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410.2 Gas Pipe Sizing Reference Tables <br /> The gas supply must be capable of handling the entire gas Table 25: Gas Pipe Sizing Calculation <br /> load required at the location. Gas line sizing is based on Worksheet <br /> gas type, the pressure drop in the system, the gas pressure Instructions: Enter values in empty boxes. <br /> supplied, and gas line type. For gas pipe sizing, refer to Rinnai Model Gas Input: <br /> the National Fuel Gas Code,ANSI Z223.1/NFPA 54, or the <br /> Natural Gas and Propane Installation Code, CSA B149.1 FA Btu/hr <br /> For some tables, you will need to determine the cubic Additional Appliance Total Gas Input: <br /> feet per hour of gas required by dividing the gas input by B Btu/hr <br /> the heating value of the gas (available from the local gas <br /> company). The gas input needs to include all gas products Heating Value of Gas: <br /> at the location and the maximum Btu usage at full load when C Btu/ft3 <br /> all gas products are in use. <br /> Cubic Feet Per Hour(CFH): <br /> Use the table for your gas type and pipe type to find the <br /> pipe size required. The pipe size must be able to provide the A+ B <br /> required cubic feet per hour of gas or the required Btu/hour. (CFH) = C <br /> The information below is provided as an example. The <br /> appropriate table from the applicable code must be used. (CFH) _ <br /> Answer: L(CFH) = ft3/hr <br /> Natural Gas <br /> Table 26: Pressure Drop 0.5 in. w.c. Table 27: Example <br /> Rinnai Model Gas Input: <br /> Information in table Schedule 40 Metallic Pipe <br /> obtained from NFPA 54, A Btu/hr <br /> ANSI Z223.1-2015. Inlet Pressure: Less than 2 psi <br /> Specific Gravity: 0.60 Additional Appliance Total Gas Input: <br /> Nominal Pipe Size (in.) B 1 05,000 1 Btu/hr <br /> 1/2 3/4 1 1 1 1/4 Heating Value of Gas: <br /> Length in ft(meters) Capacity in Cubic Feet of Gas per Hour C 1,000 1 Btu/ft3 <br /> 10 (3) 172 360 678 1,390 <br /> Cubic Feet Per Hour(CFH): <br /> 20 (6) 118 247 466 957 A + B <br /> 30 (9) 95 199 374 768 (CFH) = C <br /> 40 (12) 81 170 320 657 1 000+O5 DOO <br /> 50 (15) 72 151 284 583 (CFH) = 1,000 <br /> 60 (18) 65 137 257 528 Answer: <br /> 70 (21) 60 126 237 486 (CFH) _ ft3/hr <br /> 80 (24) 56 117 220 452 <br /> For this example, the pipe diameter <br /> 90 (27) 52 110 207 424 must be at least 3/4 in. pipe size and <br /> 100 (30) 50 104 195 400 10 ft (3 m) in length. <br /> Rinnai Tankless Water Heater Installation and Operation Manual 62 <br />