What can cause blocked exterior openings in HRV and ERV systems?

Blocked exterior openings in Heat Recovery Ventilation (HRV) and Energy Recovery Ventilation (ERV) systems can occur primarily due to poor installation practices or the presence of animal nests. Proper installation is crucial for ensuring that intake and exhaust openings are unobstructed and functioning effectively. If openings are poorly positioned or sealed, this can lead to reduced airflow and inefficiency in the system. Additionally, animal activity, such as nesting, can lead to significant blockages that impede the flow of air, compromising the performance of the ventilation system.

While duct sizing and insulation play important roles in overall system efficiency and performance, they do not directly cause blockages at the exterior openings. High humidity levels can affect the operation of HRV and ERV systems, but they do not physically obstruct the exterior openings. Therefore, the most direct cause of blocked openings in these systems is indeed linked to installation issues or animal interference.