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.
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