Gas Piping - Sizing Gas Lines - Weil-McLain WM97+70 Manual

WM97+ -
gas fired water boiler
Gas piping — sizing gas lines
Boiler gas connection is ½" NPT. Size gas lines large
enough to provide gas to all connected appliances.
Natural Gas:
Pipe sizing for natural gas
1. Size gas piping from meter outlet to entrance of boiler in accor-
dance with Figure 14 and Figure 15.
2. Use total input of all connected appliances. Divide total input in
Btuh by 1,000 to obtain cubic feet per hour of natural gas.
a. Pipe lengths in Figure 14 are equivalent length of straight
pipe. Convert pipe fittings to equivalent lengths using data
from Figure 15.
b. Figure 14 is only for natural gas with specific gravity 0.60, with
a pressure drop through the gas piping as listed in the table.
c. For additional gas pipe sizing information, refer to ANSI Z223.1
(or B149.1 or B149.2 for Canadian installations).
Natural gas supply pressure
1. Pressure required at gas valve inlet pressure port:
a. Maximum: 13" (330 mm) w.c. with no flow (lockup).
b. Minimum gas pressure, with gas flowing (verify during
boiler startup, while boiler is at high fire):
WM97+70: 3½" (89 mm) w.c.
WM97+110: 4½" (114 mm) w.c.
WM97+155: 3½" (89 mm) w.c.
2. Install 100% lockup gas pressure regulator in supply line if inlet
pressure can exceed 13" w.c. at any time. Adjust lockup regulator
for 13" w.c. maximum.
Propane Gas:
You must follow the instructions, beginning on page 14,
to operate the boiler on propane. Failure to comply could
result in severe personal injury, death or substantial
property damage.
Pipe sizing for propane gas
1. Contact gas supplier to size pipes, tanks and 100% lockup gas
pressure regulator.
Propane supply pressure
1. Adjust propane supply regulator provided by gas supplier for 13"
(330 mm) w.c. maximum pressure.
2. Pressure required at gas valve inlet pressure port:
a. Maximum: 13" (330 mm) w.c. with no flow (lockup).
b. Minimum gas pressure, with gas flowing (verify during
boiler startup, while boiler is at high fire):
WM97+70: 3½" (89 mm) w.c.
WM97+110: 4½" (114 mm) w.c.
WM97+155: 3½" (89 mm) w.c.
– 18 –
— Boiler Manual
Figure 14
Gas
Cubic feet per hour, natural gas, 0.60 specific gravity
pipe
total
length,
feet
½"
10 132
20 92
30 73
40 NA
50 NA
75 NA
100 NA
150 NA
Figure 15
Pipe size
inches
½
¾
1
1¼
1½
2
2½
Pipe capacity for 0.60 specific gravity
natural gas; pipe length is in equivalent
feet
Capacity
Gas pressure 13" (330 mm) w.c. or less
Pressure drop 0.3 inches (7.6 mm) w.c.
¾" 1" 1¼" 1½"
278 520 1050 1600
190 350 730 1100
152 285 590 890
130 245 500 760
115 215 440 670
105 175 360 545
96 150 305 460
90 120 250 380
Equivalent lengths of straight pipe for
typical gas line fittings
Equivalent length, feet
90° Elbow
short long line
radius radius flow
3.6 2.2 1.7
4.4 2.3 2.4
5.2 2.7 3.2
6.6 3.2 4.6
7.4 3.4 5.6
8.5 3.6 7.7
9.3 4.0 9.3
Part number 550-142-085/0712
2" 2½"
3050 4800
2100 3300
1650 2700
1450 2300
1270 2000
1020 1650
870 1400
710 1130
Tee
branch
flow
4.2
5.3
6.6
8.7
9.9
12.0
13.0