How Much Cfm Do I Need For Attic Fan

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.

How much cfm do i need for attic fan.

Divide the cubic feet measurement by the cfm rating assigned to the fan. 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. Proceed to step 2 and use the chart to determine the size and number of solar powered attic ventilation fans required to achieve a min. For proper cooling and efficient operation any whole house comfort ventilator requires adequate unobstructed outlets in the attic through soffit vents grilles or louvers.

17600 cubic feet 1600 11. 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. If you need 6 000 cfm of air flow through your house divide 6 000 by 750 to get a minimum 8 square feet of. What this means is that every eleven minutes the air in the home is being exchanged by a fan of this rating along with having windows open in each room.

Use the chart below as an attic vent fan cfm calculator. You need a minimum of 1 square foot of attic air venting for each 750 cfm of air flow. The formula above gives an approximate value of the cfm needed for an attic fan. Cfm cubic feet per minute is a measure of the amount of air the fan moves in a minute.

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. Ft of attic space for example 20 x 50 to be effective.