a fan for the ceiling
A ceiling fan circulates air by using hub-mounted revolving blades positioned on the ceiling of a room or space. Ceiling fans are usually electrically driven. They efficiently cool people by boosting air speed. Fans, unlike air conditioners, do not lower ambient temperature or relative humidity, but they do have a cooling impact by assisting in the evaporation of sweat and increasing heat exchange by convection. Fans may emit a tiny amount of heat into the room, primarily as a result of waste heat from the motor, but also as a result of friction. Because cooling air is thermodynamically expensive, fans consume substantially less energy than air conditioning.
A ceiling fan can also be employed in the winter to return warm air that has naturally risen to the inhabitants. This can have an impact on thermostat readings as well as occupant comfort, resulting in increased temperature control energy efficiency.
History
Ceiling fans of the Punkah design are based on the earliest form of a fan, which was invented approximately 500 BC in India. These were made from an Indian palmyra leaf, which has a large blade that moves slowly and in a pendular way. These punkahs move air by going to and fro, originally propelled manually by a cord and now powered electrically by a belt-driven mechanism. It provides a soft breeze rather than an airflow as compared to a rotating fan.
The earliest rotary ceiling fans arrived in the United States in the early 1860s and 1870s. They were not powered by any type of electric motor at the time. Instead, a turbine and a stream of running water were employed to drive a system of belts that turned the blades of two-blade fan units. These systems were popular in supermarkets, restaurants, and offices because they could accommodate many fan units. Some of these methods are still in use today in portions of the southern United States, where they were first useful.
Philip Diehl invented the electrically operated ceiling fan in 1882. He designed the electric motor that drove the first electrically powered Singer sewing machines, and he adapted it for use in a ceiling-mounted fan in 1882. There was no need for belt drive because each fan had its own self-contained motor unit.
Because of the ceiling fan's commercial success, he faced stiff competition almost immediately. He continued to refine his idea and created a light kit that could be attached to a ceiling fan to integrate the two functions into a single item. Most ceiling fans had four blades instead of the original two by World War I, which made them quieter and allowed them to circulate more air.
The Hunter Fan Company, Robbins & Myers, Century Electric, Westinghouse Corporation, and Emerson Electric were among the early turn-of-the-century enterprises who successfully popularized the selling of ceiling fans in the United States.
Ceiling fans had become widespread in the United States by the 1920s, and had begun to gain traction globally. Ceiling fans gradually fell out of favor in the United States from the Great Depression of the 1930s until the arrival of electric air conditioning in the 1950s, almost completely disappearing by the 1960s; those that survived were regarded relics of nostalgia.
Meanwhile, in other nations, particularly those with hot temperatures, such as India and the Middle East, where a lack of infrastructure and/or financial resources made energy-intensive and complex freon-based air conditioning systems impossible, energy-efficient ceiling fans became highly popular. H. W. (Hub) Markwardt, a Texas entrepreneur, began importing ceiling fans made in India by Crompton Greaves, Ltd. into the United States in 1973. Crompton Greaves had been producing ceiling fans since 1937, when Greaves Cotton of India and Crompton Parkinson of England created a joint venture.
These Indian-made ceiling fans were slow to catch on at first, but during the energy crisis of the late 1970s and early 1980s, Markwardt's Encon Industries branded ceiling fans (which stood for ENergy CONservation) found great success because they used less energy than the antiquated shaded pole motors used in most other American-made fans. By supplementing pricey air conditioning units with a column of gentle airflow, fans became the energy-saving appliances for domestic and commercial use.
Many American manufacturers began to develop, or considerably increased the manufacturing of, ceiling fans as a result of this revived economic success employing ceiling fans efficiently as an energy conservation application. The Casablanca Fan Company, in addition to the imported Encon ceiling fans, was created in 1974. Hunter Fan Co. (then a branch of Robbins & Myers, Inc.), FASCO (F. A. Smith Co.), and Emerson Electric (commonly branded as Sears-Roebuck) were among the other American manufacturers at the time. NuTone, Southern Fan Co., A&G Machinery Co., Homestead, Hallmark, Union, Lasko, and Evergo are examples of smaller, short-lived businesses.
Ceiling fans were popular in the United States during the 1980s and 1990s. Ceiling fans were first imported by a slew of tiny American importers, most of whom were short-lived. The sales balance between American-made ceiling fans and those imported from India, Taiwan, Hong Kong, and subsequently China shifted rapidly throughout the 1980s, with imported fans eventually gaining the lion's share of the market by the late 1980s. Even the most basic American-made fans cost between $200 and $500, whereas overseas fans rarely cost more than $150.
Ceiling fan technology hasn't advanced much since 1980, until recently[when?] with the widespread availability of energy-efficient, remote/app controlled brushless DC fans. Companies like Monte Carlo, Minka Aire, Quorum, Craftmade, Litex, and Fanimation have made significant design advances, producing higher-priced ceiling fans with more ornamental value. "Like so many other banal household goods, these old standbys are going high-style and high-tech," Washington Post writer Patricia Dane Rogers wrote in 2001.
Uses
Ceiling fans serve a variety of purposes. In a ventilated space, fans improve mixing, resulting in more uniform environmental conditions. Fans are effective in boosting tenant happiness since moving air is favored over stagnant air, especially in warm or neutral situations. Fans can help with both heating and cooling because they do not modify the temperature or humidity of the air, but rather move it around. Ceiling fans are frequently used in low-energy HVAC, passive cooling, and natural ventilation systems in buildings because of this. Fans can be an efficient approach to improve thermal comfort by allowing for a higher ambient air temperature while keeping occupants comfortable, depending on the energy use of the fan system.
In hot, humid climates, fans are an exceptionally cost-effective option.
Ceiling fans in a common place can be operated collectively, but they can also be controlled individually in a home or business situation. Individually controlled ceiling fans in an office environment can have a considerable positive impact on thermal comfort, which has been found to boost occupant productivity and happiness. In both mechanically ventilated and naturally ventilated environments, ceiling fans help to distribute fresh air. Ceiling fans are great in drawing in and circulating fresh outdoor air in naturally ventilated environments. Fans can be directed to channel and circulate conditioned air in mechanically ventilated spaces.
Direction
Depending on whether the room has to be heated or cooled, the direction in which a fan spins should change. Fans, unlike air conditioners, just move air and do not alter its temperature. Ceiling fans with a mechanism for reversing the direction in which the blades push air (usually an electrical switch on the unit's switch housing, motor housing, or bottom canopy) can therefore assist in both heating and cooling.
While some ceiling fan manufacturers (most notably Emerson) have been producing electrically reversible motors since the 1930s, most fans built before the mid-1970s are either not reversible at all or mechanically reversible (with changeable blade pitch).The blades should be pitched for downdraft with the upturned edge leading, and for updraft with the downturned edge leading. Perhaps the most well-known example of mechanical reversibility is Hunter's "Adaptair" system.
When it comes to cooling, the direction of rotation of the fan should normally be set to blow air downward (Usually counter-clockwise from beneath, but dependent upon manufacturer). As they spin, the blades should lead with the upturned edge. The wind chill effect provided by a ceiling fan accelerates the evaporation of perspiration on human skin, making the body's natural cooling process far more effective.
As a result of this phenomenon, when a fan is running, the air conditioning thermostat can be set a few degrees higher than usual, considerably lowering power consumption. Because the fan acts directly on the body rather than modifying the air temperature, it is advised that all ceiling fans be turned off while a room is vacant to save even more energy. Updraft may improve airflow in specific instances, such as when a fan is near walls, such as in a hallway. Another example of how an updraft can improve cooling is a fan in the middle of a room with a loft bed against a wall, which allows the breeze to be felt better when airflow is coming from the top.
For heating, ceiling fans should be set to blow the air upward. Air naturally stratifies, i.e. 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 at ceiling level to move down to take its place, without blowing a stream of air directly at the occupants of the room. This action works to equalize, or even out the temperature in the room, making it cooler at ceiling level, but warmer near the floor. Thus the heating thermostat in the area can be set a few degrees lower to save energy while maintaining the same level of comfort.
As a result, the area's heating thermostat can be turned down a few degrees to save energy while maintaining the same level of comfort.
Although some industrial-grade ceiling fans are reversible, the majority are not. Reversibility isn't necessary in most industrial applications due to the high ceiling heights. Industrial ceiling fans, on the other hand, de-stratify heat by fanning hot air from the ceiling down to the floor.
Shape of the blade
Flat, paddle-like blades are commonly used in downdraft and updraft residential ceiling fans, which are usually always reversible. Because industrial ceiling fans are often not reversible and only work in downdraft, blades that are shaped to have a downdraft bias can be used effectively.
However, in order to improve ceiling fan efficiency, residential ceiling fan designers have been increasingly using curved blades. While this contour efficiently boosts the fan's performance while operating in downdraft, it can obstruct performance when running in updraft.
The use of air conditioning
Ceiling fans are most commonly used in conjunction with air conditioners these days. Without a ceiling fan, air conditioning units are normally responsible for both chilling and circulating the air inside the space. Because the ceiling fan's efficiency of moving air significantly exceeds that of an air conditioner when correctly scaled for the space in which it operates, the air conditioner should be set to a low fan setting and the ceiling fan should be used to circulate the air for maximum efficiency.
Strobing and flickering
When ceiling fans are situated close to ceiling lights, they can induce shadow flicker and strobing. This is because the fan blades obscure the light sporadically, causing shadows to emerge across the room's interior surface, producing visual discomfort. Use drop-down light fixtures that are installed at the same height as, or lower than, the ceiling fan to eliminate flicker.
Parts
The following are the main components of a ceiling fan:
A motor that runs on electricity
Solid wood, plywood, steel, aluminum, MDF, or plastic are commonly used for blades (also known as paddles or wings).
Blade irons (also called as blade brackets, blade arms, blade holders, or flanges) are the components that hold and attach the blades to the motor.
The blade irons may be attached to the flywheel, which is a metal, plastic, or tough rubber double-torus attached to the motor shaft. A lock-screw secures the inner ring of the flywheel to the shaft, while screws or bolts that feed into tapped metal inserts secure the blade to the outer ring. Flywheels made of rubber or plastic can grow brittle and break, which is a typical reason of fan failure. Replacing the flywheel may necessitate disconnecting wiring and removing the switch housing, which is in the way of removing and replacing the flywheel.
Rotor, an alternative to blade irons. First patented by industrial designer Ron Rezek in 1991, the one-piece die-cast rotor receives and secures the blades and bolts right to the motor, eliminating most balance problems and minimizing exposed fasteners.
A mechanism for mounting the fan to the ceiling such as:
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, or self-supporting canopy, and allows the fan to move freely (which is very useful on vaulted ceilings.
Shackle clamp with J-hook The ceiling fan is suspended on a hardened metal hook that is fastened into the ceiling or bolted through a steel I-beam. The fan can be installed directly on a ceiling hook, eliminating the need for a connection box. To reduce vibration and electrically disconnect the fan from the ceiling hook, a porcelain or rubber grommet is employed. This mounting style is especially frequent on antique ceiling fans and industrial ceiling fans.
On heavy-duty ceiling fans with electrically reversible motors, a version of this technique using a U-bracket fastened to the ceiling with lag bolts is frequently employed to reduce the possibility of the fan unscrewing itself from the ceiling while running in clockwise. This installation is suitable for RC flat roofs with metal hooks and has become commonplace in South Asia, such as Bangladesh, India, and Pakistan.
Mounted flush (also known as "low profile" or "hugger" ceiling fans). These are unique fans that don't have a downrod or canopy like typical mount fans. The name "hugger" stems from the fact that the motor housing looks to be physically attached to the ceiling. They're perfect for spaces with low ceilings, ranging from 7'6" to 8'6". The fact that the blades are situated so close to the ceiling reduces air flow, which is a downside of this design.
A low-ceiling adaptor, available from the fan's manufacturer, can be used to mount some ball-and-socket fans. This enables for the use of the same design in both high and low ceiling environments, simplifying the purchasing decision for consumers. In recent years, it has become increasingly popular for a ball-and-socket fan's canopy (ceiling cover piece) to be screwed directly into the top of the motor housing, obviating the need for a downrod. The entire fan can be mounted directly to the ceiling mounting bracket; this is known as a dual-mount or tri-mount installation.
Other elements, which vary depending on the model and style, can include:
The fan is suspended from the ceiling by a downrod, which is a metal pipe. Depending on the fan type, downrods come in a variety of lengths and widths.
The motor is housed in a beautiful encasement (known as the "motor housing").
A switch housing is a metal or plastic cylinder located below and in the center of the fan's motor (also known as a "switch cup" or "nose column"). The switch housing hides and protects different components like as wires, capacitors, and switches; on fans that require oiling, it frequently hides the oil reservoir that lubricates the bearings. The switch enclosure also serves as a convenient mounting location for a light kit.
Blade badges are decorative adornments that are affixed to the visible underside of blades to hide the screws that connect the blades to the blade irons.
Various switches for turning the fan on and off, regulating the blades' rotation speed, changing the blades' rotation direction, and controlling any lamps that may be present.
Lamps
For aesthetic reasons, uplights are put on top of the fan's motor housing and reflect light up onto the ceiling (to "create ambience")
Downlights, often known as a "light kit," provide ambient lighting in a space and can be used to replace any ceiling-mounted lamps that were displaced when a ceiling fan was installed.
Decorative lights mounted inside the motor housing – in this configuration, the side-band of the motor housing commonly contains glass or acrylic panel parts that allow light to pass through.
Operation
The manner a fan is operated is determined by the manufacturer, style, and era in which it was created. The following are some examples of operating methods:
Control via a pull-chain or a pull-cord. This type of fan has a metal-bead chain or fabric cord that, when pulled, cycles the fan through the operational speed(s) before returning to off. There are usually one to four speeds on these fans. Some fans with lights have a second pull chain that controls the light. It's normally on/off, but it can also be three-way, with some lights, other lights, all lights, and off. To reverse direction, certain fans, mainly outdoor or Canadian-rated, feature an additional pull chain.
Variable-speed control. During the 1970s and into the mid-1980s, fans were often produced with a solid-state variable-speed control. This was a dial mounted either on the body of the fan or in a gang box at the wall, and when turned in either direction, continuously varied the speed at which the blades rotated—similar to a dimmer switch for a light fixture. A few fans substituted a rotary click-type switch for the infinite-speed dial, providing a set number of set speeds (usually ranging from four to ten).
Variable-speed controls were employed in a variety of methods by different fan manufacturers:
The variable-speed dial is completely in charge of the fan; to turn it on, crank the knob until it clicks out of the "off" position, and then select the fan's speed.
Pull-chain with variable speed. This system is identical to the variable-speed dial explained above, only the potentiometer shaft is turned by a "dual chain" setup.
Along with the variable-speed control, there is a pull-chain; the dial can be set in one position and left there, with the pull-chain solely serving to turn the fan on and off. Many of these fans come with the option of wiring an optional light kit to this pull-chain, allowing you to control both the fan and the light with just one chain. The user can turn on either the fan or the light separately, both on, or both off using this approach.
Vari-Lo. There is a pull-chain with variable-speed control. A pull-chain controls two speeds on this fan: high (full power regardless of variable-speed control position) and "Vari-Lo" (speed determined by the position of the variable-speed control). In some circumstances, the maximum speed on the Vari-Lo setting is slower than the maximum speed on the high setting.
Choke-based wall control and capacitor-based wall control
Control that is installed on the wall. The control(s) of some fans are located on the wall rather than on the fans themselves; this is extremely prevalent with industrial and HVLS fans. These switches are frequently proprietary and/or specialized.
Control of the wall using mechanical means. This type of switch comes in a variety of physical shapes. The wall control, which has some form of motor speed regulator, controls how much electricity is provided to the fan and hence how fast it spins. The regulator on older such controllers was a choke, which was a massive iron-cored coil; these devices were often large, boxy, and surface-mounted on the wall. They ranged in speed from four to eight. Newer versions of this type of control employ considerably smaller capacitors and/or solid-state circuitry instead of a choke, and the switch is often mounted in a normal in-wall gang box.
Controlling the wall with digital technology. All of the fan's operations, including on/off status, speed, rotation direction, and any attached light fixtures, are controlled by a computerized wall control, which usually does not require any extra wiring. Instead, it sends coded electrical pulses to the fan via standard house wiring, which the fan decodes and operates on using a built-in set of electronics. There are usually three to seven speeds on this type of control.
Controlled with a wireless remote. Remote controllers have gotten more affordable in recent years, making them a viable option for controlling ceiling fans. They can come with fans or be retrofitted to an existing fan. The fan's receiver device receives radio frequency or infrared control signals from the hand-held remote. However, because the controllers require batteries, these may not be suitable for commercial installations. They can also become misplaced, especially in large fan installations.
Switches in both directions. Most ceiling fans have a small sliding switch on the motor body that controls the fan's rotational direction. In one position, the fan rotates clockwise, while in the other, the fan rotates counter-clockwise. Because the fan blades are usually slanted, the air is either drawn upwards or drawn downwards. While the user has the option to choose, air is normally blasted downwards in the summer and hoisted higher in the winter. In the summer, the downward blowing is perceived as "cooling," whereas in the winter, the upward convection returns ceiling-hugging warm air to the space.
Classifications
Based on its use and functionality, ceiling fans can be divided into three groups. Each type has its own set of advantages over the others and is hence best suited to a particular purpose. Household, industrial, and large-diameter fans are among them.
Household fans often include four or five hardwood blades, a decorative motor housing, and a three-speed motor controlled by a pull-chain switch. Depending on price and consumer preferences, these fans are available with or without a light kit.
Ceiling fans for commercial or industrial use are commonly seen in businesses, schools, churches, offices, factories, and warehouses. This type of fan is intended to be more cost-effective and energy-efficient than the typical residential fan. Three or four blades, often constructed of steel or aluminum, are used in industrial or commercial ceiling fans, which run at a high speed. These energy-saving ceiling fans are built to move a significant amount of air across vast, open spaces. Metal-bladed industrial ceiling fans were popular in lower-income American households from the late 1970s through the mid-1980s, owing to their lower cost than wood-bladed variants.
In Asia and the Middle East, industrial-style ceiling fans are highly popular for home use.
In a restaurant, a 5-blade ceiling fan.
HVLS ceiling fans have a huge diameter and are designed for large places such as warehouses, hangars, shopping malls, train platforms, and gymnasiums. These fans usually spin at a slower speed, but their huge diameter, which ranges from 7' to 24' (2.1m to 7.3m), allows them to produce a gentle breeze to a large area. Airfoil-style blades are used in modern HVLS fans to provide optimized air circulation at a lower energy cost. Big Ass Fans is one of the most well-known HVLS fan manufacturers.
Ceiling fans designed for use in partially enclosed or open outdoor settings are known as indoor/outdoor ceiling fans. Traditional materials and finishes are not as impacted by moisture, temperature changes, or humidity as the body and blades are constructed of. UL Damp-rated fans are ideal for moist-prone indoor locations like bathrooms and laundry rooms, as well as covered outdoor areas like patios and porches that aren't directly exposed to rains from above. Wet-rated fans must be used in open areas where the fan may come into contact with water.
UL Wet-rated fans have a completely sealed engine that can survive rainwater, snow, and even being wiped down with a garden hose. Dry-rated, damp-rated, and wet-rated fans are available for both industrial and household use.
Types
Many different types of ceiling fans have been developed over time in response to a variety of causes, including rising energy-consumption awareness and changing décor styles. Ceiling fan development has also been influenced by the introduction and advancement of new technology. The following is a list of common ceiling fan styles and their distinguishing features:
Ceiling fans made of cast iron. Since their introduction in 1882 until the mid-1960s, these have accounted for nearly all ceiling fans produced. A particularly heavy-duty motor, usually of the shaded-pole sort, is housed in a cast-iron housing. These motors are lubricated by an oil-bath thrust bearing and must be greased on a regular basis, usually once or twice a year. Because of its sturdiness and lack of electronic components, it is not uncommon to see cast-iron fans that are more than eighty years old still operating strong and in use today.
By far the most identifiable example of a cast-iron ceiling fan today is the Hunter 'Original' (made by the Hunter Fan Co.). From 1906 to the present, it has had the longest production run of any fan in history. From its creation until 1984 (the 36" Original remained shaded pole until it was replaced with the 42" Original in 1985), the Hunter Original used a shaded-pole motor, which was later replaced with a far more efficient permanent split-capacitor motor.
The motor was downgraded in 2002 when manufacture was shipped to Taiwan; the motor, albeit still oil-lubricated, was replaced to a "skeletal" design, as explained below, with a reduced main shaft that accidentally caused reliability concerns. This motor design was changed in 2015, and it now uses a full-length primary shaft, which was a crucial component of the pre-2002 motors' durability.
Ceiling fans with 20 pole induction "pancake" motors. Crompton-Greaves, Ltd of India invented these fans with extremely efficient cast aluminum housings in 1957, and Encon Industries was the first to import them into the United States in 1973.
This Crompton-Greaves motor took 20 years to perfect thanks to a joint venture with Crompton-Parkinson of England. It is the most energy-efficient ceiling fan motor ever made (aside from the DC motor) because it uses less energy than a standard incandescent light bulb.
Ceiling fans without blades are available. Exhale fans released this type in 2012, and it uses a bladeless turbine to push air outwards from the fan, similar to how ordinary ceiling fans operate in updraft mode. In place of a traditional direct-drive motor, these fans use a brushless DC motor.
Ceiling fans without blades are available. Exhale fans released this type in 2012, and it uses a bladeless turbine to push air outwards from the fan, similar to how ordinary ceiling fans operate in updraft mode. In place of a traditional direct-drive motor, these fans use a brushless DC motor.
A pendulum fan, also known as a flap fan, is a low-speed ceiling fan that can be used to circulate air around a specific region. The back-and-forth motion enhances turbulence around cooling sources, such as the chilled waterfalls at Tulane's Lavin Bernick Center, allowing a larger volume of air to be cooled.
Ceiling fans with brushed DC motors. There were brushed DC ceiling fans produced before the current was transferred from DC to AC. These are connected to DC cables directly.
DC ceiling fans with no brushes. This type of fan employs BLDC technology, which provides significantly higher efficiency than conventional fans powered by regular AC motors. Because they are commutated electronically and use permanent magnet rotors, they are quieter than AC motor fans.
High efficiency, lower noise level, less rotor heat, integration of remote control and other convenience technologies, and so on are some of the other benefits that these fans provide. Only the high cost and the presence of complicated electronics, which may be more prone to failure and difficult to service, are disadvantages.
The latter, however, is becoming less of a worry as new technologies and improved quality control approaches emerge. These are connected to AC cables through an AC/DC adaptor.
Ceiling fans that are smart. Google Assistant, Amazon Alexa Assistant, Apple Homekit, and Wifi can all control these fans. Because of its microcontroller-based architecture, fine-control flexibility, and firmware upgrade capability, BLDC motors are used in the vast majority of these fans. A smartphone app can control the speed, brightness, and timing of the fans.
Concerns about installation safety
When fully built, a typical ceiling fan weighs between 8 and 50 pounds. While many junction boxes can support that weight while the fan is still hanging, a fan in operation generates extra forces on the item from which it is hung, including torsion, which can cause an inappropriate junction box to break.
As a result, the National Electric Code (document NFPA 70, Article 314) in the United States mandates that ceiling fans be supported by an electrical junction box designed for that purpose. Replacing a light fixture with a ceiling fan without updating to a correct junction box is a common mistake made by homeowners.
Low-hanging fans pose a threat to limbs
Another consideration when installing a ceiling fan is the blade height in relation to the floor. Building rules in the United States prevent residential ceiling fans from being positioned closer than seven feet from the floor; yet, this is occasionally insufficient. When a ceiling fan is switched on and a person fully extends his or her arms into the air, as is common during everyday actions like dressing, stretching, or changing bedsheets, the blades may strike the person's hands, inflicting harm.
Also, if carrying a long and cumbersome object, one end of the object may accidently reach the rotation path of a ceiling fan's blades, causing harm to the fan. For these reasons, building rules in the United States ban industrial ceiling fans from being mounted with blades closer than 10 feet from the floor.
"Killer Ceiling Fan," according to MythBusters
In 2004, MythBusters put to the test the claim that sticking one's neck into a running ceiling fan could result in decapitation. The "jumping kid" version of the myth was tested, with a child jumping up and down on a bed, jumping too high and entering the fan from below, and the "lover's leap" version featuring a husband leaping towards his bed and entering the fan side-on. Kari Byron and Scottie Chapman bought a standard domestic fan as well as an industrial fan with metal blades instead of wood and a more powerful engine.
They debunked the myth in both scenarios with both household and industrial fans, demonstrating that residential ceiling fans are, by design, largely incapable of causing more than minor injury, with low-torque motors that stop quickly when blocked and blades made of light materials that break easily when impacted at speed (the household fan test of the "lover's leap" scenario actually broke the fan blades).
Wobble
They debunked the myth in both scenarios with both household and industrial fans, demonstrating that residential ceiling fans are, by design, largely incapable of causing more than minor injury, with low-torque motors that stop quickly when blocked and blades made of light materials that break easily when impacted at speed (the household fan test of the "lover's leap" scenario actually broke the fan blades).
The weight of the fan blades is out of equilibrium, which causes the fan to wobble. This can happen for a variety of reasons, including warped blades, bent blade irons, blades or blade irons that aren't screwed on straight, or weight differences across blades. The vertical response forces can also create swaying if all of the blades do not exert an equal force on the air (due to various angles, for example). A motor fault can also produce wobble, but this is a rare occurrence. The mounting surface or the way the fan is mounted have no effect on the fan wobbling.
Wobbling alone will not cause a ceiling fan to topple, contrary to popular belief. Ceiling fans are fastened by clevis pins that are secured with split pins or R-clips, therefore swaying will not affect the fan's security, unless the pins/clips are not attached. There have been no complaints of a fan wobbling off the ceiling and falling to the ground. A significant wobble, on the other hand, might cause light fixture shades or covers to loosen over time and potentially fall, providing a risk of damage to anyone standing beneath the fan, as well as any broken glass.
Scottie utilized an edge finder to determine the exact center of their blades when the MythBusters were creating a fan with the purpose of chopping off someone's head, with the intention of preventing potentially highly dangerous wobbling of their steel blades.
Wobbling can be reduced by ensuring that each blade's tip is measured from a fixed position on the ceiling (or floor) and that they are all equal. If the fan has a metal plate between the motor and the blade, it can be bent to make minor adjustments. It can also be decreased by ensuring that all blades have the same pitch and are spaced evenly from one another. A balancing weight on the blades can also help to reduce it.
Disposability
Ceiling fan motors frequently contain chemicals to keep them from burning out, making them non-disposable. When chemicals are placed inside a garbage truck's motor, they can generate pollution that is harmful to human health, or, in rare situations, an explosion. When ceiling fans are left within a building after it is demolished, the same thing can happen. Ceiling fans should be recycled, sold, or donated when they are no longer in use.
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