Fans are used in several applications across industries, from exhausts and fresh air units to humidification and dehumidification units. However, system efficiencies rarely exceed 50-60%.

The latest in fan technology, the AxFlo fan, is a novel concept that is miles ahead of the competition, with unparalleled total system efficiencies of 85%. The improvement in total system efficiency is achieved by using the best in class fan, motor and VFD. The concept builds on the idea of optimisation of the components that have the greatest effect on the overall system efficiency.


The fan itself is a high efficiency axial fan. While the motor is a IE4 or IE5 permanent magnet (PM) motor, this setup also has intelligent and high-efficiency frequency drives.

Typical HVAC systems only utilise static pressure and cannot achieve efficiencies above 90% as the dynamic pressure goes to waste. To maximise the energy efficiency of the system, fans must use both static and dynamic pressures. Axial fans do this, allowing for calculations based on total pressure. Therefore, while centrifugal fans reach efficiencies between 65-70%, axial fans usually perform at up to 80%.

A major reason for the significant difference is in the way the air moves through the fan. In axial fans the airflows are parallel to the fan axis, whereas in centrifugal fans they flow perpendicular to the fan axis and thereby lose most of the velocity energy.

The minimum loss in axial fans is due to the aerodynamic design that gives straight airflow with no or very little turbulence. This difference in design generally provides higher efficiency levels in axial fans.


Air Flow in a Centrifugal Fan


Air Flow in an AxFlo Fan

Central to the design is an impeller assembled from aluminium cast hub parts and blades. The impeller is fitted in an inner tube, in which cast-profiled guide vanes are mounted on the motor. Installation is a precise operation, essential to fan efficiency and low blade clearance. The hub and rotor blades, with minimum blade tip clearances are ideal for shovelling air through the system. The curvature of the guide vanes after the rotor, straighten the air turbulences to remove air rotation and to ensure maximum pressure after the fan.


The system efficiency is a product of fan, motor & drive efficiencies.

ηfan x ηmotor x ηdrive = ηsystem

In regular AC-motor driven centrifugal fans, the motor efficiency is around 90%, drive is 97% and that of the fan is around 60% resulting in a system efficiency of 53%.

In the case of AxFlo fans, motor efficiency is 95%, VFD efficiency is 97%, and the fan efficiency is 92%, resulting in a system efficiency of 85%.

95% x 97% x 92% = 85%

ADVANTAGESAxFlo fans have several advantages over traditional fans:

  • High efficiencies of up to 92%
  • It is possible to design AHUs up to 30% shorter and 30% lighter and still have the same performance characteristics and hence cut expenditures
  • These fans for AHUs are complete plug-and-play solutions to ensure easy and fast installation
  • The fan noise levels are significantly lower than those from other fan manufacturers
  • The fan lifetimes are 20+ years, which contribute to sustainability and guarantee low maintenance costs


AxFlo fans come with a standard 12 months warranty. With significant improvement in design and technology, AxFlo fans offer remarkable returns as well:

  • Energy saving of  40-50%
  • Payback within 24 months depending on usage

Energyhive offers solution providers who have turnkey retrofitting solutions with guarantees. Please connect with us to discuss how you too can enjoy savings in your HVAC systems.v