Arbonia Sabiana Energy Smart Series Installation, Use And Maintenance Instructions page 44

English
• FREE COOLING FUNCTION
There can be climatic conditions during the year
that make it impractical to recover heat from
extracted air for treating fresh air from outside.
For example, in midseason, the outdoor air temper-
ature can be lower than the indoor air temperature
due to solar and internal factors, and this tends to
occur when the indoor temperature is between
22 and 26°C so there is more of a need for cooling
than for heating. In this case it is advisable to use
free-cooling, i.e. fresh air from outdoors to cool for
free, bypassing the heat recovery unit. Conversely,
it is possible to use fresh air for heating during a
change in season, in which case the process is known
as free-heating.
The units are equipped with a bypass damper sys-
tem that totally disables use of the recovery heat
exchanger to permit free-cooling (or free-heating).
The system is controlled on the basis of a logic sub-
ject to the feedback of the integrated temperature
probes.
The logic is as follows:
The indoor air temperature setpoints of the air con-
ditioning system in winter and summer are defined
in order to maintain conditions of comfort:
t normally t
heating
t normally t
cooling cooling
(temperatures can be modified by the installer according
to the actual settings of the plant)
The following are also defined:
t = indoor air temperature (return air)
i
EAT = External air temperature
FREE-COOLING CONDITION
EAT > t and simultaneously t
heating
FREE-HEATING CONDITION
EAT < t and simultaneously t
cooling
44
= 20°C
heating
= 26°C
>EAT
i
<EAT
i
• Pre-Treatment Function with Geothermal Coil
If a hydronic circuit with geothermal or ground water
probes is available, it is possible to feed a hydronic
pre-treatment coil, which can be used in both seasons.
A dedicated function for using the geothermal source
is available.
In winter, the coil valve is controlled to carry out the
antifreeze function. It opens if the exhaust tempera-
ture falls below 3°C and closes above 6°C.
Depending on the available water temperatures, the
coil must be sized to ensure the antifreeze function.
In summer, the coil valve is controlled to carry out
the pre-cooling function.
It opens when the outside temperature rises above
24°C.
There is a provisional closure mode if the intake
temperature is too cold, to ensure the ambient com-
fort conditions and a permanent closure when the
outside climate starts returning to winter conditions.
Pre-cooling, or geothermal water free-cooling, is
compatible with ventilation free-cooling and extends
the periods of use.
• SUMMER MODE
Summer mode is a strong air change cycle, which is
enabled when "Flush" parameter is switched on into
"Par Menu".
NOTE: Summer mode is performed 4 times a day,
except when it would imply high ventilation heat
loss..
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