Ceiling fan

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A ceiling fan is a device suspended from the ceiling of a room, which employs hub-mounted rotating paddles to circulate air.

Casablanca Fan Co. ceiling fan from the early 1980s.

Contents

[edit] History

Collage of three photos of an extraordinarily rare Panasonic-brand ceiling fan from the early 1980s; model unknown, believed to be F5210WH. Example of an early high-quality imported ceiling fan.

The first ceiling fans appeared in the early 1860s and 1870s, in the United States. At that time, they were not powered by any form of electric motor. Instead, a stream of running water was used, in conjunction with a turbine, to drive a system of belts which would turn the blades of two-blade fan units. These systems could accommodate several fan units, and so became popular in stores, restaurants, and offices. Some of these systems still survive today, and can be seen in parts of the southern United States where they originally proved useful.

The electrically-powered ceiling fan was invented in 1882 by Philip Diehl (pronounced the same as "deal"). Diehl had engineered the electric motor used in the first Singer sewing machines, and in 1882 adapted that motor for use in a ceiling-mounted fan. "The Diehl Electric Fan", as it was known, operated like a common modern-day ceiling fan; each fan had its own self-contained motor unit, eliminating the need for costly and bulky belt systems.[1]

Diehl was almost immediately up against fierce competition due to the commercial success of the ceiling fan. However, he continued to make improvements to his invention. One such improvement, the "Diehl Electrolier", was a light kit adapted onto the ceiling fan to compensate for any light fixture(s) displaced by the installation of the ceiling fan, and/or to add extra overhead lighting to the room.

By World War I, most ceiling fans were being manufactured with four blades instead of the original two. Besides making fans quieter, this change allowed them to circulate more air, thereby making more efficient use of their motors.

By the 1920s, ceiling fans had become commonplace in the United States, and had started to take hold internationally; however, during the Great Depression, ceiling fans faded out of vogue in the U.S.[1] By the end of World War II, ceiling fans had become almost non-existent, and remained that way into the 1950s. Those which remained were considered items of nostalgia. However, the ceiling fan was still very popular in other countries, notably those with warm climates which could not afford high-energy-consuming devices, namely air conditioning.

In the 1960s, some East Asian manufacturers started exporting their ceiling fans to the United States. They caught on slowly at first, but found great success during the energy crisis of the late 1970s, since ceiling fans consume far less energy than air conditioning units.

Due to this renewed commercial success, many American manufacturers started to produce (or significantly increase production of) ceiling fans, resulting in a revival of interest in the product. The well-known Casablanca Fan Company was founded in 1974. Other popular American manufacturers at the time included the Hunter Fan Co. (which was then a division of Robbins & Myers, Inc), FASCO (F. A. Smith Co.), Emerson Electric, and Lasko; the latter two were often relabeled and sold by Sears-Roebuck.

During the rest of the 1970s, and through to the late 1980s, ceiling fans remained popular in the American market. Many small American manufacturers, most of them rather short-lived, started making ceiling fans. Throughout the 1980s, the balance of sales between American-made ceiling fans and those imported from Asian manufacturers changed dramatically. The high cost of American parts and labor became prohibitive for many consumers (for example, a basic American-made ceiling fan could cost anywhere from $100 to $250, whereas the cost of the fanciest imported fans rarely exceeded $85).

Due to the ever-reducing cost of amenities such as air conditioning, ceiling fan sales once again started to decline, beginning in the early- to mid-1990s. With the reduction in sales came a reduction in research and development, as well as features. Once-standard features (such as solid wood blades, built-in variable-speed dials, high-quality stator/rotor ("stack") motors, and die-cast steel construction) have been largely replaced by cheap, standardized parts.

Since 2000 there have been important inroads made by companies offering higher price ceiling fans with more decorative value. In 2001, Washington Post writer Patricia Dane Rogers [2] wrote, “Like so many other mundane household objects, these old standbys are going high-style and high-tech.” Newer companies such as Minka, Fanimation, The Modern Fan Co., The Period Arts Fan Co. and Monte Carlo brought well-built fans with distinctive design to the market.

[edit] Uses

Unlike air conditioners, fans only move air—they do not directly change its temperature. Therefore ceiling fans that have a mechanism for reversing the direction in which the blades rotate (most commonly an electrical switch on the side of the unit) can help in both heating and cooling.

In summer, the fan's direction of rotation should be set so that air is blown downward (Usually counter-clockwise. The blades should lead with the up turned side as they spin). The breeze created by a ceiling fan speeds the evaporation of perspiration on human skin, which makes the body's natural cooling mechanism much more efficient. Since the fan works directly on the body, rather than by changing the temperature of the air, during the summer it is a waste of electricity to leave a ceiling fan on when no one is in a room.

In winter, ceiling fans should be set to turn the opposite direction (usually clockwise; the blades should spin with the downward turned side leading) and on a low speed. Air naturally stratifies — that is, warmer air rises to the ceiling while cooler air sinks. Unfortunately, this means it is colder on or near the floor where human beings spend most of their time. A ceiling fan, with its direction of rotation set so that air is drawn upward, pulls up the colder air below, forcing the warmer air nearer the ceiling to move down to take its place, without blowing a stream of air directly at the occupants of the room. This action works to even out the temperature in the room, making it cooler nearer the ceiling, but warmer nearer the floor. Thus the thermostat in the area can be set a few degrees lower to save energy, while maintaining the same level of comfort. It is important to run the fan at a low speed to minimize the wind chill effect described above.

An additional use of ceiling fans is coupling them with an air conditioning units. Through-the-wall/through-the-window air conditioning units typically found in rented properties in North America usually have both the tasks of cooling the air inside the room and circulating it. Provided the ceiling fan is properly sized for the room in which it is operating, its efficiency of moving air far exceeds that of an air conditioning unit, therefore, for peak efficiency, the air conditioner should be set to a low fan setting and the ceiling fan should be used to circulate the air.

[edit] Exception

There is an exception to the standard rule of blowing air down in the summer and pulling it up in the winter. When a ceiling fan is mounted in a room with very high ceilings (two stories/levels high or higher),or at the head of a tall set of stairs, the mode of operation is reversed. In this scenario the fan is mounted so high up that there is no significant "wind chill effect". The purpose then becomes to move hot air down in the winter and pull cold air up in the summer. [3]

[edit] Parts of a ceiling fan

The key components of a ceiling fan are the following:

Other components, which vary by model and style, can include:

[edit] Configurations

[edit] Operating a ceiling fan

A Hunter-Branded basic modern ceiling fan with standard pull-chain controls for the fan and light kit.

The way in which a fan is operated depends on its manufacturer, style, and the era in which it was made. Operating methods include:

Old-style and new-style chokes.
Three fans driven by a single motor and belts.

[edit] Types of ceiling fans

Many styles of ceiling fans have been developed over the years in response to several different factors such as growing energy-consumption consciousness and changes in decorating styles. The advent and evolution of electronic technology has also played a major role in ceiling fan development. Following is a list of major ceiling fan styles and their defining characteristics:

A cast-iron ceiling fan made by Hunter, dating from the early 1980s. This model is called the "Original".
The Emerson "Heat Fan", one of the first fans to use a stack motor.
A close-up of the dropped flywheel on a FASCO ceiling fan.

One disadvantage of this type of fan is that the flywheel, if it is made from rubber, will dry out and crack over time and eventually break; this is usually not dangerous, but it renders the fan inoperable until the flywheel is replaced.

A spinner fan (direct-drive motor with no stationary motor housing).

[edit] Innovations

In 2007, Hunter Fan Company came out with an auto-balancing ceiling fan. The technology uses a flexible disc that ensures fan blades operate smoothly and evenly with each rotation - even when weighted, tweaked or otherwise warped. The technology is beneficial to builders that have to deal with call-backs when ceiling fans are not properly installed.

In 2008, Germany based company Oliver Kessler Design released their THE SOLITAIRE punkah fan which uses a computer controlled brushless motor to mimic the slow pendular movement of a manually operated punkah fan. It features counterweights to balance the blade which can be as large as 1,5 m2 and does run very energy efficient with as little as 10 W power consumption. THE SOLITAIRE punkah also features a safety stop that cuts off the motor if anything blocks the blade. In 2009 they released the SynchTool; it can wirelessly synchronize the movements of up to 999 of their punkah fans.

In 2009, Hunter Fan Company released the first-ever ceiling fan and wireless speaker combo. The product received a lot of attention including positive review from Gizmodo and a feature on Today Show. The fan uses a small transmitter to send a signal from a sound source (an MP3, receiver, etc.) to the fan, which then "showers" down sound over the room. The product is called Concert Breeze.

[edit] Safety concerns with installation

A typical ceiling fan weighs between 15 and 50 pounds when fully assembled. While many junction boxes can support that weight while the fan is hanging still, a fan in operation exerts many additional stresses — notably torsion — on the object from which it is hung; this can cause an improper junction box to fail. For this reason, in the United States the National Electric Code (document NFPA 70, Article 314) states that ceiling fans must be supported by an electrical junction box listed for that use. It is a common mistake for homeowners to replace a light fixture with a ceiling fan without upgrading to a proper junction box.

Another concern with installing a ceiling fan relates to the height of the blades relative to the floor. American law states that no fan can be mounted with its blades closer than seven feet from the floor; this often proves, however, to not be high enough. If a person fully extends his or her arms into the air — as sometimes happens during normal tasks such as stretching, changing bedsheets, or recreation — they may become seriously injured if there is an operating ceiling fan mounted too close, Ceiling fans can not cut off a human head. Also, if one is wearing a tall hat, carrying a ladder, long wooden board, pipe, or some other long and awkward object, one end may inadvertently enter the path of rotation of a ceiling fan's blades; this can be very dangerous if the fan is operating at the time, and can cause damage to the fan regardless.

The risk of damage/injury is lower when the fan is pushing air downward, because in that case any object that hits the blades will be deflected downwards by the face of the blade (just like the air).

[edit] Wobbling

Wobbling is not at all created or influenced by the ceiling on which the fan is mounted, or the way in which the fan is mounted, or anything else along those lines. Rather, the one and only cause of wobbling is fan blades being out of weight-alignment with each other. This can happen due to a variety of factors, including: blades being warped, blade irons being bent, blades or blade irons not being screwed on straight, blades being different weights or shapes or sizes (minute differences matter), etc.

Contrary to popular misconception, wobbling will not cause a ceiling fan to fall.[citation needed] Ceiling fans are secured by clevis pins locked with cotter pins, so wobbling won't have an effect on the fan's security. To date, there are no reports of a fan wobbling itself off the ceiling and falling. However, a severe wobble can cause light fixture shades or covers to gradually loosen over time and potentially fall, posing a risk of injury to anyone under the fan, and also from any resulting broken glass. It is important that, when installing the fan, the installer closely follows the manufacturer's instructions with regard to using proper mounting screws. It is also important that all screws (especially the set screws which hold twist-on downrods in place) be tight, and any ceiling fan light fixtures are properly assembled with their shades and covers securely attached.

[edit] Starting arrangement in fan motor

Fans use a capacitor start motor owing to the high torque required to start the fan after which the torque required lowers. It has single-phase induction motor which needs starting torque. For that purpose, capacitor is used to make phase shift b/w running and starting winding.

[edit] References

  1. ^ a b c Scharff, Robert; Casablanca Fan Co.. The Fan Book. Reston, VA 22090: Reston Publishing Co, Inc.. pp. 128. ISBN 0-8359-1855-6. 
  2. ^ Dane Roger, Patricia. "Eye on Design, Washington Post June 14, 2001". pp. H5. 
  3. ^ Holladay, April. "Ceiling fan direction". WonderQuest. http://www.wonderquest.com/Fans.htm. Retrieved 2009-06-1*. 

[edit] External links

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