Question 469General Subjects - Assistant Engineer

70% to pass

In the illustrated single zone HVAC system, what statement represents the relationship between the exhaust, outside air and recirculation dampers? Illustration GS-RA-09

AThe more the exhaust and outside air dampers are open, the more the recirculation damper is closed, and vice versa.

BThe more the exhaust and recirculation dampers are open, the more the outside air damper is closed, and vice versa.

CThe exhaust, outside air, and recirculation dampers are all open or closed to the same degree for all operating conditions.

DThe more the outside air and recirculation dampers are open, the more the exhaust damper is closed, and vice versa.

AI Explanation

The correct answer is A. The more the exhaust and outside air dampers are open, the more the recirculation damper is closed, and vice versa. This relationship is due to the way the single zone HVAC system is designed to operate. The system needs to maintain a constant airflow, so as more outside air is brought in through the open outside air damper, less recirculated air is needed, causing the recirculation damper to close. Conversely, when the exhaust damper is open, more recirculated air is required, so the recirculation damper opens. The other options are incorrect because they do not accurately describe the relationships between the damper positions in a single zone HVAC system.