Rinnai V3237FFU - Manual (Page 41)

41
Rinnai Corporation V3237 Models
After determining the length of pipe required select the pipe size that will supply the
cubic feet per hour of gas required for the input rating of the Rinnai water heater.
The formula for figuring the cubic feet per hour required is:
Gas Input of Rinnai water heater(BTU/HR)
CFH =
Heating Value of Gas(BTU/FT 3 )
*Gas input requirement is on the water heater data plate
*The heating value of the gas can be obtained from the local Natural Gas Utility
Capacity Table for LP Gas
BTUH of undiluted liquified petroleum gases
(table assumes 11 inches of water column pressure at the inlet, .5 inch drop)
GAS PIPING SIZING CHART
Capacity Table for Natural Gas
cubic feet / hour
(table assumes 0.3 inch pressure drop, specific gravity of 0.60)
Nominal Length of Pipe in Feet
Iron Pipe
Size
Inches
10 20 30 40 50 60 70 80 90 100 125 150 175 200
3/4 278 190 152 130 115 105 96 90 84 79 72 64 59 55
1 520 350 285 245 215 195 180 170 160 150 130 120 110 100
1-1/4 1050 730 590 500 440 400 370 350 320 305 275 250 225 210
1-1/2 1600 1100 890 760 670 610 560 530 490 460 410 380 350 320
Nominal Length of Pipe in Feet
Iron Pipe
Size
Inches
10 20 30 40 50 60 70 80 90 100 125 150
1/2 275 189 152 129
3/4 567 393 315 267 237 217 196 185 173 162 146
1 1071 732 590 504 448 409 378 346 322 307 275 252
1-1/4 2205 1496 1212 1039 913 834 771 724 677 630 567 511
This chart is only for black iron piping and is only for sizing Rinnai Water Heater at
high fire condition. Take into account other appliance(s) when sizing the overall gas
supply at high fire conditions.
U273-430(00).indd 41 06.2.8 10:37:06 AM