Rinnai Sensei CU199i Installation And Operation Manual page 63

Natural Gas
Table 28: Pressure Drop 3.0 in. w.c.
Intended use: Initial supply
pressure of 8.0 in. w.c.
or greater.
Information in table
obtained from NFPA 54,
ANSI Z223.1 - 2015.
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 30: Pressure Drop 0.5 in. w.c.
Information in table obtained from
NFPA 54, ANSI Z223.1 - 2015.
Length in ft (meters)
10 (3)
20 (6)
30 (9)
40 (12)
50 (15)
60 (18)
80 (24)
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
250 524 986
214 448 844
190 397 748
172 360 678
158 331 624
147 308 580
138 289 544
131 273 514
Schedule 40 Metallic Pipe
Inlet Pressure:
Specific Gravity:
Nominal Pipe Size (in.)
1/2 3/4 1
Capacity in Thousands of Btu per Hour
290 608 1,150
200 418 787
160 336 632
137 287 541
122 255 480
110 231 434
101 212 400
94 197 372
Rinnai Model Gas Input:
Less than 2 psi
0.60
Additional Appliance Total Gas Input:
1 1 1/4
Heating Value of Gas:
3,670
Cubic Feet Per Hour (CFH):
2,520
2,030
1,730
1,540
1,390
Answer:
1,280
1,190
For this example, the pipe diameter
1,120
must be at least 1/2 in. pipe size and
20 ft (6 m) in length.
1,060
Rinnai Model Gas Input:
A
11 in w.c.
1.50
Additional Appliance Total Gas Input:
1 1/4
Total Gas Input:
Total Gas
2,350
1,620
Total Gas
1,300
Input
1,110
985
Answer:
892
Total Gas
821
Input
763
For this example, the pipe diameter
must be at least 1/2 in. nominal pipe
size and 10 ft (3 m) in length.
Table 29: Example
199,000
A
65,000
B
1,000
C
A
(CFH) =
199,000+65,000
(CFH) =
1,000
264
(CFH) =
Table 31: Example
199,000
Btu/hr
65,000
B
=
A
Input
=
199,000 + 65,000
264,000
=
Btu/hr
Btu/hr
Btu/ft
3
+ B
C
ft /hr
3
Btu/hr
+ B
Btu/hr
63