What is the minimum slope required for underground ducts to facilitate drainage?

The minimum slope required for underground ducts to facilitate drainage is 1/8 inch per foot. This slope is important as it helps ensure that any condensation or moisture that collects within the ducting can effectively drain away. If the slope is insufficient, water can accumulate, leading to potential issues such as mold growth, system inefficiency, and damage to the duct material.

Setting the slope at 1/8 inch per foot strikes a balance between effective drainage and practicality in construction, as it allows for adequate flow without requiring excessive elevation changes that could complicate installation or reduce system performance. Proper drainage is crucial for maintaining the integrity and efficiency of HVAC systems, especially in underground installations where moisture can be more prevalent.