Cooling Operation; Types And Configuration; Cooling Function Natural Cooling; Hydraulic Connection, Natural Cooling Function - Viessmann VITOCAL 300-G Technical Manual

Design information

3.12 Cooling operation

Types and configuration

Subject to system version the following cooling functions are possible:
■ "Natural cooling" (as option with or without mixer)
– The compressor is shut down and heat exchange occurs directly
with the primary circuit.
■ "Active cooling"
– The heat pump is used as a refrigeration unit, meaning a higher
cooling capacity is possible than with natural cooling.
– This function is only possible outside a power-OFF period, and
must be enabled separately by the system user.

Cooling function Natural cooling

Function description
With natural cooling, the heat pump control unit regulates the following
functions:
■ Switching all necessary circulation pumps, diverter valves and mix-
ers
■ Recording all essential temperatures
■ Dew point monitoring
The control unit enables the natural cooling function if the outside tem-
perature exceeds the cooling limit (adjustable). Control operated in
weather-compensated mode when cooling via heating circuit (under-
floor heating circuit). When a separate cooling circuit is used, e.g. a
fan convector, then the control is room temperature-dependent.
DHW heating by the heat pump is possible during the cooling opera-
tion.
■ Carry out the diffusion-proof thermal insulation of all brine and cold
water lines in accordance with standard practice to prevent conden-
sation.
■ Power supply (1/N/PE, 230 V/50 Hz) is required.
Recommendation: Utilise the heat pump power supply from an on-
site power distribution board.

Hydraulic connection, natural cooling function

iI
iT
A
B
VITOCAL 300-G
(cont.)
uQ
uE
iU
uR
uP
φ
iE
iZ
iR
iW
M
M iQ
M
iO
uZ
uU
M
C
Even if active cooling is selected and enabled, the control unit will ini-
tially start the natural cooling function. If the set room temperature
cannot be achieved with this function for a prolonged period, the com-
pressor starts.
A mixer can only be used with natural cooling, and particularly in cool-
ing mode on underfloor heating circuits, it keeps the flow temperature
above the dew point. To ensure the transfer of the high cooling output
in active cooling at all times, no mixer is provided.
The maximum refrigerating capacity that can be transferred depends
on the geothermal probe/geothermal collector system and the ground
temperatures.
For cooling, it is possible to connect either a heating/cooling circuit,
e.g. underfloor heating circuit or a separate cooling circuit, e.g. a fan
convector.
Components required:
Circulation pumps, diverter valves, mixers, sensors and a KM BUS
interface to the heat pump control unit.
The heat extracted from the heating/cooling circuit is transferred to the
ground by a heat exchanger. This heat exchanger is connected in ser-
ies and enables a system separation between the primary and the
heating circuit.
Note
Thermally insulate all lines on site with vapour diffusion-proof mate-
rial.
A Geothermal probe interface
B Interface to heat pump primary circuit
C Interface to heat pump/heating water buffer cylinder (secondary
circuit)
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VIESMANN
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