How Many Attic Fans Are Needed

When the attic becomes part of the home to be heated and cooled open wall gable vents and.

How many attic fans are needed.

These fans are designed to remove excess heat from your attic which in theory is supposed to lessen the load on the air conditioning in your home. It doesn t matter if the ventilation openings are spread out as long as there is sufficient space for all the air to escape. 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. Use only soffit vents as fresh air intakes for powered attic ventilators.

How an attic fan works. There should also be a 50 50 balance of attic venting and roof venting. Note that these two feet would not need to be one large opening. 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.

Attic fans exhaust hot air from your attic to the outside. With square foot living space at a premium many homeowners turn to their attics for a little extra room. An attic fan is installed on the slanted side of your roof or on one of the gable sides of your attic. Ok i would definitely not recommend an attic fan.

So if your fan is rated at 1500 cfm you will need about two feet of totally open space in your attic. 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. 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. 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.

A minimum of one square foot of inlet area for every 300 cfm of hvi certified fan capacity is required for proper fan operation. Ft of attic space for example 20 x 50 to be effective. 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. According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space.