Multi-DENCO Technical Description
FläktGroup DC-2013-0101-GB • Subject to modifications • R5-08/2020 25
3.3 Operating modes
A basic Multi-DENCO unit only has the capacity to perform cooling, therefore only
being able to control the upper limit of the temperature of the room. Heaters and humid-
ifiers can be added to the design to allow for control of both the lower limit of tempera-
ture and to control the humidification of the room.
Cooling The main function of a close control unit is to cool the air within a room to a defined set
point.
If using refrigerant, this is achieved by adjusting compressor speed, expansion valve
opening and indoor and outdoor fan speed.
If using chilled water, this is accomplished by adjusting the water valve opening and
adjusting the indoor fan speed.
Both methods use variable technology to match the heat of rejection by the
Multi-DENCO unit to the volume of heat produced within the room.
Heating
(if fitted)
If the indoor temperatures are too low then the heating function will be activated. There
are several options for this operation allowing the heating to be a start/stop operation
or variable. When heating is required, the fans can increase their speed.
Humidification
(if fitted)
If the humidity levels are below the requirements then the humidifier will be activated
to add more moisture to the air. The amount of moisture added to the air varies propor-
tionally to the demand, with the humidifier able to operate between 25 - 100% of its
rated capacity.
Dehumidification
(if enabled)
As a default factory settings, dehumidification is a secondary priority compared to tem-
perature control, therefore it will only become active and maintained if the temperature
limits are met during the whole operation. If at any point, those limits are not met, the
dehumidification operation will be stopped and the unit will operate on a temperature
control basis.
To perform dehumidification, the unit cools at a higher rate (i.e. over-cools the air) to
create condensate on the the heat exchanger coil. Heating options can then be used
to re-heat the air before it leaves the unit.
Software settings can be changed to deactivate the dehumidification modes, even if
components are fitted.
CombiCool
(if fitted)
The CombiCool options has two separate cooling circuits. CombiCool can be fitted to
A-Version, C-Version or W-Version of the Multi-DENCO units.
The CombiCool circuit is the primary circuit and is chilled water. The secondary circuit
relates to the version (e.g. A-Version). The unit will only operate one circuit at a time.
If the CombiCool circuit is unable to meet the cooling requirements of the room then
the unit changes to use the 'secondary' circuit. When possible, the unit will switch back
to the 'primary' CombiCool circuit.
This feature is ideal to provide internal redundancy to each unit.
CombiCool FreeCool
(if fitted)
The unit is fitted with the same CombiCool Coil as above, but can be configured with a
FreeCool strategy. When the Cooling Demand is low, the unit will operate with only the
FreeCool circuit operating. If this demand increases above a certain threshold, the unit
will then activate its secondary circuit (direct expansion or chilled water) and both cir-
cuits to operate at the same time to meet the cooling requirements.
An ambient sensor can be used to measure the outdoor temperatures. If the ambient
temperature is high (above a set value), then the FreeCool circuit will be deactivated
and only the secondary circuit will operate. Once the ambient temperature has reduced
then the FreeCool circuit will become available again.
FreeCool
(F-Version / P-Version Only)
In suitably lower ambient conditions the unit can operate with only the FreeCool circuit
to fulfil the cooling requirements. The ambient conditions required for "Full FreeCool"
are dependent upon the indoor operating conditions and the operating capacity.
As the ambient temperatures rise, the potential capacity of the FreeCool circuit
decreases and when this cannot meet the full demand, the direct expansion circuit is
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