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Why is Ventilation Good?
Why Use Attic Fans?
How Attic Fans Work
Caring for an Attic Fan
How Exhaust Fans Work
Caring for Exhaust Fans


Why Is Ventilation Good?

Proper ventilation in your home can replace warm air with cool, remove odors and excess moisture and reduce the level of heat and humidity in the attic, basement and crawl space. There are two types of ventilation:

  • Passive ventilators are simply openings in the walls and roof that allow heat to escape.
  • Mechanical ventilators include whole-house fans, fans, attic fans and exhaust fans. These can remove hot, moist or stale air and replace it with fresh air from the outside or from another part of the house.

Attic Fans

Why Use Attic Fans?

Though most attics have openings for ventilation, these usually are not enough to prevent the attic temperature from reaching 140°F or higher on a hot day. This heat seeps into the living areas below, causing discomfort for the occupants or increasing the load on the air conditioner. With an attic fan (also called a roof fan) you can substantially reduce the temperature of the attic air.

How Attic Fans Work

  • An attic fan should be mounted as high as possible in a gable or roof surface.
  • An attic fan exhausts hot attic air and pulls in cooler outside air.
  • Smaller than a whole-house fan, an attic fan also moves much less air. The fan blade is mounted directly on the motor shaft.
  • A thermostat in the fan housing or nearby in the attic turns the fan on at a preset temperature and turns it off when the attic temperature returns to normal.
  • An attic fan can reduce the attic temperature 20 percent or more and room temperatures as much as 10°F.

An attic fan can be equipped with a humidity control and used during the winter months to remove excess moisture from the attic, reducing the possibility that damaging ice dams will form on the roof.

Caring for an Attic Fan

  • Work on the fan from the attic or remove the protective cover and work on it from the roof.
  • Clean and perform maintenance at the beginning of each cooling season.
  • Clean the housing and fan blades.
  • Clean the screens on the fan and on the attic vents.
  • Tighten all screws and bolts, especially the setscrew securing the blade assembly to the motor shaft.
  • Lubricate the motor bearings (unless they're sealed) by pouring oil in the oil cups.

Exhaust Fans

Exhaust fans remove moisture, heat, and odors from kitchens, bathrooms, basements, and laundry rooms. They also help remove grease particles from kitchens. Exhaust fans are installed in a wall or ceiling, except for the fan in a range hood.

How Exhaust Fans Work

  • A wall-mounted fan exhausts to the outside.
  • A ceiling-mounted fan exhausts into the attic or through a duct to the outside.
  • A fan in a range hood may exhaust through a duct or recirculate the air through a charcoal filter without removing heat or moisture.

Caring for Exhaust Fans

  • Once a year: Replace the pellets in a recirculating fan's charcoal filter.
  • Once or twice a year: Clean the grill and fan blades.
  • Every 2 months: Wash the grease filter in a range hood fan
  • Every 6 months: Wash the fan blades and housing.
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