Use air duct sealant generously on joints and unions for effective sealing, without concern for aesthetics. This increases energy usage, resulting in higher utility bills. Unsealed ducts also result in inconsistent airflow, making it. There are a few methods considered best practices for sealing ductwork leaks. The best methods are the following: Short-term (Up to. Sealing ductwork leaks stops air loss, improves efficiency, and helps maintain steady temperatures throughout the house. By taking a clear step-by-step approach, we can fix these leaks without needing advanced tools or expensive services. Duct Sealing Tape or Duct Tape One of the ways you.