Limit the use of expensive air conditioning to those dog days of summer and consider installing an attic fan to cool down the house when it’s not so hot. An attic or whole-house fan are designed to work best in the evening when temperatures are at their coolest. Open windows and turn on the fan so that it draws in cool, fresh air and forces it out through attic vents and by morning you’ll be reaching for a blanket. An electrician charges $577 to install a direct-drive attic fan that cools a typical 1,500-square-foot house. This includes the labor and material. A homeowner with electrical and carpentry skills can buy one for $200 and install it, cutting the cost by 65 percent. The project involves some major work: cutting an opening in the ceiling, installing the unit in the opening, hooking up the wires and then adding the louvered cover panel. Timewise, a homeowner can do the job in a long day of work compared with an electrician who can make the installation in half the time.
Follow the fan manufacturer’s directions about wiring the unit into your home’s electrical system and to any switches or controls you choose. For the easiest installation, choose a direct-drive unit that’s designed to fit over the attic floor joists so that you don’t have to cut into them. You’ll find these units sold at home centers and lumberyards. At http://www.airvent.com in the Resources section you’ll find advice and an attic ventilation calculator.
The Home Ventilating Institute suggests how to find the right size for a whole house fan. Walk around the exterior of the house and measure its length times its width to get the total square footage of the house. Let’s say it’s 35 x 40 feet, which equals 1400 square feet. To find the size of whole house fan, multiply the square footage times three. 1400 x 3 = 4200 CFM (cubic feet per minute.) That means, buy a fan whole house fan with a 4200 CFM to effectively cool the house.
To find more DIY and contractor project costs, videos and calculators, visit www.diyornot.com on a laptop, tablet or smartphone.