Ductwork lasts 10 to 20 years on average before it needs replacing. Most ducts need work when replacing HVAC systems more than 15 years old or when upgrading to bigger or higher-efficiency units.
Signs to repair or replace ductwork:
Unbalanced heating or cooling
Rising energy bills
Reduced airflow
Noisy HVAC system with vibrating ducts
Consistently dusty home
Mold, odors, or moisture damage in air ducts
Pest infestations in the ductwork
Collapsed, loosened, torn, or rusted duct sections