What is a common cause of duct leakage in HVAC systems?

Duct leakage in HVAC systems is often most commonly caused by poor sealing. When ducts are installed, it's crucial to ensure that all joints, seams, and connections are properly sealed. If there are gaps or improper sealing methods used, conditioned air can escape from the ducts into unconditioned spaces, reducing system efficiency and leading to increased energy costs.

Poor sealing can occur due to various factors, such as installation errors, the use of inadequate sealing materials, or the natural wear and tear of seals over time. Addressing these sealing issues promptly not only improves the efficiency of an HVAC system but also enhances indoor air quality by preventing unwanted air loss and potential contamination.

Other factors listed, such as excessive insulation, correct sizing, and high humidity, do not directly contribute to duct leakage in the same way. Excessive insulation might affect overall energy performance but does not lead to leaks. Correct sizing ensures that ducts are appropriately dimensioned for airflow but does not guarantee sealing integrity. High humidity can affect comfort levels in a space but does not directly cause leaks in ductwork. Thus, poor sealing stands out as the primary cause of duct leakage in HVAC systems.