How To Size An Attic Fan

The formula above gives an approximate value of the cfm needed for an attic fan.

How to size an attic fan.

Whole house fans work on the principle of removing the hot and humid air out of the house. Attic fan size calculation. 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. 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.

The warm air escapes through the attic and to the attic vents allowing the circulation of chilly air from the windows. Simultaneously cool fresh air will be pulled through the open windows and circulated through every room effectively replacing all of the air in your home and minimizing your dependence on air conditioning. It s also important to have plenty of soffit or gable vents for the fan to draw air into the attic. Help determine optimal sizing of solar attic fans.

It helps to cool your home temperatures and the attic by approximately 30 degrees. A whole house attic fan is installed in the ceiling between the top floor and the attic as a supplement to air conditioning. This will help to avoid premature damage to the shingles or mold building up in moist hot. The whole house fan is installed inside the attic between the living space and ceiling.

Cfm cubic feet per minute is a measure of the amount of air the fan moves in a minute. A whole house fan sucks warm house. Attic fan size cfm 0 7 x sq ft area of the attic formula 1 the size of an attic fan is calculated in terms of cfm. An attic fan works by exchanging the hot air in your attic space for fresh air pulled through the vents.

This attic ventilation calculator computes the size and number of solar powered attic fans to achieve the proper ventilation for your attic. To find out if you have enough vent space divide the cubic feet of air per minute that the fan is rated for by 300 to come up with the minimum number of square feet of intake vent space needed for that size fan.