What does attic fan do?

Attic fans are designed to cool warm attics by drawing cooler outside air from attic vents (ceiling and gable) and pushing warm air to the outside. An attic fan is a device installed above your living space but under the roof that draws air from the space.

What does attic fan do?

Attic fans are designed to cool warm attics by drawing cooler outside air from attic vents (ceiling and gable) and pushing warm air to the outside. An attic fan is a device installed above your living space but under the roof that draws air from the space. It draws warm, humid air from the attic and creates a slight vacuum effect that brings fresh, fresh air from the basement and lower floors through the house. An attic fan blows out stale air from the inside and brings in fresh air from the outside.

It may not seem like much, but simply circulating attic air can greatly affect home temperature and energy consumption. Attic fans are fans that draw warm air from the attic to the outside; these fans are installed on the roof or gable of a home. Attic fans (also called whole-house fans) are specifically designed to cool your home using outside air. The fan is connected to the attic floor, usually above a main hallway or living space.

When you turn on the fan and open the windows of the house, the outside air enters through the windows and goes up the attic, where the warm indoor air leaves the house. Attic fans are designed to prevent “normal rain,” but during hurricanes, the force of wind can push water across the sheet roof. During the cold winter months, attic fans exchange and move air the same way, but with a different purpose. Choosing a more energy efficient air conditioner is one solution, but for many homes, an even better solution is an attic exhaust fan.

An easy way to find out if your home has negative air pressure is to partially open a window when the attic exhaust fan is working. If you have appliances that use natural gas or propane, an electric attic fan can cause exposure to carbon monoxide. Studies have been conducted that argue that attic fans do not reduce the energy use of a home's HVAC system. Instead of letting the heat settle and re-enter your home, attic fans “move warm, humid air out of your home and release it to cooler temperatures during the night,” says Zac Houghton, CEO of Loftera.

If you have appliances that burn natural gas (or propane), such as water heaters or ovens, installing an electric attic fan can cause carbon monoxide poisoning. One of the most common reasons for a bad experience with attic fans is poor installations that result in leaks and roof damage. No matter where you live, you can take advantage of the benefits of an attic fan to help make your home more comfortable. However, as a child, I was happily unaware of the potential problems that could arise from running an attic fan.

There are a few styles of attic fans, and they have slightly different characteristics, but they all fulfill the same task by promoting air flow in the attic. In general, the energy needed to run the fan negates any electrical savings from better attic ventilation. Locate the thermostat (small metal box) normally mounted on a beam or truss next to the fan in the attic.

Brad Heidmann
Brad Heidmann

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