77
Installing a Cascade System
8.1.1 Piping Sizes and Considerations
When plumbing a cascading system, consider the following pipe diameters and flow rates. Note that flow rates
above 6.6 ft/s may cause pipe erosion. These specifications may vary depending on installation conditions.
Piping Sizes for an NCB-H Boiler with up to 15 NPE-240A2 or NPE-240S2 Water Heaters
Model
ΔT=54°F Flow rate
(GPM)
Water Velocity
(ft/s)
Pipe Diameter (mm/in)
NCB-H NPE-240A2 or
NPE-240S2
1
1
14.38
5.61
25A
1 in.
2
21.57
5.54
30A
1
1
/
4
in.
3
28.77
5.21
40A
1
1
/
2
in.
4
35.96
6.53
40A
1
1
/
2
in.
5
43.15
4.49
50A
2 in.
6
50.34
5.24
50A
2 in.
7
57.5
6.00
50A
2 in.
8
64.72
4.39
65A
2
1
/
2
in.
9
71.92
4.75
65A
2
1
/
2
in.
10
79.11
5.34
65A
2
1
/
2
in.
11
86.30
5.84
65A
2
1
/
2
in.
12
93.49
6.33
65A
2
1
/
2
in.
13
100.68
6.79
65A
2
1
/
2
in.
14
107.87
5.11
80A
3 in.
15
115.07
5.44
80A
3 in.
Summary of Contents for NCB-190/060H
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