HVAC Code Practice Exam 2026 – Complete Test Prep

Ducts serving a Type II hood are required to have a gravity-assisted drainage slope toward the hood or an approved reservoir to prevent condensate from pooling in the duct and to ensure it flows to the hood or collection point. The minimum slope specified is 2 percent, which translates to about 1/4 inch of drop per foot of duct. This gentle slope is enough to reliably move condensate toward the hood or reservoir without adding unnecessary complexity to the ductwork. Steeper slopes, like 3, 4, or 5 percent, aren’t required for this purpose and would be more cumbersome to install, though they would still function. The key idea is providing a reliable drainage path to keep the duct dry and prevent backflow or water buildup.