Carel k.Air, User Manual, Page: 49 / 192

49
Functions k.air +030220981 rel. 1.2 - 01.12.2020
9. FUNCTIONS
9.1 D ampers
k.air manages up to six types of dampers, on/off or modulating, with the following specifi c control functions:
D amper R elationship C ontrol
Fresh air Unit activation and main control functions Air quality
Frost protection
Temperature control
Exhaust
Mixing
Supply
Unit activation None
Suction
Bypass
Heat recovery unit Temperature control
Tab. 9.a
9.1.1 S upply and return dampers
The supply and return dampers are designed to isolate the air handling unit from the supply and return ducts. They can be either
on/off or modulating, however in both cases they operate in a fully open/fully closed mode.
They are activated based on unit status: when the unit is on, without serious alarms, the dampers are opened.
The behaviour of the dampers in the transitory phases is as follows:
1. Frost protection, the dampers close
2. Start-up, opened immediately
3. Shutdown, the dampers close after the post-ventilation phase
The supply and return dampers are enabled directly from the W.In/Out confi guration menu
Note :
the signal sent to the supply and return dampers is the same, and from an electrical point of view it is possible to use
one less point in the input/output confi guration by using the same contact (supply) for both dampers.
9.1.2 F resh air - Exhaust - Mixing dampers
The fresh air, exhaust and mixing dampers can be on/off or modulating, and the available settings will be aff ected accordingly.
For modulating dampers, the request can be scaled between a minimum and a maximum value so as to allow a minimum
amount of fresh air intake. The dampers, in terms of the request signal and therefore excluding the limits, are governed by the
following relationships
1. Exhaust damper opening request % = fresh air damper opening request %
2. Mixing damper opening request % = 100 - Fresh air damper opening request % The damper request is scaled as shown in
the graph below
30220980_197_R01
MaxFreshDmp
MinFreshDmp
MaxMixDmp
MinMixDmp
Request %
Limits %
100 0
Key
MaxFreshDmp Maximum fresh air damper opening
MinFreshDmp Minimum fresh air damper opening
MaxMixDmp Maximum mixing damper opening
MinMixDmp Maximum mixing damper opening
Limits Minimum and maximum limit values for dampers
Request Damper request
Fig. 9.a
Note:
when the unit is Off or a serious alarm is active, all of the dampers will be completely closed and therefore the proportional
modifi cation limits and the relationship between fresh air damper and mixing damper will not be applied.
The damper output signal can be scaled further, based on the signal limits that are set in the IO confi guration menu.
Below is a summary of the functions available for each type of damper.
F resh air damper Mixing damper C ontrol
On/off On/off or absent Fresh air damper opens when the unit is ON
If frost protection is active, the fresh air damper closes and, if the mixing damper is fi tted, the
unit enters recirculation mode, with the fans on
The unit thus operates with outside air only, and freecooling control is not available