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Free-AIr-3-IN
© STULZ SpA – all rights reserved EN/02.2018
3.3. Working modes
Free cooling
When enabled by the electronic controller, the fans inside Free-Air-3-IN unit suck external air and
blows it directly into the room to be conditioned.
Fresh air flow is regulated by the electronic controller modulating fan speed.
3.4. Mechanical components
Casing
These machines are built using self-supporting panels made of painted galvanised sheet metal
to guarantee good corrosion resistance (not suitable for corrosive and saline environments). They
make the machine easy to inspect and, at the same time, offer adequate protection to its internal
components. The external panels are internally lined with a 3 mm layer of sound-absorbing material.
Fan boxes, in the upper and lower part of the unit, are internally lined with a 10 mm layer of sound-
absorbing material.
Internal components are accessible by removing frontal panel, extracting its fastening screws with
suitable tools.
Air filter
Air filter belongs the filter class G4, zig-zag type to increase the surface until 0,85 m
2
. It is designed to
prevent large dirt particles present in the environment from entering the internal ambient.
3.5. Motors
Fan
The fans are radial EC centrifugal type, single-intake, with rotor painted in black. The degree of
protection is IP42 and insulation class B.
3.6. Control, monitoring and safety components
All equipment is set and inspected at the factory and generally does not require further adjustments or
interventions. If, for specific reasons, it becomes necessary to perform modifications on the settings
of automatic devices, this task must only be performed, subsequent to notification to the STULZ
engineering service, by specialized product expert. STULZ units are equipped with a set of devices
designed to ensure proper operation. Intervention by any one of these automatic safety devices is a
sign of a malfunction and it is absolutely necessary to eliminate the cause of the malfunction.
DANGer
It is prohibited to make electrical by-passes on safety equipment. This intervention, in addition to
being dangerous, also immediately invalidates guarantee coverage for the product.
Interrupt electrical power to the unit before performing any repair or maintenance.
Work on the unit must only be done by expert, qualified and authorized personnel.
Automatic circuit breaker of the fan
It protects against short circuits and excessive motor current. They have adjustable thermal and
magnetic triggering devices.