Viessmann VITOCAL 300-G Operating Instructions Manual page 57

Terminology
(cont.)
Heating/cooling circuits and separate
cooling circuit
■ Heating circuit
A heating circuit is a sealed circuit
between the heat pump and consum-
ers (radiators), in which the heating
water circulates.
A heating system may have several
heating circuits, e.g. one heating cir-
cuit for the rooms occupied by you and
one heating circuit for the rooms of a
separate apartment.
■ Cooling circuit
When cooling via a heating circuit, e.g.
underfloor heating system, we refer to
a cooling circuit.
■ Separate cooling circuit
A separate cooling circuit is a sealed
circuit that supplies a cooling appli-
ance such as, for example, a fan con-
vector or a chilled ceiling. Heating is
not possible with a separate cooling
circuit.
Heating circ pump
Circulation pump for the circulation of the
heating water in the heating/cooling cir-
cuit.
Heating water buffer cylinder
Thermal energy for central heating can
be stored in a heating water buffer cylin-
der. This safeguards the heat supply for
all connected heating circuits even when
the heat pump is not operational for lon-
ger periods, e.g. during a power-OFF
period.
Actual temperature
Current temperature at the time of the
scan, e.g. actual DHW temperature.
Mixer
A mixer mixes the heated heating water
with the cooled water returning from the
heating circuit. The water heated to the
right temperature in line with demand is
delivered into the heating circuit by the
heating circuit pump. The heat pump
control unit adjusts the heating circuit
flow temperature via the mixer to the var-
ious conditions, e.g. different outside
temperature.
When cooling via a heating circuit, e.g.
underfloor heating system, the mixer
serves to maintain the temperature
above the condensation point of the
ambient air (dew point). This prevents
the formation of condensate.
Natural cooling
With this function, the temperature level
of the ground is transferred directly to the
heating/cooling circuits. Compared to
active cooling mode (see page 53), the
available cooling capacity is lower in nat-
ural cooling mode. As the heat pump is
off, this function is very energy-efficient
and therefore suitable for permanent
cooling.
Standard heating/cooling mode
When you are in the house during the
day, you can heat or cool the rooms in
standard heating or cooling mode. Set
the periods (time phases) using the time
program for central heating/cooling.
Appendix
57