Which statement best describes the operation of a dual-duct system?

• A. It uses a single duct for all zones.
• B. It provides independent supply and return air paths for multiple zones.
• C. It has no reheat.
• D. It relies solely on outdoor air for cooling.

Answer: (B)

Dual-duct systems control space temperature by supplying two separate streams of air: one heated and one cooled. Each zone gets a blend of these two supply streams through zone dampers, allowing independent temperature control for multiple areas. The key feature is the two independent supply paths, which is why this option is the best description. In practice, the return air path is typically shared back to the air handler, not independently routed per zone. The other ideas don’t fit because a dual-duct system is not about a single supply duct, it isn’t defined by absence of reheat (which some installations may have), and it isn’t driven solely by outdoor air for cooling.