39
Rinnai America
FF Models
I N S TA L L E R ’ S I N S TA L L AT I O N I N S T R U C T I O N S
Gas Piping Sizing Chart
Capacity Table for Natural Gas
cubic feet / hour
(table assumes .3 inch pressure drop, specifi c gravity of .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
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 Heaters.
The formula for fi guring 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 liquifi ed petroleum gases
(table assumes 11 inches of water column pressure at the inlet, .5 inch drop)
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
