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10 - FANS AND AIR DUCTS
10.1 Checks in the EC plug-fans
● The 50NC units are equipped with electronic variable speed
plug-fans in both the outdoor and indoor modules.
● Before commissioning, check the blade rotation direction and
ensure that the axis turns smoothly without any vibrations or
strokes.
● Once running, check the operating conditions: pressures,
fl ows and consumptions.
● The coupling between the characteristic curves of the fan and
the room is very important to provide the necessary fl ows and
pressures to the duct network.
● The indoor module fans include a flow
control pressure switch. At the factory,
this pressure switch is set to the nominal
fl ow rate. However, the fl ow rate can be
readjusted on site for diff erent conditions
using the graphic terminal (see the
"50FC" electronic control manual for more
information).
10.2 Air ducts connections
The 50NC units have been designed for indoor installation with
their two modules attached to a network of air distribution ducts.
The air supply and return ducts should be sized based on
nominal fl ow and the unit's available pressure (refer to the
technical brochure).
In the case of the indoor module, the pressure drop caused by
any optional components must be taken into account.
The duct calculation and design must be made by qualifi ed
technical personnel.
When working at heights, it is mandatory to use all
the necessary personal protective equipment (PPE)
to ensure safety.
Recommendations
It is advisable to take into consideration the following
recommendations:
● Flexible connections must be made between the ducts and
the unit that avoid the noise and vibration transmission.
● Curves in the fan supply outlet(s) must be avoided. It is
recommendable to have a straight section of duct measuring
approximately 1 meter. If it is not possible, they must be as
smooth as possible, using indoor defl ectors when the duct is
of large dimensions.
● When making the ducts, direction sharp changes must be
avoided since they can generate occasional pressure drops,
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which aff ect the available pressure and the fl ow. The location
of discharge and aspiration grilles must be studied carefully
to avoid air recirculation and the transmission and generation
of noises to the interior.
● Consideration should be given to the need to install fi lters
on the return ducts, taking into account any particles in
suspension existing that could settle inside the machine (e.g.,
textile fi bers).
● No matter the type of ducts used, they must be isolated and
not be composed of materials that propagate fi re nor expel
toxic gases in the event of a fi re. The internal surfaces must
be smooth and should not pollute the air that circulates within
them. In any case, the eff ective legislation about this issue
must be respected.
Caution: If the supply fan is accessible from any
point of the duct network, the installer must place a
protective mesh at the fan outlet in compliance with
current regulations.
Indoor module ducts
Outdoor module ducts
Note: In two-circuit models, the drive of the outdoor module may
have a single duct, provided that the pressure drop in the duct
does not cause air recirculation.
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