What size air ducts would be used with a 12,000 BTU/hr unit?

The selection of air duct size for a 12,000 BTU/hr unit is crucial for ensuring effective air distribution and maintaining system efficiency. Air ducts need to be sufficiently sized to handle the volume of air that a particular BTU rating requires. Generally, for air conditioning systems, a rule of thumb is that a 12,000 BTU/hr unit requires around 400 CFM (cubic feet per minute) of airflow.

When considering duct diameter, larger ducts can move more air with less resistance, while smaller ducts may restrict airflow. A 6-inch diameter duct is typically suited to handle the airflow required by a 12,000 BTU/hr capacity unit, ensuring that it provides enough cooling power without significant air restriction or pressure loss within the system. This optimal airflow helps maintain the efficiency of the unit and ensures that the conditioned air reaches the intended spaces effectively.

The other sizes might be either too small, causing airflow issues and reducing system performance, or unnecessarily large, leading to increased installation costs without corresponding benefits. This understanding of airflow and duct sizing is fundamental in HVAC system design and optimization.