How Much Cfm Do I Need For Attic 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.

How much cfm do i need for attic fan. To calculate the amount of attic exhaust area you will need divide the fan s capacity in cfm by 750. The formula above gives an approximate value of the cfm needed for an attic fan. 17600 cubic feet 1600 11. 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.

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. Divide the cubic feet measurement by the cfm rating assigned to the fan. 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. 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.

You need a minimum of 1 square foot of attic air venting for each 750 cfm of air flow. Use the chart below as an attic vent fan cfm calculator. Ft of attic space for example 20 x 50 to be effective. 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. Cfm cubic feet per minute is a measure of the amount of air the fan moves in a minute.