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Choosing a Whole House Fan

Whole house fans will keep you and your home cool at a fraction of the cost of air conditioning. We walk you through the pros and cons and help you choose the best option for your home.

Photo courtesy of Tamarack Technologies Inc.

By the DIY experts of The Family Handyman Magazine

Choosing a Whole House Fan

Whole house fans will keep you and your home cool at a fraction of the cost of air conditioning. We walk you through the pros and cons and help you choose the best option for your home.

Photo courtesy of Tamarack Technologies Inc.

The benefits of a whole-house fan

Whole-house fans have helped cool homes for a century. The basic design is simple: An attic-mounted fan pushes hot air out through attic vents and draws cooler, outside air in through open doors and windows. This rapid air exchange—large fans can purge a house of hot air in two to three minutes—not only removes built-up heat but also creates a pleasant breeze.

Fans had been supplanted by air conditioners for the past several decades but are now resurging in popularity. Why? First, they sip electricity while air conditioners guzzle power. Second, the latest generation of fans sport self-sealing insulated shutters that close when the fan’s not operating. (Unless you jury-rig your own cold-weather cap, older units behave just like an open window in the winter.) This auto-insulating feature prevents vast amounts of heat from escaping through the fan when it’s not in use.

Whole-house fan air movement

Illustration courtesy of Paul Perreault, BakedMediaWhole-house fan air movement

How Fans Save on Cooling Expenses

Depending on the severity of your summers, a fan can work as an efficient pre-chiller before you switch on your AC, or even as your sole source of cooling. Using only a tenth as much power as your AC, a fan bringing in cooler night and/or morning air can lower inside temperatures by 5 degrees (or more) in just a few minutes. Homeowners living in dry climates with wide day/night temperature swings may be able to do without their AC system by simply switching the fan on during cool hours and then turning off the fan and shutting the house during the hottest times of the day.

Granted, whole-house fans aren’t perfect. They can’t cool inside temps lower than outside temps, nor can they dehumidify. If you live in a humid region, you’ll still need to lean on your AC in the dog days of summer. And while most folks may prefer fresh outside air, if you suffer from allergies, realize that fans draw in outdoor pollen and dust.

Caution!

When you use a whole-house fan, it's important to open doors and windows. Otherwise the fan may cause gas-burning appliances, such as your furnace or water heater, to backdraft exhaust fumes and carbon monoxide into your home. Whole house fans are not allowed in all areas. You should check your local building codes before buying one.

How to choose a system

A local HVAC installer can help you find the fan that best fits your home and climate. Bear in mind that size isn’t everything. Larger fans are great for moving air quickly, but when you weigh the increased size against installation requirements, insulation, appearance, noise and cost, you may opt for a smaller fan. (Depending on your needs and floor plan, several smaller fans may provide better airflow.)

Attic ventilation is almost as important as the fan. A fan won’t work if the hot air doesn’t have an easy way out; without adequate ventilation the fan may force hot air down on you! Fans require 1 sq. ft. of net free vent area per 750 cfm. If you don’t want to install additional venting, it may make sense to stick with a smaller fan.

These days, there are several different types of fans to choose from (see photos). In addition to the large traditional models, manufacturers have come up with types that are easier to install and better insulated. Go online to explore the options we show and others.

Before you buy, contact your utility company to see if you’re eligible for an energy rebate. You may also be able to reclaim a portion of the cost as an energy tax credit on your income taxes.

Standard fan

Photo courtesy of Air Vent Inc.Standard fan

Insulated-door fan

Photo courtesy of Tamarack Technologies Inc.Insulated-door fan

Inline fan

Photo courtesy of Quiet Cool FanInline fan

Three Types of Whole-House Fans

Standard fan
4,500 to 6,900 cfm
($200 to $450)
Because they’re the most affordable and widely available, large-diameter fans are still a good solution for homeowners living in warmer regions. These fans cost less up front, but installation may be more difficult. Moving a joist in order to frame out a box for the fan, or installing additional attic venting might wind up costing more than the fan itself. Another disadvantage is that during the winter, the vented opening works like an open window, giving warm moist air an easy path out and into your attic. To prevent heat loss, you’ll need to build an insulated box to cover your fan during the off-season.

Insulated-door fan
1,000 to 1,700 cfm
($525 to $769)
If you live in an area with frequent cold snaps, you’ll want a fan that holds in the heat when it’s not in use. Door fans come with insulated (R-22 or R-38) panels that open every time you turn the fans on. This feature not only helps during winter months but also keeps heat out during the summer when you’re running your AC. These models don’t move as much air as standard fans, but they tend to run quieter, so they can be run all night. Like standard fans, these units are usually installed in a hallway, but some smaller models are specially designed to fit in between or around existing trusses or joists to make installation easier.

Inline fan
1,500 cfm (about $235)
Fan/insulated duct units don’t move as much air as standard fans, but by investing in one fan per bedroom, you can provide a breeze effect in the room(s) you most want to cool. The small intake port is not only less obtrusive than the large louvered panels needed with other fans but also easier to install. (A flexible duct connects the intake port to the fan.) Like insulated door fans, inline fans have damper doors within them that prevent warm air from leaking out in winter.

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August 05, 11:44 AM [GMT -5]

How well does a whole house fan work at keeping a house cool if the outside temps are peaking at 106?

August 05, 11:44 AM [GMT -5]

How well does a whole house fan work at keeping a house cool if the outside temps are peaking at 106?

July 30, 11:27 AM [GMT -5]

We have the Inline quiet cool fan and I know of 6 others who are also using this device. The best part about this fan is how quiet it is. The low rumble is hardly noticeable and can actually be soothing. The other fans that are mounted directly on the vent sound like a train coming through the house. Our model has a hinged door that drops down from one side. We can slip an insulated pad into the door and shut it up for the winter. It's make an enormous difference in the cooling environment -as long as it's cooler outside than in. So we leave it running all night, close up the windows and the shades during the day. No AC required. We only suffered slightly when it hit 105 a few times this year. -Denver, CO

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