42
RT-SVX072A-EN
configuration.
1. Connect the supply gas piping using a “ground-
joint” type union to the furnace gas train and check
for leaks.
2. Adjust the inlet supply pressure to the
recommended 7" to 14" w.c. parameter for natural
gas.
3. Ensure that the piping is adequately supported to
avoid gas train stress.
Table 14. Sizing natural gas pipe mains and branches
Gas SupplyPipe Run
(ft)
Gas Input (Cubic Feet/Hour)
1¼" Pipe 1½" Pipe 2" Pipe 2½" Pipe 3" Pipe 4" Pipe
10
1,060 1,580 3,050 4,860 8,580 17,500
20 726
1,090 2,090 3,340 5,900 12,000
30 583 873
1,680 2,680 4,740 9,660
40 499 747
1,440 2,290 4,050 8,270
50 442 662
1,280 2,030 3,590 7,330
60 400 600
1,160 1,840 3,260 6,640
70 368 552
1,060 1,690 3,000 6,110
80 343 514 989
1,580 2,790 5,680
90 322 482 928
1,480 2,610 5,330
100 304 455 877
1,400 2,470 5,040
125 269 403 777
1,240 2,190 4,460
150 244 366 704
1,120 1,980 4,050
175 224 336 648
1,030 1,820 3,720
200 209 313 602 960
1,700 3,460
Notes:
1. Table is based upon specific gravity of 0.60. Refer to the latest edition of the National Fuel Gas Code, Z223.1, unless superseded by local gas codes.
2. If more than one unit is served by the same main gas supply, consider the total gas input (cubic feet/hr.) and the total length when determining
the appropriate gas pipe size.
3. Obtain the Specific Gravity and BTU/Cu.Ft. from the gas company.
4. The following example demonstrates the considerations necessary when determining the actual pipe size:
Example: A 40' pipe run is needed to connect a unit with a 850 MBH furnace to a natural gas supply having a rating of 1,000 BTU/Cu.Ft. and a
specific gravity of 0.60
Cu.Ft/Hour = Furnace MBH Input
Gas BTU/Cu.Ft. X Multiplier Table 15, p. 42
Cu.Ft/Hour = 850
The above table indicates that a 2" pipe is required.
Table 15. Specific gravity multipliers
Specific
Gravity Multiplier
0.50 1.10
0.55 1.04
0.60 1.00
0.65 0.96
IInnssttaallllaattiioonn
To Next Page
Loading...
Need help?
General
