H Central Heating; H Guide Values For Sizing Of Solar Heating Systems - Viessmann Vitosol
100 Technical Manual

Central heating
100
75
50
E
25
D
0
A Central heating requirement for one house (built after 1984)
B Central heating requirement for one low energy house
C Hot water requirement
D Solar energy yield at 5 m
E Solar energy yield at 15 m
Guide values for sizing solar heating systems
for an angle of inclination of 25 to 70º and a deviation from south of up to 45º
Aperture area
Vitosol 100
H type s/w 2.5: 2.50 m
2
H type 5 DI: 2
4.92 m
Vitosol 200
H type D 10:
2
1.07 m
H type D 20: 2
2.14 m
H type D 30:
2
3.21 m
Vitosol 100
11
10
8
6
4
2
0
0 50 100 150 200 250 300 350 400
DHW consumption in l/d
Vitosol 200, 250 and 300
11
10
8
6
4
2
0
0 50 100 150 200 250 300 350 400
DHW consumption in l/d
VITOSOL
A
B
C
2
absorber surface (flat collector)
2
absorber surface (flat collector)
Vitosol 250:
Vitosol 300
H type H 20:
H type H 30:
60%
50%
40%
30%
60%
50%
40%
3.1 Calculating the required collector surface area
2
1.025m
2
2.14 m
2
3.21 m
Central heating by solar energy is found
to be less advantageous than DHW
heating. The period when the greatest
amount of solar energy is available does
not coincide with the time when the most
heat is required.
While the heat consumption for DHW
loading is relatively constant throughout
the year, only very little solar energy is
available at the times when the heat
demand for central heating is at its
highest (see diagram).
A relatively large collector area is
required to provide central heating
backup. In summer, this can result in
stagnation in the solar circuit. Systems
for central heating backup can be created
with very simple water connections by
using a combination cylinder (e.g.
Vitocell 333 or 353).
Solar installations for domestic hot water
applications and for backing up central
heating facilities have already been tried
and tested in practice.
Guide values for sizing the collector area
can be found in the table on page 40; a
corresponding design example is shown
on pages 65 and 75.
For DHW heating, the following diagrams
can be used to size the aperture area in
relation to the desired coverage. The
diagrams represents approximate guide
values.
Example:
Hot water consumption: 200 litres/day
DHW temperature: 45 ºC
For a required coverage of 60 %, select the
following aperture area:
H 5 m
2
for flat collectors
2 Vitosol 100, type s/w
or
1 Vitosol 100, type 5DI
H 3 m
2
for vacuum tube collectors
1 Vitosol 200, type D30
1 Vitosol 300, type H30
3 Vitosol 250
(see also calculation example on page 41
and in accordance with ESOP in the
appendix).
Note
In applications involving the wall
installation of the Vitosol 200 and 250,
oversize the absorber area by 20 %.
39