Recommended Temperature Setting for an Attic Fan

About Attic Fans

• Unventilated attic areas can reach temperatures up to 150 degrees Fahrenheit, according to writer Merle Henkenius at the PopularMechanics website. This heat buildup can shorten the life of roofing materials and lead to higher energy costs. During winter, attic fans ventilate roof areas to keep air moving to prevent ice dam formation on roofs. Though roof areas generally have basic venting equipment, these vents may not provide adequate ventilation for your climate and location. Attic fans that are thermostatically-controlled turn on when a pre-defined temperature is reached to provide additional air flow to the attic. Some fans are also equipped with humidistats that turn on when humidity reaches a particular range.

Types of Attic Fans

• Two basic types of fans are available for powered attic ventilation, electric-powered and solar-powered. Electric fans require wiring to the home electrical system. Solar-powered fans do not require special installation, although the initial cost of solar fans is generally higher. Additional features are available for attic fans at additional cost.

Calculating Attic Fan Size

• To provide adequate ventilation, attic fans should provide 10 attic air volume changes per hour. To calculate your attic's air volume, measure the cubic area of your attic by multiplying the length times the width times the height of the attic area. Then, multiply this number by 10 to determine the required air change per hour. Attic fans are sized by cubic feet per minute, so you must multiply the size of your fan in cubic feet per minute, which is indicated in your attic fan specifications, by 60 to determine whether it satisfies the 10 attic air volume changes requirement.

Recommended Temperature Fan Settings

• A thermostatically controlled fan should be set so that it turns on when the attic temperature reaches 80 degrees Fahrenheit and turns off when the temperature drops below 65 degrees Fahrenheit. This temperature range will prevent condensation buildup and will prevent overworking your air-conditioning system.