Viessmann Vitocal 222-G User Manual page 31

Vitocal 222-G/242-G/333-G/333-G NC/343-G
2.7 Vitocal 333/343-G, one heating circuit without mixer, two heating circuits with mixer,
DHW heating (for Vitocal 343-G also solar), heating water buffer cylinder and natural
cooling
2
ID: 4605090_1304_05
Note
DHW heating with solar backup is only possible with the
Vitocal 343-G.
Application range
Detached house with up to three heating circuits with different utilisa-
tion patterns (different heating circuit design layouts) and cooling
demand.
Main components
■ Vitocal 333/343-G with integral DHW cylinder and Vitotronic 200,
type WO1C
■ Heating circuit distributor with one heating circuit without mixer and
two heating circuits with mixer
■ Heating water buffer cylinder
■ NC-Box
■ Solar thermal system (option, only with the Vitocal 343-G)
Requirements
The minimum flow rate of heat pump 1 is safeguarded via heating
water buffer cylinder zP and the integral secondary pump. It is possible
to use differential pressure-dependent heating circuit pumps uZ, oZ
and q-Z.
Central heating by heat pump
Heat pump 1 and the integral primary pump start when the actual
temperature captured by cylinder temperature sensor zQ of heating
water buffer cylinder zP falls below the set temperature selected at
control unit 2.
Heat pump 1 supplies the heating circuit with heat. Control unit 2
of heat pump 1 regulates the heating water flow temperature and
thereby the heating circuits. The integral secondary pump delivers the
heating water via a 3-way diverter valve either to heating water buffer
cylinder zP or to the integral DHW cylinder.
Heating circuit pumps uZ, oZ and q-Z deliver the required water vol-
ume to the heating circuits. The heating circuit flow rate is regulated
by opening and closing the thermostatic radiator valves or the under-
floor distributor valves and/or through an external heating circuit con-
trol unit. Heat pump 1 and the secondary pump are switched off once
the actual return temperature at the return temperature sensor
exceeds the temperature set at the control unit.
VIESMANN
36
(cont.)
To balance the difference in energy between the primary and secon-
dary circuits, operate heating water buffer cylinder zP in parallel to the
heating circuits. Any heat not absorbed by the heating circuits is stored
in heating water buffer cylinder zP. In addition, heat pump 1 achieves
long runtimes.
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.
DHW heating by heat pump
In the delivered condition, DHW heating by heat pump 1 is given
priority over the heating circuits and takes precedence at night.
The heat demand is issued via the integral cylinder temperature sensor
and the control unit, which controls the integral secondary pump in
conjunction with the integral 3-way diverter valve and, in the case of
the Vitocal 343, the cylinder loading pump.
The control unit raises the flow temperature to the value required for
DHW heating.
The control unit switches the heating flow to the heating circuit via 3-
way diverter valve "Heating/DHW" if the actual temperature at the cyl-
inder temperature sensor exceeds the value set 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 343-G)
The DHW cylinder will be heated by the solar collector if the temper-
ature differential between collector temperature sensor rR and the
integral lower cylinder temperature sensor exceeds the temperature
differential set at the control unit. For this, the heat pump control unit
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.
Natural cooling function
The building can be cooled with Vitocal 333/343-G in conjunction with
NC-Box iP (accessories). Control unit 2 enables the natural cooling
function as soon as the outside temperature exceeds the cooling limit
temperature that can be adjusted at control unit 2. This enables the
components of NC-Box iP. The cooling circuit pumps iW and iR
operate continuously. The NC-Box with mixer operates in accordance
with a cooling curve. The mixer on the brine side ensures a continuous,
demand-dependent utilisation of the primary source.
Contact humidistat iE monitors the dew point (part of the NC-Box
standard delivery). Ensure that any installed room thermostats are
able to be opened manually or by servomotors when using the cooling
function.
System examples