Trane IntelliPak WEHE Series Installation, Operation And Maintenance Manual page 35

Note: Gas pressure in excess of 14" w.c. or 0.5 psig will
damage the gas train.
Failure to use a pressure regulating device will result in
incorrect gas pressure. This can cause erratic operation
due to gas pressure fluctuations as well as damage the gas
valve. Over sizing the regulator will cause irregular
pulsating flame patterns, burner rumble, potential flame
outages, and possible gas valve damage.
If a single pressure regulator serves more than one rooftop
unit, it must be sized to ensure that the inlet gas pressure
does not fall below 7" w.c. with all the furnaces operating
at full capacity. The gas pressure must not exceed 14" w.c.
when the furnaces are off.
7. Provide adequate support for all field installed gas
piping to avoid stressing the gas train and controls.
Table 6. Sizing natural gas pipe mains & branches
Gas Supply Pipe
Run (ft) 1-1/4" Pipe
10
20
30
40
50
60
70
80
90
100
125
150
175
200
Notes:
1. 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.
2. Obtain the Specific Gravity and BTU/Cu.Ft. from the gas company.
3. 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 500 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 6, p.
Cu.Ft/Hour = 500
Table 6, p. 30 indicates that a 1-1/4" pipe is required.
(a) Table is based on a specific gravity of 0.60. Use Table 3-1 for the specific gravity of the local gas supply.
RT-SVX35H-EN
1-1/2" Pipe
1050 1600
730 1100
590 890
500 760
440 670
400 610
370 560
350 530
320 490
305 460
275 410
250 380
225 350
210 320
30)
Hazard of Explosion!
Never use an open flame to detect gas leaks. It could
result in an explosion. Use a leak test solution for leak
testing. Failure to follow recommended safe leak test
procedures could result in death or serious injury or
equipment or property-only-damage.
8. Leak test the gas supply line using a soap-and-water
solution or equivalent before connecting it to the gas
train.
9. Check the supply pressure before connecting it to the
unit to prevent possible gas valve damage and the
unsafe operating conditions that will result.
Note: Do not rely on the gas train shutoff valves to isolate
the unit while conducting gas pressure/leak test.
These valves are not designed to withstand
pressures in excess of 14" w.c. or 0.5 psig.
Gas Input (Cubic Feet/Hour)
2" Pipe 2-1/2" Pipe
3050 4800
2100 3300
1650 2700
1450 2300
1270 2000
1150 1850
1050 1700
990 1600
930 1500
870 1400
780 1250
710 1130
650 1050
610 980
Installation
WARNING
(a)
3" Pipe 4" Pipe
8500
5900
4700
4100
3600
3250
3000
2800
2600
2500
2200
2000
1850
1700
17500
12000
9700
8300
7400
6800
6200
5800
5400
5100
4500
4100
3800
3500
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