How Much Cfm Do I Need For Attic Fan

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.

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. 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. 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. Ventilation rate of 10 air changes per hour.

Cfm cubic feet per minute is a measure of the amount of air the fan moves in a minute. The formula above gives an approximate value of the cfm needed for an attic fan. Use the chart below as an attic vent fan cfm calculator. 17600 cubic feet 1600 11.

You need a minimum of 1 square foot of attic air venting for each 750 cfm of air flow. For proper cooling and efficient operation any whole house comfort ventilator requires adequate unobstructed outlets in the attic through soffit vents grilles or louvers. Ft of attic space for example 20 x 50 to be effective. To calculate the amount of attic exhaust area you will need divide the fan s capacity in cfm by 750.

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. 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.