Viessmann Vitocal 222-G User Manual page 189

Vitocal 200-A
(cont.)
6.3 Vitocal 200-A, one heating circuit without mixer, one heating circuit with mixer and
active cooling function, DHW heating, heating water buffer cylinder, external heat source
(dual mode operation) and swimming pool
ID: 4605507_1304_02
Application range
Detached and two-family houses with swimming pool, cooling demand
and two heating circuits with different user patterns. Size the DHW
cylinder in accordance with current standards and requirements.
Main components
■ Vitocal 200-A with Vitotronic 200, type WO1C
■ Heating circuit distributor with one heating circuit without mixer and
one heating/cooling circuit with mixer, controlled via KM BUS
■ DHW cylinder, external heat exchanger (cylinder loading system)
■ Heating water buffer cylinder
■ External heat source with Vitotronic 200, types KO1B, KO2B or
KW6B
■ Swimming pool
■ Active cooling function
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 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. Heat pump con-
trol unit 2 regulates the heating water flow temperature and thereby
the heating circuits. Secondary pump 6 delivers the heating water
6
either to heating water buffer cylinder zP or to DHW cylinder eP. Heat-
ing circuit pumps oZ and uZ 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.
The heat not absorbed by the heating circuits is stored in heating water
buffer cylinder zP. The inverter controlled compressor adjusts its out-
put accordingly to achieve a long heat pump runtime.
Heat pump 1 and secondary pump 6 are switched off once the
actual flow temperature at flow temperature sensor 7 in the secon-
dary circuit exceeds the temperature set at the control unit.
Active cooling function
Active cooling function 2 is enabled if the value for the cooling limit
temperature that can be adjusted at control unit 2 is exceeded at
outside temperature sensor 3. Heat pump 1 and secondary pump
6 are started. The 3-way diverter valves "Heating/cooling" iO are
switched to cooling. By reversing the refrigerant circuit, cooled heating
water is transported to cooling circuit uP.
The set flow temperature is controlled via flow temperature sensor
uE and control unit 2. Contact humidistat iE ensures that no con-
densation and therefore damage can occur as a result of low temper-
atures.
VIESMANN
194
Heat pump 1 restarts when the actual temperature at buffer temper-
ature sensor zQ falls below the set value. The heat pump stops again
when the set flow temperature is reached.
During the power-OFF period the heating circuits are 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 takes place from 00:00 to
24:00 h.
The heat demand is issued via cylinder temperature sensor eQ and
control unit 2, which controls 3-way diverter valve 5 in conjunction
with secondary pump 6 and cylinder loading pump eE. Control unit
2 raises the flow temperature to the value required for DHW heat-
ing.
Cylinder temperatures of up to 60 °C can be achieved via external heat
source tP or instantaneous heating water heater 4.
Central heating with an external heat source
Depending on the system configuration, additional high limit safety cut-
outs may be needed to protect the heat pump against high tempera-
tures (preventing excessive system pressure). This should be checked
for each system individually.
A demand signal is issued to start external heat source tP if the heat
pump cannot maintain the required flow temperature (captured by sys-
tem flow temperature sensor zW of external heat source tP). Mixer
tR initially remains closed towards the heating circuit. Mixer tR opens
from the external heat source towards the heating circuit and regulates
to the required set flow temperature, only when the required minimum
flow temperature has been reached at boiler water temperature sensor
tE of the external heat source. Mixer tR closes from the external heat
source 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) does not fall below an adjustable threshold value for a
specified time. There then is either no heat demand or heat pump
1 is delivering sufficient heat.
Swimming pool heating
Swimming pool heating is activated hydraulically via the changeover
of 3-way diverter valve qYT. If the temperature falls below the set value
at swimming pool temperature controller qYQ, a demand signal is sent
to control unit 2 via EA1 extension qYR.
In the delivered condition, swimming pool heating has priority 3. The
higher set priorities are DHW heating (with priority 1) and central heat-
ing (with priority 2). If no higher priorities are present, 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.
Note
All lines where the coolant temperature can fall below the dew point
should be insulated so that they are vapour diffusion-proof.
In cooling mode, safeguard the minimum flow rate in the secondary
circuit.
To do so, use suitable valves on the heating circuit distributor. See
Vitoset pricelist.
System examples