Referring to the illustrated dual duct multiple zone HVAC system, how is the space temperature directly controlled? Illustration 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 mix variable proportions of continuously supplied hot and cold airstreams inside zone mixing boxes to maintain precise individual space temperature requirements.