How Many Attic Fans Should I Have

This is done because you need one square foot of ventilation area for every 750 cfm that your fan can push.

How many attic fans should i have.

There are many benefits of attic fans. The temperature in attics without attic fans can climb to as high as 150 degrees f. The result is a cooler attic space with plenty of air exchange. Attic fans perform this ventilation by pushing hot air out into the environment while also pulling fresh cool air into the attic.

Multiplying the total square footage of the attic by 0 7 will provide the rate required. These include the following. So if your fan is rated at 1500 cfm you will need about two feet of totally open space in your attic. You place the fans on the gable walls of your attic.

Any whole house fan that you buy should have this figure listed somewhere on the packaging. Like so many other plug in solutions attic fans certainly have the potential to make things worse rather than better. The air being exhausted must be replaced by outside air drawn through vents under the eaves in the soffit. If the home already has a fan roof vents or gable vents these should be blocked and sealed from the attic side of the home.

Powered attic ventilators should provide at least 10 air changes per hour. Your article does a great job of outlining how this happens. Now take that number and divide it by 750. With an attic fan many attics have a temperature that is the same as the outside air or just a few degrees warmer.

Attic x 0 7 700 cfm minimum fan rating add an additional 20 cfm x 1 20 if you have a steep roof and 15 cfm x 1 15 for a dark roof. Attic ventilation fans whether hard wired or powered by their own solar panels seem like a low cost and effective way to help keep your house cool. The downside of attic ventilation fans. 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.

As a general rule unless a homeowner has a highly qualified person to evaluate their house i think its safe to say that attic fans should be avoided. For particularly dark or steep roofs we recommend a slightly higher rating. When the attic becomes part of the home to be heated and cooled open wall gable vents and. Attic fans reduce heat dramatically.

Hvi recommends a ratio of 60 to 40 for soffit ventilation to gable or ridge ventilation. Also the devices have benefits like protecting your roof from damage which might be brought about by the heat and humid moving around the attic thus damaging the insulations and.