How Many Attic Fans Are Needed

Ok i would definitely not recommend an attic fan.

How many attic fans are needed.

It doesn t matter if the ventilation openings are spread out as long as there is sufficient space for all the air to escape. How an attic fan works. There should also be a 50 50 balance of attic venting and roof venting. The uniform building code requires that the amount of venting area in the attic be equal to 1 150 of the area of the floor and in most circumstances it allows a ratio of 1.

An attic fan is installed on the slanted side of your roof or on one of the gable sides of your attic. When the attic becomes part of the home to be heated and cooled open wall gable vents and. Note that these two feet would not need to be one large opening. Ft of attic space for example 20 x 50 to be effective.

A minimum of one square foot of inlet area for every 300 cfm of hvi certified fan capacity is required for proper fan operation. Ideally there should also be plenty of soffit intake space their calculations recommend 336 net square inches of open soffit ventilation to supply 700 cfm. Attic fans exhaust hot air from your attic to the outside. Vent fan location locate roof mounted fans on the back of the roof below the ridge but not so high as to be visible from the front of the house in the middle of the main part of the attic.

Because what happens is attic fans are so strong that they actually reach down into the conditioned space of your house and they do that by using the wall cavities and where the outlets and pipes come through the walls as places where they draw air from the inside of your house it s that air conditioned air and it ll pull it right up into the attic and exhaust it outside. According to the home ventilating institute hvi powered attic ventilators need to move a minimum of 700 cubic feet per minute cfm for 1 000 sq. Use the calculator below to find out how many exhaust and intake vents you will need on your house. Attic vent fans are commonly rated from 800 to 1 600 cfm making one fans suitable for attics of up to around 2 200 square feet.

So if your fan is rated at 1500 cfm you will need about two feet of totally open space in your attic. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation for every 300 square feet of attic floor space evenly split between intake and exhaust. If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation. Use only soffit vents as fresh air intakes for powered attic ventilators.