Trane SFHJ090-162 - Page 69

Installation
RT-SVX24J-EN 69
Table 16. Sizing natural gas pipe mains and branches
Gas Supply
Pipe Run
(ft)
Gas Input (Cubic Feet/Hour)*
1¼"
Pipe
1½"
Pipe
2"
Pipe
2½"
Pipe
3"
Pipe
4"
Pipe
10 1050 1600 3050 4800 8500 17500
20 730 1100 2100 3300 5900 12000
30 590 890 1650 2700 4700 9700
40 500 760 1450 2300 4100 8300
50 440 670 1270 2000 3600 7400
60 400 610 1150 1850 3250 6800
70 370 560 1050 1700 3000 6200
80 350 530 990 1600 2800 5800
90 320 490 930 1500 2600 5400
100 305 460 870 1400 2500 5100
125 275 410 780 1250 2200 4500
150 250 380 710 1130 2000 4100
175 225 350 650 1050 1850 3800
200 210 320 610 980 1700 3500
Notes:
1. *Table is based on a specific gravity of 0.60. Use Table 17, p. 69 for
the specific gravity of the local gas supply.
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 17, p. 69
Cu.Ft/Hour = 850
Table 16, p. 69 indicates that a 2" pipe is required.
Table 17. Specific gravity multipliers
Specific
Gravity Multiplier
0.50 1.10
0.55 1.04
0.60 1.00
0.65 0.96
Table 18. Gas heating capacity altitude correction factors
Altitude (Ft.)
Sea Level
To 2000
2001 to
2500
2501 to
3500
3501 to
4500
4501 to
5500
5501 to
6500
6501 to
7500
Capacity
Multiplier
1.00 .92 .88 .84 .80 .76 .72
Note: Correction factors are per AGA Std. 221.30 - 1964, Part VI, 6.12. Local codes may supersede.
Figure 46. Two-stage natural gas train for 850, 1100 Mbh heaters