Referring to the illustrated dual duct multiple zone HVAC system, how is the space temperature directly controlled? GS-RA-43 Illustration GS-RA-43: the U.S. Coast Guard has not released this illustration.

Correct Answer: Option A — The space air temperature is controlled by automatically proportioning the cold and hot air streams at the mixing unit.

Dual duct systems regulate individual compartment temperatures exclusively through terminal mixing boxes. Modulating dampers within the mixing unit automatically proportion the relative volumes of hot and cold air streams supplied to that specific space zone.