What is the best installation method for a flexible duct to a metal collar?

Using tie wraps along with mastic for sealing both the inner and outer liners provides a secure and airtight installation for a flexible duct connected to a metal collar. This method ensures that the connection is not only mechanically strong but also helps to prevent air leaks, which are critical for maintaining system efficiency and performance.

Mastic, a type of adhesive sealant, is particularly effective in creating an airtight seal that can withstand temperature variations and pressure changes within the duct system. By applying it to both the inner and outer liners, you enhance the durability and effectiveness of the connection. The tie wraps provide additional support to keep the duct tightly fitted onto the collar, reducing the chance of it loosening over time.

In contrast, relying solely on duct tape or zip ties would not achieve the same level of sealing. Duct tape, while useful for temporary fixes, may degrade over time and is often not reliable for long-term sealing in HVAC applications. Zip ties alone provide no sealing capability and cannot prevent air from escaping at the connection point. Blow-in insulation, while it can help with thermal efficiency in certain contexts, does not serve as a method for securely connecting flexible ductwork to a metal collar, making it unsuitable for this specific installation need.