Viessmann Vitocal 222-G User Manual page 166

Vitocal 200-S/222-S/242-S
5.9 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), heating water
buffer cylinder and active cooling via heating circuit M2
ID: 4605415_1304_04
Application range
Detached houses with cooling demand, two heating circuits with dif-
ferent utilisation patterns. 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.
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 control unit 2, 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 of heat pump 1/wO regulates the heating water flow
temperature subject 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.
Once the actual flow temperature value at the flow temperature sensor
inside the internal unit exceeds the set temperature selected at the
control unit, the heat pump and secondary pump 6 are switched
off.
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.
Required parameter settings
ID: 4605415_1304_04
Parameter
7000
7A00
C002
7101
7103
7111
71FE
3003
System examples
(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
2 Cooling via heating circuit M2/HC2
180 Min. flow temperature, cooling
4 Cooling curve slope
1 Enable active cooling
1 Vitotrol 200A or 300B remote control activated for heating circuit M2/HC2
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 top
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 the integral cylinder temperature sensor (for solar) exceeds
a temperature differential set at control unit 2. For this, control unit
2 controls solar circuit pump rE which is integrated into Solar-Divicon
rW.
The control unit stops solar circuit pump rE again if the temperature
falls below the temperature differential.
Active cooling function
The active cooling function is enabled by control unit 2 if the value
for the cooling limit temperature that can be adjusted at the control unit
is exceeded at outside temperature sensor 3. Heat pump 1/wO and
secondary pump 6 start. The 3-way diverter valves "Heating/cooling"
iO are switched to cooling. Reversing the refrigerant circuit cools the
water, which is pumped to heating circuit uP, now functioning as a
cooling circuit.
The set flow temperature is controlled via flow temperature sensor
uE and the control unit. Contact humidistat iE ensures that no con-
densation and therefore damage can occur as a result of low temper-
atures.
Note
All lines where the cold water 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. Open valves on the heating circuit distributor fully and perma-
nently or install an overflow valve.
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VIESMANN
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