Common mistakes to avoid when selecting and designing chilled beam systems include oversizing or undersizing the system, neglecting to consider the specific application and space requirements, and failing to account for factors like pressure drop and airflow rates. It’s also essential to avoid selecting products based solely on initial cost, as this can lead to higher operating costs and reduced system performance over time. Instead, consider the total cost of ownership, energy efficiency, and long-term maintenance requirements when selecting a chilled beam system.