What is the horsepower of the fan servicing AHU-1 based on the sample drawings?

The horsepower of a fan servicing an air handling unit (AHU) is determined by several factors including the airflow required, the static pressure the fan must overcome, and the efficiency of the fan system. In the context of the sample drawings mentioned in the question, the selection of a fan's horsepower rating is typically based on airflow calculations and the specific performance requirements set by the design.

For AHU-1, a 25 horsepower fan would be appropriate if the calculations reveal that the unit requires a substantial airflow capacity and has to overcome a particular static pressure that aligns with the 25 hp rating. This horsepower level indicates a balance between providing sufficient air movement and ensuring operational efficiency without being excessively oversized, which could lead to increased operational costs or inefficiencies.

When determining the fan horsepower from the accompanying drawings, one must ensure that the unit's flow rate and pressure drop conditions align with the characteristics of a 25 hp fan. Given these calculations, it is logical that a 25 hp rating was chosen for AHU-1 based on its operational requirements outlined in the drawings.

The other options, while valid horsepower ratings for fans, would either be underpowered or overpowered for typical applications of air handling units, which emphasizes the significance of performing a detailed