Technical information

25
13.4.- Extraction fan (axial)
This is the adequate extraction system when using an econo-
miser or motor-driven damper and an extraction of over 25%
of total impulse air flow is required, and the return is ducted
(see graph in Fig. 12).
The system comprises two axial fans located inside a rain
hood, which also includes a surge pressure damper.
Up to approximately 30% of outdoor air intake, it acts as a
barometric damper.
When this intake degree is reached, the fans become opera-
tive with direct outdoor discharge.
When the return duct connection is at the bottom of the unit,
the extraction fan assembly is supplied fully installed on the
side of the unit. It includes all wiring connections and is ready
for use (see Fig. 12).
If the return duct connection is on the side of the unit, it must
be installed at the job site directly on the front surface of the
return duct, as close as possible to the unit. In this case, a
wiring hose is included for the connection of the fans to the
electrical box of the unit.
- Fig. 12 -
Economiser with axial extraction fan
EXTRACTION
RETURN
AIR
OUTDOOR
AIR
FULLY
FACTORY
INSTALLED
ACCESSORY
BOTTOM RETURN ASSEMBLY
OUTDOOR
AIR
RETURN
AIR
SIDE RETURN DUCT
IN THIS CASE, THE ACCESSORY SHOULD BE INSTALLED ON THE FRONT
OF THE RETURN DUCT. FOR THIS PURPOSE, A FLAT FRONT SURFACE
OF 2000 x 900 mm IS REQUIRED (SEE ACCESSORY INSTALLATION
INSTRUCTIONS)
ATTENTION: INDICATE RETURN AIR DUCT
LOCATION WHEN PLACING THE ORDER.
EXTRACTION FAN GRAPH
11000 12000 13000 14000 15000 16000 17000 18000 19000 20000 21000 22000 23000 24000
TOTAL AIR FLOW m
3
/h
AVAILABLE PRESSURE (Pa)
160
140
120
100
80
60
40
20