Drains shall be located at the lowest points in horizontal ducts to facilitate drainage.

Drains shall be located at the lowest points in horizontal ducts to facilitate drainage.

• A. High Points
• B. Midpoints
• C. Low Points
• D. Bottom Edges

Answer: (C)

In horizontal ducts, moisture from the cooled air tends to condense and pool as liquid. Gravity pulls that condensate to the lowest point, so placing a drain there allows the water to exit by gravity and prevents standing liquid inside the duct. This is why the drain is located at the lowest point. Drains at high points would leave condensate trapped, midpoints wouldn’t capture all the liquid, and “bottom edges” isn’t a standard drainage location.

In horizontal ducts, moisture from the cooled air tends to condense and pool as liquid. Gravity pulls that condensate to the lowest point, so placing a drain there allows the water to exit by gravity and prevents standing liquid inside the duct. This is why the drain is located at the lowest point. Drains at high points would leave condensate trapped, midpoints wouldn’t capture all the liquid, and “bottom edges” isn’t a standard drainage location.