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A ceiling fan is a mechanical fan mounted on the ceiling of a room or space, usually electrically powered , suspended from the ceiling of a room, that uses hub-mounted rotating blades to circulate air.
They cool people effectively by introducing slow movement into the otherwise still, hot air of a room. Fans do not reduce air temperature, unlike air-conditioning equipment but create a wind chill effect by evaporating sweat in the summer. In fact they heat up the air slightly due to the waste heat from the motor and friction between the moving air.
Fans use significantly less power than air conditioning as cooling air is thermodynamically expensive. Conversely, a ceiling fan can also be used to reduce the stratification of warm air in a room by forcing it down to affect both occupants' sensations and thermostat readings, thereby improving climate control energy efficiency.
Punkah-type ceiling fans date back to BC, and are native to India. Unlike modern rotary fans, these punkah fans move air by moving to and from, and were operated manually by cord. The first rotary ceiling fans appeared in the early s and s 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 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 by Philip Diehl. He had engineered the electric motor used in the first electrically powered Singer sewing machines , and in he adapted that motor for use in a ceiling-mounted fan.
Each fan had its own self-contained motor unit, with no need for belt drive. Almost immediately he faced fierce competition due to the commercial success of the ceiling fan.
He continued to make improvements to his invention and created a light kit fitted to the ceiling fan to combine both functions in one unit. By World War I most ceiling fans were made with four blades instead of the original two, which made fans quieter and allowed them to circulate more air.
By the s, ceiling fans were commonplace in the United States, and had started to take hold internationally. From the Great Depression of the s, until the introduction of electric air conditioning in the s, ceiling fans slowly faded out of vogue in the U. In , Texas entrepreneur H. Crompton Greaves had been manufacturing ceiling fans since through a joint venture formed by Greaves Cotton of India and Crompton Parkinson of England. These Indian manufactured ceiling fans caught on slowly at first, but Markwardt's Encon Industries branded ceiling fans which stood for ENergy CONservation eventually found great success during the energy crisis of the late s and early s, since they consumed less energy than the antiquated shaded pole motors used in most other American made fans.
The fans became energy saving appliances for residential and commercial use by supplementing expensive air conditioning with a cooling wind-chill effect. Fans used for comfort create a wind chill by increasing the heat transfer coefficient , but do not lower temperatures directly. Due to this renewed commercial success using ceiling fans effectively as an energy conservation application, many American manufacturers also started to produce, or significantly increase production of, ceiling fans.
In addition to the imported Encon ceiling fans, the Casablanca Fan Company was founded in Other American manufacturers of the time included the Hunter Fan Co.
Smith Co. Through the s and s, ceiling fans remained popular in the United States. Many small American importers, most of them rather short-lived, started importing ceiling fans. Throughout the s, the balance of sales between American-made ceiling fans and those imported from manufacturers in India , Taiwan , Hong Kong and eventually China changed dramatically with imported fans taking the lion's share of the market by the late s.
Even the most basic U. Since , important inroads have been made by companies such as Monte Carlo, Minka Aire, Quorum, Craftmade, Litex and Fanimation - offering higher price ceiling fans with more decorative value.
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 push air most commonly an electrical switch on the unit's switch housing, motor housing, or lower canopy can help in both heating and cooling.
While ceiling fan manufacturers mainly Emerson have had electrically reversible motors in production since the s, most fans made before the mids are either not reversible at all or mechanically reversible have adjustable blade pitch instead of an electrically reversible motor.
In this case, the blades should be pitched to the right or left if the motor spins clockwise for downdraft, and to the opposite side for updraft. Hunter's "Adaptair" mechanism is perhaps the most well-known example of mechanical reversibility. In very rare cases, fans are both mechanically and electrically reversible, allowing for the fan to push air in either direction, while rotating either clockwise or counter-clockwise. For cooling, the fan's direction of rotation should be set so that air is blown downward Usually counter-clockwise from beneath.
The blades should lead with the upturned edge as they spin. The breeze created by a ceiling fan creates a wind chill effect , speeding 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, it is a waste of electricity to leave a ceiling fan on when no one is in a room unless air conditioning is in operation.
For heating, ceiling fans should usually be set to turn the opposite direction usually clockwise; the blades should spin with the downward turned edge leading. Air naturally stratifies—that is, warmer air rises to the ceiling while cooler air sinks, meaning that colder air settles near the floor where people spend most of their time.
A ceiling fan, with its direction of rotation set so that air is drawn upward, pulls the colder air off the floor, 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. The most commonplace use of ceiling fans today is in conjunction with an air conditioning unit. Without an operating ceiling fan, air conditioning units typically 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.
The way in which a fan is operated depends on its manufacturer, style, and the era in which it was made. Operating methods include:. 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 typical ceiling fan weighs between 8 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 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.
Building codes throughout the United States prohibit residential ceiling fans from being mounted with the blades closer than seven feet from the floor; [ citation needed ] this sometimes proves, however, to not be high enough. If a ceiling fan is turned on and a person fully extends his or her arms into the air, as sometimes happens during normal tasks such as stretching or changing bedsheets, it is possible for the blades to strike their hands, potentially causing injury.
Also, if one is carrying a long and awkward object, one end may inadvertently enter the path of rotation of a ceiling fan's blades, which can cause damage to the fan. Building codes throughout the United States also prohibit industrial ceiling fans from being mounted with the blades closer than 10 feet from the floor for these reasons.
In , MythBusters tested the idea that a ceiling fan is capable of decapitation if an individual was to stick his or her neck into a running fan. Two versions of the myth were tested, with the first being the "jumping kid", involving a kid jumping up and down on a bed, jumping too high and entering the fan from below and the second being the "lover's leap", involving a husband dressed in a costume, leaping towards his wife in bed and entering the fan side-on. First, Kari and Scottie purchased a regular household fan and also an industrial fan, which has metal blades as opposed to wood and a more powerful motor.
They and Tory then fashioned their human analogs - ballistic gel busts of Adam with actual human craniums, pig spines to approximate human spines, and latex arteries filled with fake blood - and then constructed rigs for both scenarios. They busted the myth in both scenarios with both household and industrial fans, as tests proved that residential ceiling fans are, apparently by design, largely incapable of causing more than minor injury, having low-torque motors that stop quickly when blocked and blades composed of light materials that tend to break easily if impacted at speed the household fan test of the "lover's leap" scenario actually broke the fan blades.
They did find that industrial fans, with their steel blades and higher speeds, proved capable of causing injury and laceration - building codes require industrial fans to be mounted with blades 10 feet above the floor, and the industrial fan test of the "lover's leap" scenario produced a lethal injury where the fan sliced through the jugular and into the vertebrae - but still lost energy rapidly once blocked and were unable to decapitate the test dummy.
As a finale, Scottie, Tory and Kari created an even more dangerous fan with a lawn mower engine as the fan motor and razor sharp blades made from sheet metal in an attempt to duplicate the result, and even it was unable to achieve decapitation, but it caused lethal and horrifying injuries that compelled Adam to put it into the " MythBusters Hall of Fame.
Wobbling is usually caused by the weight of fan blades being out of balance 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, or weight variation between blades.
Also, if all the blades do not exert an equal force on the air because they have different angles, for instance , the vertical reaction forces can cause wobbling. Wobble can also be caused by a motor flaw, but that very rarely occurs.
Wobbling is not affected by the way in which the fan is mounted or the mounting surface. Contrary to popular misconception, wobbling alone will not cause a ceiling fan to fall. 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.
When the MythBusters were designing a fan with the goal of chopping off someone's head, Scottie used an edge finder to find the exact center of their blades with the aim of eliminating potentially very dangerous wobbling of their steel blades. Wobbling may be reduced by measuring the tip of each blade from a fixed point on the ceiling or floor and ensuring each is equal.
If the fan has a metal plate between the motor and blade, this may be gently adjusted by bending. From Wikipedia, the free encyclopedia. This article has multiple issues. Please help improve it or discuss these issues on the talk page. Learn how and when to remove these template messages.
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Unsourced material may be challenged and removed. This section does not cite any sources. Please help improve this section by adding citations to reliable sources. The Fan Book.
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