Rinnai RSC199i Installation And Operation Manual page 59

Natural Gas
Table 26: Pressure Drop 3.0 in. wc
Intended use: Initial supply
pressure of 8.0 in. wc
or greater.
Information in table
obtained from NFPA 54,
ANSI Z223.1 - 2021.
Length in ft (meters)
10 (3)
20 (6)
30 (9)
40 (12)
50 (15)
60 (18)
70 (21)
80 (24)
90 (27)
100 (30)
Propane (Undiluted)
Table 28: Pressure Drop 0.5 in. wc
Information in table obtained from
NFPA 54, ANSI Z223.1 - 2021.
Length in ft (meters)
10 (3)
20 (6)
30 (9)
40 (12)
50 (15)
60 (18)
70 (21)
80 (24)
90 (27)
100 (30)
Rinnai Tankless Water Heater Installation and Operation Manual
Schedule 40 Metallic Pipe
Inlet Pressure:
Specific Gravity:
Nominal Pipe Size (in.)
1/2 3/4
Capacity in Cubic Feet of Gas per Hour
454 949 1,790
312 652 1,230
250 524
214 448
190 397
172 360
158 331
147 308
138 289
131 273
Schedule 40 Metallic Pipe
Inlet Pressure:
Specific Gravity:
Nominal Pipe Size (in.)
1/2 3/4
Capacity in Thousands of Btu per Hour
291 608 1,150
200 418 787
160 336 632
137 287 541
122 255 480
110 231 434
101 212 400
94 197 372
89 185 349
84 175 330
Less than 2 psi
0.60
1 1 1/4
3,670
2,520
986 2,030
844 1,730
748 1,540
678 1,390
624 1,280
580 1,190
544 1,120
514 1,060
Rinnai Model Gas Input:
11 in wc
1.50
Additional Appliance Total Gas Input:
1 1 1/4
Total Gas Input:
2,350
1,620
Total Gas
1,300
1,110
985
Answer:
892
821
763
For this example, the pipe diameter
716
must be at least 1/2 in. nominal pipe
677
size and 10 ft (3 m) in length.
Table 27: Example
Rinnai Model Gas Input:
199,000
A
Additional Appliance Total Gas Input:
65,000
B
Heating Value of Gas:
1,000
C
Cubic Feet Per Hour (CFH):
(CFH) =
199,000+65,000
(CFH) =
Answer:
264
(CFH) =
For this example, the pipe diameter
must be at least 1/2 in. pipe size and
20 ft (6 m) in length.
Table 29: Example
199,000
A
65,000
B
Total Gas
=
A
Input
=
199,000 + 65,000
Input
Total Gas
264,000
=
Input
Btu/hr
Btu/hr
Btu/ft
3
A + B
C
1,000
ft /hr
3
Btu/hr
Btu/hr
+ B
Btu/hr
59