Unlike dampers, booster fans do not restrict airflow and therefore do not place additional stress on the HVAC system.
In general, blocking more than approximately 30% of a home's vents—whether with manual or smart dampers—can significantly increase static pressure within the ductwork. Excessive static pressure may negatively affect HVAC performance, potentially causing overheating during the heating season or coil freezing during the cooling season.
Booster fans work differently. Rather than restricting airflow, they help improve and redistribute airflow throughout the duct system. By increasing airflow in underperforming rooms, they can help reduce overall system imbalance and improve comfort. In many cases, this can also help the main blower move air more efficiently through the ductwork.
Even when SmartCocoon fans are not running, the device is designed to allow airflow to continue through the vent. The device does not completely block the vent, helping to prevent excessive pressure buildup within the HVAC system.
It is also important to note that when one room experiences weak airflow, other rooms typically receive excess airflow, since the HVAC system is designed to deliver a fixed amount of air throughout the home. By improving airflow to under-served rooms, SmartCocoon can help create a more balanced and comfortable environment throughout the house.
When properly installed and used as intended, booster fans are not expected to cause damage to the HVAC system.