Typically speaking, a company will use a glorified shop vac, various carpet cleaning hose attachments in conjunction with carpet cleaning machinery and or even a glorified shop vac with a spinning brush. Most contact cleaning companies will spend 30 minutes to 2 hours in attempting to reach as much ductwork that a person is physically able to reach. A small minority of contact cleaning companies will even make a good go at it and will spend up to 8 hours at an average
residential jobsite. It is even fair to say that if a contact cleaning company spent all day, if the ductwork was completely exposed and if the ductwork was small enough, a contact cleaning company could technically perform a thorough job if the technician
was motivated to perform a thorough job. The contact cleaning method of air duct cleaning is very limited in what dirt, dust and debris is actually pulled out of a ventilation and or HVAC system. 2” diameter vacuum hoses cannot suck up 3” diameter beer cans or soda pop cans.