The ahu market is gradually moving away from the ‘traditional’ belt-drive centrifugal fan solutions to direct-drive technology. And with good reason, says Les Fish, md of Ziehl-Abegg UK.
A REVOLUTION is taking place in the UK air handling unit market, with the transition from what might be referred to as the traditional belt-drive centrifugal fan solution to the direct-drive centrifugal fan, (often referred to as a plug fan).

Perhaps the first step taken in the transition process was the move away from forward curved radial impellers to its backward curved variant, enabling a step increase in system efficiency, even with belt-drive arrangements.

The next step was to change from belt-drive, backward curved, radial impellers to direct-drive units, enabling the transmission losses and also the air-restriction losses inherent in belt-drive systems to be eliminated.

The adoption of direct-drive, backward-curved fan arrangements has been embraced widely throughout mainland Europe for several years, but the UK has been somewhat slower to make the transition.

There does appear to be some momentum in the change-over process from belt-drive to direct drive, now that the 'early-adopters' have populated the market with some very efficient ahus, and the change-over is likely to accelerate as a result of legislation aimed at improving the efficiency of air movement equipment, and end-users pushing for reduced energy bills at a time of rising electricity costs.

Add to this, the ability to reduce the footprint of ahus, reduce maintenance (with no belts to re-tension and replace and no belt residue to clean up), the possibility of reduced downstream filtration requirements (and the resultant possibility to reduce the fan by one size), and the adoption of direct-drive solutions would appear to be inevitable.

There are those who put forward an economic argument against replacing belt-drive solutions with direct-drive solutions, because of the cost of the frequency inverter which is normally included in the larger plug-fan systems.

However, the use of a frequency inverter provides control opportunities not available with belt-drive systems, and when the cost comparison is made including capital cost, installation, balancing, commissioning and lifetime operating costs, the inverter-driven, direct-drive, plug-fan solution becomes very attractive.

Ziehl-Abegg launched its new range of EFF1 motored ER-C plug-fans, which further improves ahu operating efficiencies, at the recent ISH exhibition.

The ER-C range of plug fans features steel impellers with diameters from 225mm to 1120mm, and air free blowing volumes ranging from 4,000m3/h to 133,000m3/h.

Ziehl-Abegg UK
01245 449010