According to duct installation guidelines, ducts must be __________.

The requirement that ducts must be sealed is vital for maintaining energy efficiency and ensuring proper air distribution within a mechanical system. Sealing ducts prevents air leaks, which can significantly diminish the effectiveness of heating and cooling systems. When ducts are not adequately sealed, conditioned air escapes into unconditioned spaces, leading to inconsistent temperatures and increased energy consumption.

Sealing also helps to improve indoor air quality by minimizing the potential for contaminants to enter the duct system from the surrounding environment. According to the North Carolina Mechanical Code, proper sealing methods, such as using mastic or metal tape, are prescribed to ensure secure joints and connections in the ductwork. This attention to detail helps to promote a more efficient, healthier, and cost-effective HVAC operation.

In contrast, while duct insulation is important for thermal efficiency and ducts may require grounding in certain installations, the primary focus of the question is on the physical integrity of the duct system, which is best served through sealing.