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svf
series
500/600
Pipe Sizing
Size the piping and the pumps to provide the required
temperature rise See Figure 10 for boiler head loss
curves. See Table 5 for maximum and minimum flow
rate through the boiler and head loss versus flow rate.
NOTICE
Pipe sizing should be based on the desired
temperature rise for the system, corresponding to the
recommended maximum flow rate. Failure to follow
these guidelines can result in system issues.
NOTICE
DO NOT design the piping and components for a
boiler flow rate above or below the ranges given in
Table 5 without using one of the piping strategies
listed below. Insufficient flow will cause nuisance
outages due to limit operation. Excessive flow can
damage the boiler heat exchanger from erosion.
Size system piping per Table 6, or apply recognized
engineering practices to size the piping
IMPORTANT
The SVF 500 and 600 boilers have 2" NPT male
connections. Installer to provide reducers to adapt
from external piping to the boiler supply and return
connections if the system allows.
Higher flow rates than shown in Table 5:
• Use Primary/Secondary piping See pages 22,
24, and 25
• Add a differential pressure bypass valve to
bypass the excessive flow in a Variable/Primary
flow system, or provide an alternative engineering
solution See the figures on page 23
Lower flow rates than shown in Table 5:
• Use Primary/Secondary piping
• In a Variable/Primary flow system, it is
recommended to install a flow switch that is set at
the minimum flow rate of the boiler. The variable
circulator will increase water flow and prevent the
boiler from firing with an insufficient flow rate. The
higher water flow will make the flow switch contact,
which will start the boiler
550-100-273/0523
boiler manual
1
Figure 10 Pressure drop versus flow rate for SVF boilers
SVF 500/600: Pressure Drop vs. Flow
40
35
30
t )
25
( f
p
r o
D
20
r e
u
s s
r e
P
15
10
5
0
0
10
20
30
Table 5
Flow rate and pressure drop data
SVF 500
Minimum Water
GPM
Pressure
48
38
32
27
10 PSI
24
21
19
17
16**
SVF 600
Minimum Water
GPM
Pressure
57
46
38
33
10 PSI
29
25
23
21
20**
* Suggested design flow rate (30°F temp, rise, water only)
** Minimum Flow Rates (GPM):
SVF 500: High Fire = 16, Low Fire = 4
SVF 600: High Fire = 20, Low Fire = 4
Table 6
Recommended pipe sizing per flow rate
Sch 40 Pipe
Maximum
Diameter
Flow Rate
GPM
2
45
3
140
4
290
5
500
insTallaTion
40
50
60
70
80
Flow (gpm)
100% Rate
Boiler Head Loss
(Feet W.C.)
Temp Rise (°F)
20
7 5
25
4 7
30*
3 5
35
2 8
40
2 3
45
2 1
50
1 9
55
1 7
60
1 6
100% Rate
Boiler Head Loss
(Feet W.C.)
Temp Rise (°F)
20
11 9
25
6 8
30*
4 7
35
3 6
40
3 0
45
2 5
50
2 2
55
2 0
60
1 9
SCH 40 Pipe
Maximum
Diameter
Flow Rate
GPM
6
800
8
1650
10
3000
12
4750
1
2
90
230080
3
4
5
6
7
8
19
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