Viessmann Vitocal 222-G User Manual page 229

Vitocal 300-A/350-A
7.7 Vitocal 300/350-A, one heating circuit without mixer, two heating circuits with mixer,
DHW heating, heating water buffer cylinder, external heat source (dual mode parallel
operation) and swimming pool
ID: 4605095_1304_06
Application range
Detached houses and apartment buildings with swimming pool, with
up to three heating circuits with different utilisation patterns. Size the
DHW cylinder in accordance with current standards and require-
ments.
Main components
■ Vitocal 300/350-A with Vitotronic 200, type WO1B
■ Heating circuit distributor with one heating circuit without mixer and
two heating circuits with mixer
■ DHW cylinder, external heat exchanger
■ Heating water buffer cylinder
■ External heat source with Vitotronic 200, type KO1B, KO2B, KW6B
■ Swimming pool
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, oZ and q-
Z.
Note
In type AWCI, circulation pump for cylinder heating 5 is replaced by
an internal and fully wired 3-way diverter valve.
Central heating by heat pump
Heat pump 1 starts when the actual temperature captured by buffer
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. The secondary pump 6 delivers the
heating water either to heating water buffer cylinder zP or to DHW
cylinder eP. Heating circuit pumps uZ, oZ and q-Z 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
7
the valves of the underfloor heating distributor.
Heat pump 1 and secondary pump 6 are switched off once the
actual return temperature at the return temperature sensor exceeds
the temperature set at the control unit.
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.
VIESMANN
234
(cont.)
Heat pump 1 restarts when the actual temperature at temperature
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.
DHW heating
In the delivered condition, DHW heating by heat pump 1 is given
priority over the heating circuits and should ideally take place during
the night.
The heat demand is issued via cylinder temperature sensor eQ and
control unit 2, which controls circulation pump for cylinder heating
5 in conjunction with secondary pump 6 and cylinder loading pump
eE. The control unit raises the flow temperature to the value required
for DHW heating.
The cylinder temperature can be raised with the external heat
source.
Central heating with an external heat source
A demand signal is issued to the external heat source tP if the heat
pump cannot maintain the required flow temperature (captured by sys-
tem flow temperature sensor zW of the external heat source tP).
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 flow temperature has been reached at boiler
water temperature sensor tE of the external heat source. Mixer tR
closes towards the heating circuit when the required flow temperature
has been achieved.
External heat source tP stops if mixer tR is closed towards the heating
circuit and the flow temperature (captured at system flow temperature
sensor zW) no longer falls below an adjustable threshold value for a
specified time. There then is either no heat demand or heat pump
1 is delivering sufficient heat.
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.
Swimming pool heating
Swimming pool heating is produced hydraulically via the changeover
of 3-way diverter valve qYT. A demand signal is sent to control unit
2 if the temperature falls below the set value selected at swimming
pool temperature controller qYQ.
In the delivered condition, the swimming pool heating is supplied with
priority 3. The higher set priorities are DHW heating (with priority 1)
and central heating (with priority 2). The control unit makes a check,
and if there are no higher priorities, 3-way diverter valve qYT changes
over to swimming pool heating, and the swimming pool water is heated
until the set value at swimming pool temperature controller qYQ is
reached.
System examples