How To Size An Attic Fan

Calculate the required cfm air flow.

How to size an attic fan. Measure the length and width of each floor of your home with the tape measure. The whole house fan is installed inside the attic between the living space and ceiling. Select if your roof is more flat of peaked. How to size attic exhaust vent fans for your home attic size.

Cfm cubic feet per minute is a measure of the amount of air the fan moves in a minute. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space. Then enter the height at the highest point. Always have a balanced ventilation system.

By sizing and implementing a whole house fan you can pull the warm stale air from your entire home into the attic where it s vented outside. Multiply length times. The warm air escapes through the attic and to the attic vents allowing the circulation of chilly air from the windows. Without an attic fan the temperature in your attic can climb to a searing 150 degrees.

Next multiply the square feet of attic space by 0 7 to get the minimum number of cubic feet of air per. 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. Multiply the total air volume in cubic feet by 30 which represents a complete air change every 2 minutes. To determine the size of your attic multiply the width by the length of the attic floor in feet.

By dispelling hot air from your attic an attic fan can reduce the temperatures of your upper level rooms by 10 degrees extend the life of your roof shingles and cut air conditioning expenses by up to 30 percent. Some professionals multiply the square feet value with 0 6 instead of 0 7. Find the overall air volume of your home. Whole house fans work on the principle of removing the hot and humid air out of the house.

It helps to cool your home temperatures and the attic by approximately 30 degrees. Then click on calculate. Enter the length and width of your attic or ceiling crawl space. How to size a whole house attic fan.

The formula above gives an approximate value of the cfm needed for an attic fan. Attic fan size calculator step 1.