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Preliminary 003
Access V4.X Configuration manual
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2019-05-13
Free cooling
This function is used during the summer to cool the building night-time using cool outdoor air, thereby
reducing the need for cooling during the day and saving energy.
Configuration > Functions > Function Activation > Free cooling > “Yes”
Free cooling requires an outdoor sensor (or an inlet temperature sensor) and either a room sensor or an
extract air sensor. The outdoor sensor can be placed in the fresh air inlet duct. Free cooling is only
activated when all the start conditions are fulfilled.
Start conditions:
•
Less than four days have passed since the unit was last in running mode.
•
The outdoor temperature during the previous running period exceeded a set limit (22°C).
•
It is between 00:00 and 07:00 in the day (settable).
•
The unit is stopped by schedule
•
The unit is scheduled to run in next 24 hours.
Data & Settings > Demand Control > Free cooling >
If the outdoor sensor is located in the fresh air inlet duct and/or an extract air sensor is selected and ALL
the start conditions are fulfilled, free cooling is activated and will run for 3 minutes to ensure that the
temperature measurement when using an extract air sensor reflects the corresponding room
temperature and that the outdoor temperature sensor senses the outdoor temperature even if it is
placed in the fresh air inlet duct. If the outdoor sensor is not located in the fresh air inlet duct and a
room sensor is selected, the unit will not start free cooling as long as all the temperatures are not within
the start and stop temperature intervals.
After three minutes, the stop conditions will be controlled. Stop conditions:
•
Outdoor temp above the set max. value (18°C) or below the set min. value (condensation risk,
10°C).
•
The room temp/extract air temp. is below the set stop value (18°C).
•
The unit is running by schedule, extended running or is stopped by external switch..
•
It is past 07:00 in the day.
If any stop condition is fulfilled after three minutes, the unit will stop again. Otherwise, operation will
continue until a stop condition is fulfilled.
When free cooling is active, the fans run at normal speed or the set value for pressure/flow control. An
offset can also be entered for the fan setpoints during free cooling. The digital output ”Free cool run” is
active. The outputs Sequences (temperature) are interlocked.
After free cooling has been active, the heating output is blocked for 60 minutes (configurable time).