Viessmann VITOSOLIC 200 Installation And Service Instructions Manual page 60

System examples
System example 9
Additional function for DHW heating
The requirements for the additional func-
tion are achieved through circulation
pump R5 qT.
Suppression of DHW cylinder reheat-
ing by the boiler
Coding address "67" in boiler control
unit 2 defaults a third set DHW tem-
perature (setting range 10 to 95 °C). This
value must be below the first set DHW
temperature. DHW cylinder 2 qI will only
be heated by boiler 1 (solar circuit
pump R1 eE runs) if this set value cannot
be achieved by the solar thermal sys-
tem.
DHW heating without solar energy
DHW cylinder 2 qI is heated by
boiler 1. The cylinder thermostat with
cylinder temperature sensor 3 of boiler
control unit 2 regulates circulation
pump for cylinder heating 4.
Central heating with solar energy
Circulation pump R4 eT starts to heat
heating water buffer cylinder rP if DHW
cylinder 1 qP cannot be heated and the
temperature differential between collec-
tor temperature sensor S1 eQ and buffer
cylinder temperature sensor S4 rQ is
greater than start temperature differen-
tial ΔT2on. The pump will stop if the
actual temperature falls below the stop
temperature differential ΔT2off or it rea-
ches the set buffer cylinder temperature
Tcyl2set.
60
(cont.)
The temperature inside heating water
buffer cylinder rP will be limited by the
electronic temperature limiter or high
limit safety cut-out rR (if required).
Circulation pump R4 eT is stopped
roughly every 15 min for approx. 2 min,
(times adjustable), to check whether the
temperature at collector temperature
sensor S1 eQ is high enough to change
over to DHW cylinder heating qP.
Three-way diverter valve R6 rZ is
switched to position "AB-A" and the heat-
ing return water is routed to boiler 1 via
heating water buffer cylinder rP, if the
temperature differential between buffer
cylinder temperature sensor S5 rE and
heating circuit return temperature sen-
sor S6 rT exceeds temperature differ-
ential ΔT6on. If the temperature of the
preheated return water is too low, boiler
1 reheats the water to the required flow
temperature. Three-way diverter valve
R6 rZ is switched to position "AB-B" if
the actual temperature falls below the
stop temperature differential ΔT6off.
Central heating without solar energy
Three-way diverter valve R6 rZ remains
at zero volt (position "AB-B") if the tem-
perature differential between buffer cyl-
inder temperature sensor S5 rE and
heating circuit return temperature sensor
S6 rT is less than temperature differen-
tial ΔT6off. There will be no flow through
heating water buffer cylinder rP.
Boiler 1 supplies the heating circuit
with heat according to the heating curve
set at boiler control unit 2.