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Gas Piping
If a flexible gas connector is required or allowed by
the authority that has jurisdiction, black iron pipe shall
be installed at the gas valve and extend outside the
furnace cabinet. The flexible connector can then be
added between the black iron pipe and the gas supply
line.
Gas Supply
1.
This unit is shipped standard for left or right side
installation of gas piping (or top entry in horizontal
applica tions). Connect the gas supply to the piping
assembly.
2.
When connecting the gas supply piping, consider
factors such as length of run, number of fittings, and
furnace rating to avoid excessive pressure drop. Table
9 lists recommended pipe sizes for typical applications.
3.
The gas piping must not run in or through air ducts,
clothes chutes, gas vents or chimneys, dumb waiters,
or elevator shafts.
Nominal
Internal
Iron Pipe
Diameter
Size
inches
inches
(mm)
(mm)
1/2
.622
(12.7)
(17.799)
3/4
.824
(19.05)
(20.930)
1
1.049
(25.4)
(26.645)
(919.25)
1-1/4
1.380
(31.75)
(35.052)
1-1/2
1.610
(38.1)
(40.894)
2
2.067
(50.8)
(52.502)
(111.85)
2-1/2
2.469
(63.5)
(67.713)
(178.39)
3
3.068
(76.2)
(77.927)
(311.48)
Note: Capacity given in cubic feet (m³) of gas per hour and based on 0.60 specific gravity gas.
Page 22 of 39
CAUTION
Gas Pipe Capacity - ft³/hr (m³/hr)
10
20
30
(3.048)
(6.096)
(9.144)
175
120
97
(4.96)
(3.40)
(2.75)
360
250
200
(10.19)
(7.08)
(5.66)
680
465
375
(13.17)
(10.62)
1400
950
770
(39.64)
(26.90)
(21.80)
2100
1460
1180
(59.46)
(41.34)
(33.41)
3950
2750
2200
(77.87)
(62.30)
6300
4350
3520
(123.17)
(99.67)
11000
7700
6250
(218.03)
(176.98)
4.
The piping should be sloped 1/4 inch (6.4 mm) per
15 feet (4.57 m) upward toward the meter from the
furnace. The piping must be supported at proper
intervals [every 8 to 10 feet (2.44 to 3.01 m)] with
suitable hangers or straps. Install a drip leg in vertical
pipe runs to the unit.
5.
A 1/8" N.P.T. plugged tap or pressure post is located
on the gas valve to facilitate test gauge connection.
See Figure 28.
6.
In some localities, codes may require the installation
of a manual main shut off valve and union (furnished
by the installer) external to the unit. The union must be
of the ground joint type.
Compounds used on threaded joints of gas piping must
be resistant to the actions of liquified petroleum gases.
NOTE: If emergency shutoff is necessary, shut off the
main manual gas valve and disconnect main power to the
furnace. The installer should properly label these devices.
Length of Pipe - feet (m)
40
50
60
(12.192)
(15.240)
(18.288)
82
73
66
(2.32)
(2.07)
(1.87)
170
151
138
(4.81)
(4.28)
(3.91)
320
285
260
(9.06)
(8.07)
(7.36)
660
580
530
(18.69)
(16.42)
(15.01)
990
900
810
(28.03)
(25.48)
(22.94)
1900
1680
1520
(53.80)
(47.57)
(43.04)
3000
2650
2400
(84.95)
(75.04)
(67.96)
5300
4750
4300
(150.07)
(134.50)
(121.76)
Table 9.
Issue 2302
IMPORTANT
70
80
90
(21.336)
(24.384)
(27.432)
61
57
53
(1.73)
(1.61)
(1.50)
125
118
110
(3.54)
(3.34)
(3.11)
240
220
205
(6.80)
(6.23)
(5.80)
490
460
430
(13.87)
(13.03)
(12.18)
750
690
650
(21.24)
(19.54)
(18.41)
1400
1300
1220
(39.64)
(36.81)
(34.55)
2250
2050
1950
(63.71)
(58.05)
(55.22)
3900
3700
3450
(110.43)
(104.77)
(97.69)
100
(30.480)
50
(1.42)
103
(2.92)
195
(5.52)
400
(11.33)
620
(17.56)
1150
(32.56)
1850
(52.38)
3250
(92.03)
507335-03
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