36
Rinnai Tankless Water Heater Installation and Operation Manual
Propane (Undiluted)
Table 16: Pressure Drop 0.5 in. wc
Information in table
obtained from NFPA 54,
ANSI Z223.1
Nominal Pipe Size (in.)
1/2
3/4
1
1 1/4
Length in ft
(meters)
Capacity in Thousands of Btu per Hour
10 (3)
291
608
1,150
2,350
20 (6)
200
418
787
1,620
30 (9)
160
336
632
1,300
40 (12)
137
287
541
1,110
50 (15)
122
255
480
985
60 (18)
110
231
434
892
80 (24)
101
212
400
821
100 (30)
94
197
372
763
Schedule 40 Metallic Pipe
Inlet Pressure:
11 in wc
Specific Gravity:
1.50
Table 17: Example
Rinnai Model Gas Input:
Additional Appliance Total Gas Input:
Total Gas Input:
Answer:
For this example, the pipe diameter must
be at least 1/2 in. nominal pipe size and
10 ft (3 m) in length.
A
199,000
Btu/hr
B
65,000
Btu/hr
Total Gas
Input
=
264,000
Btu/hr
Total Gas
Input
=
A + B
Total Gas
Input
=
199,000 + 65,000
