So what exactly are the functions of these exhaust air duct systems? Their main function is to ensure that the hot air that is generated by the dryer for drying the clothes has an outlet and the air gets blows away. If the exhaust duct systems are not laid properly or maintained properly then there is every likelihood of problems cropping up First and foremost if the ducts are bent are not properly laid, then the air from the dryer would not be able to pass. This could put stress on the dryer machines which could become ineffective and slow in its functions. Exhaust air duct systems to your home.