 300 330 360 385 425 465 515 560 605 645 685 730 770

High 195 230 270 305 340 375 410 445 480 605 650 695 740 800 855 900 945 985

Default Cool CFM

Low 70 90 115 135 165 190 210 230 245 170 200 235 265 305 345 380 420 455

Medium−Low 80 100 130 160 185 210 230 255 275 245 270 305 335 370 410 440 470 505

Medium−High 120 140 170 195 225 255 280 305 330 350 385 420 455 495 530 570 610 645

High 145 175 215 250 280 315 345 375 410 455 500 555 605 645 680 725 770 810

Decrease (–10%) Cool CFM

Low 60 75 95 115 135 150 175 195 220 140 160 185 205 240 280 305 335 360

Medium−Low 60 75 100 125 150 175 195 215 235 145 180 215 250 290 325 355 385 420

Medium−High 90 110 140 165 190 215 235 255 270 230 265 305 345 380 420 450 480 510

High 120 140 170 195 225 255 275 300 325 330 365 405 445 485 525 560 595 635

Page 14

TABLE 11

G71MPP−60D−135 BLOWER PERFORMANCE (less filter) −− Side Return Air with Optional RAB Return Air Base

0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE

Heating Adjust CFM Selections

Heating Input Range and Blower Volume − CFM

40% 50% 60% 70% 80% 90% 100%

Increase (+15%) Heat CFM 1020 1180 1340 1500 1650 1800 1955

Increase (+7.5%) Heat CFM 950 1095 1245 1395 1535 1680 1825

Default Heat CFM 885 1020 1160 1300 1435 1575 1715

Decrease (–7.5% ) Heat CFM 820 945 1075 1200 1335 1475 1610

Decrease (–15% ) Heat CFM 745 870 990 111 0 1230 1350 1470

COOLING BLOWER PERFORMANCE

Cooling Adjust CFM

Selections

Blower Speed Selections

First Stage Cool Speed − cfm Second Stage Cool Speed − cfm

Low

Medium−

Low

Medium

High

(Default)

Low

Medium−

Low

Medium

High

(Default)

Increase (+10%) Cool CFM 1080 1155 1310 1480 1550 1660 1875 2105

Default Cool CFM 985 1055 1190 1325 1400 1510 1720 1920

Decrease (–10%) Cool CFM 875 945 1060 1190 1250 1345 1530 1715

The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 450 cfm. The following control board configurations are available. See Installation Instructions for details and DIP switch settings. Heat Mode (Heating Blower Performance Table): With a single−stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey−shaded columns). With two−stage thermostat there are two modes available. Traditional two−stage mode − W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70% and 100% grey−shaded columns only). Variable Rate Capacity Mode − furnace automatically adjusts firing rate based on first− and second−stage cycle times. (all columns) Cool Mode (Cooling Blower Performance table):

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 450 cfm.

G71MPP−60D−135 BLOWER MOTOR WATTS − COOLING − Side Return Air with Optional RAB Return Air Base

Blower Speed

Options

Motor Watts @ Various External Static Pressures − in. wg.

First Stage Second Stage

0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Increase (+10%) Cool CFM

Low 90 110 140 165 190 210 235 260 285 235 265 305 340 380 415 450 480 515

Medium−Low 105 130 160 190 210 230 255 285 310 290 325 370 410 450 490 515 545 575

Medium−High 145 170 205 235 265 290 325 355 390 420 460 510 555 595 640 680 715 755

High 200 230 270 305 345 385 415 445 480 580 630 690 745 800 850 895 935 975

Default Cool CFM

Low 70 90 115 140 165 190 210 230 250 170 200 235 270 305 335 370 400 430

Medium−Low 90 105 125 150 175 200 225 250 270 200 230 270 310 355 400 435 465 495

Medium−High 115 140 170 195 225 250 275 300 325 330 365 400 440 485 525 555 585 615

High 145 175 205 240 270 295 330 365 395 435 480 530 580 625 675 715 750 790

Decrease (–10%) Cool CFM

Low 60 75 95 115 135 155 175 195 215 135 155 180 205 240 280 305 330 355

Medium−Low 70 90 110 130 150 170 195 215 235 160 185 215 240 275 310 345 375 410

Medium−High 85 105 130 155 180 205 230 250 270 220 255 295 335 370 410 440 475 510

High 120 140 170 195 220 240 270 295 325 330 365 400 440 480 525 555 585 615

Page 15

G71MPP PARTS ARRANGEMENT

FIGURE 1

BURNER BOX ASSEMBLY

HEAT EXCHANGER

WARM HEADER

(COLLECTOR BOX)

COLD HEADER

(COLLECTOR BOX)

COMBUSTION AIR

PRESSURE SWITCHES

CONDENSER COIL

BURNER ACCESS PANEL

BLOWER ACCESS

PANEL

SIGHT GLASS

VARIABLE SPEED

COMBUSTION AIR INDUCER

VARIABLE SPEED

BLOWER MOTOR

INTEGRATED

CONTROL

ELBOW

(shipping location)

TRANSFORMER

BAG ASSEMBLIES

(shipping location)

VARIABLE CAPACITY

GAS VALVE

SHIPPING BLOCK

(−135 units only)

PRESSURE SWITCH

ASSEMBLY WITH

PRESSURE

CONDITIONING

DEVICE

Page 16

I−UNIT COMPONENTS

G71MPP unit components are shown in figure 1. The gas valve, combustion air inducer and burners can be accessed by removing the burner access panel. Electrical components are in the control box (figure 2) found in the blower compartment. G71MPP units are factory equipped with a bottom return air

panel in place. The panel is designed to be field removed as required for bottom air return. Markings are provided for side return air and may be cut out in the field.

CAUTION

Electrostatic discharge can affect electronic components. Take precautions during furnace installation and service to protect the furnace’s electronic controls. Precautions will help to avoid control exposure to electrostatic discharge by putting the furnace, the control and the technician at the same electrostatic potential. Neutralize electrostatic charge by touching hand and all tools on an unpainted unit surface, such as the gas valve or blower deck, before performing any service procedure.

ELECTROSTATIC DISCHARGE (ESD)

Precautions and Procedures

A−Control Box

1. Control Transformer (T1)

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

2. Door Interlock Switch (S51)

A door interlock switch rated 14A at 125VAC is wired in series with line voltage. When the blower door is removed the unit will shut down.

FIGURE 2

CONTROL BOX G71MPP

SURELIGHT® INTEGRATED

CONTROL

TRANSFORMER

CIRCUIT BREAKER

DOOR INTERLOCK

SWITCH

3. Circuit Breaker (CB8)

A 24V circuit breaker is also located in the control box. The switch provides overcurrent protection to the transformer (T1). The breaker is rated 3A at 32V. If the current exceeds this limit the breaker will trip and all unit operation will shutdown. The breaker can be manually reset by pressing the button on the face. See figure 3.

FIGURE 3

CIRCUIT BREAKER CB8

PRESS TO RESET

WARNING

Shock hazard. Disconnect power before servicing. Integrated

Control Board is not field repairable. If control is inoperable, simply replace entire control.

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

4. Integrated Control Board(A92)

G71MPP units are equipped with the Lennox SureLight

®

variable capacity integrated control. The system consists of an ignition / blower control (figures 4 and 5) with control pin designations in tables 12 and 13 and ignitor (figure 12). The control provides gas ignition, safety checks and indoor blower control with variable capacity rate gas heating. The furnace combustion air inducer, gas valve and indoor blower are controlled in response to various system inputs such as thermostat signal, prove and limit switch signal and flame signal. The control operates with a conventional single or two−stage thermostat. The board features a seven segment LED display, indicating furnace status (including indoor blower) and error codes. The LED flashes in single digits. For example using table 25 under LIMIT CODE, a 2" followed by 5" followed by 0", the limit switch circuit is open. The board also has two 120 volt accessory terminals (used for a humidifier and electronic air cleaner) rated at (1) one amp each.

Page 17

Electronic Ignition

At the beginning of the heat cycle the SureLight

®

integrated control monitors the low fire combustion air inducer pressure switch. The control will not begin the heating cycle if the low fire pressure switch is closed (by−passed). Likewise the control will not begin the high fire heating cycle if the high fire pressure switch is closed, and will remain in low fire heat. However, if the high fire pressure switch closes during the low fire heat pre−purge, the control will allow high fire heat. Once the low fire pressure switch is determined to be open, the combustion air inducer is energized on ignition speed. When the differential in the pressure switch is great enough, the pressure switch closes and a 15−second pre−purge begins. If the switch is not proven within 2−1/2 minutes, the inducer is de−energized and the control will initiate vent calibration. If the vent calibration is unsuccessful the control goes into a 5 minute delay. The control will attempt vent calibration 3 more times before going into a 1 hour soft lockout. After the 15 second pre−purge period the SureLight ignitor warms up for 20 seconds after which the gas valve opens for a 4−second trial for ignition. The ignitor stays energized during this trial until flame is sensed. If ignition is not proven during the 4−second trial for ignition, the control will try four more times with an inter purge and warm−up time between trials of 35 seconds. After a total of five trials for ignition (including the initial trial), the control goes into Watchguard− Flame Failure mode. After a 60−minute reset period, the control will begin the ignition sequence again.

Thermostat Selection Modes

See table 14 for DIP switch settings

The control can be made to operate in three modes: variable capacity, three−stage timed or two−stage. The variable capacity and two−stage modes are only operational with a two−stage thermostat. The thermostat selection is made using dip switches one and / or two (figure 4) and must be positioned for the particular application.

Variable Capacity

Using a two−stage thermostat the system will operate in a variable capacity sequence mode. In this mode, the control will vary the firing rate anywhere between 40% and 100% of full capacity. The indoor blower will be automatically ad-

justed accordingly to provide the appropriate airflow at any rate. On the initial call for low fire, the furnace will operate at 40% and will remain there until the heat call is satisfied or a call for high fire is initiated. If there is a call for high fire the rate will increase by 10% if the current rate is above 60%. However if the current rate is below 60% the rate will increase to 70%. After this initial rate increase to 70% capacity, the furnace will increase rate by 10% every 5 minutes while a high fire heat call is present. If the high fire heat call is satisfied but the low fire heat call is still present, the furnace will remain at the current firing rate until the demand is satisfied or another call for high fire is initiated.

Three Stage Timed

Using a single−stage thermostat the system will operate in a three stage timed mode. Upon a call for heat and a successful ignition, the combustion air inducer will operate at 40% and the indoor blower will adjust to the appropriate cfm. After a field selectable 7 or 12 minute delay period, the inducer RPM will increase and the unit will operate at 70%. The indoor blower will adjust to the appropriate cfm. After a factory set non−adjustable 10 minute delay expires the furnace will increase rate to 100%. The indoor blower will adjust to the appropriate cfm.

Two−Stage

The system will also operate in conventional two−stage mode.

While in two−stage mode, the furnace will fire on low fire (70% rate). The combustion air inducer will operate at 70% and the indoor blower will adjust to the appropriate cfm. The unit will switch to high fire on a W2 call from the thermostat. After a 30 second recognition period (during which the integrated control will recieve a continuous W2 call) expires the furnace will increase to 100% rate. The inducer will increase to 100% speed and the indoor blower will adjust to appropriate cfm. If there is a simultaneous call for first and second stage heat, the unit will fire on first stage heat and switch to second stage heat after 30 seconds of operation.

Page 18

INTEGRATED CONTROL

THERMOSTAT CONNECTIONS (TB1)

1/4" QUICK CONNECT TERMINALS

H= 24V HUMIDIFIER OUTPUT L= LENNOX SYSTEM OPERATION MONITOR

NEUTRALS= 120 VAC NEUTRAL

FIGURE 4

+

FLAME SENSE

COMBUSTION

AIR INDUCER CONNECTOR

DIP SWITCHES

OUTDOOR AIR

SENSOR TERMINALS (Future Use)

DISCHARGE AIR

SENSOR TERMINALS (Future Use)

W915

W951

W914

ON−BOARD

LINKS

INDOOR

BLOWER

CONNECTOR

EAC

HUM

LINE VOLTAGE

TERMINALS

NEUTRAL

TERMINALS

IGNITOR

CONNECTOR

7−SEGMENT

DIAGNOSTIC LED

DIAGNOSTIC

PUSH BUTTON

FACTORY TEST

HEADER PINS.

FACTORY USE ONLY.

TABLE 12

SureLight Board

®

6 Pin Terminal Designation

PIN # Function

1 Data Input From Motor

2 Common

3 Furnace Size Resistor Input

4 Data Output To Motor

5 5 Volt Bias Supply

6 Furnace Size Resistor Input

TABLE 13

SureLight Board 12Pin Terminal Designation

PIN # Function

1 Not used

2 High Fire Pressure Switch

3 Rollout In

4 Ground

5 24V Hot

6 Primary Limit In

7 Gas Valve

8 Gas Valve Common

9 24V Neutral

10 Ground

11 Primary Limit Switch Out

12 Low Fire Pressure Switch

Page 19

FIGURE 5

G71MPP INTEGRATED CONTROL CONFIGURATION GUIDE

Page 20

TABLE 14

Thermostat Selection Switch Settings

Operation

Thermostat Switch 1 Switch 2 Switch 3

Variable Capacity Heat

(40% to 100%)

Two−Stage Off On Off

Three−Stage Heat

(40%, 70%, 100%)

Single−Stage On Off 2nd stage delay

OFF = 7 minutes ON = 12 minutes

3rd stage delay

10 minutes fixed

Two−Stage Heat (W1 70%, W2 100%) Two−Stage Off Off Off

Heating Operation DIP Switch Settings −− Figure 4 Switch 1 −− Thermostat Selection −− This unit may be used

with either a single−stage or two−stage thermostat. The thermostat selection is made using a DIP switch which must be properly positioned for the particular application. The DIP switch is factory−positioned for use with a two− stage thermostat. If a single−stage thermostat is to be used, the DIP switch must be repositioned. See table 14.

Switch 2 −− Operating Mode with Two−Stage Thermostat −− If a two−stage thermostat is used, the furnace can

operate in either variable−capacity or conventional two− stage mode. When variable−capacity mode is selected, the firing rate of the unit is varied to maximize comfort. Conventional two−stage mode is the factory default setting. See table 14.

Switch 3 −− Second−Stage Heat On Delay −− If a single− stage thermostat is used, the integrated control can be used to energize second−stage heat after either 7 minutes or 12 minutes of first−stage heat operation. See table 14.

Switches 4 and 5 −− Blower−Off Delay −− The blower−on delay of 45 seconds is not adjustable. The blower−off delay (time that the blower operates after the heating demand has been satisfied) can be adjusted by moving switches 4 and 5 on the integrated control. The unit is shipped from the factory with a blower−off delay of 90 seconds. The blower off delay affects comfort and is adjustable to satisfy individual applications. Adjust the blower off delay to achieve a supply air temperature between 90° and 110°F at the exact moment that the blower is de−energized. Longer off delay settings provide lower supply air temperatures; shorter settings provide higher supply air temperatures. Table 15 provides the blower off timings that will result from different switch settings.

TABLE 15

Blower Off Delay Switch Settings

Blower Off Delay

(Seconds)

Switch 4 Switch 5

60 Off On

90 Off Off 120 On Off 180 On On

Indoor Blower Operation DIP Switch Settings Switches 6 and 7 −− Continuous Indoor Fan Operation −−

Blower Speed − Switches 6 and 7 are used to select blower

motor speeds during continuous indoor blower operation. The unit is shipped from the factory with DIP switches positioned for medium low (2) speed during continuous indoor blower operation. The table below provides the continuous blower speeds that will result from various switch settings. Refer to tables 1 through 11 for corresponding cfm values.

TABLE 16

Continuous Indoor Fan

Speed

Switch 6 Switch 7

1 − Low (28%) Off On

2 − Medium Low

(38%)

(Factory)

Off Off

3 − Medium High

(70%)

On Off

4 − High (100%) On On

Switches 8 and 9 −− Cooling Mode Blower Speed −−

Switches 8 and 9 are used to select cooling blower motor speed. The unit is shipped from the factory with the DIP switches positioned for high speed (4) indoor blower motor operation during the cooling mode. The table below provides the cooling mode blower speeds that will result from different switch settings. Refer to tables 1 through 11 for corresponding cfm values.

TABLE 17

Cooling Mode Blower Speeds

Speed

Switch 8 Switch 9

1 − Low On On

2 − Medium Low Off On

3 − Medium High On Off

4 − High (Factory) Off Off

Page 21

Switches 10 and 11 −− Cooling Mode Blower Speed Adjustment −− Switches 10 and 11 are used to select blower

speed adjustment settings. The unit is shipped from the factory with the DIP switches positioned for NORMAL (no) adjustment. The DIP switches may be positioned to adjust the blower speed by +10% or −10% to better suit the application. The table below provides blower speed adjustments that will result from different switch settings. Refer to tables 1 through 11 for corresponding cfm values. With switches 10 and 11 set to ON, motor will bypass ramping profiles and all delays and immediately upon a call for cool, run at COOLING speed selected. LED will continue to operate as normal. This mode is used to check motor operation.

TABLE 18

Blower Speed Adjustment

Adjustment

Switch 10 Switch 11

+10% (approx.) On Off

NORMAL (Factory) Off Off

−10% (approx.) Off On MOTOR TEST On On

Switches 12 and 13 −− Cooling Mode Blower Speed Ramping −− Switches 12 and 13 are used to select cooling

mode blower speed ramping options. Blower speed ramping may be used to enhance dehumidification performance. The switches are factory set at option A which has the greatest effect on blower motor performance. Table 19 provides the cooling mode blower speed ramping options that will result from different switch settings. The cooling mode blower speed ramping options are detailed below.

TABLE 19

Cooling Mode Blower Speed Ramping

Ramping Option

Switch 12 Switch 13

A (Factory) Off Off

B On Off C Off On D On On

Ramping Option A (Factory Selection)

D Motor runs at 50% for 30 seconds. D Motor then runs at 82% for approximately 7−1/2 min-

utes.

D If demand has not been satisfied after 7−1/2 minutes,

motor runs at 100% until demand is satisfied.

D Once demand is met, motor runs at 50% for 30 sec-

onds then ramps down to stop.

OFF

1/2 MIN 50% CFM

COOLING DEMAND

7 1/2 MIN 82% CFM

100% CFM

1/2 MIN 50% CFM

Ramping Option B

S Motor runs at 82% for approximately 7−1/2 minutes. If

demand has not been satisfied after 7−1/2 minutes, motor runs at 100% until demand is satisfied.

S Once demand is met, motor ramps down to stop.

OFF

82%CFM

100% CFM

COOLING DEMAND

7 1/2 MIN

Ramping Option C

S Motor runs at 100% until demand is satisfied.

S Once demand is met, motor runs at 100% for 45 sec-

onds then ramps down to stop.

OFF

100% CFM

DEMAND

45 SEC.

Ramping Option D

S Motor runs at 100% until demand is satisfied.

S Once demand is met, motor ramps down to stop.

OFFOFF

100% CFM

COOLING DEMAND

Page 22

TABLE 20

Low Heat Blower Speeds

Thermostat

Demand

Blower

Speed

Adjust-

ments

DIP SWITCH SETTINGS

14 15 16

Low Heat (R to W1)

+15% On Off On

+7.5% On Off Off

Normal Off Off Off

−7.5% On On Off

−15% On On On

Switches 14 through19 −− Heating Mode Blower Speed

−− Switches 14 through 19 are used to select heating mode

blower motor speeds. These switches are factory set at the OFF position which provides 100 % of normal speed during HIGH HEAT demand, 70% of normal speed during MID− RANGE HEAT demand and 40% of normal speed during LOW HEAT demand. Switches 14, 15 and 16 are used to adjust the LOW FIRE blower motor speed. Switches 17, 18 and 19 are used to adjust the HIGH FIRE blower motor speed. Figure 6 and tables 20 and 21 provides the heating mode blower speeds that will result from different switch settings. Figure 6 indicates the effect the DIP switch settings (tables 20 &21 above) have upon the heating airflow at various furnace firing rates. Refer to tables 1 through 11 for corresponding cfm values.

TABLE 21

High Heat Blower Speeds

Thermostat

Demand

Blower

Speed

Adjust-

ments

DIP SWITCH SETTINGS

17 18 19

High Heat

(R to

W1 & W2)

+15% On Off On

+7.5% On Off Off

Normal

Off Off Off

−7.5% On On Off

−15% On On On

Low Fire

Dip Switches

14, 15, 16

High Fire

Dip Switches

17, 18, 19

Airflow Determination

S Identify blower speed adjustment points at low and high fire S Airflow will lie on straight line between these two points and will fall within

the shaded area as shown EXAMPLE −7.5% at low fire +7.5% at high fire

40%

50%

60%

70%

80%

90%

100%

RATE (%)

+15% +7.5%

−7.5%

−15%

Nominal

−15%

Nominal

−7.5%

+7.5%

+15%

Increasing

Airflow

FIGURE 6

Page 23

On−Board Link W914 −− Figure 4

On−board link W914, is a clippable connection between terminals DS and R on the integrated control. W914 must be cut when the furnace is installed with either the Harmony IIIt zone control or a thermostat which features humidity control. If the link is left intact the PWM signal from the Harmony III control will be blocked and also lead to control damage. Refer to table 26 for operation sequence in applications including G71MPP, a thermostat which features humidity control and a single−speed outdoor unit. Table 27 gives the operation sequence in applications with a two− speed outdoor unit.

On−Board Link W951 −− Figure 4

On−board link W951 is a clippable connection between terminals R and O on the integrated control. W951 must be cut when the furnace is installed in applications which include a heat pump unit and a thermostat which features dual fuel use. If the link is left intact, terminal O" will remain energized eliminating the HEAT MODE in the heat pump.

On−Board Link W915 −− Figure 4

On−board link W915 is a clippable connection between terminals Y1 and Y2 on the integrated control. W915 must be cut if two−stage cooling will be used. If the link is not cut the outdoor unit will operate in second−stage cooling only.

Diagnostic LED −− Figure 4

The seven−segment diagnostic LED displays operating status, target airflow, error codes and other information. The table on page 58 lists diagnostic LED codes.

Diagnostic Push Button −− Figure 4

The diagnostic push button is located adjacent to the seven−segment diagnostic LED. This button is used to enable the Error Code Recall mode and the Field Test mode. Press the button and hold it to cycle through a menu of options. Every five seconds a new menu item will be displayed. When the button is released, the displayed item will be selected. Once all items in the menu have been displayed, the menu resumes from the beginning until the button is released.

Error Code Recall Mode

Select "E" from the menu to access the most recent 10 error codes. Select c" from the Error Code Recall menu to clear all error codes. Button must be pressed a second time while c" is flashing to confirm command to delete codes. Press the button until a solid ≡" is displayed to exit the Error Code Recall mode.

Field Test Mode

Use the diagnostic push button to scroll through the menu as described above. Release the button when the LED flashes −" to select the Field Test mode.

While in the Field Test mode the technician can: D Initiate furnace ignition and move to and hold low−fire

rate by applying a R to W1 jumper.

D Initiate furnace ignition sequence and move to and

hold high−fire rate by applying a jumper from R to W1 and W2.

D Initiate furnace ignition sequence and move to and

hold mid−fire rate by applying a jumper to R and W2.

D Apply then remove the jumper from R to W1 and W2 to

change the firing rate from low fire to mid fire and high fire.

D

A vent calibration sequence can be initiated even if a

thermostat signal is not present. Press and hold the push button until a solid C" is displayed. Release the button and calibration will begin. The furnace will perform the high−fire and low−fire pressure switch calibrations and display CAL". After calibration, the LED will return to the flashing −" display.

During Field Test mode operation, all safety switches are still in the circuit (they are not by−passed) and indoor blower performance and timings will match DIP switch selections. Current furnace firing rate, indoor blower CFM and flame signal will be displayed. To exit the Field Test mode, press and hold the button. The menu will resume from the beginning. Also, cycle the main power to exit the Field Test mode. The integrated control will automatically exit the Field Test mode after 45 minutes of operation.

Page 24

TABLE 22

Idle Menu Options

These options are displayed on the menu when the button is pressed during normal operation

DISPLAY

ACTION (when button released)

No change (idle) remain in idle mode

Solid E" enter diagnostic mode

Solid −" enter field test mode

NOTE − No change implies the display will continue to show whatever is currently being displayed for normal operation

TABLE 23

Field Test Menu Options

These options are displayed when the button is used in Field Test Mode

DISPLAY

ACTION (when button released)

No change (blinking −") remain in field test mode

Solid −" exit field test mode

Solid c" start pressure switch calibration

TABLE 24

Field Test Menu Options

These options are displayed when the button is used in diagnostic recall mode

DISPLAY ACTION (when button released)

No change (displaying error history) remain in diagnostic recall mode

Solid (3 horizontal bars) exit diagnostic recall mode

Solid c" clear error history

Once the button is released to clear the error history a blinking c" will be shown on the display for up to 10 seconds. During this time the user must press and release the button one additional time to confirm the action of deleting the error history. Once the error history is deleted it cannot be recovered.

Page 25

TABLE 25

LED 7 Segment Status / Error Code

Press the diagnostic push button and hold it to cycle through a menu of options. Every five seconds a new menu item will be displayed. Release the button when the desired mode is displayed.

When the solid E" is displayed, the control enters the Error Code Recall mode. Error Code Recall mode menu options: No change (displaying error history) remains in Error Code Recall mode; solid ≡" exits Error Code Recall mode; and solid c" clears the error history. Must press button while flashing c" is displayed to clear error codes. When the solid −" is displayed, the control enters the Field Test mode. Field Test mode menu options: Solid C" starts pressure switch calibration; blinking −" exits Field Test mode.

Flash Code Diagnostic Code / Status of Furnace

S Idle mode (Decimal blinks at 1 Hz 1/2 sec. On and 1/2 sec. Off A CFM Display (1 sec. On 1/2 sec Off, CFM value) C Staged Cooling (1 sec. On 1/2 sec. Off or 2 Stage 1 sec. pause CFM pause, Repeat codes) d Dehumidification Mode (1 sec. On 1 sec Off, CFM, Pause Repeat Codes) h Variable Capacity Heat (1 sec On 1/2 sec Off % of input rate Pause CFM Pause Repeat Codes) H Staged Heat (1 sec On 1/2 sec Off or 2 Stage 1 sec, CFM Pause Repeat Codes)

110 Low Line Voltage 113 High Line Voltage

115 Low 24V (control will restart if the error recovers) 125 Control failed self check, internal error, failed hardware. Control will restart if error recovers 180 Outdoor Air Sensor Failure − no error if just disconnected, only show if shorted or out of range 200 Rollout circuit open or previously opened 201 Circulator / COM failure − unable to communicate w / circulating motor (blower) 202 Circulating motor / resistor mis−match or resistor missing 204 Gas Valve Miswired − Resume normal operation after error corrected 223 Low Pressure Switch Failed Open 224 Low Pressure Switch Failed Closed 225 High Pressure Switch Failed Open 226 High Pressure Switch Failed Closed 227 Low Pressure Switch Opened during TFI or Run mode 228 Unable to perform successful pressure switch calibration mode 240 Low Flame Mode − Run Mode 241 Flame sense out of sequence − flame still present 250 Limit switch circuit open 270 Watchguard − Exceed maximum number of retries. No flame current sensed

271

Watchguard − Exceed maximum number ignition retries where the last retry was due to pressure switch opening

272

Watchguard − Exceed maximum number of recycles where the last recycle was due to pressure switch opening

273 Watchguard − Exceed maximum number of recycles where the last retry was due to flame failure 274 Watchguard − The limit remained open longer than 3 minutes 275 Watchguard − Flame sensed out of sequence; flame signal gone 290 Ignitor circuit Fault − failed ignitor or triggering circuitry 291 Restricted airflow − available CFM below min. firing rate 292 Circulator motor unable to start (seized bearings, stuck wheel, etc) 294 Inducer motor amp draw too high 310 Discharge air sensor failure − no error if just disconnected, only show if shorted or out of range

311 Restricted airflow heating mode − target input rate reduced to match available circulator CFM 312 Restricted airflow cooling or continuous fan mode − information only

Page 26

TABLE 26

OPERATING SEQUENCE

G71MPP, ComfortSenset 7000 Thermostat and Single−Stage Outdoor Unit

OPERATING

SEQUENCE

SYSTEM DEMAND SYSTEM RESPONSE

System

Condition

Step

Thermostat Demand Relative Humidity

Compressor

Blower

CFM

(COOL)

Comments

Y1 O G

W1

Status D

NO CALL FOR DEHUMIDIFICATION

Normal Operation 1 On On On Acceptable

24

VAC

High 100%

Compressor and indoor blower follow thermostat demand

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable

24

VAC

High 100%

ComfortSenset 7000 thermostat energizes Y1 and de−energizes D on a call for de−humidification

Dehumidification

Call

2 On On On Demand

0

VAC

High 70%

PRECISION MODE (operates independent of a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable

24

VAC

High 100%

Dehumidification mode begins when humidity is greater than set point

Dehumidification

call

2 On On On Demand

0

VAC

High 70%

Dehumidification

call ONLY

1 On On On Demand

0

VAC

High 70%

ComfortSenset 7000 thermostat will keep outdoor unit energized after cooling temperature setpoint has been reached in order to maintain room humidity setpoint.

On−board links at indoor unit with a single−stage outdoor unit: With Condensing unit − Cut W914 (R to DS) on SureLight

®

integrated control;

With Heat Pump − Cut W914 (R to DS) & W951 (R to O) on SureLight

®

integrated

control.

Page 27

TABLE 27

OPERATING SEQUENCE

G71MPP, ComfortSenset 7000 Thermostat and Two−Stage Outdoor Unit

OPERATING

SEQUENCE

SYSTEM DEMAND SYSTEM RESPONSE

System

Condition

Step

Thermostat Demand Relative Humidity

Compressor

Blower

CFM

(COOL)

Comments

Y1

Y2

O

G

W1W

2

Status D

NO CALL FOR DEHUMIDIFICATION

Normal Operation −

Y1

1 On On

On

Acceptable

24

VAC

Low 70%

Compressor and indoor blower follow thermostat demand

Normal Operation −

Y2

2 On

On

Acceptable

24

VAC

High 100%

ROOM THERMOSTAT CALLS FOR FIRST STAGE COOLING

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation 1 On On

On

Acceptable

24

VAC

Low 70%

ComfortSenset 7000 thermostat energizes Y2 and de−energizes D on a call for de−humidification

Dehumidification

Call

2 On

On

Demand

0

VAC

High 70%

PRECISION MODE (operates independent of a Y1 thermostat demand)

Normal Operation 1 On On

On

Acceptable

24

VAC

Low 70%

Dehumidification mode begins when humidity is greater than set point

Dehumidification

call

2 On

On

Demand

0

VAC

High 70%

Dehumidification

call ONLY

1 On

On

Demand

0

VAC

High 70%

ComfortSenset 7000 thermostat will keep outdoor unit energized after cooling temperature setpoint has been reached in order to maintain room humidity setpoint.*

ROOM THERMOSTAT CALLS FOR FIRST AND SECOND STAGE COOLING

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation 1 On

On

Acceptable

24

VAC

High 100%

ComfortSenset 7000 thermostat energizes Y2 and de−energizes D on a call for de−humidification

Dehumidification

Call

2 On

On

Demand

0

VAC

High 70%

PRECISION MODE (operates independent of a Y1 thermostat demand)

Normal Operation 1 On On

On

Acceptable

24

VAC

Low 70%

Dehumidification mode begins when humidity is greater than set point

Dehumidification

call

2 On

On

Demand

0

VAC

High 70%

Dehumidification

call ONLY

1 On

On

Demand

0

VAC

High 70%

ComfortSenset 7000 thermostat will keep outdoor unit energized after cooling temperature setpoint has been reached in order to maintain room humidity setpoint.

On−board links at indoor unit with a two−stage outdoor unit: Cut factory link from Y1 to Y2 or cut W915 (Y1 to Y2) on SureLight

®

integrated control. With Condensing unit − Cut W914 (R to DS) on SureLight

®

integrated control;

With Heat Pump − Cut W914 (R to DS) & W951 (R to O) on SureLight

®

integrated control.

Page 28

B−Blower Compartment Figure 7

FIGURE 7

SECONDARY

LIMITS (2)

Power Choke

(5 Ton Only)

Blower Motor

(B3)

To Remove Blower From Unit: Remove Integrated Control,

Door Interlock Switch, Bolts and Wiring Jackplugs.

Then Slide Out Front of Unit.

1. Secondary Limit (S21)

The secondary limits (S21) on G71MPP units are located in the blower compartment on the back side of the blower housing. See figure 7. All G71MPP units are equipped with two secondary limits. When excess heat is sensed in the blower compartment, the limit will open. If the limit is open, the furnace control energizes the supply air blower and closes the gas valve. The limit automatically resets when unit temperature returns to normal. The switch is factory set to open at 125°F and cannot be adjusted.

2. Blower Motor (B3)

WARNING

During blower operation, the ECM motor emits energy that may interfere with pacemaker operation. Interference is reduced by both the sheet metal cabinet and distance.

The G71MPP line uses two different motor sizes, a 1/2 HP and 1 HP. The motor communicates with the integrated control via a 2−way serial connection. The motor receives all necessary functional parameters from the integrated control and does not rely on a factory program like traditional variable speed motors. The wiring harness connecting the motor to the integrated control includes a resistor which sets the motor parameters the integrated control will use. See wiring diagram regarding wiring harness. G71MPP units use a threephase, electronically controlled D.C. brushless motor (controller converts single phase a.c. to three phase D.C.), with a permanent-magnet-type rotor (figure 8). Because this motor has a permanent magnet rotor it does not need brushes like conventional D.C. motors. Internal components are shown in figure 8. The stator windings are split into three poles which are electrically connected to the controller. This arrangement all o w s moto r windin g s to turn on and off in sequence by the controller.

IMPORTANT

Earlier ECM motors used on other Lennox furnace models are not interchangeable with motors used on the G71MPP furnace line.

A solid-state controller is permanently attached to the motor. The controller is primarily an A.C. to D.C. converter. Converted D.C. power is used to drive the motor. The controller contains a microprocessor which monitors varying conditions inside the motor (such as motor workload).

G71MPP BLOWER MOTOR COMPONENTS

FIGURE 8

STATOR

(WINDINGS)

OUTPUT

SHAFT

BEARING

ROTOR

The controller uses sensing devices to sense what position the rotor is in at any given time. By sensing the position of the rotor and then switching the motor windings on and off in sequence, the rotor shaft turns the blower.

All G71MPP blower motors use single phase power. An external run capacitor is not used. The motor uses permanently lubricated ball-type bearings..

Internal Operation

The motor is controlled via serial communication between the ignition control on the furnace and the controller attached to the motor shell. The messages sent back and forth between the two controls serve to communicate rotational direction, demand, motor size, current draw, torque, and rpm, among other variables.

Motor rpm is continually adjusted internally to maintain constant static pressure against the blower wheel. The controller monitors the static work load on the motor and motor ampdraw to determine the amount of rpm adjustment. Blower rpm may be adjusted any amount in order to maintain a constant cfm as shown in Blower Ratings Tables. The cfm remains relatively stable over a broad range of static pressure. Since the blower constantly adjusts rpm to maintain a specified cfm, motor rpm is not rated. Hence, the terms cool speed" , heat speed " or speed tap" in this manual, on the unit wiring diagram and on blower B3, refer to blower cfm regardless of motor rpm.

Initial Power Up

When line voltage is applied to B3, there will be a large inrush of power lasting less than 1/4 second. This inrush charges a bank of DC filter capacitors inside the controller. If the disconnect switch is bounced when the disconnect is closed, the disconnect contacts may become welded. Try not to bounce the disconnect switch when applying power to the unit.

Page 29

Motor Start-Up

When B3 begins start-up, the motor gently vibrates back and forth for a moment. This is normal. During this time the electronic controller is determining the exact position of the rotor. Once the motor begins turning, the controller slowly eases the motor up to speed (this is called soft-start"). The motor may take as long as 10-15 seconds to reach full speed. If the motor does not reach 200rpm within 13 seconds, the motor shuts down. Then the motor will immediately attempt a restart. The shutdown feature provides protection in case of a frozen bearing or blocked blower wheel. The motor may attempt to start eight times. If the motor does not start after the eighth try, the controller locks out. Reset controller by momentarily turning off power to unit.

The DC filter capacitors inside the controller are connected electrically to the motor supply wires. The capacitors take approximately 5 minutes to discharge when the disconnect is opened. For this reason it is necessary to wait at least 5 minutes after turning off power to the unit before attempting to service motor.

DANGER

Disconnect power from unit and wait at least five minutes to allow capacitors to discharge before attempting to service motor. Failure to wait may cause personal injury or death.

Power Choke (L13)

A choke coil is used on G71MPP 5 ton 1 hp units. The ch oke is located on the blower housing and is used to supress transient current spikes.

FIGURE 9

BLOWER B3 HARNESS CONNECTORS

MOTOR with IINTEGRATED

CONTROLLER

SHAFT

P49 4 Pin

P48 5 Pin

J48 5 Pin Line Voltage Connector

J49 4 Pin Control Connector

J48 5 Pin

J49 4 Pin

Page 30

Troubleshooting

To verify motor operation see steps below:

1− Remove J48 (5 pin power plug) from P48 on the motor.

2− With the power on at the furnace and door switch depressed, use a test meter to verify 120V between pins 4 and 5 on J48.

3− Reconnect J48 to P48 on the motor.

4− Remove J49 (4 pin low voltage connector) from P49 on the motor.

5− Using test jumpers, apply 24V to pins 3 and 4 on P49 on the motor.

Note: Do not apply 24V to pins 2 and 4 on P49. Doing so will cause permanent damage to the motor.

6− Motor should run at 75%.

7− Test is complete. Remove jumpers and reconnect plugs.

Another option is to use the TECMate PRO with the 16 to 4 pin adaptor. The use of the TECMate PRO isolates the motor from the integrated control. Follow the instructions provided with the kit. If the motor runs do not replace.

FIGURE 10

BLOWER B3 HARNESS CONNECTORS

MOTOR with IINTEGRATED

CONTROLLER

SHAFT

P49 4 Pin

P48 5 Pin

P49 4 Pin

J48 Connector installed on motor

P49 4 Pin

120v

0

240v

5

4

3

2

1

J48 Connector

24v Transformer

J49 Connector

Page 31

Harmony IIIt

When the G71MPP is installed in Harmony III applications, the Harmony III signal is connected to the DS terminals on the integrated control (figure 4). In this application dip switch one and dip switch two (which configures to various thermostats), is overridden. The discharge air temperature (if used) is also ignored. In order for proper operation on board jumper W914 must be clipped.

The PWM signal (70−90 Hz with a 3−97% duty cycle) controls the indoor blower motor linearly between the minimum (shown in table 28) and the maximum CFM set by COOL- ING dip switches eight through 13. (3% duty cycle = MIN, 97% duty cycle = MAX).

TABLE 28

Minimum CFM

Cool Speed

1/2HP 1HP

High 250 450

Medium−High 250 450

Medium−Low 250 450

Low 250 450

If there is a W1 heat call while the indoor blower is controlled by Harmony III PWM signal, the integrated control will after a successful ignition sequence and stabilization period, modulate the correct firing rate.

Note − All on / off heating and cooling indoor blower delays are still present with Harmony III.

PWM signal is present at all times with a default value of 3% duty cycle. Upon the need for a higher duty cycle (more CFM), the duty cycle will step up at a rate of 1% per second. Upon a need for less duty cycle, (less or no CFM) the duty cycle will immediately step down to the demanded % or default 3% (off).

Along with the PWM signal is a 24VAC Enable signal that is connected on the integrated control terminal G". The integrated control will not obey the PWM signal unless the enable signal is present.

C−Heating Components

1. Ignitor

The ignitor is made of durable silicon nitride. Ignitor longevity is enhanced by controlling voltage to the ignitor. The SureLight

®

control provides a regulated 95 volts to the ignitor for consistent ignition and long ignitor life. Ohm value should be 25 to 47. See figure 12 for ignitor location.

2. Flame Sensor

A flame sensor is located on the left side of the burner support. See figure 11. The sensor is mounted on the flame rollout plate and the tip protrudes into the flame envelope of the left−most burner. The sensor can be removed for service without removing any part of the burners. During operation, flame is sensed by current passed through the flame and sensing electrode. The SureLight control allows the gas valve to remain open as long as flame signal is sensed. To check flame sense signal use the push−button found on the integrated control and go to Field Test Mode. The menu will display the flame signal. Table 29 shows the flame signal for the G71MPP unit.

TABLE 29

Flame Signal in Microamps

Normal

Low Drop Out

2.6 or greater 2.5 or less 1.1

NOTE − A much higher than normal micro amp reading (15 for example) may appear when checking flame signal.

FIGURE 11

5/16"

Sensor

Page 32

FIGURE 12

21/64"

7/32’

5/8 "

Ignitor Location

BURNERS TOP VIEW

BURNERS FRONT VIEW

MEASUREMENT IS TO I.D. OF RETENTION RING

IGNITOR

BRACKET

3. Duralock Heat Exchanger

G71MPP units use an aluminized steel primary and stainless steel secondary heat exchanger assembly. Heat is transferred to the air stream from all surfaces of the heat exchanger. The shape of the heat exchanger ensures maximum efficiency.

The combustion air inducer pulls fresh air through the burner box. This air is mixed with gas in the burner venturi and at the corbel orifices. The gas / air mixture is then burned at the entrance of each clamshell. Combustion gases are then pulled through the primary and secondary heat exchangers and exhausted out the exhaust vent pipe.

4. Flame Rollout Switches (S47)

Flame rollout switch S47 is a high temperature limit located on each side of the burner box. Each furnace is equipped with two identical switches. The limit is a N.C. SPST manual-reset limit connected in series with the primary limit S10. When S47 senses rollout, the circuit breaks and the ignition control immediately stops ignition and closes the gas valve. If unit is running and flame rollout is detected, the gas valve will close and ignition control will be disabled. Rollout can be caused by a blocked heat exchanger, flue or lack of combustion air. The switch is factory set to trip (open) at 250°F and cannot be adjusted. The switch can be manually reset. To manually reset a tripped switch, push the reset button located on the control.

5. Primary Limit Control (S10)

Figure 13 shows the primary limit (S10) used on G71MPP units located in the heating vestibule panel. S10 is provided with a shield on some models (figure 13) and must not be removed. Note orientation of shield and limit if limit is replaced. When excess heat is sensed in the heat exchanger, the limit will open. Once the limit opens, the furnace control energizes the supply air blower and de−energizes the gas valve. The limit automatically resets when unit temperature returns to normal. The switch is factory set and cannot be adjusted . In the event of restricted air flow, the ignition control board will reduce firing rate and indoor blower airflow in 10% increments until a sustainable air flow is reached. If the furnace reaches 40% firing rate, and adequate air flow is not available, the furnace will shutdown and enter one hour watchguard.

FIGURE 13

PRIMARY LIMIT LOCATION

limit faces shield

limit shield

090, −110 and

−135 only

Page 33

6. Backup Secondary Limit Control (S113) (G71MPP−090, 110, 135 only)

Backup secondary limit control S113 is a N.C. auto−reset switch located on the combustion air inducer. S113 acts as a backup to primary limit S10 in the event of an indoor blower failure. S113 contacts open when temperature on the CAI reaches 142°.

7. Gas Valve (GV1)

The G71MPP uses a variable capacity gas valve (figure 35) and is applicable for single stage, two−stage or varaiable capacity settings. See Thermostat selection modes" in the ignition control section (section A− subsection 4.) for more details The valve is internally redundant to assure safety shut−off. If the gas valve must be replaced, the same type valve must be used.

A 24VAC 2−pin plug and gas control switch are located on the valve. 24V applied to the pins enables valve operation.

Inlet and outlet pressure taps are located on the valve. LPG change over kits are available from Lennox. Kits include burner orifices and an LP gas valve.

DANGER

Danger of explosion.

There are circumstances in which odorant used with LP/propane gas can lose its scent. In case of a leak, LP/propane gas will settle close to the floor and may be difficult to smell. An LP/propane leak detector should be installed in all LP applications.

The burner box is sealed and operates under a negative pressure. A pressure hose is connected from the burner box to the gas valve. The gas valve senses the pressure in the burner box and uses that to set the maximum manifold pressure while the pressure switch with pressure conditioning device adjusts the gas flow. This will compensate for different vent configurations which can greatly affect the rate of the unit.

8. Variable Speed Combustion Air Inducer Pressure Switch (S18)

All G71MPP units are equipped with two pressure switch assemblies (one dual switch and one single switch see figure

14) to allow for multiple unit installations without any hose

routing changes. The pressure switches serve four func-

tions. First they establish calibration points for the vent calibration routine. The combustion air inducer’s speed at a given firing rate is a function of the vent system restriction. The calibration routine establishes the inducer speed required to make low and high fire switches for a given vent pipe installation and interpolates the speeds required to achieve all intermediate rates between these two points. The pressure conditioning device (low fire) and the high fire switch are utilized for this function. The setting for low−fire switch on dual assembly is such that it does not normally enter into the vent calibration routine.

Second, the switches prove combustion air inducer operation by sensing a vacuum energizing the control circuit and allowing ignition. The low fire pressure switch provides this function. Thirdly the switches interrupt the combustion process in the event vent outlet or combustion air intake blockage. Both switches provide this function. Finally the switches interrupt the combustion process if the condensate drainage system becomes blocked to the point the condensate level builds up in the cold end header box/ secondary coil or vent system. Both switches serve this function.

If either switch assembly (dual or single) is to be replaced, replace the entire assembly. Individual switch components can not be replaced.

WARNING

The pressure switch is a safety shut−down control in the furnace and must not be jumpered for any reason other than troubleshooting.

To troubleshoot the pressure switches, temporarily jumper them. The unit will not fire with the switches jumpered. Therefore, the pressure switches must be bypassed after the combustion air inducer is activated. This will determine if the pressure switches and furnace are operating properly. However, this may not indicate if the sealed combustion system is operating properly.

FIGURE 14

DUAL COMBUSTION AIR PRESSURE SWITCH

high fire

low fire

positive

pressure

negative pressure

SINGLE COMBUSTION AIR PRESSURE SWITCH

operating pressure

to valve

system pressure across

heat exchanger

pressure conditioning device

Page 34

Vent Calibration

The vent calibration sequence establishes furnace operating parameters in a specific installation. The integrated control board runs the calibration and may be repeated as necessary to maintain proper furnace operation. Prior to calibration, all duct work (and returns) vent pipe and condensate trap (primed) must be connected.

If calibration is successful the data is stored in memory and will be used to determine furnace operation and maintain parameters during heat call. If calibration is not successful, the integrated control will proceed to a 5 minute delay and signal the appropriate code. After the 5 minute delay the calibration will be repeated 4 more times with a 5 minute delay in between. If still unsuccessful after the 4 trials (total

5) the integrated control will go into a 1 hour soft lockout. Calibration may be initiated by:

S Initial call for heat S Cycling main power off / on and then call for heat S Venting conditions change (affecting high and low

pressure switch operation) S Ramp down low fire switch check failed (calibration

will follow next call for heat) S The service technician (by pressing the push button

found on the integrated control until the control cycles through to Field Test Mode")

The integrated control will do the following during calibration:

1− Verify both low pressure switch and high pressure switch are open. If either are closed log error and end calibration.

2− Start inducer at a predetermined low RPM (1600). 3− After a 7.5 second delay and if the low pressure

switch is still open, increase the RPM by 250. If after a 5 second delay the low pressure switch is still open, repeat steps 1, 2 and 3.

4− Decrease RPM by 50, wait 5 seconds and look for the low pressure switch to open. Repeat this step until it is closed.

5− Keep this RPM as RPM1. 6− Increase RPM to 1250. Wait 5 seconds. 7− Check high pressure switch, if open, increase RPM

by 250. Repeat this step until closed. 8− Decrease RPM by 50, check after 5 seconds. Re-

peat this step until switch is open. 9− Keep this RPM as RPM2. 10− Set RPM to 0. End calibration.

NOTE − If after a successful calibration and a heat call is present the integrated control will by−pass the prepurge state and go straight into ignitor warm up.

After calibration, the integrated control stores the RPM1 and RPM2 values. The low fire (40%) and high fire (100%) RPM points are calculated by adding margin values to the RPM1 and RPM2 values.

The integrated control also initiates a low fire switch check at the end of a normal heating cycle described below. If this check fails the pressure switch calibration will follow on the next call for heat.

1− The inducer runs 15 seconds at the last firing rate before the heat call ended.

2− Inducer runs at 40% firing rate RPM (RPM1 + low pressure switch open RPM margin value).

3− If low pressure switch is open, set flag for calibration on next call for heat. Turn inducer off until next call for heat.

4− If low pressure switch is closed move inducer speed to RPM1. Allow 5 seconds for stabilization.

5− If low pressure switch opens turn off inducer. No further action.

6− If low pressure switch is still closed, decrease inducer speed 1/2 of the low pressure switch open RPM margin. Allow 5 seconds to stabilize.

7− If low pressure switch is open turn off inducer. No further action.

8− If low pressure switch is still closed, set flag for calibration on next call for heat and turn off inducer.

Measuring pressure differential Figure 15

Checks of pressure differential can aid in troubleshooting. When measuring the pressure differential, readings should be taken at the pressure switch. Lack of differential usually indicates problems in the intake or exhaust piping, b u t may indicate problems in the heat exchanger, condensing coil, header boxes, combustion inducer or other components.

The differential pressure is the difference in pressure measured across the cold end header box orifice.

Page 35

FIGURE 15

negative and positive taps (same on other side)

orifice

1 − Remove thermostat demand and allow unit to cycle off.

2 − Install a tee in the negative (−) line and a tee in the positive (+)

line running from the lower pressure switch to the cold end header box.

3 − Install a manometer with hose from the negative (−) side of

the manometer to the tee installed in the negative (−) line and with hose from the positive (+) side of the manometer to the tee in the positive (+) line.

NOTE − Both sides of the cold end header box are negative. However the (+) port reads less negative pressure than the (−) port.

4 − Operate unit and observe manometer reading.

Readings will change as heat exchanger warms.

a. Take one reading immediately after start-up. b. Take a second reading after unit has reached steady state (approximately 5 minutes). This will be the pressure differential.

The pressure differential should be greater than those listed in tables 31 and 32.

5 − Remove thermostat demand and allow to cycle off.

6 − Remove manometer and tee’s. Reinstall combustion air

sensing hoses to the pressure switch.

7 − Repeat steps 1 through 6 for the single pressure switch

with pressure conditioning device. Tee into both hoses from the pressure switch to the gas valve and install manometer. Readings should be greater than those shown in table 33.

Duel Pressure Switch

Single Pressure Switch with Pressure Conditioning Device

+

−

The CAI is installed on the cold end header box. The cold end header box is a single piece made of hard plastic. The box has an internal channel where the combustion air inducer creates negative pressure at unit start up. The channel contains an orifice used to regulate flow created by the CAI. The box has pressure taps for the CAI pressure switch hoses.

The dual pressure switches measure the pressure differential across the CAI orifice (difference in the channel and cold end header box). The single pressure switch measures differential across the burner box and channel. A window is provided on the bottom right hand side of the cold end header box to indicate orifice size. See figure 15. See table 30 for orifice size per unit. If replace-

ment is necessary the gaskets used to seal the box to the vestbule panel and the CAI to the box, must also be replaced.

TABLE 30

G71MPP Unit

C.A.I. Orifice Size

−070 0.938"

−090 1.063"

−110 1.250"

−135 1.625"

TABLE 31

Dual Pressure Switch

0’ to 7500’

G71MPP Unit

Set Point

High Fire

Set Point

Low Fire

−070 1.37" 0.30"

−090 1.22" 0.25"

−110 1.32" 0.20

−135 0.83" 0.15"

TABLE 32*

Dual Pressure Switch

7501’ to 10,000’

G71MPP Unit

Set Point

High Fire

Set Point

Low Fire

−070 1.22" 0.30"

−090 1.02" 0.25"

−110 1.12" 0.20"

−135 0.63" 0.15"

*Unit may require conversion kit at this altitude. See High Altitude table.

TABLE 33

Single Pressure Switch

G71MPP Unit

Set Point

High Fire

−070

.27"

−090

−110

−135

Page 36

II−PLACEMENT AND INSTALLATION

TABLE 34

OUTDOOR TERMINATION KITS AND CORRESPONDING EQUIVALENCIES

UNIT

MODEL

VENT

PIPE

DIA.

(in.)

Vent Pipe Length Equivalency (feet)

Outdoor Exhaust Accel-

erator

(Dia. X

Length)

Outdoor Exhaust Accel-

erator

(Dia. X

Length)

1−1/2"

Concentric

Kit

2"

Concentric

Kit

3"

Concentric

Kit

2" Wall Plate

Kit

3" Wall Plate

Kit

2" Wall

Ring Kit

1−1/2" X 12"

2" X 12" 71M80 69M29 60L46

22G44 30G28

44J40 81J20

15F74

36B−070

2 4

Not

Allowed

12

Not

Allowed

Not

Allowed

4 4* 4

2−1/2 5

Not

Allowed

15

Not

Allowed

Not

Allowed

5 5* 5

3 8

Not

Allowed

24

Not

Allowed

Not

Allowed

8 8* 8

4 14

Not

Allowed

42

Not

Allowed

Not

Allowed

14 14* 14

60C−090

2

Not

Allowed

1

Not

Allowed

3 3

Not

Allowed

1 1**

2−1/2

Not

Allowed

2

Not

Allowed

6 6

Not

Allowed

2 2**

3

Not

Allowed

2

Not

Allowed

6 6

Not

Allowed

2 2**

4

Not

Allowed

4

Not

Allowed

12 12

Not

Allowed

4 4**

60C−110

2−1/2

Not

Allowed

2

Not

Allowed

6 6

Not

Allowed

2 2

3

Not

Allowed

2

Not

Allowed

6 6

Not

Allowed

2 2

4

Not

Allowed

4

Not

Allowed

12 12

Not

Allowed

4 4

60D−135

3

Not

Allowed

6

Not

Allowed

Not

Allowed

15

Not

Allowed

6

Not

Allowed

4

Not

Allowed

10

Not

Allowed

Not

Allowed

25

Not

Allowed

10

Not

Allowed

*Requires field−provided and installed 1−1/2" exhaust accelerator.

Proposed vent pipe size : ______ Termination kit catalog number : _____________

Vent pipe equivalency value from table 34: ______ Total number of 90° elbows required (indoors and outdoors)

______ X 5 = ______ equivalent feet of pipe Total number of 45° elbows required (indoors and outdoors)

______ X 2.5 = ______ equivalent feet of pipe Linear feet of straight pipe required : ______

Add equivalent feet of vent pipe listed in steps 2 through 5.

Step 1 Step 2

Step 3

Step 4

Step 5

Step 6

If the total is equal to, or less than, the allowable maximum given in table 36, the proposed pipe size is acceptable. If the total exceeds the maximum allowed vent pipe length, repeat the process above using the next larger diameter pipe until an acceptable total is achieved.

NOTE − In Direct Vent systems, total the equivalent length of either the exhaust OR intake piping run, depending upon which will be LONGER. Intake and exhaust pipe diameter must be the same size and must be terminated in the same pressure zone. Intake and exhaust pipe should be roughly the same length.

Equivalent Feet

TOTAL

FIGURE 16

Page 37

A−Vent Piping Guidelines

The G71MPP can be installed only as a Direct Vent gas central furnace.

NOTE − 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 35 and 36. Table 35 lists the minimum equivalent vent pipe lengths permitted. Table 36 lists the maximum equivalent pipe lengths permitted.

Maximum vent length is defined as:

Total length (linear feet) of pipe,

Plus Equivalent length (feet) of fittings, Plus Equivalent length (feet) of termination. NOTE − Include ALL pipe and ALL fittings, both indoors

and outdoors. Measure equivalent length of intake and exhaust pipe separately. Use the greater of the two lengths to determine vent pipe diameter to be used for both intake and exhaust.

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 37.

NOTE − The exhaust pipe should be offset a minimum of 12 inches to avoid the possibility of water droplets being released from the exhaust termination. The minimum exhaust vent length is 15 ft. Shorter exhaust vent lengths may result in the discharge of water droplets from the exhaust termination, in spite of the 12−inch vertical offset. See figure

17.

Each 90° elbow (including those provided with the furnace) of any diameter is equivalent to 5 feet (1.52m) of vent pipe of the same diameter. Two 45° elbows are equivalent to one 90° elbow of the same diameter. One 45° elbow is equal to 2.5 feet (.76m) of vent pipe of the same diameter.

In some applications which permit the use of several different sizes of vent pipe, a combination vent pipe may be used. Contact Lennox’ Application Department for assistance in sizing vent pipe in these applications.

FIGURE 17

Exhaust Pipe Offset

12" Min.

Upflow and Downflow Application

Rooftop Termination

Upflow and Downflow Application

Side Wall Termination

Horizontal Application

Rooftop Termination

Horizontal Application

Side Wall Termination

Page 38

NOTE − The flue collar on all models is sized to accommodate 2" Schedule 40 flue pipe. When vent pipe which is larger than 2" must be used in an upflow application, a 2" elbow must be applied at the flue collar in order to properly transition to the larger diameter flue pipe. This elbow must be added to the elbow count used to determine acceptable vent lengths. Assign an equivalent feet value to this elbow according to the larger size pipe being used. Contact the Application Department for more information concerning sizing of vent systems which include multiple pipe sizes.

Use the following steps to correctly size vent pipe diameter.

Refer to Vent Pipe Size Determination Worksheet Figure 16.

1 − Determine the vent termination and its corresponding

equivalent feet value according to table 34.

2 − Determine the number of 90° elbows required for both

indoor and outdoor (e.g. snow riser) use. Calculate the corresponding equivalent feet of vent pipe.

3 − Determine the number of 45° elbows required for both

indoor and outdoor use. Calculate the corresponding equivalent feet of vent pipe.

4 − Determine the length of straight pipe required.

5 − Add the total equivalent feet calculated in steps 1

through 4 and compare that length to the maximum values given in table 36 for the proposed vent pipe diameter. If the total equivalent length required exceeds the maximum equivalent length listed in the appropriate table, evaluate the next larger size pipe.

IMPORTANT

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

TABLE 35

MINIMUM VENT PIPE LENGTHS

G71MPP

MODEL

MIN. EQUIV.

VENT LENGTH

EXAMPLE

070, 090

15 ft.*

5 ft. plus 2 elbows of 2", 2−1/2", 3"

or 4" diameter pipe

110**

5 ft. plus 2 elbows of 2−1/2" 3" or 4"

diameter pipe

135***

5 ft. plus 2 elbows of 3" or 4"

diameter pipe

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

**G71MPP−60C−110 must have 90° street ell (supplied) installed directly into unit flue collar.

***G71MPP−60D−135 must have 3" to 2" reducing ell (supplied) installed directly into unit flue collar.

TABLE 36

MAXIMUM VENT PIPE LENGTHS

ALTITUDE

G71MPP

MODEL

MAXIMUM EQUIVALENT VENT

LENGTH FEET

2"

PIPE

2−1/2"

PIPE

3"

PIPE4"PIPE

0 − 7500

(0 − 2286 m)

070 75 135 150 250 090 50 100 125 225

110* 20 60 125 200

135** n/a n/a 125 180

7501 − 10000

(2287 − 3048 m)

070 60 125 150 250 090 25 60 125 225

110* n/a 40 90 200

135** n/a n/a 70 180

n/a −− Not allowed. *G71MPP−60C−110 must have 90° street ell (supplied) installed directly into

unit flue collar. **G71MPP−60D−135 must have 3" to 2" reducing ell (supplied) installed directly

into unit flue collar. NOTE − Elbows and pipe required for vent terminations must be added

when calculating equivalent vent length.

B−Joint Cementing Procedure

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

WARNING

DANGER OF EXPLOSION!

Fumes from PVC glue may ignite during system check. Allow fumes to dissipate for at least 5 minutes before placing unit into operation.

1 − Measure and cut vent pipe to desired length.

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

or rough edges. If end is not chamfered, edge of pipe may remove cement from fitting socket and result in a leaking joint.

3 − Clean and dry surfaces to be joined.

4 − Test fit joint and mark depth of fitting on outside of pipe. 5 − Uniformly apply liberal coat of PVC primer for PVC or

use a clean dry cloth for ABS to clean inside socket surface of fitting and male end of pipe to depth of fitting socket.

NOTE − Furnace flue collar and air inlet fitting are both ABS pipe. Use transition solvent cement when joining ABS pipe to PVC pipe.

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

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

NOTE − Time is critical at this stage. Do not allow primer to dry before applying cement.

Page 39

7 − Immediately after applying last coat of cement to pipe,

and while both inside socket surface and end of pipe are wet with cement, forcefully insert end of pipe into socket until it bottoms out. Turn PVC pipe 1/4 turn during assembly (but not after pipe is fully inserted) to distribute cement evenly. DO NOT turn ABS or cellular core pipe.

NOTE − Assembly should be completed within 20 seconds after last application of cement. Hammer blows should not be used when inserting pipe.

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 a defective assembly due to insufficient solvent.

9 − Handle joints carefully until completely set.

C−Venting Practices

The thickness of construction through which vent pipes may be installed is 24" (610mm) maximum and 3/4" (19mm) minimum. If a G71MPP furnace replaces a furnace which was commonly vented with another gas appliance, the size of the existing vent pipe for that gas appliance must be checked. Without the heat of the original furnace flue products, the existing vent pipe is probably oversized for the single water heater or other appliance. The vent should be checked for proper draw with the remaining appliance.

1. Use recommended piping materials for exhaust pip-

ing.

2. Secure all joints so that they are gas-tight using ap-

proved cement. Suspend piping using hangers at a minimum of every 5

feet (1.52m) for schedule 40 PVC and every 3 feet (.91m) for ABS−DWV, PVC− DWV, SPR−21 PVC, and SDR−26 PVC piping. A suitable hanger can be fabricated by using metal or plastic strapping or a large wire tie.

3. 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.

4. Isolate piping at the point where it exits the outside wall

or roof in order to prevent transmission of vibration to the structure.

5. When furnace is installed in a residence where unit is

shut down for an extended period of time, such as a vacation home, make provisions for draining condensate collection trap and lines.

Exhaust Piping (Figures 19 and 20)

NOTE − A 2" diameter street ell is located on the blower deck of 60C−110 units. Street ell must be

glued with ABS

solvent cement directly into the unit flue collar. See figure

19. A 3" to 2" reducing ell is located on the blower deck of the 60D−135 units. In upflow or downflow applica- tions, the reducing ell must be

glued with ABS solvent

cement directly into the unit flue collar.

1. Choose the appropriate side for venting in upflow or downflow positions. Exhaust piping exits from the top of the unit in horizontal air discharge applications. Glue the field−provided exhaust vent pipe (or provided street ell or reducing ell in upflow or downflow applications) to the flue collar. All PVC cement joints should be made according to the specifications outlined in ASTM D 2855. Refer to pipe and fittings specifications and gluing procedures.

IMPORTANT

Exhaust piping and condensate trap must be installed on the same side of the unit in upflow and dowflow applications or use alternate drain kit 76M20.

2. All horizontal runs of exhaust pipe must slope back toward unit. A minimum of 1/4" (6mm) drop for each 12" (305mm) of horizontal run is mandatory for drainage. Horizontal runs of exhaust piping must be supported every 5 feet (1.52m) using hangers.

NOTE − Exhaust piping should be checked carefully to make sure there are no sags or low spots.

3. On the opposite side of the cabinet, glue the provided 2" vent plug into the unused flue collar.

4. Route piping to outside of structure. Continue with installation following instructions given in piping termination section.

CAUTION

Do not discharge exhaust into an existing stack or stack that also serves another gas appliance. If vertical discharge through an existing unused stack is required, insert PVC pipe inside the stack until the end is even with the top or outlet end of the metal stack.

CAUTION

The exhaust vent pipe operates under positive pressure and must be completely sealed to prevent leakage of combustion products into the living space.

FIGURE 18

STRAPPING

(metal, plastic

or large wire

ties)

Page 40

VENT PLUG

(Must be

glued in

place)

PLUG

TYPICAL EXHAUST PIPE CONNECTIONS AND CONDENSATE TRAP INSTALLATION

IN UPFLOW OR DOWNFLOW DIRECT VENT APPLICATIONS

(Right−Hand Exit in Upflow Application Shown)

FIGURE 19

CONDENSATE

TRAP

(Must be installed

on same side as

exhaust piping)

PLUG

*2" diameter street elbow provided.

**3" to 2" diameter reducing elbow provided.

G71MPP−135 with

3" OR 4" vent pipe

2"**

2"

G71MPP−070,

or −090 with

2−1/2", 3", or 4"

vent pipe

3" dia. pipe***

TRANSITION (use only if 4"

pipe is

required)

4"

2"

2" dia. pipe

2−1/2", 3", OR

4"

TRANSITION

2"

G71MPP−110 with

2−1/2", 3", OR 4"

vent pipe

2"*

TRANSITION

2−1/2", 3", OR

4"

2"

or

45°

MAX

45°

MAX

SIDE VIEW

*** Max 2" pipe length between reducing elbow and transition when 4" pipe is used.

FIGURE 20

TYPICAL EXHAUST PIPE CONNECTIONS

HORIZONTAL DIRECT VENT APPLICATIONS

(Horizontal Right−Hand Air Discharge Application Shown)

2"

2" dia.

pipe*

2−1/2", 3", OR

4"

DO NOT transition from smaller to larger pipe size in horizontal runs.

TRANSITION

−36B−070

−36C−090

−60C−090

−60C−110*

−60D−135*

−36B−070

−36C−090

−60C−090

*2" maximum length

for −135 only.

Intake Piping

The G71MPP furnace may be installed only in direct vent applications.

The G71MPP unit is designed for either left−side or right− side air intake connections in either upflow or downflow applications. In horizontal applications, air intake must be brought in through the top. Intake air piping is independent of exhaust piping.

Page 41

TYPICAL AIR INTAKE PIPE CONNECTIONS

UPFLOW OR DOWNFLOW DIRECT VENT APPLICATIONS

(Right−Hand Exit in Upflow Application Shown)

FIGURE 21

PLUG

(Must be

glued in

place)

*Limit pipe length to 4" in G71MPP−135 applications.

−36B−070

−36C−090

−60C−090

−36B−070

−36C−090

−60C−090

−60C−110

−36B−070

−36C−090

−60C−090

−60C−110

−60D−135*

2

2−1/2",

3" OR

4

TRANSITION

2"*

TRANSITION

2−1/2",

3" OR

4

FIGURE 22

TYPICAL AIR INTAKE PIPE CONNECTIONS

HORIZONTAL DIRECT VENT APPLICATIONS

(Horizontal Right−Hand Air Discharge Application Shown)

2”*

2”

TRANSITION

2”

2−1/2”,

3” OR 4”

2−1/2”,

3” OR 4”

*Limit pipe length to 4" in

−135 applications.

2”

−36B−070

−36C−090

−60C−090

−60C−110

−60D−135*

−36B−070

−36C−090

−60C−090

−60C−110

−36B−070

−36C−090

−60C−090

2”

Page 42

FIGURE 23

VENT TERMINATION CLEARANCES

FOR INSTALLATIONS IN THE USA AND CANADA*

A − Clearance above grade − 12 in. (305mm) minimum. B − Clearance to window or door that may be opened −

for vent installations in USA − 12 in. (305mm) minimum. for vent installations in Canada − 12 in. (305mm) minimum

for appliances  100,000 Btuh (30 kW); 36 in. (0.9m) minimum for appliances > 100,000 Btuh (30

kW). C − Do not position terminations directly under roof eaves. D − Clearance to electric meters, gas meters, regulators, and

relief equipment −

for vent installations in USA − 48 in (1219mm) minimum.

for vent installations in Canada − see current edition of CSA

B149 Code.

E − Clearance to non−mechanical air supply inlet or outlet

for vent installations in USA − 48 in. (1219mm) minimum horizontal and below, 12 in. (305mm) minimum above. for vent installations in Canada − 12 in. (305mm) minimum

for appliances  100,000 Btuh (30 kW); 36 in. (0.9m) minimum for appliances > 100,000 Btuh (30 kW).

F − Clearance to mechanical air supply inlet −−

for vent installations in USA − 36 in. minimum (914mm).

G − Clearance to mechanical air supply inlet −−

for vent installations in Canada − 72 in. (1829mm) minimum.

H − Do not point terminations into recessed areas such as win-

dow wells, stairwells or alcoves.

J − Do not position terminations directly above a public walk-

way.

* Note −

(I) Dimensions are from the current edition of The National Fuel Gas Code − ANSI-Z223.1/NFPA 54 for USA installations. In Canada, refer to current edition of CSA B149 installation codes. Local codes or regulations may require different clearances.

less than 10 ft (3.048M)

C

D

E

F

G

(II) In Non-Direct Vent installations, combustion air is taken from indoors and the flue gases are discharged to the outdoors.

− G71MPP VENT TERMINATION

− AIR INLET OF OTHER APPLIANCE

Page 43

Details of Intake and Exhaust Piping Terminations for Direct Vent Installations

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

Intake and exhaust pipes may be routed either horizontally through an outside wall or vertically through the roof. In attic or closet installations, vertical termination through the roof is preferred. Figures 24 through 32 show typical terminations.

1. Exhaust and intake exits must be in same pressure zone. Do not exit one through the roof and one on the side. Also, do not exit the intake on one side and the exhaust on another side of the house or structure.

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

3. If necessary, install a field−provided transition to adapt larger vent pipe size to termination pipe size.

4. On roof terminations, the intake piping should terminate straight down using two 90° elbows (See figure

24).

5. Exhaust piping must terminate straight out or up as shown. In rooftop applications, a reducer may be required on the exhaust piping at the point where it exits the structure to improve the velocity of exhaust away from the intake piping. See table 37.

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

6. On field supplied terminations for side wall exits, exhaust piping should extend a maximum of 12 inches (305mm) beyond the outside wall unless supported. Intake piping should be as short as possible. See figure 25.

7. On field supplied terminations, the end of the exhaust pipe must extend a minimum of 8" (203mm) beyond the end of the intake pipe.

8. If intake and exhaust piping must be run up a side wall to position above snow accumulation or other obstructions, piping must be supported every 3 ft. (.9m) as shown in figure 18. Refer to figure 28 for proper piping method. In addition, wall termination kit must be extended for use in this application. See figure 31. When exhaust and intake piping must be run up an outside wall, the exhaust piping must be terminated with pipe sized per table 37. 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.

9. Based on the recommendation of the manufacturer, a multiple furnace installation may use a group of up to four termination kits assembled together horizontally, as shown in figure 30.

TABLE 37

EXHAUST PIPE TERMINATION SIZE REDUCTION

G71MPP

MODEL

Exhaust Pipe Size Termination Pipe Size

070 2", 2−1/2", 3" or 4" 1−1/2" 090 2", 2−1/2", 3" or 4" 2" 110 2−1/2", 3" or 4" 2"* 135 3" or 4" 2"*

*Approved 3" concentric termination kit terminates with 2−5/8" ID pipe.

FIGURE 24

DIRECT VENT ROOF TERMINATION KIT

(15F75 or 44J41)

UNCONDITIONED

ATTIC SPACE

1/2" (13) FOAM INSULATION IN

UNCONDITIONED

SPACE

SIZE TERMINATION

PIPE PER TABLE 37.

3(76) MAX.

12" (305) ABOVE AVERAGE SNOW ACCUMULATION

3" (76) OR

2" (51) PVC

PROVIDE SUPPORT

FOR INTAKE AND

EXHAUST LINES

8" (203) MIN

Inches(mm)

FIGURE 25

1/2" (13) ARMAFLEX

INSULATION IN

UNCONDITIONED SPACE

1−1/2" (38) PVC

12" (305) MAX. (unless supported)

6" (152)

MAXIMUM

2" (51) PVC

COUPLING

8" (203)

MINIMUM

OUTSIDE

WALL

Inches (mm)

TOP VIEW WALL RING KIT

(15F74)

1/2" (13)

ARMAFLEX

INSULATION

FIELD−

PROVIDED

REDUCER MAY

BE REQUIRED

TO ADAPT

LARGER VENT

PIPE SIZE TO

TERMINATION

Page 44

FIGURE 26

12" (305) ABOVE

AVERAGE SNOW

ACCUMULATION

EXHAUST

TERMINATION

INTAKE

TERMINATION

INTAKE

Inches (mm)

DIRECT VENT CONCENTRIC ROOFTOP TERMINATION

(71M80, 69M29 or 60L46)

FIELD−PROVIDED

REDUCER MAY BE REQUIRED

TO ADAPT LARGER VENT

PIPE SIZE TO TERMINATION

FIGURE 27

EXHAUST

TERMINATION

INTAKE

TERMINATION

INTAKE

12" (305) Min.

above grade.

Inches (mm)

DIRECT VENT CONCENTRIC WALL TERMINATION

(71M80, 69M29 or 60L46)

FIELD−PROVIDED

REDUCER MAY

BE REQUIRED TO

ADAPT LARGER VENT PIPE SIZE

TO TERMINATION

FIGURE 28

See venting table 36 for maximum venting lengths with this arrange-

ment.

12" (305) ABOVE AVERAGE SNOW ACCUMULATION

UNCONDITIONED

SPACE

12" (305) MAX. for 2" (51)

(unless supported)

8 (203)

MIN.

1/2" (13) FOAM

INSULATION

1/2" (13) FOAM

INSULATION IN

UNCONDITIONED

SPACE

PROVIDE SUPPORT

FOR INTAKE AND

EXHAUST LINES EVERY

36" (914)

OUTSIDE WALL

Inches(mm)

SIDE VIEW

DIRECT VENT WALL RING TERMINATION

(15F74)

SIZE

TERMINATION

PIPE PER

TABLE 37.

FIELD−PROVIDED

REDUCER MAY

BE REQUIRED TO

ADAPT LARGER

VENT PIPE SIZE

TO TERMINATION

FIGURE 29

1/2" (13) Foam Insulation

in Unconditioned Space

EXHAUST VENT

INTAKE VENT

WITHOPTIONAL

ELBOW

OUTSIDE WALL

EXHAUST VENT

INTAKE

VENT

WITH OPTIONAL

ELBOW

Front View

Side View

Inches (mm)

FIELD−

PROVIDED

REDUCER MAY

BE REQUIRED

TO ADAPT

LARGER VENT

PIPE SIZE TO

TERMINATION

DIRECT VENT WALL TERMINATION KIT

(22G44, 44J40, 30G28 or 81J20)

FIGURE 30

EXHAUST

VENT

INTAKE

VENT

WITH OPTIONAL

ELBOW

5−1/2"

(140)

Front View

12"

(305)

5"

(127)

18" MAX.

(457)

EXHAUST VENT

OPTIONAL VENT TERMINATION FOR MULTIPLE UNIT

INSTALLATION OF DIRECT VENT WALL TERMINATION KIT

Inches (mm)

Side View

Page 45

FIGURE 31

12" MIN.

(305)

Above Grade

COVER EXHAUST

VENT WITH

1/2" (13)

FOAM

INSULATION

Front View

Side View

DIRECT VENT TERMINATION

WALL TERMINATION KIT (22G44, 44J40, 30G28 or 81J20) EXTENDED VENT FOR GRADE CLEARANCE

Inches (mm)

5"

(127)

5-1/2"

(140)

EXHAUST

AIR

GRADE

12"

(305)

8" (203)

Minimum

12" (305)

Minimum

ABOVE GRADE

EXHAUST

AIR

GRADE

12" (305) MAX. for 2" (51) 20" (508) MAX. for 3" (76)

(unless supported)

INTAKE

AIR

INTAKE

AIR

G71MPP DIRECT VENT APPLICATION

USING EXISTING CHIMNEY

NOTE − Do not discharge exhaust gases directly into any chimney or vent stack. If vertical discharge through an existing unused chimney or stack is required, insert piping inside chimney until the pipe open end is above top of chimney and terminate as illustrated. In any exterior portion of chimney, the exhaust vent must be insulated.

FIGURE 32

8" − 12"

(203mm − 305mm)

3" − 8" (76mm− 203mm)

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

ALTERNATE

INTAKE PIPE

INSULATION (optional)

EXTERIOR

PORTION OF

CHIMNEY

INSULATE

TO FORM

SEAL

SHEET

METAL TOP

PLATE

MINIMUM 12"

(305mm) ABOVE

ROOF

*SIZE TERMINATION PIPE PER TABLE 37.

Condensate Piping

This unit is designed for either right- or left-side exit of condensate piping in either upflow or downflow applications; however, it must be installed on the same side of the unit as the exhaust piping. In horizontal applications, the condensate trap should extend below the unit. A 5−1/2" service clearance is required for the condensate trap. Refer to figure 33 for condensate trap locations.

NOTE − If necessary the condensate trap may be installed in an alternate location in upflow applications using kit number 76M20.

FIGURE 33

CONDENSATE TRAP LOCATIONS

(Unit shown in upflow position)

Horizontal

left and

optional

downflow

Horizontal

right and

optional

downflow

Optional

upflow

Optional

upflow

NOTE − In upflow applications where side return air filter is installed on same side as the condensate trap, filter rack must be installed beyond condensate trap to avoid interference.

Page 46

1 − Determine which side condensate piping will exit the

unit. Remove plugs from the condensate collar at the appropriate location on the side of the unit.

NOTE − The condensate trap is factory−shipped with two rubber O−rings and two rubber clean−out caps installed. Check to make sure that these items are in place before installing the trap assembly.

2 − Install condensate trap onto the condensate collar.

Use provided HI/LO screws to secure two upper flanges of the trap to the collar. Use provided sheet metal screw to secure bottom trap flange to side of unit. See figure 34.

NOTE − In upflow and downflow applications, condensate trap must be installed on the same side as exhaust piping.

CAUTION

DO NOT use a power driver to tighten screws which secure condensate trap to cabinet. Screws should be hand−tightened using a screw driver to avoid the possibility of damage to the trap assembly.

3 − The grey−colored condensate trap (101661−01) pro-

vided with the unit is manufactured using ABS material. This is the only trap that is to be used with this unit. Use ABS to PVC transition solvent cement to glue a field−provided PVC coupling or PVC pipe to the trap. Install a tee and vent pipe near the trap.

NOTE − The condensate trap drain stubs (both sides) have an outer diameter which will accept a standard 3/4" PVC coupling. The inner diameter of each stub will accept standard 1/2" diameter PVC pipe.

NOTE − Vinyl tubing may be used for condensate drain. Tubing must be 1−1/4" OD X 1" ID and should be attached to the drain stubs on the trap using a hose clamp.

4 − Glue the field−provided drain line to the tee. Route the

drain line to an open drain. As an alternate, clear vinyl tubing may be used to drain condensate away from the trap. Secure the vinyl tubing to the drain stubs on the trap using a hose clamp. Do not overtighten the hose clamp.

Condensate line must be sloped downward away from condensate 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.

CAUTION

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

5 − If unit will be started immediately upon completion of

installation, prime trap per procedure outlined in Unit Start−Up section.

6 − Glue the provided cap onto the unused condensate

drain line stub.

CONDENSATE ASSEMBLY

FIGURE 34

COUPLING

CAP

CONDENSATE TRAP

(grey)

NIPPLE

TEE

VENT

CLEAN−OUT ACCESS

(both sides)

HI/LO SCREWS (DO NOT use power driver. Hand−tighten

using screw driver.)

SCREW

O−RINGS

Page 47

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.

B−Heating Start-Up

FOR YOUR SAFETY READ BEFORE OPERATING

WARNING

Do not use this furnace if any part has been underwater. A flood−damaged furnace is extremely dangerous. Attempts to use the furnace can result in fire or explosion. Immediately call a qualified service technician to inspect the furnace and to replace all gas controls, control system parts, and electrical parts that have been wet or to replace the furnace, if deemed necessary.

WARNING

Danger of explosion. Can cause injury or product or property damage. Should the gas supply fail to shut off or if overheating occurs, shut off the gas valve to the furnace before shutting off the electrical supply.

CAUTION

Before attempting to perform any service or maintenance, turn the electrical power to unit OFF at disconnect switch.

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 allow 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 sufficient water to ensure proper condensate drain operation.

BEFORE BEFORE PLACING THE UNIT INTO OPERATION, 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 G71MPP is equipped with a gas control switch. Use only your hand to move the control switch. Never use tools. If the switch will not move by hand, do not try to repair it. Call a licensed professional service technician (or equivalent). Force or attempted repair may result in a fire or explosion.

Placing the furnace into operation:

G71MPP units are equipped with an automatic ignition system. Do not

attempt to manually light burners on this

furnace. Each time the thermostat calls for heat, the burners will automatically light. The ignitor does not get hot when there is no call for heat on units with this ignition system.

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 35)

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 the gas valve switch to the OFF position. See

figure 35. 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.

GAS VALVE

GAS VALVE SHOWN IN OFF POSITION

INLET OUTLET

NEGATIVE AIR

PRESSURE PORT

POSITIVE AIR

PRESSURE PORT

SUPPLY

PRESSURE TAP

MANIFOLD

PRESSURE TAP

FIGURE 35

8 − Move gas valve switch to the ON position. See fig ure

35. Do not force.

Page 48

9 − Replace the upper access panel.

10− Turn on all electrical power to to the unit.

11− Set the thermostat to desired setting.

NOTE − When unit is initially started, steps 1 through 11 may need to be repeated to purge air from gas line.

12− If the appliance will not operate, follow the instructions

Turning Off Gas to Unit" and call your service technician or gas supplier.

Turning Off Gas to Unit

1 − Set the thermostat to the lowest setting. 2 − Turn off all electrical power to the unit if service is to be

performed.

3 − Remove the upper access panel. 4 − Move the gas valve switch to the OFF position. 5 − Replace the upper access panel.

C−Safety or Emergency Shutdown

Turn off unit power. Close manual and main gas valves.

D−Extended Period Shutdown

Turn off thermostat or set to UNOCCUPIED" mode. Close all gas valves (both internal and external to unit) to guarantee no gas leak into combustion chamber. Turn off power to unit. All access panels and covers must be in place and secured.

IV−HEATING SYSTEM SERVICE CHECKS

A−C.S.A. Certification

All units are C.S.A. (formally A.G.A. and C.G.A. combined) design certified without modifications. Refer to the G71MPP Installation Instruction.

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.

WARNING

Do not exceed 600 in−lbs (50 ft−lbs) torque when attaching the gas piping to the gas valve.

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 disconnected and isolated. Gas valves can be damaged if subjected to more than 0.5psig (14" W.C.). See figure 36.

FIGURE 36

MANUAL MAIN SHUT−OFF VALVE

GAS VALVE

CAP

GAS PIPING TEST PROCEDURE

When checking piping connections for gas leaks, use preferred means. Kitchen detergents can cause harmful corrosion on various metals used in gas piping. Use of a specialty Gas Leak Detector is strongly recommended. It is available through Lennox under part number 31B2001. See Corp. 8411−L10, for further details.

Do not use matches, candles, flame or any other source of ignition to check for gas leaks.

D−Testing Gas Supply Pressure

When testing supply gas pressure, connect test gauge to supply pressure tap on the gas valve. See figure 35. Check gas line pressure with unit firing at maximum rate. Low pressure may result in erratic operation or underfire. High pressure can result in permanent damage to gas valve or overfire. See table 38 for operating pressure at unit gas connection (line).

On multiple unit installations, each unit should be checked separately, with and without units operating. Supply pressure must fall within range listed in table 38.

TABLE 38

All G71MPP Units

Natural LP

Line Pressure WC" 4.5 − 10.5 11.0 − 13.0

Page 49

E−Check Manifold Pressure

To correctly measure manifold prressure, the differential pressure between the positive gas manifold and the negative burner box must be considered. Use pressure test adapter kit (available as Lennox part 10L34) to assist in measurement.

1 − Connect test gauge +" connection to manifold pres sure tap on the gas vavle.

2 − Tee into the gas valve regulator vent hose and connect test gauge −" connection.

3 − Start unit on low heat (40%) rate) and allow 5 minutes for unit to reach steady state.

4 − While waiting for the unit to stabilize, notice the flame. Flame should be stable and should not lift from burnere. Natural gas should burn blue.

5 − After allowing unit to stablize for 5 minutes, record manifold pressure and compare to value given in table

42.

6 − Repeat stpes 3, 4 and 5 on high fire.

CAUTION

Do not attempt to make adjustments to the gas valve.

F− Proper Gas Flow (Approximate)

1 − Operate unit at least 15 minutes before checking gas

flow. Determine the time in seconds for one revolutions of gas through the meter. A portable LP gas meter (17Y44) is available for LP applications.

2 − Compare the number of seconds and the gas meter

size in table 39 to determine the gas flow rate. Multiply the gas flow rate by the heating value to determine the unit input rate. If manifold pressure is correct and the unit input rate is incorrect, check gas orifices for proper size and restriction.

3 − Remove temporary gas meter if installed.

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

TABLE 39

Gas Flow Rate (Ft.

3

/Hr.)

Seconds for 1

Revolution

Gas Meter Size

1/2 cu ft Dial 1 cu ft Dial

10 180 360 12 150 300 14 129 257 16 113 225 18 100 200 20 90 180 22 82 164 24 75 150 26 69 138 28 64 129 30 60 120 32 56 11 3 34 53 106 36 50 100 38 47 95 40 45 90 42 43 86 44 41 82 46 39 78 48 38 75 50 36 72 52 35 69 54 33 67 56 32 64 58 31 62 60 30 60

G− Proper Combustion

Furnace should operate minimum 15 minutes with correct manifold pressure and gas flow rate before checking combustion. Take combustion sample beyond the flue outlet and compare to the tables below. The maximum carbon monoxide reading should not exceed 100 ppm.

TABLE 40

High Fire

Unit

CO2%

For Nat

CO2%

For L.P.

G71MPP−36B−070 6.8 − 7.8 8.5 − 9.5

G71MPP−36C−090 7.2 − 8.2 8.5 − 9.5

G71MPP−60C−090 7.2 − 8.2 7.2 − 8.2

G71MPP−60C−110 7.6 − 8.6 7.6 − 8.6

G71MPP−60D−135 7.5 − 8.5 7.5 − 8.5

TABLE 41

Low Fire

Unit CO2%

For Nat

CO2%

For L.P.

G71MPP−36B−070 5.0 − 6.0 5.8 − 6.8

G71MPP−36C−090 4.9 − 5.9 5.7 − 6.7

G71MPP−60C−090 4.9 − 5.9 5.7 − 6.7

G71MPP−60C−110 5.0 − 6.0 6.2 − 7.2

G71MPP−60D−135 5.0 − 6.0 5.7 − 6.7

Page 50

H− High Altitude

NOTE − In Canada, certification for installations at elevations over 4500 feet (1372 m) is the jurisdiction of local authorities.

G71MPP units require no manifold pressure adjustments for operation at altitudes up to 10,000 feet (3048m) above sea level. Units installed at altitude of 7,501 to 10,000 feet (2287 to 3048m) require a pressure switch change per table 42. Table 42 lists conversion kit requirements, pressure switch requirements and manifold pressures at all altitudes.

NOTE − The values given in table are measurements only. The gas valve should not be adjusted.

The combustion air pressure switch is factory−set and requires no adjustment.

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.

TABLE 42

Conversion Kit Requirements and Manifold Test Pressures

Model

Input

Size

LP/Propane

Kit

High Altitude Pressure

Switch Kit

Manifold Pressure at All Altitudes (in. w.g.)

0 − 10,000

(0 − 3048 m)

0 − 7,500

(0 − 2286 m)

7,501 − 10,000

(2287 −

3048m)

Low Fire

(40% rate)

High Fire

(100% rate)

Natural Gas LP/Propane Natural Gas LP/Propane

−070

33W41 Not required

33W27

0.7 2.0 3.5 10.0

−090 40W05

−110 40W06

−135 40W07

NOTE − Pressure switch is factory set. No adjustment necessary. All models use the factory installed pressure switch from 0−7,500 feet (0− 2286m).

NOTE − See previous page for manifold pressure measurement procedure.

Page 51

V−TYPICAL OPERATING CHARACTERISTICS

A−Blower Operation and Adjustment

1 − Blower operation is dependent on thermostat control

system.

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

base fan switch. With fan switch in ON position, blower operates continuously. With fan switch in AUTO position, blower cycles with demand or runs continuously while heating or cooling circuit cycles.

3 − Depending on the type of indoor thermostat, blower

and entire unit will be off when the system switch is in OFF position.

B−Temperature Rise

Temperature rise for G71MPP 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.

To Measure Temperature Rise:

1 − Place plenum thermometers in the supply and return air

plenums. Locate supply air thermometer in the first horizontal run of the plenum where it will not pick up radiant heat from the heat exchanger.

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

ond−stage heat. If using a single−stage thermostat fur-

nace must fire at least 10 minutes before switching to second−stage heat.

3 − After plenum thermometers have reached their high-

est and steadiest readings, subtract the two readings.

The difference should be in the range listed on the unit

rating plate. If the temperature is too low, decrease

blower speed. If temperature is too high, first check the

firing rate. Provided the firing rate is acceptable, in-

crease blower speed to reduce temperature.

C−External Static Pressure

1 − Tap locations shown in figure 37. 2 − Punch a 1/4" diameter hole

in supply and return air ple-

nums. Insert manometer

hose flush with inside edge

of hole or insulation. Seal

around the hose with perma-

gum. Connect the zero end

of the manometer to the dis-

charge (supply) side of the system. On ducted sys-

tems, connect the other end of manometer to the return

duct as above. For systems with non−ducted returns,

leave the other end of the manometer open to the at-

mosphere.

3 − With only the blower motor running and the evaporator

coil dry, observe the manometer reading. Adjust blow-

er motor speed to deliver the air desired according to

the job requirements.

4 − External static pressure drop must not be more than

0.8" W.C.

5 − Seal around the hole when the check is complete.

FIGURE 37

STATIC PRESSURE TEST

Page 52

VI−MAINTENANCE

WARNING

ELECTRICAL SHOCK, FIRE,

OR EXPLOSION HAZARD.

Failure to follow safety warnings exactly could result in dangerous operation, serious injury, death or property damage. Improper servicing could result in dangerous operation, serious injury, death, or property damage. Before servicing, disconnect all electrical power to furnace. When servicing controls, label all wires prior to disconnecting. Take care to reconnect wires correctly. Verify proper operation after servicing.

At the beginning of each heating season, system should be checked as follows by a qualified service technician:

Blower

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

WARNING

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

Filters

All G71MPP 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 43 lists recommended filter sizes.

TABLE 43

Furnace

Cabinet Size

Filter Size

Side Return Bottom Return

B Cabinet (17−1/2") 16 X 25 X 1 (1) 16 X 25 X 1 (1)

C Cabinet (21") 16 X 25 X 1 (1) 20 X 25 X 1 (1)

D Cabinet (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.

Electrical

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

operating).

3 − Check amp−draw on the blower motor.

Motor Nameplate__________Actual__________

Winterizing and Condensate Trap Care

1 − Turn off power to the unit.

2 − Have a shallow pan ready to empty condensate water.

3 − Remove the drain plug from the condensate trap and

empty water. Inspect the trap then reinstall the drain plug and refill trap with water.

Cleaning Heat Exchanger

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

1 − Turn off electrical and gas supplies to the furnace.

2 − Remove the upper and lower furnace access panels.

3 − Disconnect the 2−pin plug from the gas valve.

4 − Remove gas supply line connected to gas valve. Re-

move gas valve/manifold assembly.

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

plug from the ignitor.

6 − Disconnect wires from flame roll−out switches.

7 − Remove burner box cover and remove four burner box

screws at the vestibule panel and remove burner box. Set burner box assembly aside.

NOTE − G71MPP−135 units are secured to the vestibule panel by two additional screws. These screws must be removed for servicing; however it is not necessary to replace the screws. NOTE − If necessary, clean burners at this time. Follow procedures outlined in Burner Cleaning section.

8 − Loosen three clamps and remove flexible exhaust tee.

9 − Remove 3/8 inch rubber cap from condensate drain

plug and drain. Replace cap after draining.

10 − Disconnect condensate drain line from the conden-

sate trap. Remove condensate trap (it may be necessary to cut drain pipe). Remove screws that secure condensate collars to either side of the furnace and remove collars. Remove drain tubes from cold end header collector box.

11 − Disconnect condensate drain tubing from flue collar.

Remove screws that secure both flue collars into place. Remove flue collars. It may be necessary to cut the exiting exhaust pipe for removal of the fittings.

12 − Mark and disconnect all combustion air pressure tub-

ing from cold end header collector box.

13 − Mark and remove wires from pressure switches. Re-

move pressure switches. Keep tubing attached to pressure switches.

14 − Disconnect the 4-pin plug from the combustion air in-

ducer. Disconnect the two wires to the backup secondary limit, if applicable. Remove four screws which secure combustion air inducer to collector box. Remove combustion air inducer assembly. Remove ground wire from vest panel.

15 − Remove electrical junction box from the side of the fur-

nace.

16 − 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.

17 − Remove the primary limit from the vestibule panel.

Page 53

18 − Remove two screws from the front cabinet flange at

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

19 − Remove screws along vestibule sides and bottom

which secure vestibule panel and heat exchanger assembly to cabinet. Remove two screws from blower rail which secure bottom heat exchanger flange. Remove heat exchanger from furnace cabinet.

20 − Back wash heat exchanger with soapy water solution

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

(135°C) .

21 − Thoroughly rinse and drain the heat exchanger. Soap

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

22 − Reinstall heat exchanger into cabinet making sure that

the clamshells of the heat exchanger assembly are resting on the support located at the rear of the cabinet. Remove the indoor blower to view this area through the blower opening.

23 − Re-secure the supporting screws along the vestibule

sides and bottom to the cabinet.

24 − Reinstall cabinet screws on front flange at blower

deck. 25 − Reinstall the primary limit on the vestibule panel. 26 − Route heating component wiring through hole in blow-

er deck and reinsert strain relief bushing. 27 − Reinstall electrical junction box. 28 − Reinstall the combustion air inducer. Reconnect the

4−pin plug to the wire harness. Reconnect the two

wires to the backup secondary limit, if applicable. 29 − Reinstall pressure switches and reconnect pressure

switch wiring. 30 − Carefully connect combustion air pressure switch

hosing from pressure switches to proper stubs on

cold end header collector box. 31 − Reinstall condensate collars on each side of the fur-

nace. Reconnect drain tubing to collector box. 32 − Reinstall condensate trap on same side as exhaust

pipe. Reconnect condensate drain line to the conden-

sate trap. 33 − Use securing screws to reinstall flue collars to either

side of the furnace. Reconnect exhaust piping and ex-

haust drain tubing. 34 − Replace flexible exhaust tee on combustion air induc-

er and flue collars. Secure using three existing hose

clamps. 35 − Reinstall burner box assembly in vestibule area. 36 − Reconnect flame roll−out switch wires.

37 − Reconnect sensor wire and reconnect 2−pin plug from

ignitor.

38 − Secure burner box assembly to vestibule panel using

four existing screws. Make sure burners line up in

center of burner ports.

39 − Reinstall gas valve manifold assembly. Reconnect

gas supply line to gas valve. 40 − Reinstall burner box cover. 41 − Reconnect 2−pin plug to gas valve. 42 − Replace the blower compartment access panel. 43 − Refer to instruction on verifying gas and electrical con-

nections when re−establishing supplies. 44 − 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. 45 − Replace heating compartment access panel.

Cleaning the Burner Assembly

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

Remove upper and lower furnace access panels. 2 − Disconnect the 2−pin plug from the gas valve. 3 − Disconnect the gas supply line from the gas valve. Re-

move gas valve/manifold assembly. 4 − Mark and disconnect sensor wire from the sensor. Dis-

connect 2-pin plug from the ignitor at the burner box. 5 − Remove burner box cover and remove four screws

which secure burner box assembly to vest panel. Re-

move burner box from the unit.

NOTE − G71MPP−135 units are secured to the vesti-

bule panel by two additional screws. These screws

must be removed for servicing; however it is not nec-

essary to replace the screws.

6 − Use the soft brush attachment on a vacuum cleaner to

gently clean the face of the burners. Visually inspect

the inside of the burners and crossovers for any block-

age caused by foreign matter. Remove any blockage. 7 − Reconnect the sensor wire and reconnect the 2−pin

plug to the ignitor wiring harness. 8 − Reinstall the burner box assembly using the existing

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

center of the burner ports. 9 − Reinstall the gas valve manifold assembly. Reconnect

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

er box cover. 10 − Reconnect 2−pin plug to gas valve. 11 − Replace the blower compartment access panel. 12 − Refer to instruction on verifying gas and electrical con-

nections when re−establishing supplies. 13 − 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. 14 − Replace heating compartment access panel.

Page 54

VII− Wiring and Sequence of Operation

NOTE − The thermostat selection DIP switch on the control board is factory−set in the TWO−STAGE" position.

Applications Using a Two−Stage Thermostat

A − Heating Sequence −− Control Board Thermostat Selection DIP switch in Variable Capacity" Position

1. On a call for heat, thermostat first−stage contacts close sending a signal to the integrated control. The integrated control runs a self-diagnostic program and checks high temperature limit switches for normally closed contacts and pressure switches for normally open contacts.The combustion air inducer is energized at ignition speed, which is approximately the same as the inducer speed at 70 percent firing rate.

2. Once the control receives a signal that the low−fire pressure switch has closed, the combustion air inducer begins a 15−second pre−purge in ignition speed.

3. After the pre−purge is complete, a 20−second initial ignitor warm−up period begins. The combustion air inducer continues to operate at the ignition speed.

4 − After the 20−second warm−up period has ended, the gas

valve is energized and ignition occurs. At the same time, the control module begins an indoor blower 45−second ON−delay. When the delay ends, the indoor blower motor is energized at a speed that matches the firing rate. After the 10−second ignition stabilization delay expires, the inducer speed is adjusted to the appropri-

Page 55

ate target rate. If the furnace is operating in the initial heating cycle after power−up, the initial firing rate will be approximately 40 percent. The firing rate on subsequent cycles will be automatically adjusted by the integrated control based on thermostat cycles. The firing rate will vary and will range from 40 percent to 90 percent. The furnace will continue this operation as long as the thermostat has a first−stage heating demand.

5 − If second−stage heat is required, the thermostat sec-

ond−stage heat contacts close and send a signal to the integrated control. The integrated control either increases the firing rate to 70 percent (if the current rate is at or below 60 percent) or increases the firing rate by 10 percent (if the current rate is above 60 percent). If the call for heat continues 5 minutes beyond this initial upstage, the rate will be increased by 10 percent every 5 minutes until the call for heat is satisfied or the furnace reaches 100 percent rate. As the firing rate increases, the indoor blower motor is adjusted to a speed which is appropriate for the target rate.

6 − If second−stage heat demand is satisfied, but first

stage is still present, the furnace will continue to operate at the present firing rate until the heat cycle ends.

7 − When the demand for first− and second−stage heat is

satisfied, the gas valve is de−energized and the field− selected indoor blower off delay begins. The combustion air inducer begins a 20−second post−purge period.

8 − When the combustion air post−purge period is com-

plete, the inducer is de−energized. The indoor blower is de−energized at the end of the off delay.

Applications Using A Single−Stage Thermostat

B − Heating Sequence −− Control Board Thermostat Selection DIP switch in Single−Stage" Position

1. On a call for heat, thermostat first−stage contacts close sending a signal to the integrated control. The integrated control runs a self-diagnostic program and checks high temperature limit switches for normally closed contacts and pressure switches for normally open contacts.The combustion air inducer is energized at the ignition speed, which is approximately the same as the inducer speed at 70 percent firing rate.

2. Once the control receives a signal that the low−fire pressure switch has closed, the combustion air inducer begins a 15−second pre−purge at the ignition speed.

3. After the pre−purge is complete, a 20−second initial ignitor warm−up period begins. The combustion air inducer continues to operate at the ignition speed.

4 − After the 20−second warm−up period has ended, the gas

valve is energized and ignition occurs, which initiates a 10−second ignition stabilization delay. At the same time, the control module sends a signal to begin an indoor blower 45−second ON−delay. When the delay ends, the indoor blower motor is energized at a speed which is appropriate for the firing rate. After the 10−second ignition stabilization delay expires, the inducer speed is adjusted to 40 percent speed.The integrated control also initiates a second−stage on delay (factory−set at 7 minutes; adjustable to 12 minutes).

5 − If the heating demand continues beyond the second−

stage on delay, the integrated control energizes the combustion air inducer at 70 percent speed. The indoor blower motor is adjusted to a speed which matches the target rate. A fixed, 10−minute third−stage on delay is initiated.

6 − If the heating demand continues beyond the third−

stage on delay, the integrated control energizes the inducer at high speed. The indoor blower motor is adjusted to a speed which is appropriate for the target rate.

7 −When the thermostat heating demand is satisfied, the

gas valve is de−energized and the combustion air inducer begins a 20−second post−purge. The field−selected indoor blower off delay begins.

8 − When the combustion air post−purge period is com-

plete, the inducer is de−energized. The indoor blower is de−energized at the end of the off delay.

Applications Using a Two−Stage Thermostat

C − Heating Sequence −− Control Board Thermostat Selection DIP switch in Two−Stage" Position (Factory Setting)

1. On a call for heat, thermostat first−stage contacts close sending a signal to the integrated control. The integrated control runs a self-diagnostic program and checks high temperature limit switches for normally closed contacts and pressure switches for normally open contacts.The combustion air inducer is energized at ignition speed, which is approximately the same as the inducer speed at 70 percent firing rate.

2. Once the control receives a signal that the low−fire pressure switch has closed, the combustion air inducer begins a 15−second pre−purge at the ignition speed.

3. After the pre−purge is complete, a 20−second initial ignitor warm−up period begins. The combustion air inducer continues to operate at the ignition speed.

4 − After the 20−second warm−up period has ended, the gas

valve is energized and ignition occurs. At the same time, the control module sends a signal to begin an indoor blower 45−second ON−delay. When the delay ends, the indoor blower motor is energized at a speed that matches the firing rate. After the 10−second ignition stabilization delay expires, the inducer speed is adjusted to the appropriate target rate. The inducer will remain at the 70 percent speed as long as the thermostat has a first−stage heating demand.

5 − If second−stage heat is required, the thermostat sec-

ond−stage heat contacts close and send a signal to the integrated control. The integrated control initiates a 30−second second−stage recognition delay.

6 − At the end of the recognition delay and on all subse-

quent calls for heat in the same heating cycle, the integrated control energizes the combustion air inducer at high speed. The control also checks the high−fire pressure switch to make sure it is closed. As the inducer speed is increased to high, the indoor blower motor is adjusted to a speed which is appropriate for the target rate.

7 − When the demand for high−fire (second stage) heat is

satisfied, the gas valve is de−energized and the field− selected indoor blower off delay begins. The combustion air inducer begins a 20−second post−purge period.

8 − When the combustion air post−purge period is com-

plete, the inducer is de−energized. The indoor blower is de−energized at the end of the off delay.

Page 56

A − Sequence of Operation and Troubleshooting Flow Chart

IGNITION AND CALL FOR LOW FIRE WITH TWO−STAGE THERMOSTAT

Call For 2nd Stage Heat Call For Heat Satisfied

Limit

Switch

Closed?

Limit

Closes Within 3

Minutes?

NO

Soft Lockout:

Error Code

Flashes

flashes

YES

Rollout

Circuit

Closed?

Low

Pressure

Switch

Open?

Low

Pressure Switch

Closed Within 150

Seconds?

High

Pressure

Switch

Open?

YES

NO

YES

NO

De−Energize

Gas Valve

De−Energize

Gas Valve

Error Code

Flashes

Error Code

Flashes

Rollout

Circuit

Closes?

Hard Lockout:

Error Code

Flashes

Error Code Flashes

After 5 Seconds

Error Code Flashes

After 5 Seconds

L I G H T

O F F

Safety Check

After

(Low Heat Speed)

Verify There

Is No Main Burner

Flame

YES

Low Pressure Switch Opens

High Pressure

Switch Opens

YES

NO

Pressure Switch

Calibration

Pre−Purge

15 Seconds

YES

Gas Valve Energized

Flame

Sensed Within

4 seconds?

Gas Valve

De−energized

Interpurge

(15 Seconds)

5th

Unsuccessful

Trial?

Wait For Ignition

Stabilization Delay

Post−Purge

(20Seconds)

Soft Lockout:

Error Code

Flashes

YES

NO

YES

Call For

Heat

Ends?

NO

YES

YES NO C A L L

F O R

1 S T

S T A G E

H E A T

3A2

1

OR

Call

For

Heat?

NO

4

Calibrations

Attempted?

Calibration

Successful?

Wait

5 minutes

NO

Soft Lockout:

Error Code

Flashes

YES

2

1

2

Set Target Firing Rate

Based on Thermostat

Signals Present

SOF T LOCKOU T IS RESE TAUTOMATICALLY AFTER ONE HOUR WITH A CALL FOR HE AT ACTIVE, OR B Y CYCLING THE CAL L FOR HE AT, OR B Y CYCLING POWER TO THE CONTROL.

HARD LOCKOU T IS RESE T BY CYCLING POWER TO THE CONTROL.

1

2

Indoor blower OFF

Combustion Air

Inducer On

(100% rate speed)

Indoor Blower

ON (100%)

Heat OFF Delay

Indoor Blower OFF After Heat OFF Delay (High Heat Speed)

Combustion

Air Inducer

On (100% rate

speed)

Indoor Blower

ON (70%)

Combustion Air

Inducer OFF

After Post−Purge

Indoor Blower OFF After

Heat OFF Delay

Combustion Air Inducer

ON at 70% Rate Speed

Ignitor ON 20 Seconds

Indoor

Blower

ON?

Indoor blower OFF After Heat OFF Delay

Indoor Blower Delay

Timer Started

Ignition Trial Begins

(Ignitor ON)

Ignitor OFF

Combustion Air

Inducer OFF

Page 57

CALL FOR HIGH FIRE WITH TWO−STAGE THERMOSTAT

1st Call

for High

Fire?

Wait for Call for Heat Satisfied

2 Stage

Thermostat

2nd Stage

Recognition Delay

(30 Seconds)

YES

High

Pressure Switch

Closes Within

10 Seconds?

NO

Error Code

Flashes

NO

YES

Wait 5

Minutes

3A

2

1

2

1

System will always light at 70% even if 2nd stage call for heat is in place

If the high pressure switch does not close within 5 attempts, the system

will operate at low fire for the remainder of the call for heat at request

Combustion Air Inducer ON

(100% Rate Speed)

Increase Combustion

Air Inducer Speed

if Not at 100%

Rate Speed

Adjust Indoor

Blower to

Appropiate speed

Page 58

CALL FOR HEAT SATISFIED

1st Stage Heat

2nd Stage Heat

2nd Stage

Call for Heat

satisfied?

NO

1st Stage

Call for Heat

satisfied?

Gas valve

De−Energized

YES

NO

Wait for Call −

2−StageThermostat

Wait for Call −

Single StageThermostat

1 4

3A 3B

YES

OR

Combustion Air Inducer

switched to 70% rate speed

Adjust Indoor Blower

to appropiate speed

Combustion Air Inducer OFF

after 20−Second Post Purge

Indoor Blower OFF

after OFF Delay

RUN MODE (2 STAGE THEREMOSTAT) 1ST OR 2ND STAGE CALL FOR HEAT ALL INPUTS MONITORED (LIMIT, PRESSURE, CALL FOR HEAT / COOL, FLAME LEVEL)

RUN MODE (SINGLE STAGE THERMOSTAT) ALL INPUTS MONITORED (LIMIT, PRESSURE, CALL FOR HEAT / COOL, FLAME LEVEL)

Page 59

IGNITION AND CALL FOR LOW FIRE WITH SINGLE−STAGE THERMOSTAT

Call For Heat Satisfied

Limit

Switch

Closed?

Limit

Closes Within 3

Minutes?

NO

Soft Lockout:

Error Code

Flashes

flashes

YES

Rollout

Circuit

Closed?

Low

Pressure

Switch Open?

Low

Pressure Switch

Closed Within 150

Seconds?

High

Pressure

Switch

Open?

YES

NO

YES

NO

De−Energize

Gas Valve

De−Energize

Gas Valve

Error Code

Flashes

Error Code

Flashes

Rollout

Circuit

Closes?

Hard Lockout:

Error Code

Flashes

Error Code Flashes

After 5 Seconds

Error Code Flashes

After 5 Seconds

L I G H T

O F F

Safety Check

Verify There

Is No Main Burner

Flame

YES

Low Pressure Switch Opens

High Pressure Switch Opens

YES

NO

Pre−Purge

15 Seconds

YES

Gas Valve

Energized

Ignition Trial Begins

Flame

Sensed Within

4 seconds?

Gas Valve

De−energized

Interpurge

(15 Seconds)

5th

Unsuccessful

Trial?

Wait For Ignition

Stabilization Delay

Post−Purge

(20 Seconds)

Soft Lockout:

Error Code

Flashes

YES

NO

YES

Call For

Heat

Ends?

NO

YES

YES NO

C A L L

F O R

H E A T

3B

1

4

Move to Mid Firing Rate and High Firing Rate after 2nd and 3rd Stage Delays

(based on DI P Switch selections)

Pressure Switch

Calibration

Call For

Heat?

NO

4

Calibrations

Attempted?

Calibration

Successful?

Wait

5 minutes

NO

Soft Lockout:

Error Code

Flashes

YES

SOFT LOCKOUT IS RESET AUTOMATICALLY AFTER ONE HOUR WITH A CALL FOR HEAT ACTIVE, OR BY CYCLINGTHE CALL FOR HEAT, OR BY CYCLING POWER TO THE CONTROL.

HARD LOCKOUT IS RESE T BY CYCLING POWER TO THE CONTROL.

1

2

1

2

1

Set to

Low Firing Rate

Indoor Blower OFF After Heat OFF Delay (Low Heat Speed)

Combustion Air

Inducer ON

(100%)

Indoor Blower

ON

(100% Speed)

Indoor Blower OFF

After Heat OFF Delay

(High Heat Speed)

Combustion Air

Inducer ON

(100%)

Indoor Blower

ON

(70%)

Combustion Air Inducer

OFF After Post−Purge

Indoor Blower OFF After

Heat OFF Delay

Combustion Air Inducer ON at

Ignition at 70% rate speed

Indoor

Blower On?

Indoor Blower OFF

After Heat OFF Delay

Ignitor ON 20 Seconds

Ignitor ON

Indoor Blower On

Delay Timer Started

Ignitor OFF

Combustion Air

Inducer OFF

Ignitor OFF

Page 60

CALL FOR COOLING

1st Stage Cooling

Request Received

Energize 1st Stage

Cooling Contactor

(Compressor & Fan)

2nd Stage

Cooling

Request?

YES

2nd Stage

Cooling Request

Still Active?

De−Energize 1st

Stage Cooling

Contactor

(Compressor & Fan)

YES

1st Stage

Cooling Request

Still Active?

NO

YES

Energize 2nd Stage

Cooling Contactor

(Compressor & Fan)

1st Stage

Cooling Request

Still Active?

De−Energize 2nd

Stage Cooling

Contactor

(Compressor & Fan)

Energize and

Low Cooling mode

(High Cooling mode)

Per Ramping Profile

NO

YES

NO

5

1

2

1

2

1

Indoor Blower On

After 2−second delay

Energize Indoor Blower

(Per Ramping Profile)

Energize Indoor Blower

Maintain Indoor Blower

Maintain Indoor Blower at

De−Energize Indoor Blower

2nd stage cooling operation requires a 2−stage thermostat, a 2−stage cooling system and jumpers W915 must be be cut. The control will not respond to a 2nd stage cooling request unless a 1st stage cooling request is active

Indoor blower cooling mode and high cooling mode have a specific ON, OFF and speed ramping profiles. The specific profile is selected using the DIP switches on the control.

Page 61

CONTINUOUS LOW SPEED INDOOR BLOWER SEQUENCE OF OPERATION

(Speed Determined by

Dip Switch settings)

De−Energize

Ramping Profile

NO

Request

for Heat

Received?

Request for Cooling Received?

NO

YES

Call for Fan

Removed?

YES

NO

YES

Go to Call for Cooling

Go to Call for Heat − 2 Stage

Thermostat

Go to Call for Heat − Single Stage

Thermostat

6

1

4

5

1

Call for

Continuous Blower

Indoor Blower On

Maintain Indoor

Blower at set speed

Maintain Indoor

Blower at set speed

OR

Maintain Indoor

Blower at set speed

Indoor Blower Per

Indoor blower low cooling mode and high cooling mode, have specific ON − OFF and speed ramping

profiles. The specific profile is selected using the dip switches on the control.

Page 62

VIII− Field Wiring

TABLE 44

Field Wiring Applications

Thermostat

DIP Switch Settings and On−Board Links (figure 4)

Wiring Connections

DIP Switch 1

W915

(Y1 to Y2)

Two−Stage

Cooling

W914

(DS to R)

Dehumidifi-

cation or

Harmony

IIIt

W951

(O to R)

Heat Pumps

1Heat / 1 Cool

NOTE − Use DIP switch 3 to set second−stage heat ON delay. OFF−7 minutes. ON−12 minutes.

ON Intact Intact Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

*

1 Heat / 2 Cool

NOTE − Use DIP switch 3 to set second−stage heat ON delay. OFF−7 minutes. ON−12 minutes.

ON Cut Intact Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

*

1 Heat / 2 Cool with t’stat with dehumidification mode

NOTE − Use DIP switch 3 to set second−stage heat ON delay. OFF−7 minutes. ON−12 minutes.

ON Cut Cut Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

*

* R" required on some units.

Page 63

TABLE 44

Field Wiring Applications

Thermostat

DIP Switch Settings and On−Board Links (figure 4)

Wiring Connections

DIP Switch 1

W915

(Y1 to Y2)

Two−Stage

Cooling

W914

(DS to R)

Dehumidifi-

cation or

Harmony

IIIt

W951

(O to R)

Heat Pumps

2 Heat / 2 Cool OFF Cut Intact Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

*

2 Heat / 2 Cool with t’stat with dehumidification mode

OFF Cut Cut Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

*

2 Heat / 1 Cool OFF Intact Intact Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

*

* R" required on some units.

Page 64

TABLE 44

Field Wiring Applications (Continued)

Thermostat

DIP Switch Settings and On−Board Link (figure 4)

Wiring Connections

DIP Switch

W915

(Y1 to Y2)

Two−Stage

Cooling

W914

(DS to R)

Dehumidifi-

cation or Harmony

IIIt

W951

(O to R)

Heat Pumps

Dual Fuel Single Stage Heat Pump

ComfortSense 7000 L7724U thermostat w/ dual fuel capabilities Capable of 2 stage gas heat control

DIP Switch 1

OFF

Intact Intact Cut

L7724U T’STAT

CONTROL

TERM. STRIP

HEAT PUMP

67M41*

Y

H

L

Y2

D

B

L

Y2

T

outdoor

sensor

Dual Fuel Two Stage Heat Pump

ComfortSense 7000 L7724U thermostat w/ dual fuel capabilities Capable of 2 stage gas heat control

DIP Switch 1

OFF

Cut Intact Cut

CONTROL TERM.

STRIP

HEAT PUMP

out blue

67M41*

H

L

Y2

D

B

L

Y2

T

outdoor sensor

L7724U T’STAT

* Connect W1 to W1 ONLY if using defrost tempering kit 67M41

Lennox G71MPP Unit Information

Specifications and Main Features

Frequently Asked Questions

User Manual