Viessmann Vitocal 222-G User Manual page 161

Vitocal 200-S/222-S/242-S
5.8 Vitocal 222-S/242-S, type AWT-AC, one heating circuit without mixer, one heating cir-
cuit with mixer, DHW heating (with solar backup only for Vitocal 242-S) and heating water
buffer cylinder
ID: 4605406_1304_03
Application range
Detached houses, two heating circuits with different utilisation pat-
terns. Size the DHW cylinder in accordance with current standards and
requirements.
Main components
■ Vitocal 222-S/242-S, type AWT-AC, with Vitotronic 200 control unit,
type WO1C
■ Heating circuit distributor with one heating circuit without mixer and
one heating circuit with mixer (via KM BUS)
■ Integral DHW cylinder
■ Heating water buffer cylinder
■ Solar thermal system (only for Vitocal 242-S)
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.
5
Central heating by heat pump
If the actual temperature captured by buffer temperature sensor zQ of
heating water buffer cylinder zP is lower than the set value selected
at the control unit, the heat pump, consisting of internal unit 1 and
external unit wO, starts. Heat pump 1/wO supplies heating circuits
uP and oP with heat via buffer cylinder zP.
Control unit 2 in heat pump internal unit 1 regulates the heating
water flow temperature according to the outside temperature.
Secondary pump 6 in internal unit 1 delivers the heating water via
3-way diverter valve 5 either to heating water buffer cylinder zP or
to integral DHW cylinder eP. Heating circuit pumps uZ and oZ deliver
the required water volume to the heating circuits.
Required parameter settings
ID: 4605406_1304_03
Parameter
7000
7A00
C002
VIESMANN
166
(cont.)
Value Function
6 With heating circuit A1/HC1, M2/HC2, DHW cylinder
3 Solar control module, type SM1
2 Variable speed solar circuit pump with PWM activation
Any heat not absorbed by the heating circuits is stored in the heating
water buffer cylinder. As a result and through the matched output of
the inverter controlled compressor, long heat pump runtimes are ach-
ieved.
Once the actual flow temperature value at the flow temperature sensor
inside internal unit 1 exceeds the set temperature selected at the
control unit, the heat pump and secondary pump 6 are switched
off.
The heat pump restarts only when the temperature at temperature
sensor zQ in the heating water buffer cylinder falls below the set value.
During the power-OFF period, the heating circuits will be supplied with
heat from the heating water buffer cylinder.
DHW heating by heat pump
In the delivered condition, DHW heating by heat pump 1/wO is given
priority over the heating circuits and takes precedence at night.
The heat demand is issued via the integral cylinder temperature sensor
and control unit 2, which controls integral secondary pump 6 in
conjunction with integral 3-way diverter valve "Heating/DHW" 5.
The heat pump raises the flow temperature to the value required for
DHW heating.
The control unit regulates the heating flow to the heating circuit via the
3-way diverter valve, when the actual temperature captured by the
cylinder temperature sensor exceeds the set value selected at the
control unit.
The flow temperature can be raised > 60 °C via integral instantaneous
heating water heater 4.
DHW heating with solar backup (only for Vitocal 242-S)
The integral DHW cylinder eP will be heated by the solar thermal sys-
tem if the temperature differential between collector temperature sen-
sor rR and integral cylinder temperature sensor rZ (for solar) exceeds
a temperature differential set at control unit 2. For this, heat pump
control unit 2 controls solar circuit pump rE which is integrated into
Solar-Divicon rW.
The control unit stops the solar circuit pump again if the temperature
falls below the temperature differential.
System examples