In terms of duct installation, why must the key slot face downward?

The requirement for the key slot to face downward during duct installation is primarily to prevent water accumulation. When the key slot is positioned facing down, it allows any potential condensation or moisture that may enter the duct system to drain away rather than collect inside. This is crucial for maintaining air quality and preventing mold, corrosion, or other moisture-related issues that can arise in the ductwork. Ensuring that moisture does not accumulate helps to maintain system efficiency and prolongs the lifespan of the duct materials.

While there may be other considerations in duct installation, such as access for maintenance, insulation effectiveness, and airflow optimization, the prevention of water accumulation is a fundamental aspect of ensuring the long-term functionality and safety of the duct system.