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i. When correct input is obtained, replace cap that conceals
gas valve regulator adjustment screws. Main burner flame
should be clear blue, almost transparent See Fig. 61.
j. Remove jumper R to W.
Fig. 61 - - Burner Flame
CAUTION
!
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in reduced furnace
life.
The 26,000 BTUH model has a lower nominal manifold
pressure than other models. Do not adjust the natural gas
manifold pressure above 1.8- -in. W.C.
The 26,000 BTUH model can be identified by the green
label affixed to the solenoid of the gas valve.
Refer to the Adjustment section for setting the manifold
pressure.
USE TABLE 22 WHEN ADJUSTING 26,000 BTUH
MODEL MANIFOLD PRESSURE.
MANIFOLD PRESSURE TAP
SET SCREW: 3/32" HEX HEAD
ACCEPTS 5/16" HOSE CONNECTION
1/2" NPT
INLET
INP
INLET PRESSURE
TAP SET SCREW:
3/32" HEX HEAD
ACCEPTS 5/16"
HOSE CONNECTION
1/8" NPT INLET
PRESSURE TAP
Representative drawing only, some models may vary in appearance.
Standard Capacity Gas Valve with Tower Pressure Ports
MANIFOLD PRESSURE TAP
SET SCREW: 3/32" HEX HEAD
ACCEPTS 5/16" HOSE CONNECTION
1/2" NPT
INLET
INP
INLET PRESSURE
TAP SET SCREW:
3/32" HEX HEAD
ACCEPTS 5/16"
HOSE CONNECTION
1/8" NPT INLET
PRESSURE TAP
Representative drawing only, some models may vary in appearance.
26,000 BTUH Low Capacity Gas Valve with Tower Pressure
Ports
Fig. 62 - - Gas Valves
1/2" NPT
OUTLET
OUTP
REGULATOR SEAL CAP
ON/OFF SWITCH
(REGULATOR ADJ.
UNDER CAP)
A170140
1/2" NPT
OUTLET
OUTP
REGULATOR SEAL CAP
1.5"
ON/OFF
(REGULATOR ADJ.
W.C
SWITCH
UNDER CAP)
.
A170118
NOTE: Contact your HVAC distributor or gas supplier for metric
gas meter Tables, if required.
2. Verify natural gas input rate by clocking meter.
a. Turn off all other gas appliances and pilots served by the
meter.
b. Jumper R to W.
For 40,000 BTUH models through 120,000 BTUH models:
DO NOT set manifold pressure less than 2.8- -in. w.c. (697 Pa)
or more than 3.8 in. w.c. (947 Pa) for natural gas. If required
manifold pressure is outside this range, change main burner
orifices to obtain manifold pressure in this range.
c. Run furnace for 3 minutes.
d. Measure time (in sec) for gas meter to complete one revolu-
tion and note reading. The 2 or 5 cubic feet dial provides
A11461
a more accurate measurement of gas flow.
e. Refer to Table 19 for cubic ft. of gas per hr.
Table 19 – Gas Rate (CU ft./hr)
SEC-
SIZE OF TEST DIAL
ONDS
1
FOR 1
Cu
REVO-
Ft.
LUTION
10
360
11
327
12
300
13
277
14
257
15
240
16
225
17
212
18
200
19
189
20
180
21
171
22
164
23
157
24
150
25
144
26
138
27
133
28
129
29
124
30
120
31
116
32
113
33
109
34
106
35
103
36
100
37
97
38
95
39
92
40
90
41
88
42
86
43
84
44
82
45
80
46
78
47
76
48
75
49
73
50
72
51
71
52
69
53
68
54
67
54
NOTICE
SEC-
SIZE OF TEST DIAL
ONDS
2
1
FOR 1
5 Cu
Cu
Cu
REVO-
Ft.
Ft.
Ft.
LUTION
720
1800
55
65
655
1636
56
64
600
1500
57
63
555
1385
58
62
514
1286
59
61
480
1200
60
60
450
1125
62
58
424
1059
64
56
400
1000
66
54
379
947
68
53
360
900
70
51
343
857
72
50
327
818
74
48
313
783
76
47
300
750
78
46
288
720
80
45
277
692
82
44
267
667
84
43
257
643
86
42
248
621
88
41
240
600
90
40
232
581
92
39
225
563
94
38
218
545
96
38
212
529
98
37
206
514
100
36
200
500
102
35
195
486
104
35
189
474
106
34
185
462
108
33
180
450
110
33
176
439
112
32
172
429
116
31
167
419
120
30
164
409
124
29
160
400
129
28
157
391
133
27
153
383
138
26
150
375
144
25
147
367
150
24
144
360
157
23
141
355
164
22
138
346
171
21
136
340
180
20
133
333
2
5
Cu
Cu
Ft.
Ft.
131
327
129
321
126
316
124
310
122
305
120
300
116
290
112
281
109
273
106
265
103
257
100
250
97
243
95
237
92
231
90
225
88
220
86
214
84
209
82
205
80
200
78
196
76
192
75
188
74
184
72
180
71
178
69
173
68
170
67
167
65
164
64
161
62
155
60
150
58
145
56
140
54
135
52
130
50
125
48
120
46
115
44
110
42
105
40
100
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