Sizing Pipe Diameters And Circulation Pump; H Sizing Pipe Diameters - Viessmann Vitosol
100 Technical Manual

3.2 Sizing pipe diameters and circulation pump

3.2 Sizing pipe diameters and circulation pump
Sizing pipe diameters
Particularly for large solar heating
systems (upwards of approx. 20 m
collector area), we recommend the low
flow mode (operation with low flow rate),
where the specific volume flow can be
reduced to approx. 15 litres/(m
Advantages:
H A high temperature level is reached
quickly in the collector circuit.
H The low flow rate in the collector circuit
means that much smaller pipe
cross−sections are required.
H A smaller pump capacity is required.
For solar heating systems up to 20 m
collector area, we recommend the high
flow operation (operation with a high
flow rate). This reduces the temperature
spread between flow and return.
The higher flow rate requires a larger
pipework size.
In the high flow operating mode, the
pipes can be sized on the basis of a mean
flow rate of
H approx. 40 litres/h and m 2
aperture area
(approx. 0.67 litres/min and m
area) for Vitosol 100 and 250,
H 60 to 80 litres/h and m 2
aperture area
2
(1 to 1.33 litres/min and m
area) for Vitosol 200, 250, 300 and
Vitosol 100, type 5 DI
Vitosol 100 (high flow operating mode)
Number of collectors
Type s/w 2.5
Volume flow
Copper pipe
Flow velocity
Pressure drop in the pipework
Vitosol 250 (high flow operating mode)
Number of collectors
Volume flow
Copper pipe
Flow velocity
Pressure drop in the pipework
Vitosol 200 and 300 (high flow operating mode)
Absorber surface area
Volume flow
Copper pipe
Flow velocity
Pressure drop in the pipework
42
With all four collector types, a uniform
2
flow rate through all collectors is
guaranteed. To reduce the pipework and
associated effort/costs, we recommend an
installation in series (see page 43) of
2
· h). respectively two rows of collectors.
To minimise the pressure drop through
the piping of the solar heating systems,
ensure that the flow velocity in the copper
pipe never exceeds 1 m/s. We
recommend flow velocities between
0.4 and 0.7 m/s. At these flow velocities,
pressure drops of between
2
1 and 2.5 mbar/m pipe length occur.
For the installation of the collectors, we
recommend the use of commercial
copper pipe and red bronze fittings or
non−galvanized steel pipe. The
cross−sections should be sized for a
conventional heating system on the basis
of throughput and flow rate (see the
tables below and the installation
examples on pages 43 to 48).
2
aperture
aperture
2
litres/min 3.5
dimensions 15 × 1
m/s
mbar/m
litres/min
dimensions
m/s
mbar/m
2
m 2
litres/min 2
dimensions 15 × 1
m/s
mbar/m
3 4
5.0 6.7 8.5
18 × 1 22 × 1 22 × 1
0.4 to 0.7
1.0 to 2.5
3
3
15 × 1 15 × 1
0.4 to 0.7
1.0 to 2.5
3 4 5
3 4 5
15 × 1 18 × 1 18 × 1
0.4 to 0.7
1.0 to 2.5
Do not use galvanized pipes, galvanized
fittings or graphitised gaskets. Hemp
should be used only in conjunction with
pressure and temperature−resistant
*1
sealants .
The components used must be resistant
to the process medium (for composition,
see the datasheet for the specific
collector).
The thermal insulation of external piping
must be resistant to temperature, UV
radiation and to attack by birds or
animals.
Insulate internal hot pipework according
to current practice (fire protection, touch
protection), e.g. using high−temperature
resistant insulation, as offered by
Armacell.
*1
A suitable material is the Viscotex solar
paste supplied by
Locher
CH 9450 Altstätten
*
5 6 8
10.0 13.5
28 × 1.5 28 × 1.5 35 × 1.5
4 5
4 5
18 × 1
6 8 10
6 8 10
18 × 1 22 × 1 28 × 1.5 28 × 1.5 35 × 1.5
10 12
17.0 20.0
35 × 1.5
6
6
18 × 1
12 15
12 15
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