Lennox G40UH(X) User Manual

Page 26
F− Proper Gas Flow (Approximate)
& Combustion
Furnace should operate at least 5 minutes before check-
ing gas flow. 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 13 below. Adjust manifold pressure on gas valve to
match time needed. Manifold pressure should not exceed
values listed in table 12. If manifold pressure matches
table 12 and rate is incorrect, check gas orifices for proper
size and restriction. After furnace has operated for 15 min-
utes take a combustion sample beyond the flue outlet and
compare to table 14. The maximum carbon monoxide
reading should not exceed 100ppm.
NOTE− To obtain accurate reading, shut off all other gas
appliances connected to meter.
IMPORTANT
For safety, shut unit off and remove manometer as
soon as an accurate reading has been obtained.
Take care to replace pressure tap plug.
TABLE 13
GAS METER CLOCKING CHART
Seconds for One Revolution
G40UH
Natural LP
G40UH
Unit
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
DIAL
−45 82 164 205 410
−70 55 110 136 272
−90 41 82 102 204
−110 33 66 82 164
−135 27 54 68 136
−155 23 46 58 116
Natural−1000 btu/cu ft LP−2500 btu/cu ft
TABLE 14
G40UH Unit CO
2
Range Nat CO
2
Range LP
24A−045(X) 5.50 − 6.50 6.80 − 7.80
36A−045 5.80 − 6.80 6.60 − 7.60
24A−070 7.00 − 8.00 8.00 − 9.00
36A−070(X) 6.80 − 7.80 7.80 − 8.80
48B−070 6.80 − 7.80 7.80 − 8.80
36B−090 7.20 − 8.20 7.70 − 8.70
48B−090(X) 7.20 − 8.20 7.70 − 8.70
36C−110 6.50 − 7.50 7.50 − 8.50
48C−110 6.90 − 7.90 8.50 − 9.50
60C−110(X) 6.50 − 7.50 7.50 − 8.50
48C−135 6.70 − 7.70 7.60 − 8.60
60D−135 6.70 − 7.70 7.60 − 8.60
60D−155 6.80 − 7.80 7.80 − 8.80

Lennox G40UH(X) Specifications

General

Brand	Lennox
Model	G40UH(X)
Category	Furnace
Language	English