The main purpose of the fan is to circulate air in such a way that it provides a comfortable environment to the occupants of a given room or area. Based on this definition, a fan can be considered to be anything from the movement of leaf to the motorized movement of a blade. The different types of commonly known fans include industrial fans, ceiling fans, oscillating fans, and even personal cooling fans. The history of the fan dates back to Egyptian times when large leaves were used by slaves to cool royalty during the hot summer months. During the industrial revolution companies began using wind powered fans to keep their workers and machinery cool. The more common electric powered fan was invented by Philip Diehl in 1882. Throughout time Diehl’s simple belt driven fan has advanced into complex air circulation devices found in today’s commercial and residential settings.
A fan can be thought of as a series of systems working together to perform a specific task: circulating air. A typical fan is a series of blades placed in a manner that when rotated provides an output of air. The blades of the fan are typically driven by an electric motor that can be mounted in a fixed position (ceiling, wall, etc.) or portable (simple oscillating, box fan, etc.). The combination of the electrical system, drive system, and blade system provide the desired output of air circulation.
Depending on the application, a variety of fans could be employed. Ceiling fans are typically used to move air up or down depending on the given climate of a room. The user has the option to choose the direction and speed in which the blades rotate and in turn control which direction the air is forced.
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WINTER COMFORT |
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Smaller box and oscillating fans can be used to force out hot air outside during the day and pull in cool air at night. Unlike ceiling fans, these portable fans do not require “hard-wiring” and can simply be plugged into a wall socket. Smaller “personal fans” can typically be run using batteries and are used to cool a much smaller area than the aforementioned fans.
Fans are used for both commercial and residential applications and are designed for the area in which they will be used. Most commercial applications use the fans to cool machinery and personnel so they are typically run longer and harder than those used for residential applications.
The fan only helps to circulate air and in no way changes the actual temperature of the air. The air only feels cooler because of the velocity at which the air is moved across your body (wind chill). A fan can not directly control air quality, humidity, pressure, or actual temperature. As with any motorized device the motor will only last a given number of years. The lifetime of a fan is stated by the manufacturer and can range from five to fifty years; this average lifespan is generally reflected in the price.
Another important factor to consider with these fans is how they will be powered. The availability of electricity plays a major factor in the locations in which fans can be used. The number of speeds at which the motor can operate also determine how much air can be circulated in a given amount of time.
Fans typically have a metal housing which is composed of a simple electrical motor and the associated wiring. The blades used on the fan can be made from a variety of materials including wood, steel, plastic, and even composite. In some cases a filter can be directly attached to the fan to help minimize the entrance of particulates into a given area. Depending on the use of the fan (commercial or residential) different size blades and motors can be used.
An important factor to consider with these fans is how they will be powered. The availability of electricity plays a major factor in the locations in which fans can be placed. When ceiling fans are installed the support system above must be strong enough to properly support the weight of the moving fan. Fans are fairly self contained and are simple to construct or obtain.
Portable fans come in a variety of shapes and sizes and are powered using a common 110v receptacle. Ceiling fans are typically run off of a dedicated 110 volt electrical feed. Ceiling fans are generally placed in the center of the room or the area in the room that has the tallest ceiling height. These fans are mounted to the ceiling joists or rafters using an outlet box with supports that tie into the rafters. Ceiling fans can be hung at various heights depending on the given height of the room. The following chart shows how the size of the room determines the blade size that will properly circulate the air.
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29” Fan |
Bathroom, hallways |
Up to 50 Sq. Feet |
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36” Fan |
Breakfast nooks, laundry rooms |
Up to 75 Sq. Feet |
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42” Fan |
Small bedrooms, small kitchens |
Up to 100 Sq. Feet |
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50” or 52” Fan |
Standard bedrooms, family rooms |
Up to 400 Sq. Feet |
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54” Fan |
Great rooms, large areas |
Over 400 Sq. Feet |
Source: (http://www.emersonfans.com/frame_choosing.html)
Blade size is also based on the amount of air that the user wishes to move. Fans typically come with various speed settings that affect the number of rotations of the fan in a given amount of time. Most consumers are told to look for an EER (Energy Efficiency Rating) when purchasing air conditioning devices. This scale is not used when rating fans; instead the fan is categorized based on its output in cubic feet per minute. The following chart shows the differences in operating costs of a fan compared to air conditioning units.
Source: http://www.emersonfans.com/frame_energy.html
Obviously the air conditioning units play a greater role in the actual conditioning of the air in a room but the fan is an excellent economical option for circulating air.
The fan is typically considered to be a subsystem of the larger HVAC system. The fan most commonly used to circulate cool or hot air that is produced by the HVAC system throughout a given area.
