10
INSTALLATION (continued)
PIPE INSTALLATION
1. Install the gas piping in accordance with applicable
local codes.
2. Check gas supply pressure. Each duct furnace must
be connected to a manifold pressure and a gas supply
capable of supplying its full rated capacity as
specifi ed in Table 5. A fi eld LP tank regulator must be
used to limit the supply pressure to a maximum of 14
inches W.C. (3.5 kPa). All piping should be sized in
accordance with the latest edition of ANSI Standard
Z223.1 (NFPA 54), National Fuel Gas Code; in
Canada, according to CSA B149. See Tables 1 & 4
for correct gas piping size. If gas pressure is excessive
on natural gas applications, install a pressure
regulating valve in the line upstream from the main
shutoff valve.
3. Adequately support the piping to prevent strain on
the gas manifold and controls.
4. To prevent the mixing of moisture with gas, run the
take-off piping from the top, or side, of the main.
5. Standard duct furnaces, optional two-stage and
modulation units are supplied with a combination
valve which includes:
a. Manual
“A”
valve
b. Manual
“B”
valve
c. Solenoid
valve
d.
Pressure regulator
Pipe directly into the combination valve (see Figure 6).
6. Gas valve has a pressure test post requiring a
3/32 inch hex head wrench to read gas supply and
manifold pressures. Open 1/4 turn counterclockwise
to read, turn clockwise to close and reseat. A
5/16 inch ID hose fi ts the pressure post.
7. Provide a drip leg in the gas piping near the gas duct
furnace. A ground joint union and a manual gas
shutoff valve should be installed ahead of the unit
heater controls to permit servicing. The manual
shutoff valve must be located external to the jacket
(See Figure 6).
8. Make cer tain that all connections have been
adequately doped and tightened.
Do not over tighten the inlet gas piping
into the valve. This may cause stresses that will crack
the valve!
NOTICE: Use pipe joint sealant resistant to the action
of liquefied petroleum gases regardless of gas
connected.
Check all pipe joints for leakage
using a soap solution or other approved method.
Never use an open fl ame or severe personal injury
or death may occur!
1. Determine the required Cu. Ft./Hr. by dividing the input by 1000. For SI/Metric measurements: Convert BTU/Hr. to kilowatts. Multiply the units
inputs (kW) by 0.0965 to determine Cu. Meters./Hr. 2. FOR NATURAL GAS: Select pipe size directly from the table. 3. FOR PROPANE GAS:
Multiply the Cu. Ft./Hr. value by 0.633; then, use the table. 4. Refer to the metric conversion factors listed in the General Safety section for SI Unit
measurement conversions.
Maximum Capacity of Pipe in Cubic Feet of Gas per Hour (Cubic Meters per Hour) for Gas Pressures of 0.5 psig (3.5 kPa) or Less,
and a Pressure Drop of 0.5 Inch Water Column (124.4 Pa)
(Based on a 0.60 Specifi c Gravity Gas)
Nominal
Iron Internal
Length of Pipe, Feet (meters)
Pipe Size
Diameter
10 20 30 40 50 60 70 80 90 100
125
150
175
200
Inch
Inch
(3.0) (6.1) (9.1) (12.2) (15.2) (18.3) (21.3) (24.4) (27.4) (30.5) (38.1) (45.7) (53.3) (61.0)
1/2
0.622
175
120 97 82 73 66 61 57 53 50 44 40 37 35
(4.96) (3.40) (2.75) (2.32) (2.07) (1.87) (1.73) (1.61) (1.50) (1.42) (1.25) (1.13) (1.05) (0.99)
3/4 0.824 360 250 200 170 151 138 125 118 110 103 93 84 77 72
(10.2) (7.08) (5.66) (4.81) (4.28) (3.91) (3.54) (3.34) (3.11) (2.92) (2.63) (2.38) (2.18) (2.04)
1 1.049 680 465 375 320 285 260 240 220 205 195 175 160 145 135
(19.3) (13.2) (10.6) (9.06) (8.07) (7.36) (6.80) (6.23) (5.80) (5.52) (4.96) (4.53) (4.11) (3.82)
1
1/4
1.380
1400 950 770 660 580 530 490 460 430 400 360 325 300 280
(39.6) (26.9) (21.8) (18.7) (16.4) (15.0) (13.9) (13.0) (12.2) (11.3) (10.2) (9.20) (8.50) (7.93)
1
1/2
1.610
2100
1460
1180 990 900 810 750 690 650 620 550 500 460 430
(59.5) (41.3) (33.4) (28.0) (25.5) (22.9) (21.2) (19.5) (18.4) (17.6) (15.6) (14.2) (13.0) (12.2)
2 2.067 3950 2750 2200 1900 1680 1520 1400 1300 1220 1150 1020 950 850 800
(112) (77.9) (62.3) (53.8) (47.6) (43.0) (39.6) (36.8) (34.5) (32.6) (28.9) (26.9) (24.1) (22.7)
2
1/2 2.469 6300 4350 3520 3000 2650 2400 2250 2050 1950 1850 1650 1500 1370 1280
(178) (123) (99.7) (85.0) (75.0) (68.0) (63.7) (58.0) (55.2) (52.4) (46.7) (42.5) (38.8) (36.2)
3 3.068 11000 7700 6250 5300 4750 4300 3900 3700 3450 3250 2950 2650 2450 2280
(311) (218) (177) (150) (135) (122) (110) (105) (97.7) (92.0) (83.5) (75.0) (69.4) (64.6)
4 4.026 23000
15800
12800
10900 9700 8800 8100 7500 7200 6700 6000 5500 5000 4600
(651) (447) (362) (309) (275) (249) (229) (212) (204) (190) (170) (156) (142) (130)
Table 4 - Gas Pipe Size
