Page 18
Installer’s Guide
Table 3. Gas Flow in Cubic Feet Per Hour
2 Cubic Foot Dial
Sec.
Flow
Sec.
Flow
Sec.
Flow
Sec.
Flow
8
900
29
248
50
144
82
88
9
800
30
240
51
141
84
86
10
720
31
232
52
138
86
84
11
655
32
225
53
136
88
82
12
600
33
218
54
133
90
80
13
555
34
212
55
131
92
78
14
514
35
206
56
129
94
76
15
480
36
200
57
126
96
75
16
450
37
195
58
124
98
73
17
424
38
189
59
122
100
72
18
400
39
185
60
120
104
69
19
379
40
180
62
116
108
67
20
360
41
176
64
112
112
64
21
343
42
172
66
109
116
62
22
327
43
167
68
106
120
60
23
313
44
164
70
103
124
58
24
300
45
160
72
100
128
56
25
288
46
157
74
97
132
54
26
277
47
153
76
95
136
53
27
267
48
150
78
92
140
51
28
257
49
147
80
90
144
50
Figure 18. Burner and Valve
Outlet Pressure Boss
2nd Stage (HI)
Manifold Pressure
Adjustment
Regulator
Vent
Inlet Pres-
sure Boss
Gas Valve
ON/OFF
Toggle
Switch
High Fire Coil
Terminal (H)
1st Stage
(LO)
Manifold
Pressure
Adjustment
Common
Terminal (C)
Coaxial Coil
Terminal (M)
Chart Flow Reading
2
Chart Flow Reading
4
10X Chart Flow Reading
4
For 1 Cu. Ft. Dial Gas Flow CFH =
For 1/2 Cu Ft. Dial Gas Flow CFH =
For 5 Cu. Ft. Dial Gas Flow CFH =
4. Before connecting the piping circuit to the unit, bleed the air
from the supply line and then cap or plug the line and test the
pressure at the tapped shut-off cock. The pressure reading
should not exceed 14 inches water column.
5. Using an appropriate backup wrench on the gas valve inlet boss,
connect the gas piping to the unit. Check the completed piping
for leaks using a soap and water solution or the equivalent.
6. After installation of the gas pipe in the unit, the pipe opening
should be closed with the filler/barrier plug provided.
Manifold Pressure
Check the manifold pressure at the unit gas valve. Do not exceed
the recommended pressure shown on the unit nameplate.
Input Check and Adjustment
1. Make sure all gas appliances are off except the furnace.
2. Clock the gas meter with the furnace operating (determine the
dial rating of the meter) for one revolution.
3. Match the “Sec” column in the gas flow (in cfh) Table 3, with the
time clocked.
4. Read the “Flow” column opposite the number of seconds
clocked.
5. Use the following factors if necessary.
NOTE:
For manifold pressures and orifice sizes for gas with other
BTU ratings, contact the local gas utility. Manifold
pressure should be 1.8 (low) to 3.5 (high) inches water column
(+0.1). Input for natural gas must not exceed the value shown on
the unit nameplate.
6. Multiply the final figure by the heating value of the gas obtained
from the utility company and compare to the nameplate rating.
This must not exceed the nameplate rating.
7. Changes can be made by adjusting the manifold pressure.
a. Attach a manifold pressure gauge.
b. Remove the slot screw on top of the gas valve for 1st stage
manifold pressure adjustment. Remove slot screw on outlet
side for 2nd stage adjustment (See Figure 18).
c. Turn the adjustment nut in to increase the gas flow rate, and
out to decrease the gas flow rate using a 3/32" hex wrench.
