The rectangular flexible duct, despite its advantages, also presents certain shortcomings that should be considered when evaluating its suitability for an HVAC system. These drawbacks include:

Relative Cost: It is generally more expensive than other ducting options that offer similar solutions, which can be a disadvantage, particularly for large-scale installations.

High Labor Cost: Its installation requires a high level of precision and professional touch, leading to potentially higher labor costs as professionals consider various factors during the installation process.

Air Leakage Risk: If not installed and sealed properly, there’s a risk of air leakage, which can compromise the efficiency of the HVAC system.

Limited Airflow Capacity: Might have limitations in terms of airflow capacity and pressure ratings compared to other duct types.

High Pressure Drop: Experiences a higher pressure drop, which can affect the overall performance and energy efficiency of the HVAC system.

Not Suitable for All Applications: Some flexible duct products may not be appropriate for high-temperature applications or might need extra insulation to maintain energy efficiency.

Considering these shortcomings, it is essential to assess the specific requirements of an HVAC system and to adhere to proper installation and maintenance guidelines to minimize these issues.