How to install air ducts: Air ducts are one of the most important factors in a house or a building’s ventilation and overall HVAC system. The purpose of these ducts is to carry and remove air. On a large scale, air ducts are the main vehicle for what is called ventilation or ventilation air. Think of air ducts as a bridge to having the proper indoor air quality and a comfortable temperature. There are three main ventilation areas: supply air, return air and exhaust air. You’ll find a how to install air ducts guide video below for your reference.