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. Refer to the National Fuel Gas Code, NFPA 54, for proper gas line sizing. The below information is provided as an example.

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)

 

3/4

1

1 1/4

1 1/2

 

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

 

 

 

 

 

90

83

157

322

482

 

 

 

 

 

100

79

148

304

455

 

 

 

 

 

125

70

131

269

403

 

 

 

 

 

150

63

119

244

366

 

 

 

 

 

175

58

109

224

336

 

 

 

 

 

200

54

102

209

313

 

 

 

 

 

Length

 

Pipe Size (inches)

 

 

 

 

 

1/2

3/4

1

1 1/4

 

 

 

 

 

 

10

291

608

1150

2350

 

 

 

 

 

20

200

418

787

1620

 

 

 

 

 

30

160

336

632

1300

 

 

 

 

 

40

137

287

541

1110

 

 

 

 

 

50

122

255

480

985

 

 

 

 

 

60

110

231

434

892

 

 

 

 

 

80

101

212

400

821

 

 

 

 

 

100

94

197

372

763

 

 

 

 

 

125

89

185

349

716

 

 

 

 

 

150

84

175

330

677

 

 

 

 

 

175

74

155

292

600

 

 

 

 

 

200

67

140

265

543

 

 

 

 

 

20

VA Series Indoor LS Manual

Page 20
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Rinnai R98LSI-ASME, R75LSI, R94LSI, R50LSI installation manual Pipe Sizing Procedure Example

R50LSI, R94LSI, R75LSI, R98LSI-ASME, R98LSI specifications

The Rinnai R50LSI, R75LSI, R94LSI, R98LSI, and R98LSI-ASME are high-efficiency tankless water heaters designed for residential and commercial applications. Each model in this line-up boasts unique features and technologies that cater to varying hot water needs while emphasizing energy efficiency and reliability.

The R50LSI is the most compact option in the lineup, providing up to 5.1 gallons per minute (GPM) of hot water at a 35°F rise in temperature. It is an ideal choice for smaller households or apartments where space is a premium. It operates using a direct vent system, ensuring safe exhaust of combustion gases outside the home. The R75SLI, with a maximum output of 7.5 GPM, is suited for needs such as multiple showers running simultaneously, making it perfect for medium-sized homes.

Moving on to the R94LSI and R98LSI, these models provide even greater capacity and efficiency. The R94LSI offers an impressive 9.4 GPM flow rate, while the R98LSI reaches a peak of 9.8 GPM, supporting larger family requirements and ensuring hot water availability for multiple applications concurrently. Both models incorporate Rinnai’s advanced Circ-Logic technology, which allows users to set schedules for recirculating hot water, minimizing wait time and enhancing convenience.

For commercial applications, the R98LSI-ASME is a specialized model that includes the American Society of Mechanical Engineers (ASME) certification. This makes it suitable for larger facilities, such as restaurants, schools, and other institutions that demand a robust and efficient solution for comprehensive hot water needs.

All these models feature a user-friendly digital controller, enabling easy temperature adjustments and real-time monitoring. Moreover, their compact design means they can be installed in various locations, saving valuable space. The Rinnai tankless water heaters utilize a highly efficient condensing technology, resulting in a lower carbon footprint and reduced energy costs.

With a robust warranty program and the reliability that Rinnai is known for, the R50LSI, R75LSI, R94LSI, R98LSI, and R98LSI-ASME embody the pinnacle of water heating technology. These models not only provide the convenience of on-demand hot water but also contribute to energy conservation, making them an excellent choice for environmentally conscious consumers.