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98618/035-20009-001
Rev. B (1205)
In the USA use the following formula
to calculate the furnace
input.
For natural gas multiply the heat content of the gas BTU/SCF (or Default 1030 BTU/SCF, times 2 cubic ft. of gas measured at the gas meter, times a
barometric pressure and temperature correction factor of 0.960; times 3600, then divided by the time (In seconds) it took to measure 2 cubic ft. of gas
from the gas meter.
For propane (LP) gas multiply the heat content of the gas BTU/SCF (or Default 2500 BTU/SCF, times 1 cubic ft. of gas measured at the gas meter,
times a barometric pressure and temperature
correction factor of 0.960; times 3600, then divided by the time (In seconds) it took to measure 1 cubic
ft. of gas from the gas meter.
The formula
for US input
calculation
using
a cubic
foot
gas
meter:
BTU/f 3 x 2 cu.ft, x 0.960 x 3600
=
BTUH/H
Seconds it took to measure the 2 cu.ft, of gas
NATURAL
GAS INPUT CALCULATION
EXAMPLE:
1030 x 2 x 0.960 x 3600
=
79,997.38
90.5
Natural Gas
BTU/SCF
1030
I
BTU/f 3 x 1 cu.ft, x 0.960 x 3600
=
Seconds it took to measure the 2 cu.ft, of gas
PROPANE
(LP) GAS INPUT CALCULATION
EXAMPLE:
2500 x 1 x 0.960 x 3600
=
108
Propane Gas
BTU/SCF
2500
BTUH/H
80.000.00
In Canada you will use the following
formula
to calculate the furnace
input if you are using a cubic foot gas meter.
For Natural Gas multiply the Heat content of the gas MJ/m 3 (or Default 39.2), times 2 cu. ft. of gas x 0.02831 to convert from cubic feet to cubic
meters measured at the gas meter, times a barometric
pressure and temperature
correction factor of 0.960; times 3600, then divided by the time it
took to measure 2 cu.ft, of gas from the gas meter.
For Propane (LP) Gas multiply the Heat content of the gas MJim 3 (or Default 93.14), times 1 cu. ft. of gas x 0.02831 to convert from cubic feet to
cubic meters measured at the gas meter, times a barometric pressure and temperature correction factor of 0.960; times 3600, then divided by the
time it took to measure 1 cu.ft, of gas from the gas meter.
The formula
for metric input calculation
using a cubic foot gas meter:
MJ/m 3 x (2 cu.ft, x Cony) x 0.960 x 3600
=
MJ/H
x
0.2777
=
kW
x
3412.14
Seconds it took to measure the 2 cu.ft, of gas
NATURAL
GAS INPUT CALCULATION
EXAMPLE:
39.2 x 2 x 0.960 x 3600
=
84.76
x
0.2777
=
23.54
x
3412.14
90.5
Natural Gas
BTU/SCF
1030 = 39.2 MJ/m 3
PROPANE
(LP) GAS INPUT CALCULATION
EXAMPLE:
93.15 x 1 x 0.960 x 3600
=
84.41
x
0.2777
=
23.45
x
3412.14
108
Propane Gas
BTU/SCF
2500+93.15
MJ/m 3
=
BTUH/H
=
80,312.62
=
80,000.00
In Canada
use the following
formula
to calculate the furnace
input if you are using a gas meter that measures cubic meters.
For Natural Gas multiply the Heat content of the gas MJ/m 3 (or Default 39.2), times 0.0566 m3 of gas measured at the gas meter, times a barometric
pressure and temperature correction factor of 0.960; times 3600, then divided by the time it took to measure 0.0566 m3 of gas from the gas meter.
For Propane (LP) Gas multiply the Heat content of the gas M Jim 3 (or Default 93.14), times 0.00283 m3 of gas measured at the gas meter, times a
barometric pressure and temperature
correction factor of 0.960; times 3600, then divided by the time it took to measure 0.0283 cm of gas from the
gas meter.
The formula
for metric
input
calculation
using
a cubic
foot
gas
meter:
MJ/m 3 x (2 cu.ft, x Cony) x 0.960 x 3600
=
MJ/H
x
Seconds it took to measure the 2 cu.ft, of gas
NATURAL
GAS INPUT CALCULATION
EXAMPLE:
39.2 x 2 x 0.960 x 3600
=
84.76
x
90.5
Natural Gas
BTU/SCF
1030 = 39.2 MJ/m 3
PROPANE
(LP) GAS INPUT CALCULATION
EXAMPLE:
93.15 x 1 x 0.960 x 3600
=
84.41
x
108
Propane Gas
BTU/SCF
2500+93.15
MJ/m 3
0.2777
=
kW
x
3412.14
0.2777
=
23.54
x
3412.14
0.2777
=
23.45
x
3412.14
=
BTUH/H
=
80,312.62
=
80,000.00
DO NOT ADJUST the manifold pressure regulator if the actual input is equal to or within 8% less than the furnace input specified on the rating plate
or if the furnace rise is above the specified rise range on the rating plate.
If the actual input is significantly
higher
than the furnace
input specified
on the rating plate then replace the gas orifice spuds with the gas ori-
fice spuds of the proper size for the type of gas you are using.
For altitudes above 2,000 ft. (610 m) the furnace input MUST BE DERATED. Refer to the GAS CONVERSION
FOR PROPANE (LP) AND HIGH
ALTITUDES
IN SECTION IV for information on high altitude conversions.
18
Unitary Products Group
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