Fan coils with automatic power factor correction
Advanced Air’s new range of fan coil units include ECM motors which can be selected to give a leading current characteristic. Most all buildings have an inductive or lagging current characteristic. With the ECM having leading current this acts in opposition to the lagging current thereby automatically providing a level of power factor correction. This has an impact on energy usage and charges for the electricity consumed in commercial buildings.
It can also make a contribution to reducing the costs of power factor correction equipment. Andrew Sargent, General Manager of Advanced Air, said many consultants are now looking at the significant benefits of using leading current motors since they appreciate the advantages of “in built” power factor correction. They also identify with the low carbon emissions achieved with ECM technology, particularly when applied to variable air volume (VAV) fan coil units.
Apart from this power factor correction the motors are supplied with a smart card which can provide constant air volume from the fan irrespective of downstream pressure. This allows the air volume to be preset in the factory or in situ through the BMS. Presetting the air volume means that no commissioning work needs to be undertaken at the fan coil and a simple air balance at the diffuser is all that is required.
The actual fan deck comprises one or two horizontally mounted fans depending on the total cooling required. The motors driving these fans are much larger than conventional units, 250 watts compared to 75 watts. With large fans at slow speed very low noise levels can be achieved, down to NR25 in some applications. Also because there are fewer fans and motors compared to conventional units they are lower in cost both in terms of first cost and whole life costs.