ductwork

/ˈdʌktˌwɜrk/
noun
  1. A system of tubes or channels used to carry air, especially in heating, ventilation, and air conditioning (HVAC) systems.
    • The old building's ductwork needed to be replaced to improve airflow.
    • The technician cleaned the ductwork to remove dust and allergens.
    • Properly sealed ductwork can save energy and lower utility bills.