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Part number 550-100-026/0404
GAS-FIRED WATER BOILER SERIES 2 — Boiler Manual
22
Table 4 Pipe capacity for 0.60 specific gravity natural gas
Gas piping
(continued)
5
Natural Gas:
Pipe sizing for natural gas
1. Refer to Table 4 for pipe length and diameter. Base on
rated boiler input (divide by 1,000 to obtain cubic
feet per hour).
a. Table 4 is only for natural gas with specific gravity 0.60,
with a pressure drop through the gas piping of 0.30"
w.c.
b. For additional gas pipe sizing information, refer to
ANSI Z223.1 (or B149.1 or B149.2 for Canadian
installations).
Natural gas supply pressure requirements
1. Pressure required at gas valve inlet pressure port:
• Maximum: 13" w.c. with no flow (lockup) or with
boiler on
• Minimum: 5" w.c. with gas flowing (verify during boiler
startup, while boiler is at high fire)
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.
Gas pipe
length
(feet)
Capacity of pipe for pipe size of:
(Capacity in 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
Propane Gas:
Ultra boilers are shipped ready to fire
natural gas ONLY (exception: Ultra-80-LP
is propane-ready). You must install the
propane orifice if the boiler will be
connected to propane. See page 9. Failure
to comply could result in severe personal
injury, death or substantial property
damage.
Pipe sizing for natural gas
1. Contact gas supplier to size pipes, tanks and 100%
lockup gas pressure regulator.
Propane supply pressure requirements
1. Adjust propane supply regulator provided by gas
supplier for 13" w.c. maximum pressure.
2. Pressure required at gas valve inlet pressure port:
• Maximum: 13" w.c. with no flow (lockup) or with
boiler on
• Minimum: 4" w.c. with gas flowing (verify during boiler
startup, while boiler is at high fire)