To prevent thermal shocks inside the solar circuit, the operation of
the solar thermal system will be interrupted at collector temperatures
> 120 °C (collector protection).
Solar DHW heating
The solar circuit pump starts and the DHW cylinder is heated up if
the temperature differential between the collector temperature sen-
sor and the cylinder temperature sensor (in the solar circuit return) is
greater than the start temperature differential set at the solar control
unit.
The heat pump will be prevented from heating the cylinder if the tem-
perature at the cylinder temperature sensor (in the DHW cylinder,
top) exceeds the set value selected at the heat pump control unit.
The solar thermal system heats the cylinder to the set value selected
at the solar control unit.
Note
.
■ Aperture area that can be connected: See the "Vitosol" technical
guide.
Solar central heating backup
The solar circuit pump and the circulation pump for cylinder heating
start if the temperature differential between the collector temperature
sensor and the cylinder temperature sensor (solar) is greater than
the start temperature differential selected at the heat pump control
unit. The heating water buffer cylinder is heated.
Heating stops when the temperature differential between the collec-
tor temperature sensor and the cylinder temperature sensor (solar)
is less than half the hysteresis (standard: 6 K) or if the actual tem-
perature captured by the lower cylinder temperature sensor corre-
sponds to the selected set temperature.
See also the "Vitosol" technical guide.
Solar swimming pool heating
See "Vitosol" technical guide.
Solar control unit
Solar control module, type SM1 (accessories): See page 145.
Note
The Solar-Divicon (part no. Z017690) also includes a solar control
module: SDIO/SM1A electronics module
See Viessmann pricelist, register 13.
Sizing the solar expansion vessel
Solar expansion vessel
Design and function
With shut-off valve and fixings
A
Heat transfer medium
B
Nitrogen charge
C
Nitrogen buffer
D
Minimum safety seal 3 l
E
Safety seal
F
Delivered condition (pre-charge pressure 4.5 bar, 0.45 MPa)
G
Solar thermal system filled, without heat effect
H
At maximum pressure and the highest heat transfer medium
temperature
A solar expansion vessel is a sealed vessel where the gas space
(nitrogen charge) is separated from the space containing liquid (heat
transfer medium) by a diaphragm and the pre-charge pressure is
subject to the system height.
Specification
b
b
a
a
Expansion vessel
Part no.
Capacity
Pre-charge
pressure
Ø a
b
Connection
Weight
l
bar (MPa)
mm
mm
kg
A
7248241
18
4.5 (0.45)
280
370
R ¾
7.5
7248242
25
4.5 (0.45)
280
490
R ¾
9.1
7248243
40
4.5 (0.45)
354
520
R ¾
9.9
B
7248244
50
4.5 (0.45)
409
505
R 1
12.3
7248245
80
4.5 (0.45)
480
566
R 1
18.4
Design information
(cont.)
VITOCAL
VIESMANN
129
5831388
7