Flow Velocity And Pressure Drop - Viessmann VITOSOL SERIES Technical Manual

Information regarding design and operation
Pressure drop Vitosol 200-T, type SP2, Vitosol 300-T
Relative to water, corresponds to Tyfocor LS at approx. 60 °C
200
100
50
40
30
25
20
15
10
5
4
3
12
2
60 70 100 150
Flow rate in l/h
A 2 m 2
B 3 m 2

Flow velocity and pressure drop

Flow velocity
To minimise the pressure drop through the solar thermal system pipe-
work, the flow velocity in the copper pipe should not exceed 1 m/s. In
accordance with VDI 6002-1, we recommend flow velocities of
between 0.4 and 0.7 m/s. At these flow velocities, a pressure drop of
between 1 and 2.5 mbar/m pipe length will result.
Note
A higher flow velocity results in a higher pressure drop; a substantially
lower velocity will make venting harder.
Flow rate
(total collector area)
l/h l/min
125
150
175
200
250
300
VIESMANN
126
B
A
200 300 400 500 800
Flow velocity in m/s
Pipe dimension
DN 10 DN 13
Dimensions
12 x 1 15 x 1
2.08 0.44 —
2.50 0.53 0.31
2.92 0.62 0.37
3.33 0.70 0.42
4.17 0.88 0.52
5.00 1.05 0.63
(cont.)
The air that collects at the collector must be routed downwards through
the solar flow line to the air vent valve. For the installation of collectors,
we recommend sizing the pipes as for a normal heating system accord-
ing to flow rate and velocity (see the following table).
Subject to the flow rate and pipe dimension, different flow velocities
result.
DN 16 DN 20 DN 25
18 x 1 22 x 1 28 x 1.5
— —
— —
0.24 —
0.28 0.18
0.35 0.22
0.41 0.27
DN 32 DN 40
35 x 1.5 42 x 1.5
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VITOSOL