How Many Attic Fans Should I Have

The downside of attic ventilation fans.

How many attic fans should i have. 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. There are many benefits of attic fans. The air being exhausted must be replaced by outside air drawn through vents under the eaves in the soffit. Multiplying the total square footage of the attic by 0 7 will provide the rate required.

Attic fans perform this ventilation by pushing hot air out into the environment while also pulling fresh cool air into the attic. The temperature in attics without attic fans can climb to as high as 150 degrees f. 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. Powered attic ventilator fans designed to cool your attic by drawing the hot and humid air out of the attic and bring in a flow of chilly air from outside.

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. Dwight barnett is a certified master inspector with the american. This is done because you need one square foot of ventilation area for every 750 cfm that your fan can push. 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.

Your article does a great job of outlining how this happens. You place the fans on the gable walls of your attic. Attic fans reduce heat dramatically. The result is a cooler attic space with plenty of air exchange.

Any whole house fan that you buy should have this figure listed somewhere on the packaging. For particularly dark or steep roofs we recommend a slightly higher rating. With square foot living space at a premium many homeowners turn to their attics for a little extra room. Powered attic ventilators should provide at least 10 air changes per hour.

These include the following. Hvi recommends a ratio of 60 to 40 for soffit ventilation to gable or ridge ventilation. 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. Like so many other plug in solutions attic fans certainly have the potential to make things worse rather than better.

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.