Gas Piping - Lennox G40UH Series Installation Instructions Manual

Resize the common venting system to the minimum
size determined by using the appropriate tables in ap-
pendix G. (These are in the current standards of the
National Fuel Gas Code ANSI Z223.1 in the USA, and
the appropriate Category 1 Natural Gas and Propane
appliances venting sizing tables in the current stan-
dards of the CSA B149 Natural Gas and Propane
Installation Codes in Canada.)

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.
WARNING
Do not exceed 600 in−lbs (50 ft−lbs) torque when at-
taching the gas piping to the gas valve.
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.
Nominal
Internal
Iron Pipe Iron Pipe
Diameter Diameter
Size
inches
inches
(mm)
(3.048)
(mm)
3/8 .493
(9.53) (12.522) (2.69)
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)
95 65 52
(1.84) (1.47)
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.
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.
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 inside vertical pipe runs
to the unit.
5 − 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 − Install a 1/8 inch NPT plugged tap in the field piping
upstream of the gas supply connection to the unit. The tap
must be accessible for test gauge connection. See figure 19.
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)
45 40 36
(1.27) (1.13) (1.02)
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 20
IMPORTANT
70 80 90
(21.336) (24.384) (27.432)
33 31 29
(.73) (.88) (.82)
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)
27
(.76)
50
(1.42)
103
(2.92)
195
(5.52)
400
(11.33)
620
(17.56)
1150
(32.56)
1850
(52.38)
3250
(92.03)