Are whole-house fans a good option in humid climates?

[Tony]

I bought a home with a fan that was disconnected when A/C was installed.

Would it be worthwhile to reconnect and use it during the humid summers where I live?

[home improvement guy]

A whole-house fan can be a great way to ventilate your home, but on really hot and humid days it can't compete with your air conditioner, which cools and dehumidifies air.

AC experts say it's best to operate whole-house fans when temperatures are below 80 degrees and the humidity level is less than 75 percent.

Since your home already has a fan, you may want to hire a licensed electrician to reconnect it so you can use it during certain times of the year. But you'll probably prefer to run your air conditioning system when the humidity level and temperature rise.

Whole-house fans were popular in the 1950s, before central air conditioning was common. To operate the fans, you must open windows, as the fans pull in fresh air from outside and push out hot, stale air through the attic. Generally, homeowners turn fans on at night, when outside temperatures drop, and close windows and turn fans off during the day.

Whole-house fans use 80 percent less energy than traditional air conditioning units. In climates, where summers can be hot and humid, some people use them in spring and fall to save on cooling costs. In other climates, a whole-house fan may handle all or most home-cooling needs.

A new fan, which should be quieter than older models, will cost $250 to $1,500, depending on how much air it must move. Installation costs range from $700 to $1,000.

A handy homeowner may be able to install a whole-house fan, as could a handyman service or HVAC company. But experts recommend hiring a licensed electrician to handle wiring. Fan installation requires the installer to cut a ceiling hole in a central location. The fan attaches to ceiling joists from the attic, and the installer should seal seams and holes around the fan and joists. An electrician needs to pull power to the fan and, most often, wire in a wall switch, though some fans come with remote controls or Wi-Fi-enabled controls.

When off, basic or older whole-house fans may let air seep in from the attic. Purchased or handmade covers are a good idea. Many newer models feature insulated doors that automatically close when the fan is switched off.