How to clean air ducts correctly and what to expect from air duct cleaning company? Standard way of cleaning air ducts is the common question from new home owners and not only. Technically this question is more about quality of the process. In order to find the answers you need to know the general conception of cleaning the ducts. However some systems do not have return duct system, they have either single return vent or in very rare cases do not have one (mobile homes). The biggest part of any system is the main line (supply and return) main lines contain most of dust and debris. All the systems have return and supply sides to recirculate the air in your house, they require alternate cleaning. All supply vents that blow hot or cold air in the house come from supply main duct (line). Some systems may have relatively the same return side construction (multiple return vents). WellDucttechnicians use only HEPA certified negative air machines for indoor use and gasoline powered truck mounted machines for outdoor use. Standard way of cleaning air ducts. That is the most important part to clean, however some “blow and go” air duct cleaning companies simply do not have proper equipment to perform it right.