Field assessment of economy fan coil unit performance in cooling capacity and acoustic compliance analysis

This study investigated cooling capacity concerns in 2-pipe economy fan coil units used in Korea, prompted by frequent field replacement claims and HVAC design engineer feedback. Comprehensive field testing of approximately 100 economy FCUs revealed significant performance discrepancies. KS B 6377 certified models (n=49) performed 6.9% below ratings, while uncertified models (n=54) averaged 9.0% below rated airflow specifications. Detailed in-situ evaluation of selected models showed uncertified units achieving only 68% of rated airflow at maximum fan speed, whereas certified models delivered 138% of rated airflow. Laboratory testing of certified models revealed internal inconsistencies, with cooling capacity ranging from 85.4% to 118.2% of rated capacity as a result of varying airflow rates despite meeting NC-40 acoustic criteria. Reduced cooling capacity results from intentionally diminished airflow rates used for noise mitigation-a concerning compromise of thermal comfort for acoustic compliance. Recommendations include implementing advanced low-noise fan technologies and specifying precise fan flowrate conditions in KS B 6377 certification standards.