Ceiling fan

Definition

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

History

The first ceiling fans appeared in the 1860's and 1870's, in America. 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 2-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 been seen in parts of the southern United States where they originally proved useful.

Contrary to popular belief, the electrically-powered ceiling fan was not invented in 1886 by father-and-son team John and James Hunter^{[citation needed]}. In reality, it was invented four years earlier, 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.

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 of a light kit adapted onto the ceiling fan to compensate for any light fixture(s) displaced by the installation of the ceiling fan.

By World War I, most ceiling fans were being manufactured with four blades instead of the original two. This change allowed the fan to circulate more air, thereby making more efficient use of its motor.

By the 1920's, ceiling fans had become extremely commonplace in the United States, and had started to take hold internationally^{[citation needed]}.

However, during the Great Depression, ceiling fans faded out of vogue in the U.S., reputedly because "In its rush to forget the past, America forgot the ceiling fan"^{[citation needed]}. By the end of World War II, and into the 1950's, ceiling fans had become almost non-existent. 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 such as air conditioning.

In the 1960's, some Oriental 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 1970's, because 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. 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; those latter two were often re-labeled and sold by Sears-Roebuck.

During the rest of the 1970's, and through to the late 1980's, ceiling fans remained extremely popular in the American market. Many small American manufacturers, most of them rather short-lived, started making and selling ceiling fans. Throughout the 1980's, the balance of sales between American-made ceiling fans and those imported from overseas 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 $150 to $250, whereas the cost of an imported fan would be closer to $25 to $80).

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 1990's. 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.

While few companies still offer high-quality ceiling fans, the majority of fans sold today consist of: (a) a poorly-ventilated import motor, (b) particle-board blades with a computer-printed plastic design finish, and (c) a stylized decorative motor encasement ("housing") and adornments. It should be stated that all of these fans cost the same approximate amount to produce, since the motors and blade materials are all standardized and widely available.

Uses

Most ceiling fans can be used in two different ways; that is, most fans have a mechanism, commonly an electrical switch, for reversing the direction in which the blades rotate.

In summer, when the fan's direction of rotation is set so that air is blown downward (typically counter-clockwise, when standing under the fan and looking upwards), the breeze created by a ceiling fan speeds the evaporation of sweat on human skin, which is experienced as a cooling effect.

In winter, buildings in colder climates are usually heated. Air naturally stratifies--that is, warmer air rises to the ceiling while cooler air sinks to the floor. A ceiling fan, with its direction of rotation set so that air is sucked upward (typically clockwise, when standing under the fan and looking upwards), takes cool air from lower levels in the room and pushes it upward towards the ceiling. The warm air, which naturally rose to the ceiling, is forced out of the way of the incoming cool air: it travels along the ceiling and down the walls, to lower levels where people in the room can feel it. This heat-reclaiming action allows for cost reduction, by making it so that less fuel needs to be expended in order to heat the room to a comfortable temperature and keep it there.

Parts of a ceiling fan

The key components of a ceiling fan are:

An electric motor
- Some fans, such as the Hunter "Original", use an oil-bath motor. This type of motor is extremely powerful, heavy-duty, and reliable, but does require periodic oiling. More info below.
- Some fans, notably the high-end models, use a "stack" motor. This type of motor is trademarked by different companies under varying names, including XLP-2000 (Casablanca), K55 (Emerson), and K63 (Emerson). Stack motors do not require oiling, and are very powerful and reliable. They were used in American fans, mostly in the 1970's and 1980's, although a few manufacturers still use them today. Many companies made their own version of this motor, including (but not limited to): Casablanca, Emerson, FASCO, Hunter, and Marley. More info below.
- Many fans, including nearly all those produced in modern years, use a direct-drive motor (also known as a "spinner" motor). While a scant few direct-drive motors are of moderately high quality (notably those used in industrial fans), the overwhelmingly vast majority are cheaply made and prone to noise generation and/or failure. This type of motor is used in all Hampton Bay and Harbor Breeze fans. More info below.
One to six paddles (called "blades"); usually made of wood, MDF, metal, or plastic; which mount under, on top of, or on the side of the motor.
Metal arms, called blade irons (alternately blade brackets, blade arms, or flanges), which connect the blades to the motor
A mechanism for mounting the fan to the ceiling
- Some fans mount using a "ball-and-socket" system. With this system, there is a metal or plastic hemisphere mounted on the end of the downrod; this hemisphere rests in a ceiling-mounted metal bracket and allows the fan to move freely (which is very useful on vaulted ceilings). Some companies have come up with slight modifications of this design, notably Casablanca's "Hang-Tru" mounting system and the mounted system used on several SMC-brand fans.
- Some fans mount using a "J-hook" (also known as a "claw-hook") system. In this system, a metal hook (which comes in a variety of configurations) secures to a ceiling-mounted metal bolt (again, available in a variety of configurations). Usually, there is a rubber bushing inserted between the hook and the bolt, as a noise-reduction agent.
- Some fans can mount using an LCA (Low-Ceiling Adapter). This eliminates the need for a downrod, and is therefore useful in rooms with low ceiling clearance. An LCA is a special kit which must be purchased from the fan's manufacturer. This is mostly applicable only to fans which mount using the J-hook system or the Hang-Tru system.
- In recent years, it has become increasingly common for a ball-and-socket fan to be designed such that the canopy (ceiling cover piece) can optionally be screwed directly into the top of the motor housing; then the whole fan can be secured directly onto the ceiling mounting bracket. This is known as a "close-to-ceiling" mount.

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

A downrod (also known as a "drop rod"), which is a metal tube used to suspend the fan from the ceiling. Downrods come in many lengths.
A decorative encasement for the motor (known as the "motor housing").
- Fans without a motor housing are known as "spinner" fans. However, there is a point of common confusion here. All fans lacking a motor housing are referred to as "spinners"; direct-drive motors are referred to as "spinner motors" because all spinner fans use direct-drive motors. However, many fans which have a direct-drive motor also have a motor housing; those fans are spinner-motor fans, not spinners.
A switch housing (also known as a "switch cup"), which is a metal cylinder mounted below and in the center of the fan's motor. The switch housing is used to conceal and protect various components, which can include wires, capacitors, and switches. The switch housing also makes for a convenient place to mount a light kit.
Blade badges, which are decorative adornments attached to the visible underside of the blades for the purpose of concealing the screws used to attach the blades to the blade irons.
Assorted switches used for turning the fan on and off, adjusting the speed at which the blades rotate, changing the direction in which the blades rotate, and operating any lamps that may be present
Lamps
- Uplights, which are installed on top of the fan's motor housing and project light up onto the ceiling, for aesthetic reasons (to "create ambiance")
- Downlights, often referred to as a "light kit", which add ambient light to a room and can be used to replace any ceiling-mounted lamps that were displaced by the installation of a ceiling fan
- Decorative light bulbs mounted inside the motor housing, for aesthetic reasons. In this type of setup, the motor housing often has glass panel sections which allow light to shine though.

Operating a ceiling fan

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

Pull-chain/pull-cord control. This is, by far, the most common method of operation for household fans. This style of fan is equipped with a metal-bead chain or cloth cord which, when pulled, cycles the fan through the operational speed(s) and then back to off. These fans typically have three speeds (high, medium, and low); however, the speed range can be anywhere from one through four. With most fans, the speed cycle is (starting from the "off" position) 1st pull/2nd/3rd/4th = high/medium/low/return to off. However, some fans work in reverse--that is, low/medium/high/return to off.

Variable-speed control. During the 1970's and 1980's, fans were often produced with a variable-speed control. This was a dial mounted on the fan which, when turned in either direction, infinitely varied the speed at which the blades rotated--similar to a dimmer switch for a light fixture. Different fan manufacturers used the variable-speed control in different ways:
- Only variably-speed control--In this setup, the variable-speed control controls the fan entirely. To turn the fan on, the operator turns the knob until it clicks out of the "off" position, and can then choose the fan's speed.
- Variable-speed control with on/off pull-chain--In this setup, a pull-chain is present along with the variable-speed control. The variable-speed dial can be set in one place and left there, and the pull-chain serves only to turn the fan on and off.
- Variable-speed control with fan/light chain--In this setup, common on many early Casablanca fans, a pull-chain is present along with the variable-speed control; it controls both the fan's on/off status, and any attached light fixture. When no light fixture is present, this setup operates in exactly the same manner as the Variable-speed control with on/off pull-chain setup. When a light is connected, however, operation is as follows (starting from 'off'): 1st pull/2nd/3rd/4th = only fan on/only light on/fan and light on together/return to both fan and light off.
- VariLow--With the VariLow setup, both a pull-chain and variable-speed control are present. The pull-chain has two operational settings (starting from off): 1st pull/2nd/3rd = fan on full-power (high)/fan's speed set by variable-speed control/return to off.

Wall-mounted control. Some fans do not have their control(s) mounted on them. Instead, the control(s) is/are mounted on the wall, and is/are usually [a] proprietary and/or specialized switch[es].
- Digital controls. This style of control was invented by the Casablanca Fan Co., which named it "IntelliTouch"; later, they added other controls which use the same technology, "AdvanTouch" and "ComforTouch". With this style of control, all of the fan's functions--on/off status, speed, direction of rotation, and any attached light fixtures--are controlled by a computerized wall control. This control typically does not require any special wiring. Instead, it sends coded electrical pulses to the fan, which decodes and acts on them using a built-in set of electronics. This style of control typically has anywhere from three to six speeds.
- Choke. This style of switch takes varying physical forms. In this setup, the fan itself only has one speed (in other words, it is wired such that it permanently runs on high). The wall control, which contains a resistor of some sort, determines how much power is delivered to the fan ("chokes" it) and therefore how fast it spins. Older incarnations of this type of control employed an iron-core transformer as their resistor; these controls were typically large, boxy, and surface-mounted on the wall. Those controls have anywhere from four to eight speeds, typically four or five. Newer versions of the choke-style control employ electronic equipment as their resistor; this is much smaller, so the switch is typically mounted in a standard in-wall gang box; these typically have four speeds.

Rotary click dial. While it is very rare, some ceiling fans were manufactured with a rotary click-type switch integrated into the switch housing. These fans typically have five speeds.

Wireless remote control. In recent years, infrared remote controls have become an affordable and popular option for controlling ceiling fans. While some models do employ this as their sole form of operation, it is more common for a person to purchase an after-market kit and install it on their fan. These controls are compatible with fans which use the pull-chain system, the variable-speed system, the choke system, and the rotary dial system. The hand-held remote transmits infrared signals to a receiver unit installed in the fan; that unit interprets and acts on the signals.

Bases for comparison

There are several factors which determine a fan's usefulness and efficiency. Each of these factors can be used as a basis for comparison when deciding between different candidate fans.

A fan's usefulness (in other words, airflow generated) is measured by its CFM (Cubic Feet of air moved per Minute) rating. The following factors all have an effect on a fan's CFM rating:

Length of the fan's blades. The longer a fan's blades are, the larger percentage of a room's air volume upon which the fan will have a useful impact. This factor is of greater importance in large rooms.
Total surface area of the fan's blades. The greater a blade's surface area, the more air it is able to move. However, there can be "too much" surface area (refer to Blade surface area to air-feed ratio below).
Pitch of the fan's blades. The angle at which the fan's blades are tilted relative to the X-axis is referred to as the "blade pitch". The steeper (greater) the pitch, the greater the airflow. Since increased pitch also means increased drag, only fans with well-made motors can support steep pitches. Cheaply-made fans typically have a pitch between 9 and 13 degrees. 15 degrees and upwards is considered very good, with numbers in the 20s being the highest.
Speed of rotation. The speed at which a fan rotates, measured in RPM, directly correlates to the amount of air moved. Faster rotation equals greater airflow.
Blade surface area to air-feed ratio. In general, more blade surface area means greater airflow. However, if there is too much blade surface area, there will not be adequate space between the blades for air to be drawn through. Fans which have an unusually large blade surface area, such as fans with decorative palm-leaf-style blades or many fans with six blades, do not have adequate space between the blades for an unrestricted amount of air to be drawn through. This results in reduced airflow. The effect of this ranges from negligible to dramatic, depending on the exact dimensions involved. Contrary to popular belief, more blades typically does not equal more airflow. Most four-bladed fans move more air than comparable five-bladed fans; this is indeed noticeable on five-bladed fans which have an option to install only four of the blades. Also due to this effect, the overwhelmingly vast majority of industrial fans have three blades.
Height of the fan relative to the ceiling. If a fan is too close to the ceiling, the airflow is restricted; that is, the fan will not be able to draw as much air through its blades as it has the potential to do. For this reason, "hugger"-style fans (those which mount directly to the ceiling without the use of a downrod) are all inherently disadvantaged. The distance that a fan should be mounted from the ceiling is directly correlated with its air-moving potential; no fan should be mounted with its blades closer than 24 inches to the ceiling, however that figure is often far greater with industrial fans. Unfortunately, this is often impossible in household situations due to the fact that a minimum 9' ceiling height would be required to meet safety codes ("blades must be mounted a minimum of 7' from the floor").

In addition to all of the aforementioned factors, there are certain other factors which have an effect on a fan's perceived usefulness:

Height of the fan relative to the observer. The closer the fan is to the observer, the more air movement the observer will feel. A fan mounted close to the ceiling in a high-ceilinged room will have a lower perceived usefulness than if it were mounted closer to the ground.
Tilt of the fan's blades relative to the Z-axis. A few fan manufacturers, notably FASCO, constructed their fans such that the blades had an "up-tilt"; that is, they were tilted relative to the Z-axis (see picture at right). While this increased the area of the room over which the fan had a direct effect, it decreased the airflow concentrated immediately under the fan; for observers situated directly under the fan, this lowered its perceived usefulness.
Humidity of the room. Since a fan creates its cooling effect by speeding the evaporation of moisture on human skin, its perceived usefulness is directly correlated with the amount of humidity (moisture) in the room. In dry environments, such as desert climates, a fan has a lesser perceived usefulness than in humid environments; this is especially notable during cold weather, where a humid environment has a pronounced wind-chill effect which is lacking in dry environents.

In terms of efficiency (in other words, airflow generated versus energy input), one common basis for comparison is to divide the fan's CFM rating by its input wattage. So, if the fan moves 6630 CFM on its highest speed, and uses 85 watts to do so, its energy efficiency is 78. A consumer can apply that same equation to several candidate fans to objectively compare their energy efficiency.

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:

Cast-iron ceiling fans. Cast-iron ceiling fans account for almost all ceiling fans made from their invention in 1882 through the 1950's. A cast-iron housing encases a very heavy-duty oil-bath motor, usually of the shaded-pole variety. These fans must be oiled periodically, usually once or twice per year, since they use an oil-bath system for lubrication. Because these fans are so sturdily-built, and due to a total lack of electronic components, it is not uncommon to see cast-iron fans aged eighty years or more running strong and still in use today.
- The Hunter 'Original' (see picture at right) (manufactured by the Hunter Fan Co., formerly a division of Robbins & Myers, Inc.) is an example of a cast-iron ceiling fan. It has enjoyed the longest production run of any fan in history, dating from 1906 to the present (it is still being manufactured as the "Classic Original", with several spin-off models). As a result, this fan's physical appearance is arguably the most well-known of any fan, making it the quintessential example of a cast-iron oil-bath ceiling fan. ^{[citation needed]} The Original employed a shaded-pole motor from its inception until the late 1980's, at which point it was changed to a permanent split-capacitor motor. Though the fan's physical appearance remained unchanged, the motor was further downgraded in 2002 when production was shipped overseas; (the motor, though still oil-lubricated, was switched to a skeletal design; see details on skeletal motors below).

Stack-motor ceiling fans. In the late 1970's, due to rising energy costs prompted by the energy crisis, Emerson invented a new style of electric motor designed specifically for ceiling fans, the "stack" motor. This motor aided in the comeback of ceiling fans in America, since it was far cheaper to operate than air conditioning. With this design (which consists of a basic stator and squirrel-cage rotor), the fan's blades mount to a hub (the "flywheel"). The flywheel can be made of either metal or reinforced rubber, and can be mounted either flush with the fan's motor housing (concealed) or prominently below the fan's motor housing (known as a "FASCO-mount" or "dropped flywheel"). Many manufacturers used and/or developed their own stack motors, including (but not limited to) Casablanca, Emerson, FASCO, Hunter, and NuTone. Some manufacturers trademarked their personal incarnation of this motor: for example Emerson came out with the "K55" an "K63", and Casablanca with the "XLP-2000". While this motor is not nearly as widely-used as in the 1970's and 1980's, it can still be found in some high-end fans such as certain Casablancas and Emersons. Stack motors are fairly energy-efficient and powerful. One of the earliest stack-motor fans was the Emerson "Universal" (see picture at left). It was a very utilitarian (basic, crude) fan, with a dropped flywheel and large fiberglass (or plastic) blades. This fan was produced from 1976 through 1983, and while targeted at residential settings also found great success in commercial settings. Another stack-motor fan; one without the dropped flywheel; is the Casablanca "Delta" pictured at the beginning of this article.

One disadvantage of this type of fan is that the flywheel, if it is made from rubber, can degrade over time and eventually fail; this is not dangerous, but it renders the fan inoperable until the flywheel is replaced.

Direct-drive ceiling fans (also known as "spinner-motor fans"; some classify as "spinners"). Direct-drive motors (also known as "spinner motors") are the cheapest motors to produce, and on the whole are the most prone to failure and noise generation ^{[citation needed]}. While the very first spinner motors (which debuted in the 1960's) were relatively heavy-duty, the quality of these motors has dropped significantly in the intervening years. This type of motor has become the standard for today's ceiling fans; it has been [and is] used in all Hampton Bay and Harbor Breeze ceiling fans, and has become commonly used by all other brands.
- Spinner fans, commonly simply called "spinners", employ a direct-drive (spinner) motor and and don't have a stationary decorative cover (motor housing). This accounts for all industrial-style fans (though industrial fans often have more moderately high-quality motors), and many inexpensive residential-style fans (particularly those made overseas).
- Spinner-motor fans, sometimes confusingly (and incorrectly) referred to as "spinners", employ a direct-drive (spinner) motor and do have a stationary decorative cover (motor housing). Spinner-motor fans account for nearly all fans manufactured from the late 1980's to the present, including all fans made overseas.

Skeletal motors, which are a high-quality subset of direct-drive motors, can be found on some nicer fans. Examples of skeletal motors include Hunter's "AirMax" motor and Casablanca's "XTR200" motor. Skeletal motors differ from regular direct-drive motors in that:
- They have an open ("skeletal") design, which allows for far better ventilation and therefore a longer lifespan. This is in comparison to a regular direct-drive motor's design, in which the motor's inner workings are completely enclosed within a tight metal shell which may or may not have openings for ventilation; when openings are present, they are almost always small to the point of being inadequate.
- They are larger than regular direct-drive motors--so, more powerful and therefore less prone to burning out.

File:NuTone friction drive.jpg

A friction-drive ceiling fan made by NuTone (bottom cover removed to show motor detail).

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. Its advantage was its tremendously low power consumption, but the fans were unreliable and very noisy, in addition to being grievously underpowered. Friction-drive ceiling fans employ a low-torque motor that is mounted transversely in relation to the flywheel. A rubber wheel mounted on the end of the motor's shaft drove a hub (via contact friction, hence the name) which, in turn, drove the flywheel. It was a system based on the fact that a low-torque motor spinning quickly can drive a large, heavy device at a slow speed without great energy consumption (see Gear ratio).

Gear-drive ceiling fans. These were similar to (and even less common than) the friction drive models; however, instead of a rubber wheel on the motor shaft using friction to turn the flywheel, a gear on the end of the motor shaft turned the flywheel (which was equipped with interlocking gear teeth).

Belt-driven ceiling fans. As stated earlier in this article, the first ceiling fans used a water-powered system of belts to turn the blades of fan units (which consisted of noting more than blades mounted on a flywheel). For period-themed decor, a few companies (notably Fanimation) have created reproduction belt-drive fan systems. The reproduction systems feature an electric motor as the driving force, in place of the water-powered motor.

Laws governing installation

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, such as a metal junction box, not plastic.^[1]^[2] However, some 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 to a proper metal junction box; failure to use a proper junction box may result in a fan that wobbles or worse yet, a fan unexpectedly falling down.^[1]

Notes

^ ^a ^b Installing fan: metal junction box (not plastic), 17-Aug-2006, AceHardware-InstallFans
^ Link to document NFPA 70, NFPA-Doc70

References

Scharff, Robert. The Fan Book. Reston, VA 22090: Reston Publishing Co, Inc. p. 128. ISBN 0-8359-1855-6. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: location (link)

External links

Fan-interest sites

Major ceiling fan manufacturers

Manufacturers specializing in art-type fans

Vintage ceiling fan sales and/or fan repair

[AceHWF-1] Installing fan: metal junction box (not plastic), 17-Aug-2006, AceHardware-InstallFans

[2] Link to document NFPA 70, NFPA-Doc70

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