Viessmann VITOSOLIC 200 Installation And Service Instructions Manual page 15

System example 2
■ Actual temperature dropping below
the stop temperature differential ΔToff
■ Exceeding the electronic temperature
limit of control unit eZ (max. 90 °C)
■ Reaching the temperature selected at
high limit safety cut-out qW (if installed)
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 qP 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
The upper section of DHW cylinder qP is
heated by boiler 1. The cylinder ther-
mostat with cylinder temperature sen-
sor 3 of boiler control unit 2 regulates
circulation pump for cylinder heat-
ing 4.
(cont.)
Central heating with solar energy
Circulation pump R4 eT is started to heat
heating water buffer cylinder rP if the
DHW cylinder qP cannot be heated and
the temperature differential between col-
lector temperature sensor S1 eQ and
buffer cylinder temperature sensor S4
rQ is greater than start temperature dif-
ferential 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.
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 start temperature dif-
ferential 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.
System examples
15