5.11.3 Free cooling (FreeCDtr11y)
The purpose of the 'Free cooling' function is to ensure that overheated living area
can be cost efficiently cooled down by using the lower outside temperatures just by
increasing the air circulation.
Activation of the function occurs, when
●
Outside air (TOa) is sufficiently low compared to the apartment temperature
(extract or room), and
●
Apartment temperature is above its actual se configurable hysteresis,
and
●
Outside temperature is above set minimum limit, and
●
Free cooling is configured
For de-activation a hysteresis of 2K (fix) is used.
During activation, the operating mode is set to Comfort and kept there until one of
the activation criteria is no longer fulfilled.
In case of cascade control, the actual room temperature setpoint (depending on
the operating mode) is used.
As there is no room temperature setpoint available for supply air control, a
configurable virtual room temperature setpoint is used.
Available parameters
Current values
BACnet object
R/RW
Note
Present plant operating mode
PrPltOpMod
MVAL,164
R
10: Free Cooling
Actual setpoint from cascade control
SpTR
AVAL,30
R
°C
Configurable virtual room setpoint for supply
control
SpTRFreeC
AVAL,109
RW
°C
Hysteresis TR for free cooling
HysSpTR
AVAL,32
RW
K
Basic settings
BACnet object
R/RW
Note
Enabling the free cooling function
EnFreeC
BVAL,162
RW
Outside air minimum limit for activation
TOaLm
AVAL,33
RW
°C
Min difference room – outside air temp. For free
cooling start
DiffTRTOaSwiOn
AVAL,35
RW
K
Minimum on time
TiPreCoolMin
PINTVAL,69
RW
s
Application functionalities
Cooling
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