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Date: 8-4-2010
Revision: 0
Form: 2396
Gas
Manifold
Pressure
(IWC)
4.4 3.6 4.0 2.0
Max RPM
6000-
7000
5100-
5500
3550-
4200
2700-
2850
Low Fire
Gas
Manifold
Pressure
(IWC)
.3 .3 .2 .2
Min RPM
1200-
1600
1200-
1600
800-
950
800-
950
Table 9 Approximate Boiler Settings
2.3.9 GAS METER READINGS
Burner input rate can be checked by taking
readings from the gas meter. Please note
checking the rate with a meter is the only way to
be sure of input. Manifold readings are only an
approximate value and may vary from unit to
unit.
In order to obtain accurate data, there must be
no other appliances using gas from the same
meter while the burner input rate is being
checked.
A stopwatch or a watch with a second hand is
required to obtain a meter reading. Clock the
amount of time it takes for the smallest dial to
complete one revolution in seconds. Use the
following formula to obtain the cubic feet per
hour throughput of the unit.
secondsin timeg
clocked V
gas of
3600
c
c
13
=
=
=
=
−
ft
hrftCFH
g
V
CFH
c
c
To obtain the Btu per hour throughput of the unit
use the following formula.
()
3-
ftBtu in fuel of valueheating =
=
v
v
h
hCFHQ
If the meter is not calibrated for gas temperature
and pressure, correction factors must be applied
to determine correct rate in SCFH (standard
cubic feet per hour). Consult the National Fuel
Gas Code (ANSI Z223.1, NFPA 54) or the local
gas utility for further information. Refer to Table
10 for correction factors for the gas pressure at
the meter. Refer to Table 11 for the gas
temperature correction factors.
Gas Pressure at Meter Corr. Factor
14" w.c. 1.034
21" w.c. 1.051
1 psig 1.061
2 psig 1.136
5 psig 1.340
Table 10 Gas Pressure Correction
Gas Temp. at Meter Corr. Factor
40 °F
1.04
50 °F
1.02
60 °F
1.0
70 °F
.981
80 °F
.963
90 °F
.945
Table 11 Gas Temperature Correction
To correct for pressure and temperature use the
following formula.
2.2B tablecorrection re temperatu
2.2A tablecorrection pressure
=
=
=
t
p
tpc
t
t
tQtQ
38