VC-21-009 -- A Simple Airflow and Power Analysis of Fan-Coil Units with Electronically Commutated Motors

Airflow and power data on 85 fan-coil units with electronicallycommutated motors were evaluated and used todevelop a simple fan model between fan motor power and fanairflow. While data on 45 units were provided by five manufacturers,data on the other 40 units were generated using anozzle airflow chamber with power measurements at a universitylaboratory. Both vertical and horizontal units were evaluated.Performance data included fan airflow and fan motorpower over a range of external static pressures and fan airflowsettings. The performance data served as the basis for developinga simple model that could be used in building simulationprograms to estimate the annual energy use of fan-coil units.A best-fit line of fan motor power versus airflow was developedfor units less than 1500 ft3/min (0.71 m3/s) in capacity. Whilethere was considerable scatter in the data, the model allowedfor a simple estimate of power at a given airflow. The fan powerfor fan-coil units with electronically commutated motors wasalso compared to the fan power for fan-coil units with permanentsplit capacitor motors for airflows ranging up to 1500 ft3/min (0.71 m3/s). Those with electronically commutated motorshad lower fan powers at all airflows when compared to unitswith permanent split capacitor motors.