Navien NCB-180, Service Manual

Page: 27 / 149

24 NCB Service Manual Version 1.0
6. Re-open the manual gas valve and check for leaks.
7. Open multiple fixtures that have high flow rates, such as
bathtub and shower faucets, to allow the boiler to operate
up to its maximum firing rate.
8. When the boiler reaches its maximum firing rate, check the
inlet gas pressure reading on the manometer. The gas
pressure must fall within the proper operating range
indicated in the previous page and also in the
specifications on page 17.
4.2.1 Gas Pipe Sizing Tables (Referenced from 2012 National Fuel Gas Code)
These tables are for reference only. Please consult the gas pipe manufacturer for actual pipe capacities.
Maximum Natural Gas Delivery Capacity
in Cubic Feet (ft 3 ) per Hour (0.60 Specific Gravity; 0.5” WC Pressure Drop). Contact your gas supplier for BTU/ft 3 ratings. Use 1,000
BTU/ft3 for simplified calculations. This table is recommended for supply pressures less than 6” WC.
Pipe
Size
Length (including fittings)
10'
(3m) 20'
(6m) 30'
(9m) 40'
(12m) 50'
(15m) 60'
(18m) 70'
(21m) 80'
(24m) 90'
(27m) 100'
(30m) 125'
(38m)
3/4"
360 247 199 170 151 137 126 117 110 104 92
1"
678 466 374 320 284 257 237 220 207 195 173
1 1/4"
1,390 957 768 657 583 528 486 452 424 400 355
1 1/2"
2,090 1,430 1,150 985 873 791 728 677 635 600 532
2"
4,020 2,760 2,220 1,900 1,680 1,520 1,400 1,300 1,220 1,160 1,020
2 1/2"
6,400 4,400 3,530 3,020 2,680 2,430 2,230 2,080 1,950 1,840 1,630
3"
11,300 7,780 6,250 5,350 4,740 4,290 3,950 3,670 3,450 3,260 2,890
4"
23,100 15,900 12,700 10,900 9,660 8,760 8,050 7,490 7,030 6,640 5,890