Ceiling fan
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A ceiling fan is a fan suspended from the ceiling of a room. It usually has a light associated with it to replace any displaced light or to provide additional light. These devices are used in two ways: To create a breeze for an apparent cooling effect ("wind chill"), or reversed to force warm air near the ceiling downward to the occupied part of the room. Ceiling fans can reduce heating costs by reducing the load on heating equipment, and they can reduce cooling costs by making warmer air comfortable.
History
The ceiling fan was invented in 1886 by father-and-son team John and James Hunter. This device was powered by water, as electric power was still scarce. Several years later, the Emerson Electric Company introduced the world's first alternating-current fan motor, which opened the doors to a major improvement upon Hunter's design. In 1903, the Hunter Fan and Motor Company began producing its "Original" line of ceiling fans, which quickly became a mainstay in the industry and underwent very few changes in design until 100 years later.
Parts of a Ceiling Fan
A standard ceiling fan has several key components:- An electric motor, usually encased by a decorative housing
- Two to six blades - usually made of wood, MDF, metal, or plastic
- A mounting system, such as a downrod or a flush mount (hugger) motor housing
- A series of controls.
Operating a Ceiling Fan
Standard ceiling fan controls usually include one for speed (high, medium, low, and off), one for the light (on and off), and one for directional control of the fan blades (clockwise and counterclockwise). These vary depending on the make, model, and age of the fan; computerized and remote-controlled ceiling fans are becoming very popular as the technology becomes regularly available.
Ceiling fans are normally used as a cooling device in warm months by pushing air down from above, thereby creating a wind chill effect. In winter months, a ceiling fan can act as a heat transferrer by reversing the direction of the blades. By doing so, the fan pulls air up, thereby pushing the warmer air that stratifies near the ceiling down along the walls; as long as the fan is set at a low speed, this will not create a wind chill. A fan on reverse has the leading edge of the fan blades being the downward edge; in most cases this rotation is clockwise when the operator is standing below and looking upwards at the fan.
Types of Ceiling Fans
Two major types of ceiling fans are common today, industrial and household.Industrial Fans
Industrial-style ceiling fans typically have three metal blades, and they have higher maximum rotational speeds than typical household ceiling fans (usually 250 to 300 RPM). Because industrial fans operate at the higher speed, and the metal blades on industrial fans are sharper than those on a household fan, industrial fans must be mounted at a greater distance from the floor than household fans. Most industrial fans range roughly from 48 to 60 inches in diameter, with a few 36-inch models available. Rather than having a controls on the fan housings, industrial fans are commonly controlled by wall-mounted speed controls; these normally have four or five speeds, but solid-state continuously-variable controls also exist. Industrial fans are commonly not reversible.Household Fans
Household ceiling fans typically have four or five wooden blades. They range in style from plain to very ornate. Standard sizes of household fans are generally 36, 42, and 52 inches in diameter; however, household fans in the United States are being manufactured as small as 29" and as large as 72". Specialty fans can even reach beyond this; for example, a Casablanca Malibu Star has an 84-inch blade span. A well-designed 52-inch ceiling fan with a blade pitch from 12 to 15 degrees will usually operate at a speed between 180 and 220 RPM on high (full speed). An exceptionally made household ceiling fan, such as the pre-2003 Hunter Original, will circulate over 10,000 cubic feet of air per minute.Normally, these fans have a switch housing suspended directly below the center of the motor; this module holds a three-speed pull chain, a switch to reverse the fan, and a center socket to which a light kit can be attached. However, many older fans do not have a reverse switch (or it is located elsewhere on the fan), and some fans feature different items as part of the switch housing:
- An on-off pull chain that operates independently of the speed control;
- A control allowing for a continuous range of speeds (known as a variable speed control);
- A light kit integrated with the switch housing itself;
- A sensor for a remote control.
Styles of Ceiling Fans
Many different styles of ceiling fans have developed over their 120-year history, as design, technology, and discoveries in energy-saving methods have evolved. Both industrial and household fans have undergone changes over the years. Many household fans are used in industrial settings, and some fans have characteristics of both a household and an industrial fan. Below is a list of ceiling fan styles and their characteristics:
- Cast iron ceiling fans: A heavy-duty motor is encased in a cast-iron housing, and must be oiled regularly, usually once per month. Because these fans are well-built, it is not uncommon to see 80-year-old cast-iron fans running and in use today. Almost all ceiling fans manufactured in the late 1800s and the first half of the 1900s were cast iron fans; the most popular of these were manufactured by Emerson Electric Company, Hunter Fan and Motor Company, Century, Dayton, Diehl, and Westinghouse. Emerson and Hunter still manufacture ceiling fans to this day (though not with cast iron motors); a less expensive line of household fans has been marketed under the Westinghouse brand name starting in the early 2000s. The most common example is the Hunter Original, which up until 2003 underwent very few changes in its design.
- Flywheel-type ceiling fans: In the late 1970's during the energy crisis, Emerson invented an electric motor specifically for ceiling fans that was significant in making the device readily available for households. The common version of this stack motor, which is referred to in the industry as the K55, has powered many ceiling fans from its inception to the present. Other companies, such as General Electric, Fasco, and Casablanca, invented similar motors. The windings are encased inside the motor, and turn a flywheel outside the motor casing to which the blades are attached. Many of the most powerful fans manufactured today, such as those by Emerson and Casablanca, incorporate the flywheel-type motor in their design.
- One of the earliest flywheel-type fans was Emerson's Universal, a crude but very powerful fan with large fiberglass or plastic blades. This fan was produced between 1976 and 1983, and was used in both industrial and residential settings. Some more recent and well-known fans that use a stack motor with a flywheel are the Casablanca Zephyr, Delta, and Victorian, the NuTone Verandah, and the Emerson Premium and 1895 Series.
- One disadvantage in this kind of fan is that if the flywheel is made of rubber, it could lose the strength necessary to support the blades, eventually breaking and rendering the fan useless until the flywheel is replaced.
- Direct drive ceiling fans: On these fans, the motor is located inside a metal shell, which it turns. The shell, to which the blades are attached, is enclosed in a standard fan motor housing. This type of motor has become the standard for today's ceiling fans, and is usually produced in foreign countries. Standard sizes of modern direct drive motors are:
- * 153mm diameter, used in fans up to 42" and in inexpensive or builder-model 52" fans
- * 172mm diameter, used in 52" fans of more moderate quality
- * 188mm diameter, used in 52" to 60" fans of higher quality
- * Recently, direct drive motors over 200mm have been produced, and only appear on a select few models.
- * Other examples of direct drive motors are the Hunter AirMax and Casablanca XTR200 motors.
- Examples of this type fan are most modern Hunters, less expensive Emerson and Casablanca fans (such as the Emerson Northwind and the Casablanca Four Seasons III), and hardware store brands such as Harbor Breeze (Lowe's) and Hampton Bay (The Home Depot).
- Friction drive ceiling fans: This short-lived type of ceiling fan was attempted by companies such as Emerson and NuTone in the late 1970's with little success. The term "friction drive" describes the way the mechanism works. Such a mechanism consists of a low-torque motor tilted on its side, mounted on the stationary part of a hub. The motor turns a wheel at the end of its shaft; this wheel then turns a rubber flywheel attached to the moving part of the hub, to which the blades are attached. Because of the low torque of the motor, in addition to the high moment of inertia of the blades on the moving part of the hub, the fan must be started on high speed, and then reduced to the desired speed. Otherwise, the motor would not provide sufficient force to start the motion of the blades, and would in turn burn out.
- Gear-driven ceiling fans: These were similar to (and even less common than) the friction drive models; however, instead of a wheel on the motor shaft using friction to turn the flywheel holding the blades, a gear on the motor turned the flywheel, which also had gear teeth.
- "Spinner" ceiling fans: On some fans, there is no decorative motor housing and the blades attach to the bare motor (this includes nearly all industrial fans). On others, the blades attach to the motor housing itself, which then rotates. A majority of spinner-type fans made today are very inexpensive (and usually poorly made); however, in the 1980's, some very powerful "spinners" were made by taking an industrial motor, adding wooden blades, and sometimes a light kit and/or a switch housing. Others were controlled with a wall control similar to (if not the same as) those used with the industrial fans themselves. Some of the highest quality "spinner"-type fans were made by Crompton Greaves (who still manufactures fans overseas today), and Evergo. Other unique "spinner" type fans were manufactured by Moss and Commander Electric.
- Belt-driven ceiling fans: Many of the oldest ceiling fans were controlled by a belt that connected all fans to one motor, which in turn drove the blades on the fans themselves. One example of a belt-driven fan today is the Fanimation Bourbon Street.
- Art-type ceiling fans: Created more for show than function, these fans can feature elaborate designs on the motor housing and/or blades, oversized blades made from special material and/or carved to resemble various objects in nature (especially palm leaves), and/or unusual methods of operating. Some extreme examples include the Fanimation Enigma (a one-bladed ceiling fan), the Casablanca Malibu Star (an 84" ceiling fan seemingly made with bicycle sprockets, fishing rods, and sailcloth), and the Quorum Jellyfish.
Changes in Technology
As technology has advanced, the number of methods of controlling ceiling fans has increased. Some of the more recent fan control types are explained below:- Remote control: A remote control sends a signal to a sensor, which is usually located either in the switch housing or the canopy (the part of the mounting device that conceals the hole in the ceiling.) The remote usually has buttons to turn the fan on or off, change the speeds, and reverse the fan's direction (although sometimes this must still be manually done), and brighten or dim the light.
- Computerized wall control: Beginning with the Casablanca Inteli-Touch, very elaborate wall controls have been designed for higher-end ceiling fans. These fans usually have more than three speeds (usually five or six), a full-range light dimmer, and a reverse feature. Most computerized wall controls have thermostats that automatically turn the fan on, up, down, or off; still others have programs that adjust the speed of the fan according to time and/or even automatically turn the light(s) on or off while the user is away from home. Several of these computerized controls have a remote control of their own which can perform several of these functions.
Laws Governing Installation
In the United States, the National Electric Code states that ceiling fans must be supported by an electrical junction box listed for that use. However, most junction boxes installed for ceiling mounted light fixtures do not meet this requirement. It is a common mistake for homeowners to replace a light fixture with a ceiling fan without upgrading the junction box. Failure to use a proper junction box may result in a fan that wobbles or worse yet, a fan unexpectedly falling down. [[Citing sources citation needed]]
See also
External links
- Antique and vintage fans
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