Daikin VAM-FA8VE Technical Data Manual page 260

11.2.3 Mechanical Fan Types and their Characteristics
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• HRV • VKM-GA(M)V1
Axial fan and centrifugal fan
Ventilation fan are roughly classified into two types: axial fans and centrifugal fans. These two types of
ventilation fans are selected depending on the operating conditions and/or application. Axial fan is normally
a propeller fan available for applications for larger flow but at smaller pressure rating ranging between 0
and 30 Pa. Centrifugal fan is either a sirocco or turbo fan available for applications that need large
pressure, and available for ducted ventilation systems.
<Propeller fan>
•
The simplest axial flow fan available for small
capacity applications ; larger air flow can be
obtained but at small pressure up to about 30 Pa,
so that large reduction in flow can occur due to
resistance (e.g. frictional resistance) when
flowing in a ducted system.
Impeller
Axial direction
Motor
<Features>
•
Air flow is larger than sirocco or turbo fans, but
the static pressure is lower.
<Installation>
•
Residential housing, external wall mount
<Applications>
•
General ventilator
•
Window-mount ventilator
•
Living room ventilator
Impeller characteristics as an essential parameter for type selection
Propeller fans have a smaller pressure rating, which means that the air flow is reduced significantly by
adverse wind. The next table shows the airflow vs. pressure characteristics that differ between propeller
and sirocco fans. Depending on the topography, altitude and/or other conditions, as a general guide,
propeller fans can be used at a height corresponding to the second floor of the building, and other types of
fans having a higher pressure rating should be used at higher locations.
* Even for independent houses, to ventilate a room that does not share any external walls, or if the house
is located in a windy place, use a pressure type fan.
Wind velocity vs. wind pressure, and ventilator capacity reduction due to wind pressures
(air flow : for 50 Hz only)
External
Wind pressure
air velocity
(PPa)
(Vm/sec)
0 0
3 3.9
5 10.8
7 20.6
10 43.1
15 96.0
20 171.5
• HRV • Heat Reclaim Ventilation
<Sirocco fan>
•
Uses the same theory as water wheel; the
impeller consists of many small fins facing
forward as shown in the figure below ; higher
static pressure can be obtained; available for
various applications.
<Features>
•
Static pressure is higher but the air flow is
smaller than propeller fans.
<Installation>
•
Housing complex
•
Ducted ventilation system
<Applications>
•
Air conditioning system ventilator
•
Cooking range hood, deep
•
Intermediate ventilator, ducted system
•
Sirocco fan
Propeller fan Sirocco fan
3 3
924m /h 432m /h
810 420
612 408
294 Reverse flow 390
Reverse flow 360
Reverse flow 264
Reverse flow 210
Impeller
Change in fan capacity due to
wind pressures
Sirocco
fan
Wind
velocity
Propeller
fan
Air flow