EDITOR’S CHOICE
INDUSTRIAL FANS
AXAIR FANS
MULTIPLE FANS IN PARALLEL: THE ADVANTAGES
OVER CONVENTIONAL TECHNOLOGY IN VENTILATION
SYSTEMS
In many cases, it is advantageous to use
multiple fans running in parallel when
compared to a large single fan in a
ventilation system. Each key benefit for both
retrofit and new installations is discussed
below.
Efficiency
Typically 40% of a commercial buildings
energy use comes from heating, ventilating
and cooling with 50% of the HVAC energy
consumption coming from fans. Given the
increasing cause for environmental concern,
designers should look to select EC plug fans
which will not only provide the necessary
reliability, but also provide optimum
efficiency and environmental benefits.
Savings as a result of moving from AC to EC
occur from both improved motor efficiency
and optimising system design. There is
potential to achieve greater efficiency
when the system’s operating range includes
multiple plug fans running closer to their
peak efficiencies, instead of one large fan
controlled over a wide operating range.
Redundancy
Continuous and consistent airflow is
essential to virtually every facility. Running
fans in parallel allows for redundancy
which is designed to improve reliability
and consistency. For example, if one fan
fails within the ECFanGrid (multiple fan
wall from Axair Fans), only that portion of
the airflow is lost, unlike single fan systems
where the entire air handler goes offline.
Moreover, the loss of airflow from one plug
fan can be offset by increasing the speed
of the remaining fans; this can be achieved
automatically in conjunction with the
building’s management system.
Flexibility
The number of plug fans in each ECFanGrid
system can vary according to the airflow
requirements. For example, in a wall of 9
fans in a 3×3 configuration where only 7
fans may be required for normal operations
to deliver the designed duty, the 8th
and 9th space can be blanked off with a
plate. If the demands on the AHU increase
through building expansion for example,
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the blanking plates can be removed and 1
or 2 fans added to the grid to meet the new
requirements.
Ease of installation
ECFanGrids are ideally suited for retrofit
AHU projects, particularly where a single
large radial fan is being replaced. It is often
the case that buildings have expanded
around an AHU over its years of operation.
This can make the extraction of the old fan
problematic but the install of the new fan
impossible without minor works to the fabric
of the building. Plug fans can be walked
through standard pedestrian doorways by
no more than two operatives: a significant
factor in maintaining a tight replacement
schedule, reducing costs and downtime.
Ease of maintenance
Unlike a traditional belt drive unit which
covers a large floor space, the ECFanGrid
is completely free of the floor. This means
that maintaining the hygiene of the AHU
is quicker, simpler and more effective. No
dust is released into the supply air as there
are no belt drives to degenerate over time.
Furthermore, component failure is quickly
dealt with due to the modular nature of the
ECFanGrid. For example, a single fan module
could be replaced and the AHU back online
within an hour of being shut down.
Noise Attenuation
Case studies show that there is the
potential to significantly lower noise when
using an ECFanGrid. There are two major
advantages to attenuate noise. First, the
noise spectrum of smaller impellers contains
higher frequencies, thus the wave lengths
are shorter, allowing for the use of shorter
attenuators. Second, the required length
of the fan section in a typical air handling
unit using a single large radial fan can be
reduced dramatically, in some cases up to
50%.
For more information on
Axair’s ECFanGrid, please visit
www.axair-fans.co.uk, call
01782 349430 or email
[email protected]