Nate Core Practice Test

What can occur in a ducted distribution system that is well sealed on the supply side but has numerous leaks on the return side?

1. A decrease in airflow

2. A positive pressure within the conditioned space

3. An accumulation of dust and debris

4. A loss of heating efficiency

The correct answer is: A positive pressure within the conditioned space

A ducted distribution system that is well sealed on the supply side but has numerous leaks on the return side will likely experience a positive pressure within the conditioned space. This occurs because the air being supplied into the space is not balanced by an equivalent amount of air returning to the system. The leaks in the return ducts allow outside air to enter the system, which can cause an imbalance, leading to an increase in pressure inside the conditioned space. When the supply side is effectively managing the airflow and pushing out conditioned air while the return side is compromised, it results in the conditioned air not being adequately cycled back to the air handler. Instead, the additional unconditioned air enters through the leaks in the return ducts, creating this positive pressure situation. This effects the air quality and can lead to potential discomfort for occupants due to stale air buildup as well. In contrast, a decrease in airflow, accumulation of dust and debris, and loss of heating efficiency are potential issues but would typically manifest under different conditions or scenarios within a less optimized duct system.