Bosch 520-HN -L Manual page 18

18 | Installation instructions
GAS LINE SIZING
The gas supply piping should be sized according to the applicable code for a maximum draw of 117,000 BTUH. Measure the length
of gas supply line and use the tables in Fig. 14 or the gas line manufacturer's sizing tables to determine the pipe diameter necessary
to accommodate the BTU demand of the unit. If there are more gas appliances drawing on the same line, size the gas line according
to the total maximum amount of BTU draw for all appliances.
Note: Under sizing the gas line may result in diminished output. See chapter 3.7 for the procedure to measure gas pressure.
FOR NATURAL GAS
Maximum Capacity of pipe in Cubic Feet of Gas per Hour for Gas Pressure of 0.5 Psig or less and a Pressure drop of 0.3 in Water
Column (0.75mbar).(Based on a 0.60 Specific Gravity Gas) Btu numbers given in thousands.
Copper tubing is prohibited for use with Natural Gas in the Commonwealth of Massachusetts and not recommended elsewhere.
Follow boxed numbers for piping just one 520 HN (example: ¾" B.I. Natural Gas pipe for 20 ft (6.1m). will handle 190,000 btu's
(55.7 kWh). For multiple appliances combine the total btu input load and then refer to applicable chart below.
Nominal
Iron
Pipe
Internal
Size
Diameter
Inches inches
3/4 0.824
1 1.049
1 - 1/4 1.380
Table 7
Tube
size,
Inches
1/2
3/4
1
1 - 1/4
Table 8
* EHD = Equivalent Hydraulic Diameter. The greater the value EHD, the greater the gas capacity of the tubing.
6 720 644 942 (2014/11)
10 20 30 40
278 190 152 130
520 350 285 245
1050 730 590 500
Lenght of Flexible Corrugated Stainless Steel Tubing (CSST), Feet
EHD* 10
18 82
23 161
30 330
37 639
Lenght of Black Iron Pipe, Feet
50 60 70 80
115 105 96 90
215 195 180 170
440 400 370 350
20 30
58 47
116 96
231 188
456 374
90 100 125 150
84 79 72 64
160 150 130 120
320 305 275 250
40 50
41 37
83 75
162 144
325 292
175 200
59 55
110 100
225 210
60
34
68
131
267
520 HN