What might cause a whole house fan to have insufficient airflow?

Insufficient airflow from a whole house fan is often caused by blocked or inadequate attic ventilation openings. These ventilation openings are crucial for enabling air to flow freely into and out of the attic space when the fan is operating. When these openings are obstructed by debris, such as leaves, dirt, or insulation, or if the design does not allow for enough air exchange, the fan will struggle to pull air through the house effectively. This situation can lead to a negative pressure within the house, resulting in inefficient operation, reduced air movement inside, and an overall compromise on the cooling effect intended by the fan system.

Other factors like fan speed settings being too high or having too many windows open can affect airflow dynamics, but they are less likely to fundamentally obstruct the flow as blocking or inadequate ventilation does. Similarly, fans that are too large could create excessive air pressure, potentially causing turbulence, but would not typically lead to insufficient airflow in the same direct manner that ventilation obstruction would. Understanding the significance of proper attic ventilation is key to ensuring effective operation of a whole house fan.