Lennox G23Q4-75, G23Q2-75, G23Q5-75, G23Q3-50, G23Q3-100 Unit Information

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G23(X)

GasPipingSizeI.P.S.

Blowerwheelnomina

Nominalcoolin

Corp. 9814-L8

Service Literature

G23(X) SERIES UNITS

G23(X) series units are mid-efficiency upflow gas furnaces manufactured with Duralokt aluminized steel clamshell type heat exchangers. G23(X) units are available in heating capacities of 50,000 to 150,000 Btuh and cooling applications up to 6 tons. Refer to Engineering Handbook for proper sizing. Unitsare factory equipped for use with natural gas. A kit is availablefor conversionto LPG operation.G23(X)-1, -2, -3 and-4modelunitsuse electronic(intermittentpilot)ignition. G23(X)-5 and -6 model units feature the Lennox SureLightT silicon nitride ignition system. All units meet the CaliforniaNitrogenOxides(NOx) Standardsand California Seasonal Efficiency requirements with the installation of flamebaffles.Allunitsusea redundantgasvalveto assure safety shut-off as required by A.G.A. or C.G.A.

Informationcontainedin this manual is intendedforuse by qualified service technicians only. All specifications are subject to change. Procedures outlined in this manual are presented as a recommendation only and do not supersede or replace local or state codes. In the absence of local or state codes, the guidelines and procedures outlined in this manual (except where noted) are recommended only.

Model No. G23Q2(X)-50 G23Q3(X)-50 G23Q2/3(X)-75 G23Q4/5(X)-75 G23Q3(X)-100

Input Btuh(kW) 50,000 (14.7) 75,000 (22.0) 100,000 (29.3) Output Btuh (kW) 40,000 (11.7) 61,000(17.8) 80,000 (23.4) lA.F.U.E. 80.7% 80.8% 80.4% 80.1% California Seasonal Efficiency 75.5% 75.6% 76.9% 74.2% 76.6% Flue size connection diameter— in. (mm) round 3 (76) 4 (102) Temperature riserange — _F (_C) 30-60 (17-33) 35-65 (19-36) 20-50 (11-28) 45-75 (25-42) High static certified by A.G.A. — in wg.(Pa) .50 (125)

in. 1/2

Natural or LPG/propane

diameter x width

Blower motor output — hp (W) 1/5 (149) 1/3 (249) 3/4 (560) 1/3 (249)

that canbe added

Shipping weight — lbs. (kg) 1 package 135 (61) 140 (64) 146 (66) 186 (84) 159 (72) Electrical characteristics 120 volts — 60 hertz — 1 phase (all models) (less than12 amps)

lAnnual Fuel Utilization Efficiency based on U.S. DOE test procedures and FTC labeling regulations. Isolated combustion system rating for non-weatherized furnaces. }Cleanable polyurethane frame type filter.

mm 12.7 in. 10 x 7 10 x 8 11-1/2 x 9 10 x 8 mm 254 x 178 254 x 203 292 x 229 254 x 203

Tons 1 to 2 1 to 3 3-1/2 to 5 1 to 3 kW 3.5 to 7.0 3.5 to 10.6 12.3 to 17.6 3.5 to 10.6

Revised 08-2001

SPECIFICATIONS

Page 1

ã 1998 Lennox Industries Inc.

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SPECIFICATIONS

Gas Piping Size I.P.S

Blower wheel nominal

Nominal cooling

External Static

Model No.

Input Btuh (kW) 100,000 (29.3) 125,000 (36.6) 150,000 (44.0)

Output Btuh (kW) 80,000 (23.4) 81,000 (23.7) 100,000 (29.3) 120,000 (35.2)

A.F.U.E. 80.7% 80.1% 80.0% 80.4% 80.0%

California Seasonal Efficiency 77.3% 75.9% 76.3% 76.8% 76.8%

Flue size connection diameter in. (mm) round 4 (102) 5 (127)

Temperature rise range EF(EC) 40-70 (22-39) 30-60 (17-33) 45-75 (25-42) 35-65 (19-36) 40-70 (22-39)

High static certified by A.G.A.  in wg. (Pa) .50 (125)

Gas Piping Size I.P.S.

Natural or LPG/propane

Blower wheel nominal

diameter x width

Blower motor output  hp (W) 1/2 (373) 3/4 (560) 1/2 (373) 3/4 (560)

Nominal cooling

that can be added

Shipping weight  lbs. (kg) 1 package 143 (65) 167 (76) 195 (88) 218 (99) 223 (101)

Electrical characteristics 120 volts  60 hertz  1 phase (all models) (less than 12 amps)

Annual Fuel Utilization Efficiency based on U.S. DOE test procedures and FTC labeling regulations. Isolated combustion system rating for non-weath erized fur-

naces.

Cleanable polyurethane frame type filter.

in. 1/2

mm 12.7

in. 10x8 11-1/2 x 9 10x10 12x12

mm 254 x 203 292 x 229 254 x 254 305 x 305

Tons 2to4 3-1/2 to 5 2to4 5 and 6

kW 7.0 to 14.1 12.3 to 17.6 7.0 to 14.1 17.6 and 21.1

G23Q3/4(X)-100G23Q4/5(X)-100G23Q3/4(X)-12

G23Q5/6(X)-125

G23Q5/6(X)-15

G23Q2(X)-50 BLOWER PERFORMANCE

Air Volume and Motor Watts at Specific Blower Taps

Pressure

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts

0 0 1225 580 530 950 450 375 785 370 295 .10 25 1215 575 520 945 445 375 770 365 290 .20 50 1190 560 505 925 435 360 745 350 280 .30 75 1150 545 485 895 420 350 720 340 275 .40 100 1090 515 460 865 410 335 690 325 265 .50 125 1030 485 440 820 385 320 645 305 250 .60 150 960 455 415 760 360 300 595 280 235 .70 175 865 410 390 690 325 285 535 250 225 .80 200 760 360 365 600 285 260 445 210 200 .90 225 630 295 340 520 245 240 ---- ---- ----

NOTE  All air data is measured external to unit with 1 in. (25 mm) cleanable foam filter (not furnished) in place. Also see Filter Air Resistance table.

High Medium Low

G23Q3(X)-50 BLOWER PERFORMANCE

External Static

Pressure

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0 0 1620 765 630 1380 650 510 1110 525 405 875 415 310 .10 25 1575 745 605 1350 635 490 1090 515 390 870 410 305 .20 50 1520 715 580 1315 620 465 1080 510 375 860 405 295 .30 75 1455 685 550 1275 600 445 1050 495 355 840 395 285 .40 100 1390 655 525 1230 580 425 1015 480 340 815 385 275 .50 125 1320 625 505 1165 550 400 975 460 325 775 365 265 .60 150 1240 585 480 1100 520 375 920 435 310 715 335 245 .70 175 1160 545 460 1030 485 360 830 390 280 620 295 220 .80 200 1075 505 440 900 425 320 700 330 250 535 250 205 .90 225 900 425 395 720 340 285 600 285 230 ---- ---- ----

NOTE  All air data is measured external to unit with 1 in. (25 mm) cleanable foam filter (not furnished) in place. Also see Filter Air Resistance table.

High Medium-High Medium-Low Low

Air Volume and Motor Watts at Specific Blower Taps

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G23Q2/3(X)-75 BLOWER PERFORMANCE

External Static

Pressure

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0 0 1600 755 620 1355 640 510 1080 510 395 865 410 310 .10 25 1545 730 595 1320 625 485 1060 500 385 855 405 305 .20 50 1490 705 570 1275 600 465 1035 490 370 830 390 295 .30 75 1425 670 550 1240 585 445 1010 475 360 810 380 285 .40 100 1370 645 530 1185 560 425 975 460 345 780 370 275 .50 125 1300 615 500 1135 535 405 940 445 330 735 345 260 .60 150 1240 585 485 1075 505 380 890 420 310 700 330 250 .70 175 1155 545 465 1000 470 360 830 390 290 625 295 230 .80 200 1045 495 430 905 425 330 720 340 265 555 260 215 .90 225 930 440 405 810 380 305 640 300 245 ---- ---- ----

NOTE  All air data is measured external to unit with 1 in. (25 mm) cleanable foam filter (not furnished) in place. Also see Filter Air Resistance table.

High Medium-High Medium-Low Low

Air Volume and Motor Watts at Specific Blower Taps

G23Q4/5(X)-75 BLOWER PERFORMANCE

External Static

Pressure

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0 0 2365 1115 1360 2130 1005 1180 1850 875 995 1600 755 840 1360 640 710 .10 25 2360 1115 1355 2105 995 1175 1830 865 995 1575 745 835 1350 635 710 .20 50 2290 1080 1325 2055 970 1155 1800 850 985 1560 735 830 1325 625 705 .30 75 2235 1055 1310 2010 950 1135 1780 840 970 1530 720 820 1310 620 700 .40 100 2175 1025 1275 1970 930 1115 1735 820 945 1500 710 910 1290 610 690 .50 125 2110 995 1250 1910 900 1085 1700 800 930 1480 700 800 1265 610 685 .60 150 2030 960 1215 1855 875 1060 1650 780 910 1450 685 790 1250 590 675 .70 175 1955 925 1185 1765 835 1030 1610 760 895 1410 665 775 1220 575 670 .80 200 1890 890 1165 1695 800 1005 1550 730 875 1370 645 760 1190 560 655 .90 225 1800 850 1145 1600 755 980 1490 705 850 1340 630 730 1160 545 625

NOTE  All air data is measured external to unit with 1 in. (25 mm) cleanable foam filter (not furnished) in place. Also see Filter Air Resistance table.

High Medium-High Medium Medium-Low Low

Air Volume and Motor Watts at Specific Blower Taps

G23Q3(X)-100 BLOWER PERFORMANCE

Air Volume and Motor Watts at Specific Blower Taps

Pressure

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts

0 0 1615 760 630 1300 615 500 1030 485 400

.10 25 1585 750 615 1290 610 490 1015 480 395 .20 50 1530 720 595 1255 590 475 1000 470 380 .30 75 1470 695 570 1220 575 455 975 460 365 .40 100 1400 660 545 1175 555 435 950 450 350 .50 125 1330 630 510 1125 530 415 910 430 340 .60 150 1250 590 485 1065 505 390 870 410 320 .70 175 1155 545 455 995 470 365 810 380 300 .80 200 1055 500 425 915 430 345 735 345 275 .90 225 950 450 400 820 385 320 650 305 250

NOTE  All air data is measured external to unit with 1 in. (25 mm) cleanable foam filter (not furnished) in place. Also see Filter Air Resistance table.

High Medium Low

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G23Q3/4(X)-100 BLOWER PERFORMANCE

External Static

Air Volume and Motor Watts at Specific Blower Taps

Pressure

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0 0 1970 930 925 1675 790 750 1500 710 655 1180 555 505 .10 25 1895 895 880 1635 770 710 1480 700 635 1175 555 495 .20 50 1850 875 855 1600 755 680 1450 685 605 1170 550 485 .30 75 1790 845 825 1560 735 655 1420 670 580 1155 545 465 .40 100 1710 805 790 1515 715 630 1370 645 550 1130 535 450 .50 125 1635 770 760 1460 690 600 1315 620 520 1100 520 425 .60 150 1555 735 725 1390 655 565 1270 600 495 1060 500 410 .70 175 1470 695 690 1300 615 525 1195 565 470 1015 480 385 .80 200 1370 645 660 1225 580 500 1110 525 435 970 460 370 .90 225 1265 595 625 1115 525 455 1025 485 400 895 420 340

NOTE  All air data is measured external to unit with 1 in. (25 mm) cleanable foam filter (not furnished) in place. Also see Filter Air Resistance table.

High Medium-High Medium-Low Low

G23Q4/5(X)-100 BLOWER PERFORMANCE

External Static

Pressure

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0 0 2465 1165 1305 2230 1050 1115 1985 935 940 1735 820 770 1530 720 650 .10 25 2425 1145 1295 2170 1025 1085 1950 920 930 1700 800 765 1500 710 645 .20 50 2375 1120 1265 2130 1005 1065 1920 905 915 1670 790 750 1470 695 635 .30 75 2315 1090 1235 2090 985 1050 1880 885 895 1645 775 745 1440 680 630 .40 100 2255 1065 1210 2045 965 1040 1840 870 890 1610 760 735 1420 670 625 .50 125 2195 1035 1185 1995 940 1010 1815 855 880 1575 745 725 1390 655 615 .60 150 2135 1010 1155 1950 920 1000 1770 835 870 1530 720 715 1350 635 600 .70 175 2075 980 1145 1890 890 985 1710 805 850 1490 705 700 1295 610 595 .80 200 1985 935 1105 1825 860 960 1650 780 830 1435 675 690 1245 590 585 .90 225 1895 895 1080 1745 825 925 1585 750 810 1365 645 675 1170 550 570

NOTE  All air data is measured external to unit with 1 in. (25 mm) cleanable foam filter (not furnished) in place. Also see Filter Air Resistance table.

High Medium-High Medium Medium-Low Low

Air Volume and Motor Watts at Specific Blower Taps

G23Q3/4(X)-125 BLOWER PERFORMANCE

External Static

Pressure

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0 0 1980 935 800 1690 800 700 1470 695 610 1165 550 465

.10 25 1905 900 770 1670 790 680 1465 690 595 1160 545 455 .20 50 1850 875 740 1630 770 650 1430 675 570 1125 530 445 .30 75 1780 840 705 1580 745 620 1410 665 545 1120 530 430 .40 100 1695 800 670 1530 720 590 1375 650 520 1095 515 410 .50 125 1605 755 640 1455 685 550 1310 620 485 1065 505 390 .60 150 1525 720 605 1380 650 520 1245 590 455 1015 480 370 .70 175 1405 665 565 1280 605 485 1165 550 425 950 450 345 .80 200 1275 600 525 1160 545 440 1030 485 385 860 405 315 .90 225 1120 530 480 1000 470 390 915 430 355 780 370 295

NOTE  All air data is measured external to unit with 1 in. (25 mm) cleanable foam filter (not furnished) in place. Also see Filter Air Resistance table.

High Medium-High Medium-Low Low

Air Volume and Motor Watts at Specific Blower Taps

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G23Q5/6(X)-125 BLOWER PERFORMANCE

External Static

Pressure

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0 0 2460 1160 1295 2220 1050 1050 2000 945 900 1775 840 755 1595 755 645 .10 25 2455 1160 1285 2210 1045 1050 1990 940 900 1755 830 760 1570 740 645 .20 50 2450 1155 1280 2180 1030 1040 1965 925 895 1720 810 755 1535 725 645 .30 75 2445 1155 1270 2155 1015 1035 1930 910 885 1690 800 745 1500 710 645 .40 100 2440 1150 1265 2125 1005 1025 1890 890 875 1660 785 750 1470 695 640 .50 125 2430 1145 1255 2090 985 1020 1860 880 870 1620 765 745 1435 675 635 .60 150 2350 1110 1235 2040 965 1000 1810 855 855 1585 750 735 1395 660 635 .70 175 2300 1085 1210 1990 940 990 1770 835 845 1540 725 725 1345 635 620 .80 200 2220 1050 1185 1925 910 970 1715 810 830 1490 705 715 1270 600 605 .90 225 2120 1000 1140 1850 875 950 1640 775 800 1420 670 690 1200 565 590

NOTE  All air data is measured external to unit with 1 in. (25 mm) cleanable foam filter (not furnished) in place. Also see Filter Air Resistance table.

High Medium-High Medium Medium-Low Low

Air Volume and Motor Watts at Specific Blower Taps

G23Q5/6(X)-150 BLOWER PERFORMANCE

External Static

Pressure

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0 0 2565 1210 1430 2300 1085 1160 2055 970 970 1840 870 825 1620 765 680 .10 25 2560 1210 1420 2265 1070 1155 2020 955 960 1810 855 825 1590 750 680 .20 50 2555 1205 1410 2225 1050 1140 1980 935 955 1770 835 810 1555 735 680 .30 75 2550 1205 1400 2185 1030 1130 1935 915 945 1740 820 805 1515 715 675 .40 100 2500 1180 1380 2150 1015 1115 1900 440 935 1700 800 800 1470 695 670 .50 125 2440 1150 1365 2100 990 1105 1860 435 925 1645 775 790 1430 675 665 .60 150 2370 1120 1335 2045 965 1085 1790 430 910 1585 750 780 1380 650 660 .70 175 2300 1085 1310 1960 925 1055 1730 815 895 1530 720 770 1315 620 645 .80 200 2210 1045 1270 1920 905 1035 1640 415 875 1470 695 755 1210 570 635 .90 225 2110 995 1240 1855 875 1030 1550 730 855 1345 635 725 1100 520 625

NOTE  All air data is measured external to unit with 1 in. (25 mm) cleanable foam filter (not furnished) in place. Also see Filter Air Resistance table.

High Medium-High Medium Medium-Low Low

Air Volume and Motor Watts at Specific Blower Taps

FILTER AIR RESISTANCE

CFM (L/S) in. w.g. (Pa)

0 (0) 0.00 (0)

200 (95) 0.01 (0) 400 (190) 0.03 (5) 600 (285) 0.04 (10) 800 (380) 0.06 (15)

1000 (470) 0.09 (20) 1200 (565) 0.12 (30) 1400 (660) 0.15 (35) 1600 (755) 0.19 (45) 1800 (850) 0.23 (55)

2000 (945) 0.27 (65) 2200 (1040) 0.33 (80) 2400 (1130) 0.38 (95) 2600 (1225) 0.44 (110)

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OPTIONAL ACCESSORIES (Must be Ordered Extra)

LPG/Propane kit

Model No.

Standard

LPG/Propane kit

Filter and Filter Rack Kits

No. & size of filters - in. (mm)

Horizontal Power Venter Kit

Twinning Kits

Continuous Low Speed Blower Switch (option- al)

Non-continuous low speed

Continuous low speed

models

X models

OPTIONAL ACCESSORIES (Must be Ordered Extra)

Model No. G23Q2(X)-50 G23Q3(X)-50 G23Q2/3(X)-75 G23Q4/5(X)-75 G23Q3(X)-100

Standard

LPG/Propane kit

Filter and Filter Rack Kits

No. & size of filters - in. (mm)

Horizontal Power Venter Kit

Twinning Kits

Continuous Low Speed Blower Switch

Non-continuous low speed

Continuous low speed

models

X models

G23Q3/4(X)-100G23Q4/5(X)-100G23Q3/4(X)-12

15K03 15K04 15K05

Single

(44J21)

(1) 20 x 25 x 1 (508 x 635 x 25)

79J15

64H88

35J93

44J06

(all models) Not used with Twinning Kits

15K01 15K02 15K03

Single

(44J20)

(1) 14 x 25 x 1 (356 x 635 x 25)

Ten Pack

44J06

(66K61)

79J15

64H88

35J93

(all models) Not used with Twinning Kits

71K82

Ten Pack

(all models)

71K82

(all models)

G23Q5/6(X)-125

(66K62)

Single

Ten Pack

(44J21)

(66K62)

(1) 20 x 25 x 1

(508 x 635 x 25)

G23Q5/6(X)-15

Single

(44J22)

Ten Pack

(66K63)

(1)16x25x1

(406 x 635 x 25)

HIGH ALTITUDE

Pressure regulator adjustment may be required depending on alti- tude. See table below for proper pressure regulator setting.

Manifold Absolute Pressure (Outlet) in. w.g. (kPa)

ALTITUDE ft. (m)

FUEL

Natural Gas 3.5 (.87) 3.3 (.82) 3.1 (.77) 3.0 (.75)

LPG/Propane 10.0 (2.49)

Pressure switch is factory set. No adjustment necessary. G23(X)-50/75 units use the factory pressure switch from 0-7500 feet (0-2286 m). G23(X)-100/125 and G23(X)-150 units require a High Altitude Pressure Switch for units installed above 5000 feet (1524 m). Order (

97J50

) for G23(X)-100/125 and (

0-4500

(0-1372)

4501-5500

(1373-1676)

18J35

5501-6500

(1677-1981)

) for G23(X)-150.

6501-7500

(1982-2286)

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TOP PANEL

BURNER ACCESS PANEL

BLOWER ACCESS

DOOR

G23(X) ORIENTATION

SUPPLY AIR OPENING

HEATING COMPARTMENT

MAKE-UP BOX ASSEMBLY

BLOWER COMPARTMENT

SureLight Control

(-5 and -6 models only)

FLUE TRANSITION

COMBUSTION AIR BLOWER

PRIMARY LIMIT

GAS VALVE

ROLLOUT SWITCH

BURNERS

MANIFOLD

BLOWER DOOR

INTERLOCK SWITCH

CIRCUIT BREAKER

SUPPLY AIR BLOWER

FIGURE 1

G23(X) GENERAL PARTS ORIENTATION

SUPPLY AIR DUCT FLANGE

COMBUSTION AIR BLOWER

PROVE (PRESSURE)

SWITCH

IGNITION CONTROL

(-1 through -4 models only)

HEATING COMPARTMENT

CONTROL BOX

BLOWER COMPARTMENT

BLOWER CAPACITOR

FIGURE 2

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

Page 8

(FLUE TRANSITION ASSEMBLY)

FIGURE4

FIGURE5

ORIFICE PLATE

FLUE OUTLET

GLASS FIBER GASKET

UPPER VEST

PANEL

G23(X) HEAT EXCHANGE ASSEMBLY

-5 and -6 G23X Models

TOP CAP

GLASS FIBER

GASKET

FLUE BOX

GLASS FIBER GASKET

COMBUSTION BLOWER

GLASS FIBER GASKET

FLUE COLLECTOR

BOX

COMBUSTION AIR BLOWER

MID VEST PANEL

PRIMARY LIMIT PRIMARY LIMIT

ALTERNATE STYLE

ROLLOUT SWITCH

ROLLOUT BRACKET

ORIFICE

MANIFOLD END PLUG

MANIFOLD AND GAS VALVE

CONTROL BOX

(-1 through -4 G23X models)

DOOR INTERLOCK

SWITCH

BURNER ASSEMBLY

TRANSFORMER

HEATEXCHANGER

(Heat Train

Assembly)

CLAMSHELL

(Each Segment)

FLAME BAFFLES (NOx UNITS ONLY)

FLAME SENSE ASSEMBLY

RIGHT MANIFOLD BRACKET

LEFT MANIFOLD BRACKET

FIGURE 3

CONTROL BOX

(-5 and -6 G23X models))

DOOR INTERLOCK

SWITCH

TRANSFORMER

CIRCUIT BREAKER

LOW VOLTAGE STRIP

BCC CONTROL

CIRCUIT BREAKER

SURELIGHT CONTROL

LOW VOLTAGE STRIP

Page 8

Page 9

I-UNIT COMPONENTS (Figures 1 and 2)

G23(X)unitcomponentsareshowninfigures1and2.The gasvalve,ignitioncontrolandburnerscanbeaccessedby removing the burner access panel. The blower, blower control and SureLight control can be accessed by removing the blower access door.

G23(X) units are factory equipped with bottom and side return air panels in place. The panels are designed to be field removed as required for bottom air return or side air return.

A-Make-Up Box (Figure 6)

Thelinevoltagemake-upboxisshowninfigure6.Thebox may be installed inside or outside the unit and may be installed on the unit left or right side (figure 8).

MAKE-UP BOX

POWER ENTRY KNOCKOUT

BOX

120V LINE VOLTAGE

PIGTAIL CONNECTIONS

COVER

B-Control Box Components (Figures 4 & 5)

SureLight control (A3), Electrical blower control components (A15), unit transformer (T1) and 24V circuit breaker (CB8)are located in the controlbox. In addition, a door interlockswitch(S51)islocatedin thecontrolbox.Jackplugs allow the control box to be easily removed for blower service.

1. Control Transformer (T1)

Atransformer locatedinthe controlbox provides powerto thelow voltage 24volt section of the unit.Transformers on all models are rated 40VA with a 120V primary and a 24V secondary.

2. Circuit Breaker (CB8)

A24Vcircuit br eaker isalso locate d in the c ontrol box . The switch provides ove rcurr ent protec tion to the transformer ( T1). Thebreaker is rated3A at 32V.Ifthe currente xcee dsthis limitthebreakerwill tr ipand allunit operation will shut down. T he brea ker can bemanually reset by pres sing the button on the face. See figure 7.

CIRCUIT BREAKER CB8

UNIT

GROUND

JACK J69

Box may be installed inside or outside unit. See Figure 8.

TO BLOWER MULLION

FIGURE 6

MAKE-UP BOX INSTALLATION

OUTSIDE INSTALLATION

MAKE-UP BOX

Line Voltage Enters Through

Knockout In Make-Up Box. J69

Passes Through Side Knockout

Into Side Of Unit.

Box may be installed inside or outside cabinet and may

be installed on left side or right side of cabinet

STARWASHERS

MUST BREAK

PAINT ON UNIT

CABINET FOR

PROPER GROUND.

UNIT

CABINET

JACK J69

PRESS TO RESET

FIGURE 7

3.Door Interlock Switch (S51)

A door interlock switch rated 14A at 125VACislocated on the blower access door.The switch is wired in series with linevoltage. When the blower dooris removed theunitwill shut down.

INSIDE INSTALLATION

MAKE-UP BOX

Line Voltage Enters Make-Up

Box Through Side Of Unit and

J69 Passes Through Bottom

Knockout in Make-Up Box.

BLOWER MULLION

PLUG P69

FIGURE 8

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4. BCC Blower Control (A15)

-1 Through -4 Models

G23(X)-1, -2, -3 and -4 model units utilize the BCC blower controlmanufacturedby Heatcraft. Seefigure10.TheBCC is a printed circuit board which controls the supply air blower and monitors primary limit and gas valve operation. The BCC is equipped with a jumper for electronic (isolation relay) or electro-mechanical thermostat selection.The controlhasanon-adjustable,factorypresetfan“on”timing.Fan “off”timing is adjustable. The board is divided into two sections, 120 and 24VAC. Line voltage comes into the board on the 120VACside. See table 1 for terminal designations.

Fan Timings

Fan“off”timing (time that thebloweroperates after theheat demand has been satisfied) is determined by the arrangement of a jumper across pins on the BCC blower control board.Seefigure9.To adjust fan“off”timing,gentlydisconnect jumper and reposition across pins corresponding with newtiming.Fan “on” time is factoryset at 45 seconds andis not adjustable.

NOTE—If fan “off” time is set too low, residual heat in heat exchanger may cause primary limit S10 to trip resulting in frequent cycling of blower. If this occurs, adjust blower to longer time setting.

Figure 9 shows the various fan “off” timings and how jumper should be positioned. Unit is shipped with a factory fan “off” setting of 90 seconds. Fan “off” time will affect comfort and efficiency and is adjustable to satisfy individual applications. Thefan “off” timing is initiated aftera heating demand butnot after a blower or cooling demand (that is, when indoor thermostat switch is changed from ON to AUTO and heating/ cooling demand is not present, the blower stops immediately).

FAN-OFF TIME ADJUSTMENT

TIMING

JUMPER



 



To adjust fan-off timing:

Remove jumper from BCC and select

one of the other pin combinations to

achieve the desired time.

TIMING PINS

(seconds)

Leave jumper off for

330 second fan-off timing.

SHOCK HAZARD. MAKE SURE TO DISCONNECT POWER BEFORE CHANGING FAN OFF TIMING.

FIGURE 9

ELECTROSTATIC DISCHARGE (ESD)

Precautions and Procedures

CAUTION

Electrostatic discharge can affect electronic components. Take precautions during furnace installation and service to protect the furnace’s electroniccontrols.Precautions will helptoavoid 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.

NEUTRAL

TERMINALS

ELECT

MECH

THERMOSTATJUMPER

(Electronic or Mechanical)

G23(X)-1, -2 ,-3 and -4 MODELS

BLOWER CONTROL - BCC

COOLING

SPEED TAP

TERMINAL

(DETACHABLE ON EARLY BOARDS ONLY))

TERMINALS

THERMOSTATTERMINAL STRIP

CONTINUOUS FAN

DUMMY

TERMINAL

BLOWER TIME

ADJUSTMENT

JUMPER

(A15)

HEATING

SPEED TAP

TERMINAL

FIGURE 10

ACCESSORY

TERMINAL

Heat Anticipator Settings Beginning with the BCC3-2 series, a 3 pin jumper has been installed on the board next to the removable 24V terminal strip to account for both programmable and electromechanical thermostat usage in the field. For electromechanical thermostat, position the jumper over the middle and bottom pin labeled ”MECH.” Set the heat anticipator setting to 0.65 amps for Honeywell valves or 0.50 amps for White Rodgers valves. For programmable (electronic) thermostats, position the jumper over the middle and top pin labeled ”ELECT.” Set the heat anticipator setting to 0.1 amps.

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Page 11

TABLE 1

BLOWER CONTROL A15 TERMINAL DESIGNATIONS

Terminal

(Designa-

tion on Wir-

ing

Diagram)

IBN (N)

N1 (N)

CABN (N) 1/4 Spade

XFMRN (N) 1/4 Spade 120VAC Transformer Common

HSIN (N) 1/4 Spade

CAB 1/4 Spade

L1 1/4 Spade 120VAC Line Voltage In

A 1/4 Spade

XFMR 1/4 Spade 24VAC In From Transformer

D 1/4 Spade

CF 1/4 Spade

H 1/4 Spade

ACC 1/4 Spade

24V (24)

LIMIT

(L)

W 1/4 Spade

VALVE

SENSE (V)

T 1/4 Spade

COM (C) 1/4 Spade 24VAC Common To Transformer

Type Function

Detachable

or Screw

Strip

Detachable

or Screw

Strip

Detachable

or Screw

Strip

Detachable

or Screw

Strip

Detachable

or Screw

Strip

1/4

Spade

1/4

Spade

3/16 or

1/4 Spade

3/16 or

1/4 Spade

120VAC Indoor Blower Common

(Electronic Air Cleaner, Humidifier,

24VAC In From Primary Limit. Limit

Open: Closes Gas Valve and Turns

24VAC Thermostat Demand Output

Through Rollout and Prove Switch

to TH Terminal of Ignition Con-

Cooling Demand

Blower Demand

24VAC to Thermostat

Heating Demand

24VAC Common

To Indoor Thermostat

120VAC Neutral

(L2 Line Voltage Neutral)

120VAC Combustion Air Blower

120VAC Hot Surface Ignition

Switched 120VAC to Accessory

24VAC Input From Transformer

On Blower Limit Closed: Allows

24VAC Input From Gas Valve

Ignition Control and Gas Valve

Common

Common (Not Used) Switched 120VAC to

Combustion Air Blower

Switched 120VAC

to Blower Cooling Tap

Dummy Connection for

Unused Blower Leads

Switched 120VAC to

Continuous Blower Tap

Switched 120VAC to

Blower Heating Tap

24VAC Common From

Etc.)

Ignition

trol

C-Ignition Control (-1 Through -4 Models)

G23(X) -1, -2, -3 and -4 model units use an intermittent pilot ignitioncontrol manufacturedby Johnson Controls. The ignition control is located on a bracket on the upper vest panel.

Unit Operation

When there is a call for heat, the control is prevented from beginning an ignition sequence until the pressure switch proves combustion air blower operation. When the pressure switch closes, the control generates a spark and opens the pilot valve to ignite the pilot. When flame is sensed, the control opens the main gas valve and the pilot ignites the main burners. The indoor blower starts after a 45 second delay. Gas valve remains open and combustion air blower continues to run until demand stops, flame sensor senses loss of flame,alimit opens ortheprove switchopens. If anyofthese events occur during a thermostat demand, the gas valve closes. Thecontrolwillattempt ignitionfor85seconds.Ifignitionis not successful, the control will lockout (indicated by flashing LED). Within one hour the control will momentarily remove then reapply the thermostat signal and the ignition sequence will begin again (Watchguard circuit). If pilot ignitionissuccessful, but flameislost whenthemainvalve opens,theignitionsequencewill retry up to 15moretimes. Ifignitionisnotsuccessfulafterthe16thtry,thecontrolwill shut-down and must be reset manually. Manual reset is accomplished by removing then reapplying thermostat demand for at least 30 seconds.

IGNITION CONTROL A3

SPARK

OUTPUT

SEE TABLE 2

FOR TERMINAL

DESIGNATIONS

FIGURE 11

DANGER

Shock hazard. Spark related components contain high voltage.

Disconnect power before servicing. Control is not field repairable. If control is inoperable, simply replace entire control.

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

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Page 12

TABLE 2

IGNITION CONTROL A3 TERMINAL DESIGNATIONS

Terminal Type Function

GROUND 1/4 Spade Cabinet Ground

THS 2 1/4 Spade

P.V.1

M.V.3

SENSE 4 1/4 Spade Microamp Flame Sensing Input

Unmarked

1/4 or

3/16Spade

1/4 or 3/16

Spade

Pin Type

Bare Wire

Safety Limit 24VAC Input

From Rollout and Prove Switch

24VAC Output to Pilot Operator

24VAC Output to Main Operator

of Gas Valve

High Voltage Spark Output

Diagnostic LED

The furnace ignition control is equipped with a diagnostic LEDusedfortroubleshootingtheunitandthe control.LED functions are shown in table 3.

TABLE 3

Furnace Control A3 Diagnostic LED

LED Stat

Steady On

Slow Flash

(1 sec. on/

5 sec. off)

Off

Meaning Remedy

Normal Opera-

tion

Control Retry

Period

Control Failure

or Power Fail-

ure or Hard

Lockout

Failed to Sense Flame. Ignition

Control Will Retry

Before Locking Out.

If Power and Gas Supply are OK,

Try Removing Tstat Demand For

At Least 30 Seconds. If LED Re-

mains Off When Demand Is Re-

turned, Replace Control.

----

Johnson G776 Ignition Control Operation

The information inthis section is protected by a copyright issued by Johnson Controls, Inc., and is reproduced with permission.

On a call for heat from the indoor thermostat, the ignition control energizes and the ignition control LED lights (steady on). The combustionair blower is energized.After a 15 second pre-purge period, the control simultaneously opens the pilot valve and sends spark to the pilot electrode.

If the pilot ignites within 85 seconds, the flame sensor detects pilot flame and signals the ignition control to to energize the main valve. The main valve cannot be energized until the sensor detects pilot flame. Spark continues until pilotflameissensed or 85 secondshas elapsed, whichever happens first.

When pilot flame is sensed, the main valve is energized and the spark turns off. The ignition control remains in “run” mode until the indoor thermostat is satisfied or flame is lost.

Ifpilotflame is not sensedbefore the end of the85second trialfor ignition, thecontrol enters the 100% shutoffmode. The spark circuit and pilot valve de-energize and the ignitioncontrol automatically begins the60 minute retry delay period. During the 60 minute delay the diagnostic LED continually flashes on for one second and off for five seconds. After the delay period, another trial for ignition sequence starts, beginning with pre-purge.

Ifpilotflamegoesoutwhiletheindoorthermostat is calling forheat, both main and pilotvalves de-energizewithin 0.8 seconds and remain de-energized for five seconds. After this delay, the spark and pilot valve energize until flame is sensedorthe85secondtrialforignitionperiod ends.Ifthis “flameout” cycle repeats 16 times (pilot flame is established and then lost), the control locks out and the LED goes off. A new trial for ignition sequence begins after the thermostat contacts are opened for 30 seconds and then closed.

If flame is detected when the thermostat calls for heat, it must extinguish within30 seconds for normaloperation. If flameisstillpresentafter30seconds,thecontrolgoesinto lockout and the LED goes off.

D-Combustion Air Blower (B6)

All G23(X) units use a combustion air blower to move air through the burners and heat exchanger during heating operation. The blower uses a shaded pole 120VAC motor. Shaded pole motors do not use run capacitors. The motor operates during all heating operation and is controlled by blower control A15. The blower operates continuously while there is a call for heat. The ignition control is prevented from proceeding through the ignition sequence until combustion air blower operation is sensed by the prove switch.

The pressure switch connected to the upper vest panel is used to prove combustion air blower operation. The switch monitors air pressure in the blower housing. During normal operation, the pressure in the housing is negative. If the pressure drops (becomes more positive), the pressure switch opens. When the pressure switch opens, the ignition control (A3) immediately closes the gas valve to prevent burner operation.

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Page 13

G23(X) UPPER VEST PANEL

(FLUE TRANSITION ASSEMBLY)

ORIFICE PLATE

FLUE OUT-

LET

GLASS FIBER

GASKET

UPPER VEST

PANEL

IGNITION CONTROL

BRACKET

IGNITION CONTROL

(-1 through -4 model units)

FIGURE 12

E-Blower Motors and Capacitors

All G23(X) units use direct drive blower motors. All motors used are 120V permanent split capacitor motors to ensure maximum efficiency. See table 4 for ratings.

TABLE 4

G23(X) BLOWER RATINGS 120V 1PH

BLOWER MOTOR HP

G23Q2(X) 1/5 5MFD 370V

G23Q2/3(X)

G23Q3(X) G23Q3/4(X) G23Q4/5(X) G23Q5/6(X)

1/3 1/3

1/2

3/4 40MFD 370V 3/4 40MFD 370V

CAP

5MFD 370V 5MFD 370V

7MF 370V

F-Flame Rollout Switch (S47)

Flame rollout switch is a high temperature limit located on rollout switch bracket (over burner assembly). The limit is a N.C. SPST manual-reset limit connected in series with the ignition control (A3). When S47 senses rollout, the ignition controlimmediately stops ignitionandcloses the gas valve. If unit is running andflame rollout is detected, the gasvalve will close and ignition control will be disabled. Rollout can be caused by a reverse draft, blocked flue or lack of combustion air. The switch is factory set and cannot be adjusted. The switch may have different setpoints for each unitmodel number.However,thesetpoint will beprinted on the side of the limit. The switch can be manually reset. To manually reset a tripped switch, push the reset button located on the control (see figure 13).

FLUE BOX

GLASS FIBER GASKET

FLUE COLLECTOR BOX

COMBUSTION AIR BLOWER

GLASS FIBER GASKET

COMBUSTION AIR BLOWER

COMBUSTION AIR BLOWER MOTOR

COMBUSTION AIR BLOWER

PROVE (PRESSURE)

NOTE-ALL components located behind up-

per vest panel including combustion air blow-

er are exposed to supply air stream.

SWITCH

ROLLOUT SWITCH (S47)

MANUAL

RESET BUTTON

FIGURE 13

G-Primary Limit Control (S10)

Primary limit (S10) on G23(X) units is located in the middle of the vestibule panel. When excess heat is sensed in the heat exchanger ,the limit will open. If the limit is tripped, the furnace control energizes the supply air blower and closes the gas valve. The limit automatically resets when temperature retur ns to nor mal .The switch is factory set and cannot be adjusted. The switch may have different setpoints for each unitmodel number.However,thesetpoint will be printed on the side of the limit.

SPADE CONNECTORS

G23(X) SERIES UNITS AND ALTERNATE STYLE

LIMIT CONTROL (S10) FOR

Units may be equipped with

either style limit.

LIMIT

INSULATING COVER (s)

FIGURE 14

3DJH 

Page 14

Units may be equipped with either flush style or extended (masted) limit (figure14). Masted limits may be installed with limit facing blower or away from blower. This orientationcannotbechanged.Whenremovinglimitfromunit,pay careful attentionto its orientation and make sure limit is reinstalled facing same direction.

H-Pilot, Spark Electrode, Flame Sensor

and Burners (-1 Through -4 Models)

Figure 17 shows the arrangement of pilot, flame sensor, spark electrode and burners. The ignition control uses direct spark to ignite the pilot. The pilot ignites the burners and the burners cross-light. The flame sensor uses flame rectification to sense ignition. The ignition control requires that pilot flame must be sensed before the main gas valve is allowed to open. Typically, a 2 to 4 second delay occurs between the pilot ignition and the main valve opening.

Figure16showsthe gap between tip of the electrodesand the burner surface. It is important that the gap be maintained for consistent ignition of pilot flame.

A flame retention ring in the end of each burner is used to maintain correct flame length and shape and to keep the flamefrom lifting offthe burner head. In addition, the burner entrance to each clamshell (Figure 3) is fitted with a flamebaffle or corbel toenhance the combustion process.

G23(X)-1, -2, -3 AND -4 MODELS BURNER PILOT/ELECTRODE

ORIENTATION

view looking at side of burners

TYPICAL BURNER ASSEMBLY

FIGURE 15

PILOT, SPARK ELECTRODE AND FLAME SENSOR

PILOT HOOD

PILOT

FLAME SENSOR

SENSE WIRE

1/8 (.125) Inch + ”1/32 (.031)

GAP SPARKELECTRODE

SPARKWIRE

FIGURE 16

PILOT HOOD

FLAME SENSOR

ORIFICE

RETAINER

PRIMARY

AIR INLET

BURNER

SPARK

ELECTRODE

PILOT MOUNTING

BRACKET

FIGURE 17

Page 14

Page 15

127(   7KH *; IXUQDFH FRQWDLQ

V HOHFWURQLF FRP SRQHQWV WKDW DUH SRODULW\ VHQVLWLYH 0DNH VXUH WKDW WKH IXUQDFH LV ZLUHG FRUUHFWO\ DQG LV SURSHUO\ JURXQGHG

DANGER

Shock hazard.

Disconnect power before servicing. Control is not field repairable. If control is inoperable, simply replace entire control.

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

I- SureLight Ignition System A3

(-5 and -6 models)

All G23(X)-5 and -6 model units are equipped with the Lennox SureLight ignition system. The system consists of ignition control board (figure 21 with control terminal designationsintable5)and ignitor(figures 18,19and20. The board and ignitor work in combination to ensure furnace ignition and ignitor durability. The SureLight integrated board controls all major furnace operations. The board also features two LED lights for troubleshooting and two accessory terminals rated at (4) four amps. See table6 for troubleshooting diagnostic codes. Table7and 8 show jack plug terminal designations. Units equipped withtheSureLightboardcanbeusedwitheitherelectronic or electro-mechanical thermostats without modification. The SureLight ignitor is made of durable silic on-nitride. Ignitor longevity isalso enhanced by voltage ramping by the control board. The board finds the lowest ignitor temperature which will succes s fully light the burner, thus increasing the life of t he ignitor.

NORMAL FLAME SIGNAL0.7 MICROAMPS

1/4”

IGNITOR

LOW FLAME SIGNAL MINIMUM FLAME SIGNAL$0.15 MICROAMPS

19/64”

0.7 MICROAMPS

SENSOR

3/8”

FIGURE 18

SENSOR

IGNITOR

FIGURE 19

NOTE -Donotremove blower access panel to read SureLight LED lights. A sight glass is provided on the access panel for viewing.

SURELIGHT IGNITOR (I) AND SENSOR (S)

LOCATION

)ODPH 6HQVRU

Aflamesensorislocatedontheleftside of the burner support. See figures 18,19and 20. The sensoris mounted on a bracket in the burner support and the tip protrudes into the flame envelope of the left-most burner. The sensor is fastened to burner supports and can be removed for service without removing any part of the burners. During operation, flame is sensed by current passed through the flameandsensingelectrode.TheSureLightcontrolallows the gas valve to remain open as long as flame signal is sensed.

FIGURE 20

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Page 16

SURELIGHT CONTROL BOARD

TABLE 5

SURELIGHT CONTROL TERMINAL DESIGNATIONS

ACB COOL ACB HEAT PARK ACB LOW ACC TX HOT HTG ACC NEUTRALS 24VACHOT 24VACRTN FLAME SENSE

Blower - Cooling Speed (Line Volt) Blower - Heating Speed (Line Volt) Alternate Blower Speeds (Dead) Continuous Low Speed Blower Accessory Terminal (Line Volt) 120VACHot to Transformer 120VACHot Input Heat Only Accessory (Line Volt) 120VACNeutrals 24VACHot from Transformer 24VACReturn from Transformer Flame Sense Terminal

FIGURE 21

TABLE 6

DIAGNOSTIC CODES

MAKE SURE TO ID LED’S CORRECTLY: REFER TO INSTALLATION INSTRUCTIONS FOR CONTROL BOARD LAYOUT.

LED #1 LED #2 DESCRIPTION

SIMULTANEOUS

SLOW FLASH

SIMULTANEOUS FAST

FLASH

SLOW FLASH ON

OFF SLOW FLASH

ALTERNATING SLOW

FLASH

SLOW FLASH OFF

ON SLOW FLASH ON

OFF

FAST FLASH SLOW FLASH

SLOW FLASH FAST FLASH

ALTERNATING FAST

FLASH

SIMULTANEOUS

SLOW FLASH

SIMULTANEOUS FAST

ALTERNATING SLOW

ALTERNATING FAST

FLASH

OFF

FLASH

Also signaled during cooling and continues fan.

Normal operation - signaled when heating demand initiated at thermostat.

Primary or Secondary limit open. Units with board 63K8901 or 24L85: Limit must

close within 5 trials for ignition or board goes into one hour limit Watchguard.

Units with board 56L83 or 97L48: Limit must close within 3 minutes or board

Pressure switch open or has opened 5 times during a single call for heat; OR:

Blocked inlet/exhaust vent; OR: Condensate line blocked; OR: Pressure switch

closed prior to activation of combustion air blower.

Flame sensed without gas valve energized.

Rollout switch open. OR: 9 pin connector improperly attached.

Circuit board failure or control wired incorrectly.

Main power polarity reversed. Switch line and neutral.

Low flame signal. Measures below .7 microAmps. Replace flame sense rod.

Improper main ground or line voltage below 75 volts; OR: Broken ignitor; OR:

Power - Normal operation

goes into one hour limit Watchguard.

Watchguard - burners fail to ignite.

Open ignitor circuit.

NOTE - Slowflash equals1 Hz (oneflash persecond). Fast flashequals 3Hz (threeflashes per second).Drop out flamesense current< 0.15microAmps

Page 16

Page 17

TABLE 7

SureLight BOARD J156 (J2) TERMINAL

PIN # FUNCTION

1 Ignitor

2 3 4 5 6

DESIGNATIONS

Not Used

Ignitor Neutral

Combustion Air Blower Line Voltage

Not Used

Combustion Air Blower Neutral

TABLE 8

SureLight BOARD J58 (J1) TERMINAL

PIN # FUNCTION

1 Primary Limit In

2 3 4 5 6 7 8 9

DESIGNATIONS

Gas Valve Common Roll Out Switch Out

Gas Valve 24V

Pressure Switch In

Pressure Switch and Primary Limit Out

Not Used

Roll Out Switch In

Ground

ELECTROSTATIC DISCHARGE (ESD)

Precautions and Procedures

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 thegas valve or blower deck, before performing any service procedure.

a-Electronic Ignition

On a call for heat the SureLight control monitors the combustionair blower pressureswitch. The control will notbegin the heating cycle if the pressure switch is closed (bypassed). Once the pressure switch is determined to be open, the combustion air blower is energized. When the differential in the pressure switch is great enough, the pressure switch closes and a 15-second pre-purge begins. If the pressure switch is not proven within 2-1/2 minutes, the control goes into Watchguard-Pressure Switch mode for a 5-minute re-set period.

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. G23X units equipped with board 24L85, 56L83 or 63K89: the ignitor stays energized for the first second of the 4-second trial. Units equipped with board 97L48: ignitor stays energized duringthetrialuntilflameissensed.If ignition is not proved during the 4-second period, 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 WatchguardFlame Failure mode. After a 60-minute reset period, the control will begin the ignition sequence again. The SureLight control board has an added feature that prolongs the life of the ignitor. After a successful ignition, theSureLightcontrolutilizeslesspowertoenergize the ignitoron successive callsfor heat. Thecontrol continues to rampdown the voltage tothe ignitor until itfinds the lowest amount of power that will provide a successful ignition. It finds this by ramping down until the ignitor will not light, then steps up the amount of power by three times. This amount of power is used for 255 cycles. On the 256th call for heat, the control will again ramp down until the lowest power is determined and the cycle begins again.

b-Fan Time Control

The fan on time of 45 seconds is not adjustable. Fan off time (time that the blower operates after the heat demand has been satisfied) can be adjusted by flipping the dip switches located on the SureLight integrated control. The unit is shipped with a factory fan off setting of 90 seconds. Fan off time will affect comfort and is adjustable to satisfy individual applications. See figure 22.

FAN-OFF TIME ADJUSTMENT

60sec. 90sec. 120sec. 180sec.

To adjust fan-off timing, flip dip switch to desired setting.

FIGURE 22

Page 17

Page 18

J-Gas Valve

TheG23(X) usesa gas valvemanufacturedbyHoneywell or White Rodgers. See figure 23. The valve is internally redundant to assure safety shut-off. If the gas valve must be replaced, the same type valve must be used.

24VAC terminals and gas control knob are located on top of the valve. All terminals on the gas valve are connected to wires from the ignition control. 24V applied to the “PV” terminals opens the pilot (-1 through -4 models)and 24V appliedto the “MV” terminals opens the valve on G23X. Inlet and outlet pressure taps are located on the valve. A regulator adjustment screw (figure 24) is located on the valve.

An LPG changeover kit is available from Lennox. The kit includes main and pilot burner orifices, burner corbel plate (Nox only), and regulator conversion kit.

K-Combustion Air Blower Prove

(Pressure) Switch (S64)

G23(X) series units are equipped with a combustion air (pressure) switch located on the vestibule panel. The switch is connected tothe combustion airblower housing by means of a flexible silicon hose. It monitors air pressure in the combustion air blower housing. The other side of the pressure switch is open to atmosphere.

The switch is a single-pole single-throw pressure switch electrically connected in series with the ignition control. The purpose of the switch is to prevent burner operation if the combustion air blower is not operating.

On start-up, the switch senses that the combustion air blower is operating. It closes a circuit to the ignition control when pressure inside the combustion air blower increases above the setpoint. The setpoint is measured in negative inches water gauge. The pressure sensed by the switch is relative to atmospheric pressure. If the flue becomes obstructed during operation, the switch senses a loss of negative pressure (drops below setpoint) and opens the circuit to the ignition control .

The switch setpoint varies with unit model number. Look for the setpoint printed on the side of the switch.

The switch is factory set and is not field adjustable. It is a safety shut-down control in the furnace and must not be bypassed for any reason.

HONEYWELL VR8204 SERIES GASVALVE

INLET

GAS VALVE SHOWN IN OFF POSITION

2))

WHITE RODGERS

36E GAS VA

LVE

INLET

GAS VALVE

SHOWN

IN OFF

POSITION

FIGURE 23

WHITE RODGERS 36E GAS VALVE

REGULATOR ADJUSTMENT SCREW LOCATION

REGULATOR

COVER SCREW

$'-867,1*

6&5(:

:KLWH

635,1*

HONEYWELL VR8204 GAS VALVE

REGULATOR ADJUSTMENT SCREW LOCATION

&$3 6&5(:

%ODFN

$'-867,1* 6&5(:

:KLWH

35(6685(

5(*8/$725

635,1*

5HG

,1/(7

35(6685(

7$3

*$6 ,1/(7

FIGURE 24

3DJH 

Page 19

II-PLACEMENT AND INSTALLATION

Make sure unit is installed in accordance with installation instructions and applicable codes.

A-Fresh Air Requirements

Until recently, there was no problem in bringing in sufficient amounts of outdoor air for combustion -- infiltration provided all the air that was needed and then some. In today’s homes built with energy conservation in mind, tight construction practices make it necessary to bring in air from outside for combustion. Consideration must also be given to the use of exhaust fans, appliance vents, chimneys and fireplaces because they draw additionalair that could be used for combustion out of the house. Unless outside air is brought into the home for combustion, negative pressure (pressure outside is greater than inside pressure) will build to the pointthat a down draft can occur in the furnace vent pipe or chimney . Combustion gases can enter the living space creating a potentially dangerous situation.

Theimportanceofthe previous paragraphcannotbeoverstated. Users may inadvertently block fresh air intakes after installation.

In the absence of local codes concerning air for combustion and ventilation, the following section outlines guidelines and recommends procedures for operating G23(X) furnaces in a manner that ensures efficient and safe operation. Special consideration must be given to combustion air needs as well as requirements for exhaust vents and gas piping. A portion of this information has been reprinted with permission from the National Fuel Gas Code (ANSI-Z223.1). This reprinted material is not the complete and official position of the ANSI on the referenced subject, which is represented only by the standard in its entirety .

In Canada, refer to the standard CAN/CGA-B149.1 and B149.2 installation codes.

Combustion Air Requirements

&$87,21

Insufficient combustion air can cause headaches, nausea, dizziness or asphyxiation. Excessive exposure to contaminated combustion air will result in safety and performance related problems. Avoidexposuretothe following substances in the combustion air supply: Permanent wave solutions; Chlorinated waxes and cleaners; Chlorine base swimming pool chemicals; Water softening chemicals; De-icing salts or chemicals; Carbon tetrachloride; Halogen type refrigerants; Cleaning solvents (such as perchloroethylene); Printing inks, paint removers, varnishes, etc.; Hydrochloric acid; Cements and glues; Antistatic fabric softeners for clothes dryers; and Masonry acid washing materials.

All gas-fired appliances require air to be used for the combustion process. If sufficient amounts of combustion air are not available, the furnace or other appliance will operate in an inefficient and unsafe manner . Enough air must be provided to meet the needs of all fuel-burning appliances, as well as appliances such as exhaust fans which force air out of the home. When fireplaces, exhaust fans, or clothes dryers are used at the same time as the furnace,much more air is required to ensure proper combustion and to prevent a down-draft situation. Insufficient amounts of air also cause incomplete combustion which can result in carbon monoxide. The requirements for providing air for combustion and ventilationdepend largely onwhether the furnace is installed in an unconfined or confined space.

Unconfined Space

An unconfined space is an area such as a basement or largeequipmentroomwithavolumegreaterthan 50cubic feetper 1,000 Btu per hour of thecombined input rating of all appliances installed in that space. This space also includesadjacent rooms which are not separated by adoor. Though an area may appear to be unconfined, it might be necessary to bring in outdoor air for combustion if the structure does not provide enough air by infiltration. If the furnace is located in a building of tight construction with weather stripping and caulking around the windows and doors,followthe procedures outlined for using air fromthe outside for combustion and ventilation.

Confined Space

A confined space is an area with volume less than 50 cubic feetper 1,000 Btu per hour of the combined input rating of all appliances installed in that space. This definition includes furnace closets or small equipment rooms.

3DJH 

Page 20

Whenthefurnace is installed sothatsupplyducts carryair circulated by the furnace to areas outside the space containingthefurnace,thereturnairmustbehandledbyducts which are sealed to the furnace casing and which terminate outside the space containing the furnace. This is especially important when the furnace is mounted on a platform in a confined space such as a closet or small equipment room. Even a small leak around the base of the unit at the platform or at the return air duct connection can cause a potentially dangerous negative pressure condition.Airforcombustion and ventilation can be brought into the confined space either from inside the building or from outside.

Air from Inside

If the confined space housing the furnace adjoins space categorizedasunconfined,air canbebroughtinbyprovid-

Air from Outside

Ifair from outsideis brought in forcombustion and ventilation,theconfined space shallbeprovidedwithtwo permanent openings. One opening shall be within 12 inches of the top of the enclosure and one within 12 inches of the bottom. These openings must communicate directly or by ductswiththeoutdoorsorspaces(crawlor attic) thatfreely communicate with the outdoors or indirectly through verticalducts.Eachopeningshallhaveaminimumfreeareaof 1square inch per 4,000Btu per hour of totalinput rating of all equipment in the enclosure (See figures 26 and 27). When communicating with the outdoors through horizontalducts, each opening shall have a minimumfree areaof 1 square inch per 2,000 Btu per total input rating of all equipment in the enclosure (See figure 28).

EQUIPMENT IN CONFINED SPACE

ALL AIR FROM OUTSIDE

(Inlet Air from Crawl Space and

CHIMNEY

OR GAS

VENT

Outlet Air to Ventilated Attic)

VENTILATION LOUVERS

(Each end of attic)

ing two permanent openings between the two spaces. Eachopening must have aminimum free areaof 1 square inch per 1,000 Btu per hour of the total input rating of all gas-fired equipment in the confined space. Each opening must be at least 100 square inches. One opening shall be within12 inchesof the top of the enclosure and one opening within 12 inches of the bottom (See figure 25).

EQUIPMENT IN CONFINED SPACE

ALL AIR FROM INSIDE

CHIMNEY OR

GAS VENT

WATER

G23(X)

FURNACE

HEATER

OPENINGS

(To Adjacent

Room)

G23

FURNACE

VENTILATION

LOUVERS

(For unheated

crawl space)

OUTLET

AIR

WATER

HEATER

INLET

AIR

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

FIGURE 26

EQUIPMENT IN CONFINED SPACE

CHIMNEY

OR GAS

VENT

G23(X)

FURNACE

ALL AIR FROM OUTSIDE

(All Air Through Ventilated Attic)

VENTILATION LOUVERS

(Each end of attic)

OUTLET

AIR

INLET AIR

(Ends 12 above

bottom)

NOTE-Each openingshall have a free areaof at least one square inch per 1,000 Btu per hour of the total input rating of all equip- ment in the enclosure, but not less than 100 square inches.

FIGURE 25

3DJH 

WATER

HEATER

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

FIGURE 27

Page 21

EQUIPMENT IN CONFINED SPACE

ALL AIR FROM OUTSIDE

CHIMNEY

OR GAS

VENT

WATER

HEATER

OUTLET AIR

G23(X)

FURNACE

INLET AIR

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

FIGURE 28

When ducts are used, they shall be of the same cross-sectional area as the free area of the openings to which they connect. The minimum dimension of rectangular air ducts shall be no less than 3 inches. In calculating free area, the blocking effect of louvers, grilles, or screens must be considered. If thedesign and freearea of protective covering is not known for calculating the size opening required, it may be assumed that wood louvers will have 20 to 25 percent free area and metal louvers and grilles will have 60 to 75 percent free area. Louvers and grilles must be fixed in the openpositionorinterlocked with the equipmentsothatthey are opened automatically during equipment operation.

B-Flue Venting Requirements

G23(X)seriesfurnacesmustbeventedincompliancewith all local codes, the venting tables provided in this manual and these instructions.

The G23(X) series units have been classified as fan assisted Category I type furnaces when vertically vented in accordance with the latest edition of ANSI Z21.47 Central Furnace Standard. The definition of a fan assisted Category I type furnace is an appliance equipped with an integral mechanical means to either draw or force products of combustion through the combustion chamber and/or heat exchanger.

The vent sizing tables in this manual have been extracted fromtheNationalFuelGasCode(NFPA54/ANSI Z223.1) and are provided for convenience to serve as a guideline for proper vent installation. Proper application, termination,constructionandlocationofvents must conform to local codes having jurisdiction. In the absence of local codes, the NFGC serves as the defining document.

Referto the tables and the venting information contained in these instructions for proper sizing and installation of the venting system.

The G23(X) series units have the following flue collar sizes: -50 unit, 3” diameter; -75 and -100 units, 4” diameter; and -125 & -150 units, 5” diameter. Use this informationinconjunctionwiththe providedventingtablestoproperlysizetheventorventconnectorthatattaches to thefurnace flue collar.

Venting Using a Masonry Chimney

The following additional requirements apply when a lined masonry chimney is beingused to vent a G23(X) furnace:

A Category I appliance must never be connected to a chimney that is servicing a solid fuel appliance. If a fireplace chimney flue is used to vent this appliance, the fireplace opening must be permanently sealed.

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Page 22

COMMON VENTING USING TILE-LINED INTERIOR MASONRY

CHIMNEY AND COMBINED VENT CONNECTOR

MINI. LENGTH = AS SHORT

AS PRACTICAL.

OTHER

APPLIANCE

G23

FIGURE 29

A chimney with one or more sides exposed to the outside of the structure is considered to be an exterior chimney.A TypeBorlistedchimneyliningsystempassingthroughan unused masonry chimney flue is not considered to be exposed to the outdoors.

Masonry chimneys used to vent Category I central furnaces must be either tile-lined or lined with a listed metal lining system or dedicated gas vent. Unlined masonry chimneys are prohibited.

A fan assisted furnace may be commonly vented into an existing lined internal masonry chimney provided:

1 - The chimney is currently serving at least one draft-

hood equipped appliance.

2 - The vent connectors and chimneyare sized in accor-

dance with the provided venting tables.

SINGLE

APPLIANCE VENTING OF A FAN ASSISTED FURNACE INTO A TILE-LINED MASONRY CHIMNEY (INTERIOR OR OUTSIDE WALL) IS

PROHIBITED

.THE CHIMNEY MUST FIRST BE LINED WITH EITHER TYPE “B” VENT OR AN INSULATEDSINGLE WALL FLEXIBLE VENTLININGSYSTEM,SIZEDIN ACCORDANCE WITH THE PROVIDED VENTING TABLES.

See figures 29 and 30 for common venting. A Type “B” vent or masonry chimney liner shall terminate

above the roof surface with a listed cap or a listed roof assembly in accordance with the terms of their respective listings and the vent manufacturer’s instructions.

Donotinstallamanualdamper,barometricdraftregulator, or flue restrictor between the furnace and the chimney.

INTERIOR

TILE-LINED MASONRY

CHIMNEY

NOTE - CHIMNEY MUST BE

PROPERLY SIZED PER THE PRO-

VIDED VENTING TABLES OR LINED

WITH LISTED METAL LINING SYSTEM.

VENT

CONNECTOR

(Double-walled, single-walled, or insulated single-

walled pipe)

PERMANENTLY SEALED

FIREPLACE OPENING

If type “B” double-wall vent is used inside a chimney, no otherappliancecanbeventedintothechimney. Outer wall oftype “B” vent pipe mustnot be exposed toflueproducts.

Insulation for the flexible vent pipe must be an encapsulated fiberglass sleeve recommended by the flexible vent pipe manufacturer. See figure 30.

The space between liner and chimney wall should NOT be insulated with puffed mica or any other loose granular insulating material.

COMMON VENTING USING

METAL-LINED MASONRY CHIMNEY

SEALED

MIN. LENGTH -- AS

5FT.

(1.5m)

MINIMUM

4 IN. MIN.

(102mm)

SHORT AS PRACTICAL

PERMANENTLY

SEALED FIREPLACE

CHIMNEY WITH

FLEXIBLE VENT

OPENING

EXTERIOR

“B” VENT OR

INSULATED

FIGURE 30

PIPE.

3DJH 

Page 23

If“B”ventoraninsulatedflexiblevent pipe cannot be used as liners, the chimney must be rebuilt to accommodate oneofthesemethodsorsomealternateapprovedmethod must be found to vent the appliance.

When inspection reveals that an existing chimney is not safefor the intended purpose, itshall be rebuilt toconform to nationally recognized standards, lined or relined with suitable materials or replaced with a gas vent or chimney suitableforventingG23(X)series units. The chimney passageway must be checked periodically to ensure that it is clear and free of obstructions.

General Venting Requirements

All G23(X) furnaces must be vented in accordance with the methods outlined in these instructions.

1 - Vent diameter recommendations and maximum runs

allowed are found in the provided venting tables.

2 - In no case should the vent or vent connector diameter

be less than the diameter specified in the provided venting tables.

For single appliance vents:

If the vertical vent or tilelinedchimney has a larger diameter or flow area than theventconnector,usethe determinethe

minimum vent capacity

verticalventdiameter

andthe vent

connector diameter to determine the maximum ventcapacity. Theflowareaoftheverticalvent,how-

ever, shall not exceed 7 times the flow area of the listedappliancecategorizedventarea,drafthoodoutlet area or flue collar area unless designed in accordance with approved engineering methods.

For multiple appliance vents:

The flow area of the largestsectionofverticalventorchimneyshallnotexceed 7 times the smallest listed appliance categorized vent area, flue collar area or drafthood outlet area unless designed in accordance with approved engineering methods.

5 - The entire length of single wall metal vent connector

shall be readily accessible for inspection, cleaning, and replacement.

6 - Single appliance venting configurations with zero lat-

eral lengths, see tables 9 and 10, are assumed to have no elbowsin the vent system.For all other vent configurations, the vent system is assumed to have two 90Eelbows. For each additional 90Eelbow or equivalent (for example two 45Eelbows equal one 90Eelbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).

7 - The common venting tables 11, 12, 13, and 14 were

generated using a maximum horizontal vent connector length of 1-1/2 feet (18 inches) for each inch of connector diameter as follows:

CONNECTOR

DIAMETER

(INCHES)

3 4-1/2 4 6 5 7-1/2 6 9 7 10-1/2

MAXIMUM HORIZONTAL

CONNECTOR LENGTH

(FEET)

8 - If the common vertical vent is offset, the maximum

common vent capacity listed in the common venting tables should be reduced by 20%, the equivalent of two 90Eelbows (0.80 x maximum common vent capacity).Thehorizontallength oftheoffsetshallnotexceed 1-1/2 feet for each inch of common vent diameter.

9 - The vent pipe should be as short as possible with

the leas t number of elbows and angles to do the job. The vent connector should be routed to the vent utilizing the shortest possible route.

10- A vent connector shall be supported without any dips

or sags and shall slope a minimum of 1/4” per linear foot of connector, back towards the appliance.

11- Vent connectors shall be firmly attached to furnace

flue collars by sheet metal screws or other approved means,exceptventconnectorsoflistedType“B”vent material which shall be assembled in accordance with the manufacturer’s instructions. Joints between sections of single wall connector piping shall be fastened by sheet metal screws or other approved means.

12- When the vent connector used for Category I ap-

pliances must be located in or pass through a crawl space or other areas which may be cold, that portion of the vent connector shall be listed double-wall Type B vent material or material having equivalent insulation qualities.

13- All venting pipe passing through floors, walls, and

ceilings must be installed with the listed clearance to combustible materials and be fire stopped according to local codes. In absence of local codes, refer to NFGC (Z223.1).

14- No portion of the venting system can extend into, or

pass through any circulation air duct or plenum.

15- Vent connectors serving Category I appliances shall

not be connected to any portion of mechanical draft systems operation under positive pressure such as Category III or IV venting systems.

16- If vent connectors are combined prior to entering the

common vent, the maximum common vent capacity listed in the common venting tables must be reduced by 10%, the equivalent of one 90Eelbow (0.90 x maximum common vent capacity).

17- Common vent diameter must always be at least as

large as the largest vent connector diameter.

3DJH 

Page 24

18- In no case, shall the vent connector be upsized more

(feet)

than two consecutive table size diameters over the size of the drafthood outlet or flue collar outlet.

19- A manual damper, barometric draft regulator or flue

restrictor must not be installed between furnace and any chimney.

20- When connecting this appliance to an existing dedi-

cated or common venting system, the venting system, must be inspected for signs of corrosion, and general condition. The sizing of the vent system must be reviewed and conform to these instructions and the provided venting tables. If the existing system is in conflict with these requirements, the venting system must be resized.

TABLE 9

CAPACITY OF TYPE B DOUBLE-WALL VENTS WITH TYPE B DOUBLE-WALL CONNECTORS

SERVING A SINGLE CATEGORY I APPLIANCE

Vent and Connector Diameter - D (inches)

Height

(feet)

NOTE: Singleappliance venting configurations with zerolateral lengths areassumed to haveno elbows inthe ventsystem. For allother vent configura- tions,the ventsystem is assumedto havetwo 90 beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).

Lateral

(feet)

0 0 78 0 152 0 251 0 375 2 13 51 18 97 27 157 32 232 4 21 49 30 94 39 153 50 227 6 25 46 36 91 47 149 59 223 0 0 84 0 165 0 276 0 415 2 12 57 16 109 25 178 28 263 5 23 53 32 103 42 171 53 255 8 28 49 39 98 51 164 64 247 0 0 88 0 175 0 295 0 447 2 12 61 17 118 23 194 26 289 5 23 57 32 113 41 187 52 280

10 30 51 41 104 54 176 67 267

0 0 94 0 191 0 327 0 502 2 11 69 15 136 20 226 22 339

5 22 65 30 130 39 219 49 330 10 29 59 40 121 51 206 64 315 15 35 53 48 112 61 195 76 301

0 0 97 0 202 0 349 0 540

2 10 75 14 149 18 250 20 377

5 21 71 29 143 38 242 47 367 10 28 64 38 133 50 229 62 351 15 34 58 46 124 59 217 73 337 20 48 52 55 116 69 206 84 322

0 0 100 0 213 0 374 0 587

2 9 81 13 166 14 283 18 432

5 21 77 28 160 36 275 45 421 10 27 70 37 150 48 262 59 405 15 33 64 44 141 57 249 70 389 20 56 58 53 132 66 237 80 374 30 NR NR 73 113 88 214 104 346

3 Inch 4 Inch 5 Inch 6 Inch

Appliance Input Rating in Thousands of Btu Per Hour

MIN MAX MIN MAX MIN MAX MIN MAX

elbows.For eachadditional 90Eelbowor equivalent(for example two45Eelbowsequal one90Eelbow)

3DJH 

Page 25

TABLE 10

(feet)

CAPACITY OF TYPE B DOUBLE-WALL VENTS WITH SINGLE-WALL METAL CONNECTORS

SERVING A SINGLE CATEGORY I APPLIANCE

Vent and Connector Diameter - D (inches)

Height

(feet)

Lateral

(feet)

0 38 77 59 151 85 249 126 373

2 39 51 60 96 85 156 123 231

4 NR NR 74 92 102 152 146 225

6 NR NR 83 89 114 147 163 220

0 37 83 58 164 83 273 123 412

2 39 56 59 108 83 176 121 261

5 NR NR 77 102 107 168 151 252

8 NR NR 90 95 122 161 175 243

0 37 87 57 174 82 293 120 444

2 39 61 59 117 82 193 119 287

5 52 56 76 111 105 185 148 277 10 NR NR 97 100 132 171 188 261

0 36 93 56 190 80 325 116 499

2 38 69 57 136 80 225 115 337

5 51 63 75 128 102 216 144 326 10 NR NR 95 116 128 201 182 308 15 NR NR NR NR 158 186 220 290

0 35 96 54 200 78 346 114 537

2 37 74 56 148 78 248 113 375

5 50 68 73 140 100 239 141 363 10 NR NR 93 129 125 223 177 344 15 NR NR NR NR 155 208 216 325 20 NR NR NR NR 186 192 254 306

0 34 99 53 211 76 372 110 584

2 37 80 55 164 76 281 109 429

5 49 74 72 157 98 271 136 417 10 NR NR 91 144 122 255 171 397 15 NR NR 115 131 151 239 208 377 20 NR NR NR NR 181 223 246 357 30 NR NR NR NR NR NR NR NR

3 Inch 4 Inch 5 Inch 6 Inch

Appliance Input Rating in Thousands of Btu Per Hour

MIN MAX MIN MAX MIN MAX MIN MAX

elbows.For eachadditional 90Eelbowor equivalent(for example two45Eelbowsequal one90Eelbow)

3DJH 

Page 26

TABLE 11

Vent

Height

Rise

Height

CAPACITY OF TYPE B DOUBLE-WALL VENTS WITH TYPE B DOUBLE-WALL CONNECTORS

SERVING TWO OR MORE CATEGORY I APPLIANCES

VENT CONNECTOR CAPACITY

Height

(feet) (feet)

onnector

Rise

3 Inch 4 Inch 5 Inch 6 Inch

MIN MAX MIN MAX MIN MAX MIN MAX

1 22 37 35 66 46 106 58 164 2 23 41 37 75 48 121 60 183 3 24 44 38 81 49 132 62 199 1 22 40 35 72 49 114 64 176 2 23 44 36 80 51 128 66 195 3 24 47 37 87 53 139 67 210 1 22 43 34 78 49 123 65 189 2 23 47 36 86 51 136 67 206 3 24 50 37 92 52 146 69 220 1 21 50 33 89 47 142 64 220 2 22 53 35 96 49 153 66 235 3 24 55 36 102 51 163 68 248 1 21 54 33 99 46 157 62 246 2 22 57 34 105 48 167 64 259 3 23 60 35 110 50 176 66 271 1 20 62 31 113 45 181 60 288 2 21 64 33 118 47 190 62 299 3 22 66 34 123 48 198 64 309

Vent and Connector Diameter - D (inches)

Appliance Input Rating in Thousands of Btu Per Hour

TABLE 12

CAPACITY OF TYPE B DOUBLE-WALL VENTS WITH TYPE B DOUBLE-WALL CONNECTORS

SERVING TWO OR MORE CATEGORY I APPLIANCES

COMMON VENT CAPACITY

ent

Hei

(feet)

6 92 81 140 116 204 161 309 248

8 101 90 155 129 224 178 339 275 10 110 97 169 141 243 194 367 299 15 125 112 195 164 283 228 427 352 20 136 123 215 183 314 255 475 394 30 152 138 244 210 361 297 547 459

FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT

4 Inch 5 Inch 6 Inch 7 Inch

Appliance Input Rating in Thousands of Btu Per Hour

Common Vent Diameter - D (inches)

3DJH 

Page 27

TABLE 13

Height

Rise

Height

CAPACITY OF TYPE B DOUBLE-WALL VENT WITH SINGLE-WALL METAL CONNECTORS

SERVING TWO OR MORE CATEGORY I APPLIANCES

VENT CONNECTOR CAPACITY

Vent

Hei

(feet) (feet)

onnector

Rise

3 Inch 4 Inch 5 Inch 6 Inch

MIN MAX MIN MAX MIN MAX MIN MAX

1 NR NR NR NR NR NR NR NR 2 NR NR NR NR NR NR 168 182 3 NR NR NR NR 121 131 174 198 1 NR NR 79 87 116 138 177 214 2 NR NR 83 94 121 150 185 230 3 NR NR 87 100 127 160 193 243 1 47 60 77 110 113 175 169 278 2 50 62 81 115 117 185 177 290 3 54 64 85 119 122 193 185 300

Vent and Connector Diameter - D (inches)

Appliance Input Rating in Thousands of Btu Per Hour

TABLE 14

CAPACITY OF TYPE B DOUBLE-WALL VENTS WITH SINGLE-WALL METAL CONNECTORS

SERVING TWO OR MORE CATEGORY I APPLIANCES

COMMON VENT CAPACITY

ent

Hei

(feet)

6 89 78 136 113 200 158 304 244

8 98 87 151 126 218 173 331 269 10 106 94 163 137 237 189 357 292 15 121 108 189 159 275 221 416 343 20 131 118 208 177 305 247 463 383 30 145 132 236 202 350 286 533 446

FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT

4 Inch 5 Inch 6 Inch 7 Inch

Appliance Input Rating in Thousands of Btu Per Hour

Common Vent Diameter - D (inches)

Removal of Unit from Common Venting System

In the event that an existing furnace is removed from a venting system commonly run with separate gas appliances, the venting system is likely to be too large to properly vent the remaining attached appliances. The followingtestshouldbeconducted whileeach appliance is in operationandthe otherappliancesnotinoperationremain connected to the common venting system. If the venting systemhas been installed improperly,thesystemmustbe corrected as outlined in the previous section.

1 - Seal any unused openings in the common venting

system.

2 - Visually inspect the venting system for proper size

and horizontal pitch and determine there is no blockage or restriction, leakage, corrosion and other deficiencies which could cause an unsafe condition.

3 - Insofar as is practical, close allbuilding doors and win-

dowsand all doors between the spaceinwhich the appliances remaining connected to the common venting system are located and other spaces of the building. Turn on clothes dryers and any appliances not connectedtothecommonventing system. Turnonanyex-

haust fans, such as range hoods and bathroom exhausts,so they will operate at maximum speed.Donot operate a summer exhaust fan. Close fireplace dampers.

4 - Following the lighting instruction, place the appliance

being inspected in operation. Adjust thermostat so appliance will operate continuously.

5 - Testfor spillageatthedrafthoodreliefopeningafter5

minutes of main burner operation. Use the flame of a match or candle, or smoke from a cigarette, cigar or pipe.

6 - After it has been determined that each appliance re-

maining connected to the common venting system properly vents when tested as outlined above, return doors,windows,exhaustfans,fireplacedampersand any other gas burning appliance to their previous condition of use.

7 - If improper venting is observed during any of the

above tests, the common venting system must be corrected.Thecommonventingsystemshouldberesizedtoapproachtheminimumsizeasdeterminedby using the appropriate tables in appendix G in the current standards of the National Fuel Gas Code ANSI Z223-1.

3DJH 

Page 28

Horizontal Venting

SIDE WALL VENTING KIT WIRING

CK-43 CONTROL BOX

PRESSURE

SWITCH

L1 MN

120VAC

354

RELAY

T1 T2 T3

SWG

POWER

VENTER

MOTOR

FIGURE 31

THERMOSTATCONNECTIONS

TERMINAL IN FURNACE

JUNCTION BOX

WR Y G

FACTORY INSTALLED WIRING FIELD INSTALLED WIRING

24 VAC

THERMOSTAT

WARNING

Donotusethis furnaceifanyparthas been underwater.Inspectthe furnace and replace any part of thecontrolsystemand any gas control which has been under water.

CAUTION

Beforeattemptingtoperformanyserviceormaintenance, turn the electrical power to unit OFF at disconnect switch.

WARNING

If overheating occurs or if gas supply failsto shut off,shut off the manual gas valve to the appliance before shutting off electrical supply.

This furnace is design certified by the American Gas Association for horizontal venting through an outside wall only with the use of a Field Controls Company Model SWG-4L side wall venting kit available from Lennox Dealer Service Center. No other Field brand venting kit or any other manufacturer’s venting kit is acceptable. Horizontal venting of this furnace without the use of the above stated kit is prohibited. See figure 31 for field wiring of side wall horizontal venting kit.

When horizontally vented, minimum clearance for termination from electric meters, gas meters, regulators and relief equipment is 4 ft. (1.2m).

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

withinrangelistedon thenameplate.Ifnot,consultthe powercompany and have voltage conditioncorrected before starting unit.

B-Heating Start-Up

FOR YOUR SAFETY READ BEFORE LIGHTING

WARNING

Shock and burn hazard. G23(X)-1 through -4 model units are equipped with

an electronic spark ignition system. Do not attempt to light manually.

BEFORE LIGHTING smell all around the appliance area for gas. Be sure to smell next to the floor because some gas is heavier than air and will settle on the floor.

Useonlyyour hand topushin or turn thegas control knob. Neverusetools.Iftheknobwillnotpushinorturnbyhand, do not try to repair it, call a qualified service technician. Forceor attempted repair may result in afire or explosion.

G23(X) -1 through -4 model units are equipped with an intermittent pilot ignition system. Do not

attempt to manually light pilot on these furnaces. Each time thermostat calls for heat, the pilot will be automatically lit. The pilot does not burn when there is no call for heat.

How To Operate Gas Valve (Figure 33)

WARNING

If you do not follow these instructions exactly, a fire or explosion may result causing property damage, personal injury or loss of life.

Gas Valve Operation (Figure 33)

1- STOP! Read the safety information at the beginning

of this section. 2 - Set thermostat to lowest setting. See figure 32. 3 - Turn off all electrical power to appliance.

THERMOSTATS

WARNING

Shock and burn hazard. G23(X)-5 and -6 model units are equipped with the

SureLight ignition system. Do not attempt to light manually..

FIGURE 32

3DJH 

Page 29

4 - This appliance is equipped with an ignition device

which automatically lights the furnace. Do not try to

light the furnace by hand. 5 - Remove upper access panel. 6 - On Honeywell VR8204 gas valves, turn knob on gas

valve clockwise

to OFF. For White Rodgers 36E gasvalves,moveswitchtoOFF.Donotforce.Seefig- ure 33.

HONEYWELL VR8204 SERIES GASVALVE

2))

GAS VALVE SHOWN IN OFF POSITION

WHITE RODGERS

36E GAS VALVE

GAS VALVE

SHOWN

IN OFF

POSITION

FIGURE 33

7 - Wait five (5) minutes to clear out any gas. If you then

smell gas,

STOP

! Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions. If you do not smell gas go to next step.

8 - For Honeywell VR8204 gas valves, turn knob on gas

valve counterclockwise

toON. For White Rodg-

ers 36E gas valves, move switch toON.

9 - Replace upper access panel. 10- Turn on all electrical power to unit. 11- Set thermostat to desired setting.

127(

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PD\ QHHG WR EH UHSHDWHG WR SXUJH DLU IURP SLORW OLQH

12- Iftheappliancestillwillnotoperate,followtheinstruc-

tions “To Turn Off Gas To Unit” and call your service technician or gas supplier.

C-Safety or Emergency Shutdown

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

D-Extended Period S hutdown

Turnoffthermostatorsetto“UNOCCUPIED”mode.Close allgasvalves(bothinternalandexternaltounit)toguarantee no gas leak into combustion chamber. Turn off power tounit.All access panels,covers and vent caps must bein place and secured.

IV-HEATING SYSTEM SERVICE CHECKS A-A.G.A Certification

All units are A.G.A. design certified without modifications. Refer to the G23(X) Operation and Installation Instruction Manual Information.

B-Gas Piping

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. See table 16 for gas pipe capacity.

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 damagedif subjectedtomorethan 0.5psig(14”W.C.).Seefigure34 thepressureisequaltoor less than 0.5psig(14”W.C.),use the manual shut-off valve before pressure testing to isolate furnace from gas supply.

GAS PIPING TEST PROCEDURE (Typical)

MANUAL MAIN

SHUT-OFF

VALVE

UNION

TEE

GAS VALVE

To Turn Off Gas To Unit

1 - Set thermostat to lowest setting.

2 - Turn off all electrical power to unit if service is to be

performed. 3 - Remove upper access panel. 4 - On Honeywell VR8204 gas valves, turn knob on gas

valve clockwise

to OFF. For White Rodgers 36E

gas valves, move switch to OFF. Do not force. 5 - Replace upper access panel.

3DJH 

1/8” NPT

PLUGGED

TAP

CONDENSATE

TRAP

GAS VALVE WILL NOT HOLD

TEST PRESSURE IN EXCESS

OF 0.5 PSIG (14W.C.)

CAP

FIGURE 34

Page 30

MAIN SHUT-OFF

gaug

GROUND

JOINT

UNION

1/8” NPT

PLUGGED

TAP

RIGHT SIDE PIPING

AUTOMATIC

GAS VALVE

MANUAL

VALVE

AUTOMATIC

GAS VALVE

LEFT SIDE PIPING

(STANDARD)

MANUAL

MAIN SHUT-OFF

VALVE

GROUND

JOINT

UNION

1/8” NPT

PLUGGED

TAP

IMPORTANT

For safety, connect a shut-off valve between the manometer and the gas tap to permit shut off o f gas pressure to the manometer.

Unit (Fuel)

GAS VALVE REGULATION

Natural L.P.

The gas valve is factory set and should not require ad- justment. See table 15.

Manifold Adjustment Procedure:

1 - Connect a test gauge to outlet pressure tap on gas

valve. Start unit and allow 5 minutes for unit to reach steady state.

2 - While waiting for the unit to stabilize, notice the flame.

Flame should be stable and should not lift from burner. Natural gas should burn blue. L.P. gas should burn mostly blue with some orange streaks.

3 - After allowing unit to stabilize for 5 minutes, record

manifold pressure and compare to values given in table 15.

TABLE 15

Operating Pressure (outlet) in. W.C.

3.5 + 0.3

0.5

10.0 +

FIGURE 35

When checkingpipingconnections forgas leaks, use preferred means. Kitchen deter sion on various metals used in

ents can cause harmful corro-

as piping. Use of a specialt

Gas Leak Detector is stronglyrecommended. It is available

h Lennox under part number 31B2001. See Corp.

throu 841 1-L10, for further details.

Donotusematches,candles, flame or an i

nition to check forgas leaks.

othersourceof

D-Check Manifold Pressure

Afterlinepressure has been checkedandadjusted,check manifold pressure. Move pressure sure tap located on unit

as valve(GV1). Checks of manifold pressure are made as verification of proper re ad

ustment. Manifold pressure for the G23(X)can be mea-

suredat an

time thegas valve is open and is supplyin

to the unit. Normal manifold pressure for natural

3.5 in. w.c. For LP

as the correct manifold pressure is 10.0

in. w.c.

etooutletpres-

ulator

as units is

IMPORTANT

For safety, shut unit off and remove manometer as soon as an accurate reading has been obtained. Take care to replace pressure tap plug.

E-Testing Gas Supply Pressure

When testing supply gas pressure, connect test gauge to inlet pressure tap (field provided). 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. For natural gas units, operating pressure at unit gasconnectionmustbebetween4.5”W.C.and13.0”W.C. For L.P. gas units, operating pressure at unit gas connection must be between 10.5” W .C.and 13.0” W.C.

Onmultipleunitinstallations, each unit shouldbechecked separately,with and without units operating. Supply pressure must fall within range listed in previous paragraph.

3DJH 

Page 31

GAS PIPE CAPACITY - FT3/HR (kL/HR)

NominalInternal

Nominal

Interna

G23(X

)

FUE

TABLE 16

Length of Pipe-Feet(m)

Iron Pipe Size

-Inches(mm)

1/4

(6.35)

3/8

(9.53)

1/2

(12.7)

3/4

(19.05)

(25.4)

1-1/4

(31.75)

1-1/2

(38.1)

(50.8)

2-1/2

(63.5)

(76.2)

(101.6)

NOTE-Capacity given in cubic feet of gas per hour (kilo liters of gas per hour) and based on 0.60 specific gravity gas.

Diameter

-Inches(mm)

.364

(9.246)

.493

(12.522)

.622

(17.799)

.824

(20.930)

1.049

(26.645)

1.380

(35.052)

1.610

(40.894)

2.067

(52.502)

2.469

(67.713)

3.068

(77.927)

4.026

(102.260)

(3.048)20(6.096)30(9.144)40(12.192)50(15.240)60(18.288)70(21.336)80(24.384)90(27.432)

(1.13)

(2.69)

175

(4.96)

360

(10.19)

680

919.25) 1400

(39.64)

2100

(59.46)

3950

(111.85)

6300

(178.39)

11000

(311.48)

23000

(651.27)

(.82)

(1.84)

120

(3.40)

250

(7.08)

465

(13.17)

950

(26.90)

460

(41.34)

2750

(77.87)

4350

(123.17)

7700

(218.03)

15800

(447.39)

(.68)

(1.47)

(2.75)

200

(5.66)

375

(10.62)

770

(21.80)

1180

(33.41)

2200

(62.30)

3520

(99.67)

6250

(176.98)

12800

(362.44)

(.57)

(1.27)

(2.32)

170

(4.81)

320

(9.06)

660

(18.69)

990

(28.03)

1900

(53.80)

3000

(84.95

5300

(150.07)

10900

(308.64)

(.51)

(1.13)

(2.07)

151

(4.28)

285

(8.07)

580

(16.42)

900

(25.48)

1680

(47.57)

2650

(75.04)

4750

(134.50)

9700

(274.67)

(.45)

(1.02)

(1.87)

138

(3.91)

260

(7.36)

530

(15.01)

810

(22.94)

1520

(43.04)

2400

(67.96)

4300

(121.76)

8800

(249.18)

(.42)

(.73)

(1.73)

125

(3.54)

240

(6.80)

490

(13.87)

750

(21.24)

1400

(39.64)

2250

(63.71)

3900

(110.43)

8100

(229.36)

(.40)

(.88)

(1.61)

118

(3.34)

220

(6.23)

460

(13.03)

690

(19.54)

1300

(36.81)

2050

(58.05)

3700

(104.77)

7500

(212.37)

(.37)

(.82)

(1.50)

110

(3.11)

205

(5.80)

430

(12.18)

650

(18.41)

1220

(34.55)

1950

(55.22)

3450

(97.69)

7200

(203.88)

100

(30.480)

(.34)

(.76)

(1.42)

103

(2.92)

195

(5.52)

400

(11.33)

620

(17.56)

1150

(32.56)

1850

(52.38)

3250

(92.03)

6700

(189.72)

F- Proper Gas Flow (Approximate)

Furnac e should operate at least 5 minutes before checking gas flow. Determine time in sec onds for two revolutions of gas through the meter. (Two revolutions as sures amore acc urate time.)Dividebytwo andcompare totime in table 17 below. Adjust manifold pressure on gas valve to match time needed.

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

TABLE 17

GAS METER CLOCKING CHART

Seconds for One Revolution

G23(X)

Unit

Natural LP

1 cu ft

Dial

2 cu ft

Dial

1 cu ft

Dial

2 cu ft

DIAL

-50 72 144 180 360

-75 48 96 120 240

-100 36 72 90 180

-125 29 58 72 144

-150 24 48 60 120

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

G-High Altitude Derate

Pressure regulator may need to be adjusted, depending onaltitude. See table18 for properpressure regulator setting.

TABLE 18

Manifold Absolute Pressure (Outlet) in. w.c.

ALTITUDE

0 - 4500 4501 - 5500 5501 - 6500 6501 - 7500

NAT. GAS 3.5 3.3 3.1 3.0

L.P. GAS 10.0 10.0 10.0 10.0

A natural to LP/propane gas changeover kit is required to convert unit. Refer to the installation instructions supplied with the changeover kit for conversion procedure.

The pressure switch is factory set. No adjustment is necessary. The G23-50/75 units use the factory pressure switch from 0 to 7500 feet. G23-100/125 and G23-150 units require a high altitude pressure switch for units installed above 5000 feet. Order Lennox part number 97J50 for G23-100/125 and 18J35 for G23-150.

H-Flame Signal

Amicroamp DC meteris needed tocheck the flamesignal on the ignition control.

Flame(microamp)signalisan electricalcurrentwhichpasses fromthe furnacecontrolthroughthesensorduringunitoperation. Current passes from the sensor through the flame to ground to complete a safety circuit.

Page 31

Page 32

To Measure Flame Signal-G776 Ignition Control:

G23(X) 1,2,3

models

A transducer (Part #78H5401 available from Lennox Repair Parts) is required to measure flame signal. See figure 36. The transducer converts microamps to volts on a 1:1 conversion. If the flame signal should read 0.15-0.25 microamps, a reading of 0.15-0.25 volts should be read on the meter. See table 19 for correct microamp reading.

Adigitalreadoutmeter must be used.Thetransducer plugs into most meters.

FLAME SIGNAL MICROAMPS

G23(X) -1, -2, -3

and -4 models

G23(X) -5 and -6

1 - Setthevoltmeterto theDCvoltagescale.Inserttrans-

ducerinto the VDC andcommon inputs. Observe correct polarities. Failure to do so results in negative (-)

values. 2 - Turn off supply voltage to control. 3 - Disconnect flame sensorleadfromterminalofignition

control. 4 - Connect (+) lead of transducer to ignition control sen-

sor connection. 5 - Connect (-) lead of the transducer to sensor wire. 6 - Turnsupply voltageon and close thermostat contacts

to cycle system. 7 - When unit lights read voltage on meter display. Re-

member 1 DC volt = 1 DC microamp. See table 19 for

correct microamp reading.

TRANSDUCER

(PART #78H5401)

FIGURE36

TABLE 19

Normal 0.25

Minimum 0.15

Normal

Low

Minimum 0.15

 $

0.7

WARNING

Fire and explosion hazard. These instructions MUST be followed exactly. Cancauseafireorexplosionresultinginproperty damage, personal injury or loss of life.

Flamesignal may rise above 0.5 microamps for the first few sec onds after ignition and then level off within the range.

V-TYPICAL OPERA TING CHARACTERISTICS A-Blower Operation and Adjustment

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

1 - Blower operation is dependent on thermostat control

system.

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

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

3 - In all cases, blower and entire unit will be off when the

system switch is in OFF position.

B-Temperature Rise

Temperature rise for G23(X) units depends on unit input, blower speed, blower horsepower and static pressure as markedontheunitrating plate. The blower speedmustbe setfor unitoperationwithintherangeof “AIRTEMP. RISE

F” listed on the unit rating plate.

To Measure Temperature Rise:

1 - Place plenum thermometers in the supply and re-

turn 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 ex- changer.

2 - Set thermostat to highest setting. After furnace

reaches equilibrium, (approximately 15 minutes) check firing rate.

3 - After plenum thermometers have reached their

highest and steadiest readings, subtract the two readings. The difference should be in the range listed on the unit rating plate. If the temperature is too low, decrease blower speed. If temperature is too high, increase blower speed to reduce temper- ature. To change blower speed taps see the Blow- er Speed Taps section in this manual.

C-External Static Pressure

1 - Measure tap locations as shown in figure 37. 2 - Punch a 1/4 diameter

hole in supply (between furnace and coil) and re- turn (between furnace and any add on such as electronic air cleaner) air plenums. Insert manome- ter hose flush with inside edge of hole or insulation. Seal around the hose with permagum. Connect the zero end of the ma- nometer to the discharge (supply) side of the sys- tem. On ducted systems, connect the other end of manometer to the return duct as above. For sys- tems with non-ducted returns, leave the other end of the manometer open to the atmosphere.

3 - With only the blower motor running and the evap-

orator coil dry, observe the manometer reading. Adjust blower motor speed to deliver the air de- sired according to the job requirements.

4 - External static pressure drop must not be more

than 0.5 W.C.

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

STATIC PRESSURE

TEST

MANOMETER

G23(X) UNIT

FIGURE 37

3DJH 

Page 33

G23(X) BLOWER REMOVAL

To Remove Blower:

1. Turn off line voltage power. Unplug J

on blower deck.

2. Disconnect thermostat wiring connections by removing low voltage terminal strip.

3. Disconnect J20/P20 located on blower deck.

4. Disconnect J43/P43 fromblow- er motor.

5. Loosen screws (2) and remove control box from unit. Holes are slotted so screws do not need to be removed.

6. Remove screws (2) and re- move blower from unit.

69 from P69 located

FIGURE 38

D-Blower Speed Taps Leadless Motors

(-1, -2, -3 and -4 Models)

Blower speed tap selection is accomplished by changing the taps at the blowermotor harness connector.Disconnect harness connector from motor to expose speed selectors. Blower speed selections are listed in table 20.

To Change Blower Speed:

1 - Turn off electric power to furnace. 2 - Remove blower acces s door. See figure 1. 3 - Disconnect blower motor harness from motor. 4 - Pull harness connector and wires through blower ac-

cess panel opening.

5 - Select desired speeds for heatingandcooling. (Red=

heating,Black = cooling,White = common).See table

20.

6 - Depress harness connector tab to release wire termi-

nal. Select connector location for new speed (refer to unit wiring diagram). Insert wire terminal until it is securely in place. See figure 39.

7 - Replace harness connector to motor .

TABLE 20

BLOWER SPEED TAP SELECTION

LEADLESS MOTORS

DEPRESS TAB TO RELEASE WIRE TERMINAL. SELECT CONNECTOR LOCATION FOR NEW SPEED(REFER TOUNITWIRING DIAGRAM). INSERT WIREUNTIL IT IS SECURELY IN PLACE.

FIGURE 39

NOTE-Q3(X)-100 furnaces use a 4 tap motor with low speed permanently blocked off so it cannot be used. Do not attempt to operate unit on low speed tap.

E-Blower Speed Taps Leaded Motors

-5 and -6 Models

Blower speed tap changes are made on the SureLight control board. See fi cured on dumm on the SureLi

ht board. The heatingtap is connected to the”ACBHEAT”terminalandthecoolin tothe”ACBCOOL” terminal.Thecontinuous blower tap is connected to the ”ACB LOW” terminal. To chan

eexistingheattap,turn off power then switch out speed tap on ”ACB HEAT” with tap connected to ”PARK M1” or ”PARKM2”. See table 21 for blower motor tap colors for each speed.

ure 21. Unused taps must be se-

terminals ”PARK M1” and or ”PARKM2”

HARNESS

CONNECTOR

MOTOR

tapisconnected

3DJH 

Page 34

TABLE 21

curedandwillnotcomeoffduringcleaning. Attach the other end of the cable to the reversible drill to complete the toolfor cleaning the heat exchanger.Seefigure3 for parts arrangement when disassembling furnace.

1 - Turn off both electrical and gas power supplies to fur-

nace.

2 - Removeflue pipe and top cap from unit.Markanddis-

connect wiring from pressure switch and ignition control (-1 through -4 model units). Remove ignition control and pressure switch from upper vestibule panel.

3 - Removeuppervestibulepaneltoexposethecombus-

tion air blower.

VI-MAINTENANCE A-Filters

Retainers for optional return air filter are shown in figure

40.

%27720 5(7851 ),/7(5

5($5 ),/7(5 &/,3

6,'( ),/7(5 &/,36 

FURNACE

FRONT

RETURN AIR

OPENING

FURNACE

BASE BOTTOM

FURNACE

BACK

),*85( 

At the beginning of each heating season, the system should be checked as follows:

1. Filters should be inspected monthly and must be cleaned or replaced when dirty to assure proper furnace operation.

2. Optional foam filters available for the G23(X) can be washedwithwaterandmilddetergent.Whendry,they should be sprayed with filter handicoater prior to reinstallation. Filter handicoater is RP Products coating no. 418 andis availableas Lennox part no. P-8-5069.

3. If replacement is necessary, order Lennox part no. 31J8101 for 14 X 25 inch filter for G23(X)-50, and 75 units, P-8-7822 for 16 X 25 inch filter for Q3(X)-100 units, and P-8-7831 for 20” x 25 ” filters used on Q3/4(X)-100, Q3/4(X)-125, Q4/5(X)-75,Q4/5(X)-100, Q5/6(X)-125 and Q5/6(X)-150 units.

B-Cleaning Heat Exchanger and Burners

NOTE-Usepapersor protectivecoveringinfrontoffurnace while cleaning furnace.

Cleaning the heat exchanger requires a steel spring “snake,” a reversible drill anda vacuum cleaner.Thesteel springsnakemaybeconstructedbypurchasinga4 ft.long by 1/4” diameter steel wire cable and a 1/4” diameter wire brush. These items are available at a hardware store. Insertwireendofbrushintothe openendofthespringcable. Crimp the cable around the brush so that the brush is se-

G23(X) BURNER AND

HEAT EXCHANGER REMOVAL

G23(X) HEAT EXCHANGER

BURNER BOX ASSEMBLY

FIGURE 41

4 - Remove three screws securing the combustion air

blower. Carefully remove the combustion air blower to avoiddamagingblower gasket. Ifgasket is damaged,it must be replaced to prevent leakage.

5 - Remove collector box located behind combustion air

blower.Caremustbetakentoavoiddamagingthecollector box gasket. If the gasket is damaged it must be replaced to prevent leakage.

6 - Mark then disconnectwires from gasvalve and rollout

switch.

7 - Disconnect gas supply piping. Remove four screws

securing the burner manifold assembly to the lower vestibule panel and remove the assembly from the unit.

8 - For NOx units only, remove the screws holding the

flame baffles in the heat exchanger clam shells. Carefully remove each baffle from each heat exchanger section.Toavoiddamagingbaffles,turnbaffles90Ebefore pulling out through heat exchanger outlet.

IMPORTANT

Mark each baffle so that they are returned to the proper heat exchanger section.

3DJH 

Page 35

G23(X) FLAME BAFFLES

(NOx UNITS ONLY)

17- For NOX units, replace flame baffles in each heat ex-

changer section. DO NOT BEND baffles. Baffles should sit on the bottom of each heat exchanger section.

18- Replace burner / manifold assembly onto lower vesti-

bule panel.

19- Reconnect wires to ignition control (-1 through -4 mod-

elunits), pressureswitch, roll-outswitch, gas valve and

combustion air blower. Refer to unit wiring diagram. 20- Reconnect vent pipe to combustion blower outlet. 21- Reconnect gas supply piping. 22- Turn on power and gas supply to unit.

FLAME BAFFLE

TO REMOVE BAFFLE: REMOVE SCREW. ROTATE BAFFLE AS SHOWN AND REMOVE FROM HEAT EXCHANGER

FIGURE 42

9 - Insert brush end of cable snake into top of one of the

heat exchanger openings. DO NOT FORCE CABLE INTO HEATEXCHANGER. Once the cable has been inserted, operate drill on slow speed. Move the cable in and out of the heat exchanger section three or four times or until sufficient cleaning is accomplished. Re-

verse drill and slowly work cable out of opening. 10- Repeat procedure for each heat exchanger section. 11- When the top heat exchanger sections are complete,

place brush end of cable snake into the bottom openings

of each of the heat exchanger sections. Clean the bottom

opening as described in step 9. 12- Remove cable from heat exchanger.Useavacuum to

remove debris knocked loose during cleaning from

each heat exchanger section. 13- Attach the exhaust end (positive pressure) of the

vacuum to the top of the heat exchanger sections.

Any loose debris will be forced to the bottom of the

heat exchanger section. Vacuum debris from bot-

tom openings. 14- Replace collector box and combustion air blower.

Check gaskets for damage. Damaged seals must be

replaced to avoid heat exchanger leaks. Replace all

screws to the collector box and combustion air blower.

Leaving off screws may cause leaks. 15- Replace upper vestibule panel, top cap, pressure

switch and ignition control. 16- Clean burner by running a vacuum with a soft brush at-

tachment over face of burners. Visually inspect inside of

burners and crossovers for any blockage caused byfor-

eign matter. Remove any blockage.

23- Set thermostat and check for proper operation. 24- Check all piping connections,factoryandfield,forgas

leaks. Use aleak detecting solution or other preferred means.

CAUTION

Somesoaps used for leak detection are corrosive tocertainmetals. Carefullyrinsepipingthoroughly after leak test has been completed. Do not use matches, candles, flame or other sources of ignition to check for gas leaks.

25- Ifaleak is detected, shut gasandelectricity offand

repair leak. 26- Repeat steps 23 and 24 until no leaks are detected. 27- Replace front access panel.

C-Supply Air Blower

1 - Check and clean blower wheel.

2 - Motors used on the LennoxG23(X)seriesunitsare

permanently lubricated and need no

brication.

D-Flue and Chimney

Flue must conform to all AGA/GAMA venting requirements.Fluepipedeterioratesfromtheinsideoutandmust be disconnected in order to check thoroughly. Check flue pipe, chimney and all connections for tightness and to make sure there is no blockage or leaks.

E-Electrical

1 - Check all wiring for loose connections. 2 - Check for correct voltage. 3 - Check amp-draw on blower motor.

further lu-

3DJH 

Page 36

THERMOSTAT

TYPICAL G23(X) FIELD WIRING DIAGRAM

(-5 and -6 MODELS SHOWN)

FLAME

ROLL-OUT

SWITCH

GAS

VALVE

COMBUSTION

AIR PROVE

SWITCH

/,0,7

COMBUSTION AIR BLOWER

FIELD

MAKE-UP

BOX

-

%/$&. :+,7(

%52:1

)86(' ',6&211(&7 6:,7&+

)851,6+(' %< ,167$//(5

/ 1

*1'

TO COMPRESSOR

CONTACTOR

7KHUPRVWDW

*:5<

*:<5

685(/,*+7 &21752/

75$16)250(5

CONTROL

BOX

DOOR

INTERLOCK

SWITCH

),(/' ,167$//(' &/$66 ,, 9 92/7$*( ),(/' ,167$//(' /,1( 92/7$*(

TO ACCESSORY IF USED.

(ELECTRONIC AIR CLEANER)

IF NOT NEEDED, DO NOT INSTALL

ACCESSORY WIRE IN J69.

G23(X) and CONDENSING UNIT

THERMOSTAT DESIGNATIONS

(Refer to specific thermostat and outdoor unit.)

G23(X)

Furnace

Condensing

Unit

POWER

HEAT

COOLING

INDOOR BLOWER

COMMON

&2035(6625

&20021

3DJH 

Page 37









 





OPERATION SEQUENCE-G23(X) -1, -2, -3 and -4 MODELS

1 - When disconnect is closed, 120V is routed through

door interlock switch (S51) to feed the line voltage side of the blower control (A3) and transformer T1 primary. Door interlock switch must be closed for A3 and T1 to receive voltage.

2 - T1 supplies 24VAC to terminal 24VAC on A3. In

turn, terminal R of A3 supplies 24VAC to termi- nal RC of the indoor thermostat (not shown).

3 - When there is a call for heat, W1 of the thermostat

energizes W of the furnace control with 24VAC.

4 - CAB of the blower control energizes the combus-

tion air blower (B6). When the combustion air blower nears full speed, combustion air prove switch (S18) closes.

5 - When S18 closes, assuming the flame rollout

switch (S47) primary limit (S10) and secondary

limits (S21) are closed, the ignition control opens

the pilot valve and begins spark.

6 - When flame is sensed, spark stops and main valve

opens to light main burners.

7 - After 45 seconds, blower control (A3) energizes

the indoor blower. 8 - When heat demand is satisfied, W1 of the thermo-

stat de-energizes W of the furnace control and the

furnace control immediately de-energizes the gas

valve. The combustion air blower immediately

stops. Also, the indoor blower runs for a desig-

nated period (90-330 seconds) as set by jumper on

blower control.

3DJH 

Page 38

BCC

TROUBLESHOOTING

FLOWCHART

START

YES

DOES UNIT OPERATE?

CHECK CIRCUIT BREAKER.

RESET IF NECESSARY.

REPLACE

BCC

(REMOVE R & G JUMPER)

120VACACROSS

N1 & CAB?

120VACACROSS

N1 & ACC?

YES

JUMPER ACROSS

R &W

COMB. AIR BLOWER

ON?

YES

COMBUSTION

AIR BLOWER

YES

CHECK

YES

24VACACROSS

R & T?

JUMPER ACROSS

SCREWS R & G

BLOWER

RUNNING ON HIGH

SPEED?

ARE BURNERS

LIT?

YES

2-INTERLOCK SWITCH

CHECK:

1-UNIT POWER

3-TRANSFORMER

4-LIMIT SWITCH

120VACACROSS

N1 & A?

YES

CHECK BLOWER

WIRING AND

BLOWER

1-COMBUSTION AIR BLOWER

REPLACE

2-IGNITION CONTROL

3-GAS VALVE

4-IGNITOR

5-LIMIT SWITCHES

6-PROVE SWITCH

BCC

CHECK:

REPLACE

BCC

120VACACROSS

N1 & ACC?

REMOVE

R & W

JUMPER

AFTER

THE SELECTED

TIME, DOES THE

BLOWER TURN

OFF?

END OF TEST

REPLACE

BCC

YES

IS BLOWER

RUNNING ON LOW

SPEED, 45 SEC.

AFTER FURNACE

LIGHTS?

REPLACE

BCC

FIGURE 43

Page 38

120VACACROSS

N1 & H?

24VACACROSS

T & V?

CHECK

WIRING

YES

CHECK BLOWER

WIRING AND

BLOWER

REPLACE

YES

BCC

Page 39

G776 IGNITION CONTROL TROUBLESHOOTING

Spark is present but pilot will not light

1993 Johnson Controls, Inc. Reprinted with permission.

Are pilot valve

START

connections correct

and secure?

Is 24VAC

between terminals 1

and ground?

Is inlet

gas pressure per

manufacturers

specifications?

WARNING

Explosion Hazard. Do not use match to test for gas pressure.

YES

Securely connect at

terminal 1 and

ground.

Replace Control.

Correct gas

pressure.

Correct or replace

pilot burner.

gap 0.1 inch and

located in pilot

Shield from drafts.

Check for clean orifice.

Is gas at pilot

burner?

YES

Is spark

stream?

YES

END

FIGURE 44

Make sure pilot line

is not kinked or

obstructed. Check

for clean orifice.

If OK, replace

pilot valve.

3DJH 

Page 40

G776 IGNITION CONTROL TROUBLESHOOTING

No spark and system will not work

1993 Johnson Controls, Inc. Reprinted with permission.

START

Is 24VAC

between THS 2

and ground?

YES

Open thermostat contacts for

30 seconds. Close contacts

and wait 2 seconds longer

than prepurge (17 sec. total).

Is spark

present now?

Did pilot remain

lit from previous

cycle?

YES

Check the following:

1) 120VAC Supply

2) Transformer

3) Thermostat

System was is lockout. Determine the Cause:

Replace gas

valve.

1) Flameout cycling.

2) Internal malfunction.

3) Flame present when it should not be.

Turn OFF

supply voltage

Is high voltage

cable securely

connected to spark

transformer?

YES

Is high voltage

cable brittle, burnt

or cracked?

Is spark electrode

ceramic cracked?

Is spark gap 0.1

inch and located in

pilot gas stream?

YES

Replace control.

YES

Connect securely

then turn ON

supply voltage.

Replace cable.

Replace pilot

burner.

Correct or replace pilot burner. Turn

ON supply voltage.

END

FIGURE 45

3DJH 

Page 41

G776 IGNITION CONTROL TROUBLESHOOTING

Pilot lights but main valve will not come on

1993 Johnson Controls, Inc. Reprinted with permission.

Connect

securely.

Replace

sensor.

START

YES

Does spark

stay on for more than

5 seconds after pilot

lights?

YES

Make sure sensor cable

and high voltage cable

are separated and not

wrapped around any

pipe or accessories.

Is main

valve wiring securely

connected to terminals

4 and ground?

YES

Is sensor

ceramic cracked?

Is 24VAC

between terminals

3 and ground?

YES

Is inlet

gas pressure per

manufacturers

specifications?

YES

Is main

valve wiring securely

connected to terminals

3 and ground?

YES

Replace

main valve.

Replace control.

Correct

gas

pressure.

Correct

wiring.

Correct.

YES

Is sensor cable

grounded out?

Is sensor

or sensor connector

shorted to a metal

surface?

If system still fails, clean pilot

assembly, or replace flame

sensor, orifice, or control.

Does sensor cable

lack continuity

or good insulation?

Disconnect main valve lead from terminal 3 and sensor cable from

terminal 4. Observing correct polarity,

connect DC microammeter between

terminalof sensor cable and terminal 4.

Is DC current

0.15 microamps or greater?

FIGURE 46

YES

Replace control.

END

Replace

cable.

3DJH 

Page 42

OPERATION SEQUENCE-G23(X) -5 and -6 MODELS WITH SURELIGHT CONTROL

1 - Whenthere is a call forheat,W1ofthe thermostat en-

ergizes W of the furnace control with 24VAC.

2 - S10 primary limit switch and S47 rollout switch are

closed. Call for heat can continue.

3 - SurelightcontrolenergizescombustionairblowerB6.

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

4 - Surelight control energizes ignitor. A 20-second

warm-up period begins. 5 - Gas valve opens for a 4-second trial for ignition. 6 - Flameis sensed, gas valveremains open for theheat

call. 7 - After 45-second delay,Surelight control energizes in-

door blower B3. 8 - Whenheatdemandissatisfied,W1ofthe indoor ther-

mostat de-energizes W of the Surelight control which

de-energizes the gas valve. Combustion air blower

B6 continues a 5-second post-purge period, and in-

doorblowerB3 completes a selected OFFtimedelay.

Page 42

Page 43

SURELIGHT CONTROL

HEATING SEQUENCE OF

OPERATION

NORMAL HEATING MODE ABNORMAL HEATING MODE

COMBUSTION AIR BLOWER ON FOR 1 SECOND.

SIGNAL IMPROPER

GROUND AT LED.

SIGNAL HOLDS

UNTIL UNIT IS

PROPERLY

GROUNDED.

IS COMBUSTION AIR BLOWER ENERGIZED?

(HTG ACC TERMINAL IS ENERGIZED WITH C.A.B.)

15-SECOND COMBUSTION AIR BLOWER PREPURGE

INITIATED BY CLOSED PRESSURE SWITCH.

POWER ON

CONTROL SELF-CHECK OKAY?

TURN INDUCER ON FOR 1 IS POLARITY REVERSED?

ROLLOUT SWITCH CLOSED?

(CONTINUOUS FLAME CHECK)

THERMOSTATCALLS FOR HEAT:

PRESSURE SWITCH OPEN?

HAS COMBUSTION AIR PRESSURE SWITCH CLOSED IN 2.5 MINUTES?

CONTINUED NEXT PAGE

SECOND.

IS THERE

PROPER GROUND?

YES

BURNER OFF?

YES

NORMAL OPERATION:

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

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

YES

IS COMBUSTION AIR

YES

IS VOLTAGE

ABOVE 75 VOLTS?

YES

GAS VALVEOFF. COMBUSTION AIR BLOWER ON.

GAS VALVEOFF. COMBUSTION AIR BLOWER OFF.

(RESET CONTROL BY TURNING MAIN POWER OFF.)

GAS VALVEOFF. COMBUSTION AIR BLOWER OFF.

INDOOR BLOWER OFF WITH DELAY.

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

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.

GAS VALVEOFF. COMBUSTION AIR BLOWER ON.

INDOOR BLOWER ON HEATING SPEED.

PRESSURE SWITCH IS IN WATCHGUARD MODE.

GAS VALVEOFF. COMBUSTION AIR BLOWER OFF.

INDOOR BLOWER OFF WITH DELAY.

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

IS 5-MINUTE RESET PERIOD COMPLETE?

INDOOR BLOWER ON.

LED #1 ALTERNATING FAST FLASH

LED#2 ALTERNATING FAST FLASH

CHECK FOR BROKEN IGNITOR OR

OPEN IGNITOR CIRCUIT

INDOOR BLOWER DELAY OFF.

LED #1 ON LED #2 ON

POLARITY REVERSED.

LED #1 -- FAST FLASH

LED #2 -- SLOW FLASH

LOW VOLTAGE SIGNAL AT LED HOLDS

UNTIL VOLTAGE RISES ABOVE 75 VOLTS.

LED #1 -- SLOW FLASH

LED #2 -- OFF

GAS VALVE OFF.

COMBUSTION AIR BLOWER OFF.

INDOOR BLOWER OFF WITH DELAY.

LED #1 OFF

LED #2 SLOW FLASH

(Sequence holds until pressure switch

closes or thermostat resets control.)

3DJH 

Page 44

HEATING SEQUENCE CONTINUED

NORMAL HEATING MODE ABNORMAL HEATING MODE

15-SECOND COMBUSTION AIR BLOWER PREPURGE

INITIATEDBY CLOSED PRESSURE SWITCH.

YES

IGNITOR WARM-UP -- 20 SECONDS.

YES

4-SECOND TRIAL FOR IGNITION.

GAS VALVE OPENS. BOARD 24L85, 56L83, 63K8901:

IGNITOR ENERGIZED FOR 1 SECOND AFTER VALVE

OPENS. BOARD 97L48: IGNITOR ENERGIZES

THROUGH OUT 4 SECOND TRIAL.

YES

FLAME STABILIZATION PERIOD.

4 SECONDS

FLAME RECTIFICATION CURRENT CHECK

CAN FLAME BE PROVEN WITHIN 4

SECONDS AFTER GAS VALVE OPENS?

(>0.15 microamps)

GAS VALVE OFF. COMBUSTION AIR BLOWER ON.

HAS CONTROL FAILED TO SENSE FLAME FOR

FIVE CONSECUTIVE TRIES DURING A SINGLE

WATCHGUARD MODE. GAS VALVEOFF.

LEDs SIGNAL WATCHGUARDFAILURECODE.

IS 60-MINUTE RESET PERIOD COMPLETE?

INDOOR BLOWER OFF.

HEATDEMAND?

YES

COMBUSTION AIR BLOWER OFF.

INDOOR BLOWER OFF WITH DELAY

YES

FLAME PRESENT?

YES

FLAME SIGNAL ABOVE 0.7 MICROAMPS?

YES

INDOOR BLOWER ON DELAYBEGINS. AFTER 45

SECOND DELAY, ACB HEAT SPEED TERMINAL IS

ENERGIZED. ACC. TERMINAL IS ENERGIZED.

YES

PRIMARY AND SECONDARY LIMIT

SWITCHES CLOSED?

YES

ROLLOUT SWITCH CLOSED?

YES

COMBUSTION AIR PRESSURE

SWITCH CLOSED?

YES

THERMOSTAT DEMAND SATISFIED.

YES

LED #1 & #2 SIMULTANEOUS SLOW FLASHES.

YES

COMB. AIR BLOWER CONTINUES 5-SECOND

POST PURGE AFTER T’STAT DEMAND IS SATISFIED.

HTG ACC. TERM. IS DE-ENERGIZED. INDOOR AIR

BLOWER COMPLETES SELECTED “OFF” DELAY BE-

FORE SHUTTING OFF.ACC. TERM. DE-ENERGIZED.

INDOOR BLOWER ON UNTIL SWITCH CLOSES.

(See table 6 DIAGNOSTIC CODES for limit reset operation).

GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.

HAS CAB SWITCH CLOSED IN 2.5 MINUTES?

HAS CONTROL RESET IGNITION

SEQUENCE FOUR TIMES?

LOW FLAME SIGNAL

(Does not affect operation of control)

LED #1 -- SLOW FLASH

LED #2 -- FAST FLASH

GAS VALVE DE-ENERGIZED.

COMBUSTION AIR BLOWER DE-ENERGIZED.

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

IS LIMIT SWITCH CLOSED?

YES

HAS PRIMARY LIMIT RESET?

INDOOR BLOWER OFF WITH DELAY.

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

GAS VALVE DE-ENERGIZED.

COMBUSTION AIR BLOWER ON.

INDOOR BLOWER OFF WITH DELAY

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

5-MINUTE PRESSURE SWITCH

WATCHGUARD MODE.

YES

Page 44

Page 45

SURELIGHT CONTROL

COOLING SEQUENCE OF OPERATION

NORMAL COOLING MODE ABNORMAL COOLING MODE

POWER ON

IGNITION CONTROL MAIN POWER ON.

SIGNAL IMPROPER

GROUND AT LED.

SIGNAL HOLDS

UNTIL UNIT IS

PROPERLY

GROUNDED.

ROLLOUT SWITCH MONITORED CONTINUOUSLY.

CHECK FOR MAIN BURNER FLAME SENSE.

LED: SLOW FLASH RATEREMAINS UNCHANGED

CONTROL SELF DIAGNOSTIC CHECK.

IS CONTROL OPERATING NORMALLY?

YES

TURN INDUCER ON FOR 1 SECOND.

IS POLARITY REVERSED?

IS ROLLOUT SWITCH CLOSED?

IS MAIN BURNER FLAME OFF?

THROUGHOUT COOLING CYCLE.

THERMOSTAT CALLS FOR COOLING.

IS THERE

PROPER GROUND?

YES

IS VOLTAGE

ABOVE 75 VOLTS?

GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.

INDOOR BLOWER OFF WITH NORMAL DELAY.

SIGNAL CIRCUIT BOARD FAILURE ATLED.

INTERRUPT MAIN POWER TO RESET CONTROL.

SIGNAL POLARITY REVERSED ATLED.

GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.

INDOOR BLOWER OFF WITH NORMAL DELAY.

SIGNAL CIRCUIT BOARD FAILURE ATLED.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.

GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.

INDOOR BLOWER OFF WITH NORMAL DELAY.

SIGNAL CIRCUIT BOARD FAILURE ATLED.

SEQUENCE HOLDS UNTIL FLAME IS NOT SENSED.

LOW VOLTAGE SIGNAL AT LET HOLDS

UNTIL VOLTAGE RISES ABOVE 75 VOLTS.

COMPRESSOR CONTACTOR AND SYSTEM FAN

ENERGIZED WITH 0-SECOND DELAY. ACB

HEATSPEED TERMINAL IS ENERGIZED. ACC.

TERMINAL IS ENERGIZED.

THERMOSTAT OPENS.

COMPRESSOR OFF.

SYSTEM FAN AND ACC. TERM. OFF

WITH 0-SECOND DELAY.

Page 45

Page 46

CONTINUOUS LOW SPEED FAN SEQUENCE OF OPERATION

LED: SLOW FLASH RATEREMAINS

UNCHANGED THROUGHOUT SEQUENCE.

MANUAL FAN SELECTION MADE ATTHERMOSTAT.

CONTROL (G) ENERGIZES SYSTEM FAN AT ACB

LOW SPEED. ACC. TERMINAL IS ENERGIZED.

THERMOSTAT CALLS FOR HEAT (W).

NO YES

THERMOSTAT CALLS FOR COOLING.

YES

SYSTEM FAN SWITCHED TO ACB COOL

SPEED. ACC. TERM. REMAINS ON.

THERMOSTAT OPENS.

HTG ACC. TERM. ENERGIZES

WITH COMB. AIR BLOWER.

BOARD NO. 63K8901

SYSTEM FAN DE-ENERGIZED. SYSTEM FAN

ENERGIZES ON ACB HEATSPEED AFTER

NORMAL DELAY.

BOARD NO. 24L85, 56L83, 97L48

SYSTEM FAN SWITCHES TO ACB HEAT SPEED

AFTER NORMAL DELAY (fan remains energized)

THERMOSTAT OPENS. COMBUSTION AIR

AND HTG ACC TERMINAL DE-ENERGIZE.

BOARD 63K89: SYSTEM FAN OFF. ACC. TERM.

OFF. (AFTER OFF DELAY COMPLETED).

BOARDS 24L85, 56L83 AND 97L48:

SYSTEM FAN SWITCHES TO

LOW SPEED AFTER NORMAL DELAY.

(fan remains energized)

MANUAL FAN SELECTION MADE ATTHERMOSTAT.

CONTROL (G) ENERGIZES SYSTEM FAN AT ACB

LOW SPEED. ACC. TERM. ENERGIZED.

Page 46

Page 47

685(/,*+7  7528%/( 6+227,1* *8,'(

#O code LED#2 Slow Flash

ACTION 1

Check wiring connections to

blower does not energize

120V field connection.

UPON INITIAL POWER UP , REMOVE ALL THERMOSTAT DEMANDS TO THE UNIT

PROBLEM: 1 UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE

Condition Possible Cause Corrective Action / Comments

1.1

Bot

h diagnostic lights fail to light

up.

LED#1-Off LED#2-Off

1.2

Diagnostic lights flash the roll-out

code.

LED#1-On, LED#2-Slow Flash

1.3

- On initial power-up the comb. air .

- Diagnostic lights flashthereverse

polarity code.

Main voltage 120V not supplied to unit.

Miswiring of furnace or improper connections.

Circuit breaker tripped or fails to close.

Door interlock switch failure.

Transformer Failure.

Failed control board.

Roll-out switch open.

Roll-out switch failure.

Miswiring or improper connections at roll-out switch.

Nine pin connector failure

120V main power polarity reversed.

1.1.1

1.1.2

1.1.3

1.1.4

1.1.5

1.1.6

1.2.1

1.2.2

1.2.3

1.2.4

1.3.1

ACTION 1 -

Determine cause of main power failure.

ACTION 1 -

to power make up box and transformer.

ACTION 2

board.

ACTION 1 -

set but does not have continuity.

ACTION 2 -

for short.

ACTION 1 -

when door is closed.

ACTION 2 -

replace loose connectors.

ACTION 3 -

closed position. Replace if defective.

ACTION 1 -

24V. Replace if defective.

ACTION 1 -

checked, replace board.

ACTION 1 -

by pushing the top button.

ACTION 2 -

out switch activation before leaving furnace.

ACTION 1 -

switch. Replace roll-out switch if switch is reset but does not have continuity.

ACTION 1 -

switch.

ACTION 1 -

connection to control board.

ACTION 2 -

plug pin.

ACTION 1 -

correctly input into control.

ACTION 2 -

120V field connection.

Check 120V main voltage.

Check for correct wiring of 120V

- Check 24V wiring to control

Replace circuit breaker if it is re-

If circuit breaker still trips, check

Check that door switch isactivated

Check wire connections to switch,

Check continuity of switch in

Check that transformer output is

If all the above items have been

Manually reset the roll-out switch

Determine the cause of the roll-

Check continuity across roll-out

Check wiring connections to

Check 9-pin connector for proper

Check continuity of the multi

Check the 120V hasline andneutral

Reverse the line and neutral at the

LED#1-Fast Flash, LED#2-Slow Flash.

1.4

- On initial power up the combus-

tion air blower does not energize.

- Diagnostic lights flash normal

power on operation.

LED#1-Slow Flash LED#2-Slow Flash

1.4.1

Open combustion air blower motor circuit.

1.4.2

Failed combustion air blower mo- tor.

3DJH 

ACTION 1 -

blower. If no power, check wire and connec- tions.

ACTION 1 -

place blower.

Check for 120V to combustion air

If power is present at blower, re-

Page 48

PROBLEM 1: UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE

Units with control boards date

fail

Condition Possible Cause Corrective Action / Comments

1.5

On initial power-up the combus-

tion air blower remains energized.

Diagnostic lights flash the im-

proper main ground.

LED#1-Alternating Fast Flash LED#2-Alternating Fast Flash

1.5.1

Improper ground to the unit.

1.5.2

6-Pin connector is improperly at-

tached to the circuit board.

1.5.3

Line voltage is below 75V.

ACTION 1 -

ground.

ACTION 2 -

the unit

ACTION 1 -

installation. Correctly insert connector into control.

ACTION 1 -

above 75V. Determine cause of voltage drop and supply correct voltage to the control.

Check that the unit is properly

Install a proper main ground to

Check 6-pin connector for proper

Check that the line voltage is

PROBLEM 2: UNIT FAILS TO OPERATE IN THE COOLING OR HEATING MODE, BUT COMBUSTION

AIR BLOWER OPERATES CONTINUOUS. UNITS WITH CONTROL BOARDS DATE CODED AFTER

NOV. 1 1997, WILL OPERATE IN COOLING BUT NOT IN THE HEATING MODE, WITH COMBUS-

TION AIR BLOWER CYCLING 5 SECONDS ON 55 SECONDS OFF.

Condition Possible Cause Corrective Action / Comments

2.1

On initial power-up the combus-

tion air blower remains energized.

Diagnostic lights flash the im-

proper main ground.

- Units with control boards date coded after Nov.1 1997; combus- tion air blower will cycle 5 seconds on 55 seconds off.

LED#1-Alternating Fast Flash LED#2-Alternating Fast Flash

2.1.1

Open ignitor circuit.

2.1.2

Broken or failed ignitor.

ACTION 1 -

connections inthe ignitor circuit.Check mult- plug connections for correct installation.

ACTION 1 -

tance across ignitor. If resistance does not read between 10.9and 19.7ohms, replacethe ignitor.

Check for correct wiringand loose

Unplug ignitor and read resis-

PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOES

Condition Possible Cause Corrective Action / Comments

3.1

Unit operates with a cooling or

continuous fan demand.

Combustion air blower will not

start with a Heating demand.

- Diagnostic lights flash the limit ure mode.

LED#1-Slow Flash, LED#2-On

3.2

- Unit operates with a cooling and

continuous fan demand.

- Combustion air blower will not

start with a Heating demand.

Diagnostic lights flash the pres-

sure switch failure code.

LED#1-Off, LED#2-Slow Flash

NOT ENERGIZE

ACTION 1 -

3.1.1

Primary or secondary (if equipped

) limit open.

3.1.2

Miswiring of furnace or improper

connections at limit switch(es).

switch(es). Switches reset automatically upon cool down.

ACTION 2 -

inlet air (including filter) and outlet air. Deter- mine causefor limit activation before placing unit back in operation.

ACTION 1 -

connections. Correct wiring and/or replace any loose connections.

3.2.1

Miswiring of furnace or improper

connections to combustion air

ACTION 1 -

connections. Correct wiring and/or replace any loose connections.

blower.

3.2.2

Pressure switch stuck closed.

ACTION 1 -

open without the combustion air blower op- erating. Replace if defective.

Check continuity across

Check for restrictions on blower

Check for correct wiringand loose

Check that the pressure switch is

3DJH 

Page 49

PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOES

sure switch failure code 2.5 minutes LED#2 Slow Flash

NOT ENERGIZE (CONT.).

Condition Possible Cause Corrective Action/Comments

3.3

- Unit operates with a cooling and

continuous fan demand.

Combustion air blower will not

start with a Heating demand.

Diagnostic lights flash the pres-

Miswiring of furnace or improper

connections to combustion air

3.3.1

blower.

ACTION 1 -

connections. Correct wiring and/or replace any loose connections.

Check for correct wiringand loose

sure switch failure code 2.5 minutes after heating demand.

LED#1-Off,

3.3.2

Combustion air blower failure.

ACTION 1 -

blower and it does not operate, replace com- bustion air blower.

If there is 120V to combustion air

LED#2-Slow Flash

PROBLEM 4: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER

ENERGIZES, IGNITOR IS NOT ENERGIZED.

Condition Possible Cause Corrective Action/Comments

4.1

Unit operates with a cooling and

continuous fan demand.

Combustion air blower energizes

with a heating demand.

- Diagnostic lights flash the pres- sure switch failure code 2.5 min- utes after heating demand.

LED#1-Off LED#2-Slow Flash

Pressure switch does not close

due to incorrect routing of the

pressure switch lines.

Pressure switch does not close

due to obstructions in the pressure

Pressure switch lines damaged

Condensate in pressure switch

Pressure switch does not close

due to a low differential pressure

across the pressure switch.

Wrong pressure switch installed in

the unit, or pressure switch is out

Miswiring of furnace or improper

connections at pressure switch.

Pressure switch failure.

4.1.1

4.1.2

lines.

4.1.3

4.1.4

line.

4.1.5

4.1.6

of calibration.

4.1.7

4.1.8

ACTION 1 -

lines are correctly routed. Correctly route pressure switch lines.

ACTION 1 -

the the pressure lines and/or taps.

ACTION 1 -

leaks. Replace any broken lines.

ACTION 1 -

condensate. Remove condensate from lines. Check that the condensate lines are located correctly.

ACTION 1 -

across the pressure switch. This pressure should exceed the set point listed on the switch.

ACTION 2 -

exhaust vent. Remove all blockage.

ACTION 3 -

and run length. See installation instruc- tions.

ACTION 1 -

switch is installed in the unit. Replace pres- sure switch if necessary.

ACTION 1 -

connections. Correct wiring and/or replace any loose connections.

ACTION 1 -

have been checked, the pressure switch may have failed. Replace pressure switch and de- termine if unit will operate.

Check that the pressure switch

Remove any obstructions from

Check pressure switch lines for

Check the differential pressure

Check for restricted inlet and

Check for proper vent sizing

Check that the proper pressure

Check for correct wiringand loose

If all the above modes of failure

3DJH 

Page 50

PROBLEM 5: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER

to ignite code.

ENERGIZES, IGNITOR IS ENERGIZED.

Condition Possible Cause Corrective Action/Comments

5.1

- Unit operates with a cooling and continuous fan demand.

-Combustion airblower energizes with Heating demand.

Ignitor is energized but unit fails

to light.

LED#1-Alternating Slow Flash LED#2-Alternating Slow Flash

5.1.1

Check that gas is being supplied to

the unit.

5.1.2

Miswiring of gas valve or loose

connections at multi-pin control

amp plugs or valve.

5.1.3

Defective gas valve or ignition

control.

ACTION 1 -

valve. Pressure should not exceed 13 WC for both natural and propane. Line pressure should read a minimum 4.5 WC for natural and 8.0WC for propane.

ACTION 1 -

connections. Correct wiring and/or replace any loose connections.

ACTION 1 -

gas valve approximately 35 seconds after heat demand is initiated.

ACTION 2 -

plied but valve does not open.

ACTION 3 -

is not supplied to valve.

Check line pressure at the gas

Check for correct wiringand loose

Check that 24V is supplied to the

Replace the valve if 24V is sup-

Replace the control board if 24V

PROBLEM 6: BURNERS LIGHT WITH A HEATING DEMAND BUT UNIT SHUTS DOWN

PREMATURELY

Condition Possible Cause Corrective Action/Comments

6.1

- Burners fire with a heating de- mand.

-Burnerslightbut unitshuts o prior to satisfying T-stat demand.

- Diagnostic lights flash the pres- sure switch code.

LED#1-Off LED#2-Slow Flash

6.2

- Combustion air blower energizes with a heating demand.

- Burners light but fail to stay lit.

-After5 tries the control diagnostics flash the watchguard burners failed to ignite code.

LED#1-Alternating Slow Flash LED#2-Alternating Slow Flash

6.1.1

Wrong concentric vent kit used for

terminating the unit.

6.1.2

Condensate drain line is not drain-

ing properly.

6.1.3

Low pressure differential at the

pressure switch.

6.2.1

Sensor or sense wire is improperly

installed.

6.2.2

Sensor or sense wire is broken.

6.2.3

Sensor or sensor wire is grounded

to the unit.

6.2.4

Control does not sense flame.

ACTION 1 -

installed. 1-1/2 dia. concentric vent (kit60

G77) for 50 and 75 inputs and 2 dia. concentric vent (kit 33K97) for 100 &125 in- puts.

ACTION 1 -

vent slope, and any blockage. Condensate should flow freely during operation of fur- nace. Repair or replace any improperly installed condensate lines.

ACTION 1 -

exhaust. Remove all blockage.

ACTION 2:

installation instructions.

ACTION 1 -

located and that the sense wire is properly attached to both the sensor and the control.

ACTION 1 - ACTION 2 -

wire. If wire or sensor are damaged replace the component.

ACTION 1 -

the sensor rod and the unit ground.

ACTION 2 -

the sensor wire and the unit ground.

ACTION 3 -

cuit.

ACTION 1 -

from the burner flame. If the microamp sig- nal is below 0.70 microamps, check the sense rod for proper location or contamina- tion.

ACTION 2 -

flame sense rod. If rod is to be cleaned, use steel wool or replace sensor. DO NOT CLEAN ROD WITH SAND PAPER. SAND PA- PER WILL CONTRIBUTE TO THE CONTAMI- NATION PROBLEM. to bend sense rod.

Check vent termination kit

Check condensate line for proper

Check for restricted vent inlet or

Check for proper vent sizing. See

Check that sensor is properly

Check for a broken sensor. Test continuity across the sense

Check for resistance between

Correct any shorts found in cir-

Check the microamp signal

Replace, clean, or relocate

NOTE:

Do not attempt

3DJH 

Page 51

PROBLEM 6: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN

guard flame failure

Condition Possible Cause Corrective Action/Comments

6.3

- Combustion air blower energizes

with a heating demand.

- Burners light.

- Roll-out switch trips during the

heating demand.

- Diagnostic lights flash roll-out

failure.

LED#1-On LED#2-Slow Flash

6.4

Combustion air blower energizes

with a heating demand.

- Burners light roughly and the

unit fails to stay lit.

- Diagnostic lights flash watch- uard flame failure.

PREMATURELY (CONT.)

6.3.1

Unit is firing above 100% of the

nameplate input.

6.3.2

Gas orifices leak at the manifold

connection.

6.3.3

Air leakage at the connections be-

tween the primary heat exchanger,

secondary heat exchanger, and

combustion air blower.

6.3.4

Insufficient flow through the heat exchanger caused by a sooted or

restricted heat exchanger.

6.3.5

Burners are not properly located in

the burner box.

6.4.1

Recirculation of flue gases. This

condition causes rough ignitions

and operation. Problem is charac-

terized by nuisance flame failures.

ACTION 1 -

matches value listed on nameplate. See installation instructions for proper proce- dure.

ACTION 2 -

size match the size listed on the nameplate or installation instructions.

ACTION 3 -

insure no leaks are present.

ACTION 4 -

matches value listed on nameplate.

ACTION 1- NOTE: ACTION 2 -

threaded orifice connection. Use approved method for leak detection (see unit instruc- tions).

ACTION 1 -

in the heat exchanger assembly. Condition will cause high CO2 with high CO.

ACTION 2 -

heat exchanger if necessary, tag and return heat exchanger to proper Lennox personnel.

ACTION 1- Check for sooting deposits or oth- er restrictions in the heat exchanger assem- bly. Cleanassembly asoutlined in instruction manual. ACTION 2 - Check for proper combustion. CO2 should measure 6.5%-8.5%. CO should measure below .04% (400PPM) in an air-free sample of flue gases for either NG or LP.

ACTION 1 -

into the center of the heat exchanger open- ings. Correct the location of the burners if necessary.

ACTION 1 -

gases away from intake vent. Remove any obstacles in front of the intake and exhaust vent which would cause recirculation.

ACTION 2 -

haust vent installation. See instructions

Check that the manifold pressure

Verify that the installed orifice

Check gas valve sensing hose to

Check the input rate to verify rate

Tighten orificeuntil leak is sealed.

Be careful not to strip orifice threads.

Check for gas leakage at the

Check for air leakage at all joints

Seal leakage if possible, replace

Check that the burners are firing

Check for proper flow of exhaust

Check for correct intake and ex-

LED#1-Alternating Slow Flash LED#2-Alternating Slow Flash

6.4.2

Improper burner cross-overs

3DJH 

ACTION 1 -

cross-overs for burrs, or any restriction or if crossover is warped. Remove restriction or replace burners.

Remove burner and inspect the

Page 52

PROBLEM 6: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN

sense code

6.5

- Combustion air blower energizes

with a heating demand.

- Burners light.

- Diagnostic lights flash watch

guard flame failure.

- NOTE Unit might go into 60

minute Watchguard mode depend- ing on intermittent nature of sen- sor signal.

LED#1-Alternating Slow Flash LED#2-Alternating Slow Flash

PROBLEM 7: CONTROL SIGNALS LOW FLAME SENSE DURING HEATING MODE

Condition Possible Cause Corrective Action/Comments

7.0

- Unit operates correctly but the

diagnostic lights flash low flame

LED#1-Slow Flash LED#2-Fast Flash

PREMATURELY (CONT.)

6.5.1

Loose sensor wire connection

causes intermittent loss of flame

signal.

7.1.1

Sense rod is improperly located on

the burner.

7.1.2

Sense rod is contaminated.

ACTION 1 -

located.

ACTION 2-

erly attached to both the sensor and the con- trol. Pay extra attentionto thepin connectors.

ACTION 1 -

location on the burner. Properly locate the sense rod or replace if rod cannot be located correctly.

ACTION 1 -

tion or coated surface. Clean the sense rod with steel wool or replace sensor. DO NOT USE SAND PAPER TO CLEAN ROD. SAND PAPER WILL CONTRIBUTE TO THE CON- TAMINATION PROBLEM.

Check that the sensor is properly

Check thatthe sense wire is prop-

Check the sense rod for proper

Check sense rod for contamina-

PROBLEM 8: INDOOR BLOWER FAILS TO OPERATE IN COOLING, HEATING, OR CONTINUOUS

FAN MODE

Condition Possible Cause Corrective Action/Comments

8.0

- Indoor blower fails to operate in

continuous fan, cooling, or heating mode.

Miswiring of furnace or improper

connections at control or indoor

120V is not being supplied to the

indoor air blower or blower motor

Defective control board

8.1.1

blower motor.

8.1.2

failure.

8.1.3

ACTION 1-

loose connections. Check for correct wiring and loose connections.

ACTION 1-

for indoor blower by energizing Y, G, and W individually on the low voltage ter- minal strip. Note that when W is ener- gized, the blower is delayed 45 seconds. If there is 120V to each motor tap but the blow- er does not operate, replace the motor.

ACTION 1 -

G, or W is energized, replace the con- trol.

Correct wiring and/or replace any

Check for120V atthe various calls

If there is not 120V when Y,

PROBLEM 9: RF STATIC DURING TIME FOR IGNITION

Condition Possible Cause Corrective Action/Comments

9.0

- AM radio interference.

9.1.2

Ignitor operation

ACTION 1 -

Call Technical Support, Dallas.

3DJH 

Lennox G23Q4-75, G23Q2-75, G23Q5-75, G23Q3-50, G23Q3-100 Unit Information

Specifications and Main Features

Frequently Asked Questions

User Manual