36
4.
Install a ground union between the water heater and the manual
shut-off valve. This is to allow easy servicing. See
Figure 47
.
5.
Turn the gas supply on and check for leaks. See
Figure 47
. Use a
chloride-free soap and water solution (bubbles forming indicate
a leak) or other approved method.
Note:
Units with inputs of 175,000 BTU/hr or above must have a
minimum of 3/4” NPT gas pipe supplied to the water heater.
BLACK PIPE
INSTALLATIONS
SEDIMENT
TRAP
GAS
CONTROL
VALVE
GROUND
JOINT UNION
(OPTIONAL)
CAP
3” MIN.
Figure 41.
Black Pipe to Gas Valve
Note:
Always secure the square on the gas valve base with a
suitable wrench when tightening or loosening the gas piping.
GAS LINE SIZING
Depending on the developed equivalent length and/or the number
of appliances connected to a common main, the size of supply gas
lines may have to be increased.
Size the supply/main gas line(s) in accordance with
Table 18
or
Table 19
.
The values given in
Table 18
or
Table 19
are for straight lengths of
iron pipe at 0.5” W. C. (125 Pa) pressure drop, which is considered
normal for low pressure systems.
Note:
Fittings such as elbows and tees will add to the pipe pressure
drop.
Schedule-40 Steel or wrought-iron pipe is the preferred material for
the gas line of this water heater. It is imperative to follow the sizing
recommendations in the latest version of the
National Fuel Gas Code
if corrugated stainless steel tubing (CSST) is used as the gas line
for this water heater.
Table 18. Supply Gas Line Sizing U. S. Units
Length in
Feet
Normal Iron Pipe Sizes (Inches)
Input In Thousands Btu/Hr
1/2”
3/4”
1”
1 1/4”
1 1/2”
2”
10
175
360
680
1400
2100
3960
20
120
250
485
950
1460
2750
30
97
200
375
770
1180
2200
40
82
170
320
660
990
1900
50
73
151
285
580
900
1680
60
66
138
260
530
810
1520
70
61
125
240
490
750
1400
80
57
118
220
460
690
1300
90
53
110
205
430
650
1220
100
50
103
195
400
620
1150
125
44
93
175
360
550
1020
150
40
84
160
325
500
950
175
37
77
145
300
460
850
200
35
72
135
280
430
800
Table 19. Supply Gas Line Sizing Metric Units
Length In
Meters
Normal Iron Pipe Sizes (inches)
Input in kW
1/2”
3/4”
1”
1 1/4”
1 1/2”
2”
3.0
51
105
199
410
615
1160
6.1
35
73
142
278
428
805
9.1
28
59
110
225
346
644
12.2
24
50
94
193
290
556
15.2
21
44
83
170
264
492
18.3
19
40
76
155
237
445
21.3
18
37
70
143
220
410
24.4
17
35
64
135
202
381
27.4
16
32
60
126
190
357
30.5
15
30
57
117
182
337
38.1
13
27
51
105
161
299
45.7
12
25
47
95
146
278
53.3
11
23
42
88
135
249
61.0
10
21
40
82
126
234
