ACG Member Todd Yates, PE, TBE, CxA published a case study “Airflow Measurement and Control with Induction Diffuser Technology” in HPAC Engineering on Airflow Measurement and Control with Induction Diffuser Technology.
With the increasing use of chilled beam systems, most of us today are familiar with induction technology. Many active chilled beam systems use some form of recirculation fan or other constant volume supply to provide primary air, usually mixed with conditioned outside air to meet ventilation requirements.
A flow hood cannot be used to measure airflow on active chilled beams since the hood disrupts induction and the normal operation of chilled beam airflow. Instead, airflow to each chilled beam is determined by measuring the air pressure drop at a factory-mounted port and using the manufacturer-provided Cv or flowchart to convert that pressure drop to airflow.