Attic Fan Intake Air

Since attic breeze solar powered fans are variable speed in terms of airflow the calculation for required air intake ventilation must be made at the fan s highest rating to ensure adequate ventilation under the full range of operation.

Attic fan intake air.

Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space. If two different types of exhaust vents are combined for example a ridge vent and a gable louver the primary path of air becomes the distance between the two types of exhaust vents. That path is supposed to be from low in the attic intake vents to the highest possible exit point in the attic exhaust vents. Not having enough intake air could lead to negative pressure.

Negative pressure can cause air conditioned air to be pulled from your home or create a vacuum in the attic that will burn out a fan our technician will assess your current intake air to determine if any additional venting is required. A minimum of 70 linear feet or 700 sq in. Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic. See figure 2.

Proper attic ventilation consists of a balance between air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge.