scope:

ABSTRACT

Four manufacturers provided laboratory airflow and power data as a function of external static pressure for 37 multispeed fan-coil units with permanent split capacitor motors. These data were used to develop an airflow performance model of fan-coil units that could be implemented in a building simulation program. The fan-coil units had fan motors ranging from 0.033 hp to 0.75 hp (25 W to 560 W) and maximum airflows that ranged from 242 ft³/min to 2646 ft³/min (0.11 m³/s to 1.25 m³/s). The model included normalized fan motor power and fan airflow at each speed setting. The normalized power versus normalized airflow data for the range of external static pressures typically plotted in a grouping of data at each speed setting. These average normalized powers and airflows were evaluated for each unit. The normalized values were combined with a linear fit to the high airflow and power curves to develop a straightforward process for generating airflow and power curves as a function of external static pressure. A procedure was developed to determine the intersection of the air system curve with the fan-coil airflow and power curves. The resulting model could be used to describe the airflow and power performance of a specific manufacturer's permanent split capacitor fan-coil unit over multiple speeds and external static pressures.