Install Instructions

Gas piping — sizing gas lines
Figure 19 Pipe capacity for 0.60 specifi c gravity
natural gas; pipe length is in equivalent
feet.
Part number 550-100-191/0917
21
®
gas-fired water boiler — 70/110/155 Boiler Manual
Pipe size
inches
Equivalent length, feet
90° Elbow Tee
short
radius
long
radius
line
fl ow
branch
fl ow
½
3.6 2.2 1.7 4.2
¾
4.4 2.3 2.4 5.3
1
5.2 2.7 3.2 6.6
1¼
6.6 3.2 4.6 8.7
1½
7.4 3.4 5.6 9.9
2
8.5 3.6 7.7 12.0
2½
9.3 4.0 9.3 13.0
Gas
pipe
total
length,
feet
Capacity
Cubic feet per hour, natural gas, 0.60 specifi c gravity
Gas pressure 13" (330 mm) w.c. or less
Pressure drop 0.3 inches (7.6 mm) w.c
.
½" ¾" 1" 1¼" 1½" 2" 2½"
10 132 278 520 1050 1600 3050 4800
20 92 190 350 730 1100 2100 3300
30 73 152 285 590 890 1650 2700
40 NA 130 245 500 760 1450 2300
50 NA 115 215 440 670 1270 2000
75 NA 105 175 360 545 1020 1650
100 NA 96 150 305 460 870 1400
150 NA 90 120 250 380 710 1130
Figure 20 Equivalent lengths of straight pipe for
typical gas line fi ttings.
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
accordance with Figure 19 and Figure 20 .
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 19 are equivalent length of straight
pipe. Convert pipe fi ttings to equivalent lengths using data
from Figure 20 .
b. Figure 19 is only for natural gas with specifi c 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 NFPA 54 - latest edition (or Natural Gas and Propane
Installation CAN/CSA B149.1 or B149.2 for Canadian
installations).
Natural gas s upply pressure
1. Pressure required at gas valve inlet pressure port:
a. Maximum: 13" (330 mm) w.c. with no fl ow (lockup).
b. Minimum gas pressure, with gas fl owing (verify during
boiler startup, while boiler is at high fi re):
EVG 70: 3½" (89 mm) w.c.
EVG 110: 3½" (89 mm) w.c.
EVG 155: 3½" (89 mm) w.c.
c. Nominal gas pressure: 7.0" (178 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 15 , 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 fl ow (lockup).
b. Minimum gas pressure, with gas fl owing (verify during
boiler startup, while boiler is at high fi re):
EVG 70: 3½" (89 mm) w.c.
EVG 110: 3½" (89 mm) w.c.
EVG 155: 3½" (89 mm) w.c.
c. Nominal gas pressure: 11.0" (279 mm) w.c.