Page 46
MANIFOLD PRESSURE CHECK SET UP
Manifold Post
Clamp
5/16” Round
Hose
Reducer
Fitting
10” Long
Square
Tubing
2” Long
Square Tubing
Tee
Gas Valve Regulator
Vent Hose
(to burner box)
Measuring Device
Figure 52
F- Proper Gas Flow (Approximate)
Furnace should operate at least 5 minutes before check-
ing gas ow. Determine time in seconds for two revolu-
tions of gas through the meter. (Two revolutions assures a
more accurate time.) Divide by two and compare to time
in table 21 below. If manifold pressure matches table 21
and rate is incorrect, check gas orices for proper size and
restriction.
NOTE- To obtain accurate reading, shut o all other gas
appliances connected to meter.
TABLE 21
GAS METER CLOCKING CHART
EL296
Unit
Seconds for One Revolution
Natural LP
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
Dial
-045 80 160 200 400
-070 55 110 136 272
-090 41 82 102 204
-110 33 66 82 164
-135 27 54 68 136
Natural-1000 btu/cu ft LP-2500 btu/cu ft
G- Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas ow rate before checking com-
bustion. See sections E- and F-. Take combustion sample
beyond the ue outlet. Table 22 shows acceptable com-
bustions. The maximum carbon monoxide reading should
not exceed 100 ppm.
TABLE 22
EL296
Model
CO
2
% For Nat CO
2
% For L.P
Low Fire High Fire Low Fire High Fire
045 5.4 - 6.4 7.5 - 8.5 6.4 - 7.4 8.8 - 9.8
070 5.3 - 6.3 7.4 - 8.4 6.3 - 7.3 8.7 - 9.7
090 5.8 - 6.8 7.6 - 8.6 6.8 - 7.8 8.9 - 9.9
110 6.1 - 7.1 8.0 - 9.0 7.1 - 8.1 9.3 - 10.3
135 6.1 - 7.1 7.8 - 8.8 7.1 - 8.2 9.1 - 10.1
The maximum carbon monoxide reading should not exceed 100ppm.
H- High Altitude
The manifold pressure, gas orice and pressure switch
may require adjustment or replacement to ensure proper
operation at higher altitudes. See table 23 or 24 for man-
ifold pressures and table 25 for gas conversion and pres-
sure switch kits.
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