LAUSR

The purpose of this study was to provide in situ field data on fan/motor efficiency and fan static pressure differentials for the fan/motor combinations used in fan coil units. Measurements were made on 321 fan coil units with permanent split capacitor motors in three university residence halls and one commercial building. Data included manufacturer, model number, airflow, static pressures at the inlet and outlet of the fan coil unit, voltage, current, and external static pressure across the unit. All units had data on static pressure differential across the fans and most had external static pressure measurements across the fan coil units. Over 97% of the units operated with external static pressure differentials at or below 0.4 in. w.g. (100 Pa). Over 78% of the units were below 0.2 in. w.g. (50 Pa). A correlation for fan/motor static efficiency versus fan static pressure differential was developed. The analysis provided estimates of both fan/motor static efficiency and fan static pressure differential that should provide users of building simulations programs with a reasonable estimate of these variables when simulating fan coil units. The data showed that fan efficacy was independent of either fan static pressure differential or external static pressure.