Pressure-independent fan-coil units
Advanced Air has its extended range of Epic fan-coil units, which all include ECM motor technology, with a smart card developed by the company to offer pressure-independent units at no extra cost. With a pressure-independent FCU, the air volume remains constant irrespective of pressure changes. Benefits include easy setting on site or in the factory of air volume against a voltage signal from the controller or BMS.
Once set, the air volume is maintained as pressure changes due to dirty filters or changes in the configuration of flexible ductwork. Airside commissioning is not needed, and just a simple balance at the diffuser is required.
The pressure-independent feature is achieved using a virtual 3D algorithm that includes motor speed, torque and fan characteristic. The smart card adjusts the control voltage signal to the motor to adjust its speed to maintain constant volume.
Andrew Sargent, general manager, says, ‘If the extra cost of some of this commissioning-free options available in the market were taken into consideration, savings of up to 25% could be made on capital costs — i.e. the purchase price of the fan-coil units. All this can be achieved with very low specific fan power, with VAV versions as low as 0.15 W/l/s and constant volume of 0.2 W/l/s.
