Weil-McLain 155 ユーザーズマニュアル

Part number 550-101-233/0903

22

Pipe capacity for 0.60 specific gravity natural gas

Gas piping

 

(continued)

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.

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

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.

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)