8
GAS PIPING
Contact your local gas service company to ensure that adequate
gas service is available and to review applicable installation codes
for your area.
Size the main gas line in accordance with Table 1. The figures shown
are for straight lengths of pipe at 0.5 in. W.C. pressure drop, which
is considered normal for low pressure systems. Note: Fittings such
as elbows, tees and line regulators will add to the pipe pressure
drop. Also refer to the current editions of the National Fuel Gas
Code or Natural Gas and Propane Installation Code.
WARNING
THE HEATER IS NOT INTENDED FOR OPERATION AT HIGHER
THAN 14.0" W.C.(3.48 kPa) - NATURAL GAS OR 14.0" W.C. (3.48
kPa) PROPANE GAS SUPPLY PRESSURE. EXPOSURE TO
HIGHER SUPPLY PRESSURE MAY CAUSE DAMAGE TO THE GAS
VALVE WHICH COULD RESULT IN FIRE OR EXPLOSION. IF
OVERPRESSURE HAS OCCURRED SUCH AS THROUGH
IMPROPER TESTING OF GAS LINES OR EMERGENCY
MALFUNCTION OF THE SUPPLY SYSTEM, THE GAS VALVE
MUST BE CHECKED FOR SAFE OPERATION. MAKE SURE THAT
THE OUTSIDE VENTS ON THE SUPPLY REGULATORS AND THE
SAFETY VENT VALVES ARE PROTECTED AGAINST BLOCKAGE.
THESE ARE PARTS OF THE GAS SUPPLY SYSTEM, NOT THE
HEATER. VENT BLOCKAGE MAY OCCUR DURING ICE STORMS.
TABLE 1 - GAS SUPPLY LINE SIZES (IN INCHES)*
MAXIMUM CAPACITY OF PIPE IN
CUBIC FEET PER HOUR
LENGTH
NOMINAL IRON PIPE SIZES (INCHES)
IN
INPUT IN THOUSANDS (BTU/HR)
FEET
1/2" 3/4"
1" 1 1/4" 1 1/2"
2"
2 1/2"
3"
4"
10
175 360 680 1400
2100 3960
6300
11000 23000
20
120 250 465
950
1460 2750
4360
7700
15800
30
97
200 375
770
1180 2200
3520
6250
12800
40
82
170 320
660
990
1900
3000
5300
10900
50
73
151 285
580
900
1680
2650
4750
9700
60
66
138 260
530
810
1520
2400
4300
8800
70
61
125 240
490
750
1400
2250
3900
8100
80
57
118 220
460
690
1300
2050
3700
7500
90
53
110 205
430
650
1220
1950
3450
7200
100
50
103 195
400
620
1150
1850
3250
6700
125
44
93
175
360
550
1020
1650
2950
6000
150
40
84
160
325
500
950
1500
2650
5500
175
37
77
145
300
460
850
1370
2450
5000
200
35
72
135
280
430
800
1280
2280
4600
LENGTH
NOMINAL IRON PIPE SIZES (INCHES)
IN
INPUT IN KW
METERS 1/2" 3/4" 1" 1 1/4" 1 1/2"
2"
2 1/2"
3"
4"
3
51
105 199
410
615
1160
1845
3221
6735
6
35
73 142
278
428
805
1277
2255
4626
9
28
59 110
225
346
644
1031
1830
3748
12
24
50
94
193
290
556
878
1552
3192
15
21
44
83
170
264
492
776
1391
2840
18
19
40
76
155
237
445
703
1259
2577
21
18
37
70
143
220
410
659
1142
2372
24
17
35
64
135
202
381
600
1083
2196
27
16
32
60
126
190
357
571
1010
2108
31
15
30
57
117
182
337
542
952
1962
38
13
27
51
105
161
299
483
864
1757
46
12
25
47
95
146
278
439
776
1610
53
11
23
42
88
135
249
401
717
1464
61
10
21
40
82
126
234
375
688
1347
IT IS IMPORTANT TO GUARD AGAINST GAS VALVE FOULING
FROM CONTAMINANTS IN THE GAS WAYS. SUCH FOULING
MAY CAUSE IMPROPER OPERATION, FIRE OR EXPLOSION.
IF COPPER SUPPLY LINES ARE USED THEY MUST BE
INTERNALLY TINNED AND CERTIFIED FOR GAS SERVICE.
BEFORE ATTACHING THE GAS LINE, BE SURE THAT ALL GAS
PIPE IS CLEAN ON THE INSIDE.
TO TRAP ANY DIRT OR FOREIGN MATERIAL IN THE GAS SUPPLY
LINE, A DIRT LEG (SOMETIMES CALLED SEDIMENT TRAP OR DRIP
LEG) MUST BE INCORPORATED IN THE PIPING (SEE FIG. 5). THE
DIRT LEG MUST BE READILY ACCESSIBLE AND NOT SUBJECT
TO FREEZING CONDITIONS. INSTALL IN ACCORDANCE WITH
RECOMMENDATIONS OF SERVING GAS SUPPLIERS. REFER TO
THE CURRENT EDITION OF THE NATIONAL FUEL GAS CODE OR
NATURAL GAS AND PROPANE INSTALLATION CODE.
To prevent damage, care must be taken not to apply too much torque
when attaching gas supply pipe to gas valve inlet.
Apply joint compounds (pipe dope) sparingly and only to the male
threads of pipe joints. Do not apply compounds to the first two
threads. Use compounds resistant to the action of liquefied
petroleum gases.
BEFORE PLACING THE HEATER IN OPERATION, CHECK FOR
GAS LEAKAGE.
Use soap and water solution or other material
acceptable for the purpose in locating the leaks.
DO NOT USE
MATCHES, CANDLES, FLAME OR OTHER SOURCES OF
IGNITION FOR THIS PURPOSE.
DISCONNECT THE HEATER AND ITS MANUAL GAS SHUTOFF
VALVE FROM THE GAS SUPPLY PIPING SYSTEM DURING ANY
SUPPLY PRESSURE TESTING EXCEEDING 1/2 PSIG (3.45 kPa).
GAS SUPPLY LINE MUST BE CAPPED WHEN DISCONNECTED
FROM THE HEATER FOR TEST PRESSURES OF 1/2 PSIG (3.45
kPa) OR LESS. THE APPLIANCE NEED NOT BE DISCONNECTED,
BUT MUST BE ISOLATED FROM THE SUPPLY PRESSURE TEST
BY CLOSING THE MANUAL GAS SHUTOFF VALVE.
FIGURE 5 - GAS PIPING AND DIRT LEG INSTALLATION
GAS METER SIZE
Be sure the gas meter has sufficient capacity to supply the full
rated gas input of the water heater as well as the requirements of
all other gas fired equipment supplied by the meter. If gas meter
is too small, ask the gas company to install a larger meter having
adequate capacity.
