Viessmann Vitocal 222-G User Manual page 217

Vitocal 300-A/350-A
7.5 Vitocal 300/350-A, one heating circuit without mixer, one heating circuit with mixer,
DHW heating via external heat source and heating water buffer cylinder (dual mode par-
allel operation)
ID: 4605058_1304_05
Application range
Detached houses and apartment buildings with up to two heating cir-
cuits with different utilisation patterns and an existing DHW cylinder
with low temperature boiler.
Main components
■ Vitocal 300/350-A with heat pump control unit Vitotronic 200, type
WO1B
■ Heating circuit distributor with one heating circuit without mixer and
one heating circuit with mixer
■ Heating water buffer cylinder
■ Existing external heat source with DHW cylinder
Heating water buffer cylinder
The minimum flow rate of the heat pump is safeguarded via heating
water buffer cylinder zP and secondary pump 6. It is possible to use
differential pressure-dependent heating circuit pumps uZ and oZ.
Central heating by heat pump
Heat pump 1 starts when the actual temperature captured by cylinder
temperature sensor zQ of heating water buffer cylinder zP falls below
the set temperature selected at the control unit.
Heat pump 1 supplies the heating circuits with heat. Control unit
2 of heat pump 1 regulates the heating water flow temperature and
thereby the heating circuits. Secondary pump 6 delivers the heating
water to heating water buffer cylinder zP. Heating circuit pumps uZ
and oZ deliver the required water volume to the heating circuits. The
flow rate in the heating circuit is regulated by opening or closing the
thermostatic radiator valves or the valves of the underfloor heating
distributor.
Required parameter settings
ID: 4605058_1304_05
Vitotronic 200, type WO1B
Parameter
7
7000
7B00
Vitotronic 200
Group
"DHW"
VIESMANN
222
(cont.)
Value Function
6 With heating circuit A1/HC1, M2/HC2, DHW cylinder
1 Enable external heat source, oil/gas
Code Function
61 : 1 Circulation pump for cylinder heating starts immediately
Heat pump 1 and secondary pump 6 are switched off once the
actual return temperature at the integral return temperature sensor
exceeds the temperature set at control unit 2.
Any heat not absorbed by the heating circuits is stored in heating water
buffer cylinder zP. This achieves a long runtime for the heat pump.
Heat pump 1 restarts when the actual temperature at upper temper-
ature sensor zQ of heating water buffer cylinder zP falls below the set
value. The heat pump stops again when the set temperature at the
heat pump return is reached.
During the power-OFF period, the heating circuits will be supplied with
heat from heating water buffer cylinder zP.
Central heating with an external heat source
A demand signal is issued to external heat source tP if the heat pump
cannot maintain the required flow temperature (captured by system
flow temperature sensor zW). External heat source tP starts; mixer
tR initially remains closed towards the heating circuit. Mixer tR opens
towards the heating circuit only when the required temperature has
been reached at boiler water temperature sensor tE of external heat
source tP.
Note
The system example is only applicable in conjunction with modulating
boilers without lower temperature limit.
Match the heating curve of the external heat source to the heating
curve of the heating circuit with the highest flow temperature. Depend-
ing on the system scope and layout, we recommend that these are
offset upwards in parallel.
DHW heating with an external heat source
The existing DHW heating by external heat source tP is retained.
DHW is heated exclusively via the external heat source.
DHW heating will be enabled in the external heat source in accordance
with the selected hysteresis.
Note
With a third-party boiler control unit, it is important to ensure that cir-
culation pump for cylinder heating tW is started when the burner is
commissioned.
System examples