The engineering team at temperzone are specialists in the application of advanced world technologies into the custom built reverse cycle packaged air conditioning units up to and beyond 180 kW cooling capacity. The innovation in temperzone has led this company to the forefront in the development of energy efficiency due to their expertise in new refrigerants and new air moving fans and motors.

The fan motors that stand out above the others in this respect are the EC motors combined with the backward curved single inlet centrifugal plug fans.

Fan manufacturers ebm-papst and Rosenberg have independently developed their own range of this type of motor/fan combination. temperzone have applied this new type of motor/fan combination in its 90, 100 and 115kW customised rooftop units named PA 3100, PA 3600 and PA 3800 respectively (only available in New Zealand).

Four fans are needed to move the air in the larger range of 125, 145, and 180 kW called the PA 4100, PA 4600 and PA 4800 series.

Costs and delivery times have been the major hurdles in the introduction of the EC motors and fans into the New Zealand market.

temperzone has negotiated with the suppliers to significantly raise the Australia and NZ stock levels for the most frequently used motors.

At the end of 2006, temperzone sold the EC motor concept design in the PA 4800 to a client who was willing to try out the practical advantages of the EC motors with backward curved fans and accept the financial penalty on the unit by offsetting this with the savings in speed control and noise attenuation.

All parties, including the client, the final user, all visiting professional engineering consultants and temperzone management were impressed with the final product.

This has resulted in an escalating quantity of orders to temperzone from clients and consultants for PA units with EC motors and backward curved fans.

The general consensus of the major advantages of these units with EC motor fans has been:
• Integrated variable speed control from 0 to full RPM by 0–10 Vdc signal.
• Soft starting of motors gives no inrush current.
• Efficiency between 95–98% compared to 50–70% for belt drive centrifugal fans.
• Supply air unit outlet size is the same height as the inlet size, thus reducing the outlet velocities from 18–20 m/s to 8–10 m/s and so eliminating the need for tapered ducting transitions.
• Supply air sound power levels are significantly lower due to lower unit exit velocities, removal of belt/drive noise and accoustic attenuation being possible in the supply air pressure chamber of the unit.
• Simplified unit design due to supply air pressure chamber within the unit and the possibility to locate the supply air spigot in many positions without altering the location of the fans.
• Fixed and stable airflows via differential pressure transducer and controller to compensate for varying duct static pressures caused by dirty filters and modulating dampers.
• Commissioning and maintenance time and costs are reduced by eliminating pulley and belt adjustments, wear and changes.

For more information on the application of plug fans to rooftop units in New Zealand, email m.vlug@temperzone.co.nz.