Gas Piping - Lennox SIGNATURE SL280UHV Installation Instructions Manual

Gas Piping

CAUTION
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 instal-
lation 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 fac-
tors such as length of run, number of fittings, and fur-
nace 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)
(3.048)
(mm)
1/2 .622 175
(12.7) (17.799) (4.96)
3/4 .824 360
(19.05) (20.930) (10.19)
1 1.049 680
(25.4) (26.645) (919.25)
1−1/4 1.380 1400
(31.75) (35.052) (39.64)
1−1/2 1.610 2100
(38.1) (40.894) (59.46)
2 2.067 3950
(50.8) (52.502) (111.85)
2−1/2 2.469 6300
(63.5) (67.713) (178.39)
3 3.068 11000
(76.2) (77.927) (311.48)
NOTE − Capacity given in cubic feet (m
Gas Pipe Capacity − ft
10 20 30
(6.096) (9.144)
120 97
(3.40) (2.75)
250 200
(7.08) (5.66)
465 375
(13.17) (10.62)
950 770
(26.90) (21.80)
460 1180
(41.34) (33.41)
2750 2200
(77.87) (62.30)
4350 3520
(123.17) (99.67)
7700 6250
(218.03) (176.98)
3
) of gas per hour and based on 0.60 specific gravity gas.
4 − The piping should be sloped 1/4 inch (6.4 mm) per 15
feet (4.57 m) upward toward the meter from the fur-
nace. The piping must be supported at proper intervals
[every 8 to 10 feet (2.44 to 3.01 m)] with suitable hang-
ers 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 figures 35 and 36.
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 petro-
leum gases.
NOTE − If emergency shutoff is necessary, shut off the main
manual gas valve and disconnect main power to the fur-
nace. The installer should properly label these devices.
TABLE 9
3 3
/hr (m /hr)
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)
Page 23
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)