Gas Piping
Pipe Sizing Procedure - Example
The gas supply must be capable of handling the entire gas load at the location. Gas line sizing is based on gas type, the pressure drop in the system, the gas pressure supplied, and gas line type. For gas pipe sizing in the United States, refer to the National Fuel Gas Code, NFPA 54. For Canadian gas pipe sizing, refer to the Natural Gas and Propane Installation Code CAN/CSA B149.1. The below information is provided as an example. The appropriate table from the applicable code must be used.
1.Determine the cubic feet per hour of gas required by dividing the gas input (on the rating plate) by the heating value of the gas (available from the local gas company). The gas input needs to include all gas products at the location and the maximum BTU usage at full load when all gas products are in use.
Gas Input of Rinnai water heater (BTU / HR)
Cubic Feet per Hour (CFH) =
Heating Value of Gas (BTU / FT 3 )
2.Use the table for your gas type to find the pipe size required for your cubic feet per hour of gas and your pipe length.
Example: The heating value of propane gas for your location is 2516 BTU / FT 3. The gas input of the R94LSi is 190,000 BTU/HR. Additional appliances at the location require 75,000 BTU/HR.
Therefore the cubic feet per hour = (190,000+75,000) / 2516 = 105.3 FT 3/ HR.
If the pipe length is 100 ft then the 3/4 inch pipe size capable of supplying 197 FT 3/ HR of propane gas will be adequate.
Length |
| Pipe Size (inches) |
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3/4 | 1 | 1 1/4 | 1 1/2 | ||
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10 | 273 | 514 | 1060 | 1580 | |
20 | 188 | 353 | 726 | 1090 | |
30 | 151 | 284 | 583 | 873 | |
40 | 129 | 243 | 499 | 747 | |
50 | 114 | 215 | 442 | 662 | |
60 | 104 | 195 | 400 | 600 | |
70 | 95 | 179 | 368 | 552 | |
80 | 89 | 167 | 343 | 514 | |
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90 | 83 | 157 | 322 | 482 | |
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100 | 79 | 148 | 304 | 455 | |
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125 | 70 | 131 | 269 | 403 | |
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150 | 63 | 119 | 244 | 366 | |
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175 | 58 | 109 | 224 | 336 | |
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200 | 54 | 102 | 209 | 313 | |
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Length |
| Pipe Size (inches) |
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1/2 | 3/4 | 1 | 1 1/4 | ||
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10 | 291 | 608 | 1150 | 2350 | |
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20 | 200 | 418 | 787 | 1620 | |
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30 | 160 | 336 | 632 | 1300 | |
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40 | 137 | 287 | 541 | 1110 | |
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50 | 122 | 255 | 480 | 985 | |
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60 | 110 | 231 | 434 | 892 | |
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80 | 101 | 212 | 400 | 821 | |
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100 | 94 | 197 | 372 | 763 | |
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125 | 89 | 185 | 349 | 716 | |
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150 | 84 | 175 | 330 | 677 | |
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175 | 74 | 155 | 292 | 600 | |
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200 | 67 | 140 | 265 | 543 | |
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20 | Manual - Rinnai Condensing Water Heaters |
