20
Part Number 550-142-320/0720
GWA
Series 3
Gas-Fired Water Boilers –
Boiler Manual
Figure 17
Gas supply piping
Table 5 Pipe capacity for 0.60 specific gravity natural gas
5 Install gas piping
Natural Gas:
1. See Table 5 for pipe length and diameter. Base on
rated boiler input (divide by 1,000 to obtain cubic feet
per hour). Table 5 is only for gas with specific gravity
0.60, with a pressure drop through the gas piping of
0.30” w.c.
2. Inlet pressure required at gas valve inlet:
• Maximum: 13” w.c.
• Minimum: 5” w.c.
• Manifold gas pressure: 3.5” w.c.
3. Install 100% lockup gas pressure regulator in supply
line if inlet pressure exceeds 13” w.c. Adjust for 13”
w.c. maximum.
Propane Gas:
1. Contact gas supplier to size pipes, tanks and 100%
lockup gas pressure regulator.
2. Adjust propane supply regulator provided by gas sup-
plier for 13” w.c. maximum pressure.
3. Inlet pressure required at gas valve inlet:
• Maximum: 13” w.c.
• Minimum: 11” w.c.
• Manifold gas pressure: 10” w.c.
1. Remove jacket front panel and see
Figure 10
to pipe gas to
boiler.
a. Install drip leg at inlet of gas connection to boiler. Where
local utility requires drip leg to be extended to the floor,
use appropriate length of nipple between cap and tee.
b. Install ground joint union for servicing, when required.
c. Install manual shutoff valve in gas supply piping outside
boiler jacket when required by local codes or utility
requirements.
2. Support piping with hangers, not by boiler or its accessories.
3. Purge all air from gas supply piping.
4. Before placing boiler in operation, check boiler and its gas
connection for leaks.
a. Close manual main shutoff valve during any pressure
testing at less than 13” w.c.
b. Disconnect boiler and gas valve from gas supply piping
during any pressure testing greater than 13” w.c.
Do not check for gas leaks with an open flame —
Use bubble test. Failure to use bubble test or check
for gas leaks can cause severe personal injury,
death or substantial property damage.
5. Use pipe dope compatible with propane gases. Apply spar-
ingly only to male threads of pipe joints so that pipe dope
does not block gas flow.
Failure to apply pipe dope as described in this
manual can result in severe personal injury, death
or substantial property damage.
Connecting gas supply piping to boiler
Gas pipe
length
(feet)
Capacity of pipe for pipe size of:
(Capacity in standard cubic feet gas per hour)
½"
¾"
1"
1¼"
1½"
10
132
278
520
1050
1600
20
92
190
350
730
1100
30
73
152
285
590
860
40
63
130
245
500
760
50
56
115
215
440
670
75
45
93
175
360
545
100
38
79
150
305
460
150
31
64
120
250
380
