Installation
14
GUNE-SVX001A-EN
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 specified
in
. A field LP tank regulator must be used to
limit the supply pressure to a maximum of 14 inches
wc (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
and
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
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 re-seat. A 5/16-inch ID hose
fits 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
8. Make certain that all connections have been
adequately doped and tightened.
Table 4.
Gas pipe size
(a)
Nominal
Iron
Pipe
Size (in)
Internal
Diameter
(in)
Length of Pipe, feet (meters)
10
20
30
40
50
60
70
80
90
100
125
150
175
200
(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)
Notes:
1.
Determine the required ft
3
/h by dividing the input by 1,000.
For SI/metric measurements: convert Btu/h to kW. Multiply the unit’s inputs (kW) by 0.0965 to determine m
3
/h.
2.
For natural gas
:
select pipe size directly from the table.
3.
For propane gas: multiply the ft
3
/h value by 0.633; then, use the table.
Refer to the metric conversion factors listed in
“General Safety Information,” p. 3
for SI Unit measurement conversions.
(a) Maximum capacity of pipe in ft
3
/h of gas (m
3
/h) for gas pressures of 0.5 psig (3.5 kPa) or less, and a pressure drop of 0.5 in. wc (124.4 Pa), based on
a 0.60 specific gravity gas.
