Operation & Installation Manual 09/2002

7. Verify furnace shut down by lowering thermostat setting below room temperature.

8. Verify that furnace restarts by raising thermostat setting above room temperature.

PRIME CONDENSATE TRAP WITH WATER

Condensate trap must be PRIMED or proper draining may not occur. The condensate trap has internal chambers which can

ONLY be primed by pouring water into the inducer drain side of condensate trap.

1. Remove upper inducer housing drain connection cap. (See

Fig. 51.)

2. Connect field-supplied 1/2-in. ID tube to upper inducer housing drain connection.

3. Insert field-supplied funnel into tube.

4. Pour 1 quart of water into funnel/tube. Water should run through inducer housing, overfill condensate trap, and flow into open field drain. (See Fig. 52.)

5. Remove funnel and tube from inducer housing and replace drain connection cap and clamp.

Fig. 52—Filling Condensate Trap

A99119

Fig. 51—Inducer Housing Drain Tube

A99118

OPERATE FURNACE

Follow procedures on operating instructions label attached to furnace.

FURNACE RESTART

With furnace operating, set thermostat below room temperature and observe that furnace goes off. Set thermostat above room temperature and observe that furnace restarts.

Step 4—Adjustments

SET GAS INPUT RATE

Furnace gas input rate on rating plate is for installations at altitudes up to 2000 ft.

44

In the U.S.A., the input ratings for altitudes above 2000 ft must be reduced by 2 percent for each 1000 ft above sea level.

In Canada, the input ratings must be derated by 5 percent for altitudes of 2001 ft to 4500 ft above sea level.

Adjust manifold pressure to obtain input rate.

Furnace input rate must be within ± 2 percent of input on furnace rating plate adjusted for altitude.

1. Determine Natural Gas Orifice Size And Manifold Pressure

For Correct Input.

a. Obtain average yearly heat value (at installed altitude) from local gas supplier.

b. Obtain average yearly specific gravity from local gas supplier.

c. Verify furnace model and size. Table 10 can only be used for furnaces with heating inputs of 20,000/13,000

(High/Low) Btuh per burner.

d. Find installation altitude in Table 10.

NOTE: For Canada altitudes of 2001 to 4500 ft, use U.S.A.

altitudes of 2001 to 3000 ft in Table 10.

e. Find closest natural gas heat value and specific gravity on

Table 10.

f. Follow heat value and specific gravity lines to point of intersection to find orifice size and manifold pressure settings for proper operation.

EXAMPLE: (0-2000 ft altitude using Table 10)

Heating value = 1050 Btu/cu ft

Specific gravity = 0.62

Therefore: Orifice No. 45

Manifold pressure 3.6-in. wc for high heat

1.5-in. wc for low heat

* Furnace is shipped with No. 45 orifices. In this example all main burner orifices are the correct size and do not need to be changed to obtain the proper input rate.

g. Check and verify burner orifice size in furnace. NEVER

ASSUME ORIFICE SIZE; ALWAYS CHECK AND

VERIFY.

2. Adjust Manifold Pressure To Obtain Input Rate.

a. Remove burner enclosure front.

NOTE: Manifold pressure MUST always be measured with burner enclosure front REMOVED.

b. Remove regulator seal caps that conceal adjustment screws for low-and high-heat gas valve pressure regulators. (See

Fig. 53.)

INLET

PRESSURE

TAP

ON/OFF

SWITCH

ON

F

F

O

LOW-FIRE

ADJUSTMENT

ALLEN SCREW

(UNDER CAP)

HIGH-FIRE

ADJUSTMENT

ALLEN SCREW

(UNDER CAP)

DO NOT bottom out gas valve regulator adjusting screw.

This can result in unregulated manifold pressure and result in excess overfire and heat exchanger failures.

NOTE: If orifice hole appears damaged or it is suspected to have been redrilled, check orifice hole with a numbered drill bit of correct size. Never redrill an orifice. A burr-free and squarely aligned orifice hole is essential for proper flame characteristics.

f. Move setup switch SW-1 to OFF position after completing low-heat adjustment.

g. Jumper R and W1 and W2 thermostat connections on control. (See Fig. 32.) This keeps furnace locked in high-heat operation.

h. Turn high-heat adjusting screw (3/32 hex Allen wrench) counterclockwise (out) to decrease input rate or clockwise

(in) to increase rate.

NOTE: DO NOT set high-heat manifold pressure less than 3.2-in.

wc or more than 3.8-in. wc for natural gas. If manifold pressure is outside this range, change main burner orifices.

i. When correct input is obtained, replace caps that conceal gas valve regulator adjustment screws. Main burner flame should be clear blue, almost transparent. (See Fig. 54.)

BURNER FLAME

BURNER

MANIFOLD

Fig. 54—Burner Flame

j. Remove jumper R-to-W1 and W2.

A89020

MANIFOLD

PRESSURE

TAP

A97358

Fig. 53—Redundant Automatic Gas Control Valve

c. Move setup switch SW-1 on control center to ON position.

This keeps furnace locked in low-heat operation.

d. Jumper R and W/W1 thermostat connections on control to start furnace.

e. Turn low-heat adjusting screw (3/32 hex Allen wrench) counterclockwise (out) to decrease input rate or clock-wise

(in) to increase input rate.

NOTE: DO NOT set low-heat manifold pressure less than 1.3-in.

wc or more than 1.7-in. wc for natural gas. If manifold pressure is outside this range, change main burner orifices.

45

DO NOT redrill orifices. Improper drilling (burrs, out-ofround holes, etc.) can cause excessive burner noise and misdirection of burner flames. This can result in flame impingement of burners and heat exchangers causing failures.

3. Verify Natural Gas Input Rate By Clocking Gas Meter.

NOTE: Be sure all pressure tubing, combustion-air and vent pipes, and burner enclosure front are in place when checking input by clocking gas meter.

a. Calculate high-altitude adjustment (if required).

UNITED STATES

At altitudes above 2000 ft, this furnace has been approved for a 2 percent derate for each 1000 ft above sea level. See

Example and Table 11 for derate multiplier factor.

CANADA

At installation altitudes from 2001 to 4500 ft, this furnace

j. Measure time (in sec) for gas meter to complete 1 revolution. Note reading.

k. Refer to Table 11 for cubic ft of gas per hr.

BURNER

ORIFICE

A93059

Fig. 55—Burner Orifice

EXAMPLE:

100,000 Btuh input furnace installed at 4300 ft.

Derate

Furnace Input Rate

X Multiplier =

at Sea Level

100,000

X

Factor

0.91

=

Furnace Input Rate at Installation

Altitude

91,000

Table 11—Altitude Derate Multiplier for U.S.A.

ALTITUDE

(FT)

0–2000

2001–3000

3001–4000

4001–5000

5001–6000

6001–7000

7001–8000

8001–9000

9001–10,000

PERCENT

OF DERATE

0

4–6

6–8

8–10

10–12

12–14

14–16

16–18

18–20

DERATE MULTIPLIER

FACTOR FOR U.S.A.*

1.00

0.95

0.93

0.91

0.89

0.87

0.85

0.83

0.81

* Derate multiplier factor is based on midpoint altitude for altitude range.

must be derated 5 percent by an authorized Gas Conversion

Station or Dealer. To determine correct input rate for altitude, see example above and use 0.95 as derate multiplier factor.

b. Reinstall burner box cover.

NOTE: Clocking gas input rate MUST always be performed with the burner box cover INSTALLED.

c. Check that gas valve adjustment caps are in place for proper input to be clocked.

d. Obtain yearly heat value average for local gas supply.

NOTE: Be sure heating value of gas used for calculations is correct for your altitude. Consult local gas utility for altitude adjustment of gas heating value.

e. Check and verify orifice size in furnace. NEVER ASSUME

THE ORIFICE SIZE. ALWAYS CHECK AND VERIFY.

f. Turn off all other gas appliances and pilots.

g. Move setup switch SW-1 to ON position. This keeps furnace locked in low-heat operation.

h. Jumper R-to-W/W1.

i. Let furnace run for 3 minutes in low-heat operation.

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Table 12—Gas Rate (cu ft/hr)

SECONDS

FOR 1

REVOLUTION

34

35

36

37

30

31

32

33

38

39

40

45

46

47

48

49

41

42

43

44

23

24

25

26

19

20

21

22

27

28

29

14

15

16

17

18

10

11

12

13

106

103

100

97

120

116

113

109

95

92

90

80

78

76

75

73

88

86

84

82

157

150

144

138

189

180

171

164

133

129

124

257

240

225

212

200

SIZE OF TEST DIAL

1

Cu Ft

2

Cu Ft

5

Cu Ft

360

327

300

277

720

655

600

555

1800

1636

1500

1385

514 1286

480 1200

450 1125

424 1059

400 1000

379

360

343

327

313

300

288

277

267

257

248

783

750

720

692

947

900

857

818

667

643

621

212

206

200

195

240

232

225

218

189

185

180

160

157

153

150

147

176

172

167

164

529

514

500

486

600

581

563

545

474

462

450

400

391

383

375

367

439

429

419

409

SECONDS

FOR 1

REVOLUTION

88

90

92

94

80

82

84

86

96

98

100

110

112

116

120

124

102

104

106

108

66

68

70

72

59

60

62

64

74

76

78

54

55

56

57

58

50

51

52

53

41

40

39

38

45

44

43

42

38

37

36

33

32

31

30

29

35

35

34

33

54

53

51

50

61

60

58

56

48

47

46

67

65

64

63

62

SIZE OF TEST DIAL

1

Cu Ft

2

Cu Ft

5

Cu Ft

72

71

69

68

144

141

138

136

360

355

346

340

133

131

129

126

124

333

327

321

316

310

122

120

116

112

109

106

103

100

97

95

92

273

265

257

250

305

300

290

281

243

237

231

82

80

78

76

90

88

86

84

75

74

72

65

64

62

60

58

71

69

68

67

205

200

196

192

225

220

214

209

188

184

180

164

161

155

150

145

178

173

170

167 l. Multiply gas rate cu ft/hr by heating value (Btu/cu ft).

m. Move setup switch SW-1 to OFF position and jumper R and W1 and W2 thermostat connections. This keeps furnace locked in high-heat operation. Repeat items ’i’ through ’l’ for high-heat operation.