Which of the following is not a prohibited location for return air?

The correct answer is living room, as it is not a prohibited location for return air systems. In residential and commercial HVAC design, return air systems are utilized to circulate air back to the heating or cooling equipment for proper airflow and efficiency.

Certain locations are prohibited for return air due to safety and health considerations. Bathrooms, furnace rooms, and garages are among those areas because they can potentially contain odors, moisture, or contaminants that could be circulated throughout the living space, leading to poor indoor air quality or hazardous conditions.

On the other hand, living rooms are considered safe and suitable for return air since they are general living spaces that typically do not present the same risks associated with the other locations. This allows for effective air circulation and helps maintain a comfortable environment in the home without compromising health and safety.