1. How Ceiling Fans Work

A ceiling fan is used for both functionality and fashion in any room. With the motor spinning its blades, it instantly brightens up and refreshes the surroundings. During summer, the perfect rotation for the blades is counterclockwise, which makes the cool air push downward, allowing for refreshing air circulation that adds to comfort. But what really sets ceiling fans apart is their versatility. Many models come with a reverse switch that allows for the fan blades to rotate clockwise during the winter months of the year. Ingeniously, this distributed warm air that has accumulated on the ceiling and is trapped, creating a warm and well-heated room. As simple as a change in the direction of the fan blades, this ceiling fan can be used to either cool or warm up a space during different seasons of the year.

All-Year-Round Use: You can use a ceiling fan throughout the year. During summer, they provide a gentle breeze that cools down a room, while during winter, they distribute warm air—naturally rising to the ceiling—and keep your space cosy and perfectly heated from all corners. This dual functionality ensures you get the most out of your ceiling fan all year round.

Style Addition: Available in different designs and varied styles, a modern ceiling fan can prove to be an stylish addition for any kind of room. Sleek and minimalist or ornate and decorative, there are fans available to suit every kind of decor. By choosing a ceiling fan that complements your style and decor, you raise your home a degree in both appearance and comfort.

History

Punkah style ceiling fans borrow their design from the very first form of the fan, which was invented in India around 500 BC. These were cut from an Indian palmyra leaf that forms its rather large blade moving slowly in a pendular manner. Originally operated manually by a cord[1] and nowadays powered electrically using a belt-driven system, these punkahs move air by going to and fro. Compared with a rotating fan, this creates an air circulation rather than an air flow.

 Randolph, the ceiling fan originally installed in the dining room of the house in Perry’s Camp, turned by the water wheel

Some of the earliest rotary ceiling fans appeared in the early 1860s and 1870s in the United States. At this time, they were not powered by any type of electric motor. Instead, it used a stream of running water, working in conjunction with a turbine, to drive a system of belts that would turn the blades of two-blade fan units. Systems like this could accommodate several fan units and enjoyed some popularity in stores, restaurants, and offices. Today, some of these systems still survive, often being found in parts of the southern United States where they originally had utility.

The electrically powered ceiling fan was invented in 1882 by Philip Diehl. Having engineered the electric motor used in the first electrically powered Singer sewing machines, he adapted that motor in 1882 for use in a ceiling-mounted fan. There was no need for belt drive as each fan had its own self-contained motor unit.

Within a year or so, he was having to ward off stiff competition resulting from the commercial success of the ceiling fan. He further improved his invention and developed a light kit fitted to the ceiling fan to have both functions together in one unit. With World War I, most ceiling fans were made with four blades instead of the original two, which would make fans quieter and allow them to circulate more air. The companies who could commercialise the selling of ceiling fans within the United States during the early turn-of-the-century were what are known today as the Hunter Fan Company, Robbins & Myers, Century Electric, Westinghouse Corporation, and Emerson Electric.

By the 1920s, ceiling fans had become a very common device in the United States and Canada, and were just starting to spread globally. From the Great Depression of the 1930s, through the popularisation of electric air conditioning in the 1950s, ceiling fans gradually fell out of fashion in the U.S.,[2] nearly becoming an afterthought in the U.S. during the 1960s; those that remained were seen as novelty items of nostalgia.

Late ’80s Usha Prima, one of the most ubiquitous ceiling fans in India

Meanwhile, ceiling fans became extremely popular in other countries, particularly those with hot climates, like India and the Middle East, where an absence of infrastructure and/or financial resources made energy-slurping, complex freon-based air conditioning equipment impracticable. In 1973, Texas entrepreneur H.O.W. It was during this time frame that Markwardt (Hub) began importing ceiling fans into the United States that were manufactured in India by Crompton Greaves, Ltd. Crompton Greaves had been manufacturing ceiling fans since 1937 through a joint venture formed by Greaves Cotton of India and Crompton Parkinson of England. These Indian made ceiling fans were slow to gain in popularity at first, but Markwardt’s Encon Industries branded ceiling fans eventually caught on during the energy crisis of the late 1970s and early 1980s since they used less energy than the outdated shaded pole motors most other American made fans were using. The fans became the energy-saving appliances for residential and commercial use by augmenting expensive air conditioning units with a column of gentle airflow.

Casablanca Fan Co. “Delta” ceiling fan from the early 1980s.

Thanks to this renewed commercial success using ceiling fans effectively as an energy conservation application, many American manufacturers also began to manufacture, or substantially increase the production of, ceiling fans. Aside from the imported Encon ceiling fans, 1974 saw the establishment of the Casablanca Fan Company. Other American manufacturers of the day were the Hunter Fan Co., which was then a division of Robbins & Myers, Inc), FASCO, F. A. Smith Co., and Emerson Electric, often branded as Sears-Roebuck. Smaller, short-lived firms include NuTone, Southern Fan Co., A&G Machinery Co., Homestead, Hallmark, Union, Lasko, and Evergo.

Through the 1980s and 1990s, ceiling fans had their heyday in the United States. Hundreds of small American importers started importing ceiling fans—most of them rather ephemeral. Throughout the 1980s, the balance of sales between American-made ceiling fans and those imported from manufacturers in India, Taiwan, Hong Kong, and finally China had changed dramatically with imported fans taking the lion’s share of the market by the late 1980s. Even the most basic U.S.-made fans sold for $200 to $500, while the most expensive imported fans rarely exceeded $150.

The technology behind ceiling fans has evolved little since 1980 with perhaps the notable exception being the semi-recent [when?] increase in availability of energy-efficient, remote-controlled brushless DC fans to the masses. However, companies like Monte Carlo, Minka Aire, Quorum, Craftmade, Litex and Fanimation have made significant steps in design – offering higher price ceiling fans with a more decorative eye. “Like so many other mundane household objects, these old standbys are going high-style and high-tech,” wrote Washington Post writer Patricia Dane Rogers in 2001.

Uses

Fans have a number of functions. Fans increase mixing within a ventilated space, providing more homogeneous environmental conditions. Moving air is generally preferred over stagnant air, especially in warm or neutral environments, so fans are useful in increasing occupant satisfaction.[4] Because fans do not change the air temperature and humidity, but move it around, fans can also aid in both the heating of a space and the cooling of it. It is for this reason that ceiling fans become a key component of low-energy HVAC, passive cooling, or natural ventilation in buildings. Provided the energy used by the fan system is taken into account, generally, fans provide a very effective means of enhancing thermal comfort by enabling raising the ambient air temperature .[5][6] This is highly economical, especially in warm and humid climates.

The ceiling fans can be controlled together in a shared space and also can be individually controlled in a home or office setting. In the office environment, individually controlled ceiling fans may make a dramatic positive improvement to thermal comfort. This enhancement of comfort has been shown to improve productivity as well as satisfaction of occupants.[6] Ceiling fans promote the distribution of fresh air in both mechanically ventilated and naturally ventilated spaces. Ceiling fans can perform admirably well in drawing and circulating fresh outdoor air in naturally ventilated spaces. In mechanically ventilated spaces, focus from the fans can be adjusted to channel and circulate conditioned air in a room.

Direction

The direction a fan rotates must be changed according to whether the room is to be heated or cooled. Because fans do not cool the air, but rather move it to distribute heat more efficiently around a room—in contrast to air conditioners—ceiling fans that have a means of reversing the direction the blades push air (generally an electrical switch on the unit’s switch housing, motor housing, or lower canopy) can be used in both heating and cooling.

Although ceiling fan manufacturers, primarily Emerson, have been in production since the 1930s using electrically reversible motors, most fans prior to the mid-1970s are not reversible at all or are mechanically reversible — that is, their blade pitch can be adjusted. In that case, with such an adjustment, the blades should be pitched with the upturned edge leading for downdraft, and with the downturned edge leading for updraft. Probably the best-known example of mechanical reversibility is Hunter’s “Adaptair” mechanism.

For cooling, the fan’s direction of rotation should generally be set so that air is blown downward — usually counterclockwise from beneath, dependent upon manufacturer. The blades should lead with the upturned edge as they spin. A breeze from a ceiling fan creates a wind chill effect, which accelerates the evaporation of perspiration from human skin, making the body’s natural cooling mechanism very effective. It would therefore imply that a thermostat setting of an air conditioner can lie a few degrees higher than usual, which will make a huge reduction in the consumption of power when a fan is present. Since the fan acts directly on the body, rather than through lowering the air temperature, it is best to turn all ceiling fans off when a room is not occupied to further minimise power consumption. Some situations, such as when a fan is near walls like in a hallway, may cause updraft to produce better airflow. Another example of how updraft can cause better cooling is when the ceiling fan is in the middle of a bedroom with a loft bed near a wall, meaning breeze can 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; the warmer it is, the more it rises to the ceiling, and cooler air sinks down to the floor. With this idea in mind, a ceiling fan will work to take the warmed air on the ceiling, with the direction of rotation set so air is pushed down along the walls and into the room to be reheated by the cooler air. This prevents a stream of air from blowing directly upon the occupants of the room, which would tend to cool them. This action tends to equalise, or level out, the temperature in the room, making it cooler at ceiling level but warmer near the floor. Thus, it enables a few degrees lower setting of the heating thermostat in the area, saving energy while maintaining the same level of comfort.

While a few industrial-grade ceiling fans are reversible, most of them are not. Since most installations in the industrial setting have exceptionally high ceiling heights, reversibility is not required. More to the point, most ceiling fans typically de-stratify heat by blowing hot air at ceiling level directly down toward the floor.

Blade shape

Residential ceiling fans are almost always reversible and use flat, paddle-like blades, equally effective in downdraft and updraft. Industrial ceiling fans typically are not reversible and thus operate only in downdraft. This means they can make effective use of blades that are contoured to have a downdraft bias.

More recently, however, residential ceiling fan designers have been making increasing use of contoured blades in an effort to boost ceiling fan efficiency. This contour, while serving to effectively increase the fan’s performance when operating in downdraft, can hinder performance when operating in updraft.

Air conditioning

The most general use today is in combined usage with an air conditioning unit. Air conditioning units normally play the roles of both cooling the air within the room and circulating the air inside if a ceiling fan is not working. Provided a ceiling fan is appropriately sized for the room which it is operating in, the efficiency in moving air far exceeds that of an air conditioning unit, so for peak efficiency the air conditioner setting should be low fan and the ceiling fan should be used to circulate the air.

Flicker and strobing

In most cases, ceiling fans have also been installed into a room that includes some other form of lighting. When the fan is too close to a light panel or lighting fixture, it may result in strobe or even a flickering effect. One such strobe or flicker effect is the brightening and dimming of light consistently while it penetrates and passes through a moving ceiling fan.[8] This happens because, during rotation, the fan blades block the light, thereby intermittently allowing shadows to fall across the interior surface of a room and causing visual discomfort. When there is a ceiling fan below an artificial lighting fixture, the rotating area of a moving fan blade can frequently block the light source from it, which may be increasingly distracting to occupants of the space. [9] For complete avoidance of strobing and easy co-existence of the ceiling fans with lighting fixtures, it is recommended that the horizontal separation between the blade and the lighting fixture be maximized. Also, the greater the vertical distance between the source and the blade, the less the concentration and frequency of strobing. Never locate a light source directly above a ceiling fan’s blades; adjust downlight and point source fixtures so their beam angles do not intersect the blades. Generally, to attain overall uniformly adequate light levels, all the recessed ceiling lighting and all lighting that would emanate light above the fan blade level should be mounted at the furthest possible point from the ceiling fan.[10] A further recommended strategy is ensuring that the light’s angle of dispersion or field angle is reduced which, in turn, will assist in diminishing the strobing effect from the fan blades. It is well known that human eyes can be dazzled at low frequencies, usually in the range of 60 to 90 hertz, but not at high frequencies above 100 hertz, also known as non-visible flicker. The strobe effect can create a serious physiological and mental effect on the human body. In an experiment, two test rooms were employed to compare the relative physiological effects of visual flicker, generated by the ceiling fan. Results gave statistical evidence that one of the three cognitive performances, the digit-span task, may have been slightly decreased due to increased effects from visual flicker.

Parts

Some of the primary components of a ceiling fan include:
An electric motor

Blades (also called paddles or wings) usually made of solid wood, plywood, steel, aluminum, MDF, or plastic
Blade irons (also called blade brackets, blade arms, blade holders, or flanges) which hold the blades and attach them to the motor.
Flywheel: a metal, plastic or hard rubber double-torus attached to the motor shaft and to which may be attached the blade irons. The inner ring of the flywheel is locked to the shaft by a lock-screw and the blade irons to the outer ring by screws or bolts that feed into tapped metal inserts. All-rubber or all-plastic flywheels can become brittle and shatter, thus being a frequent cause of fan failure. Replacing the flywheel may require disconnecting wiring and requires removing the switch housing that’s in the way for the flywheel to be removed and replaced.
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 means of mounting the fan to the ceiling such as:
Ball-and-socket system. For this system 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.
J-hook and Shackle clamp. A type of mounting system where the ceiling fan is simply supported by a hardened metal hook, screwed into the ceiling or bolted through a steel I-beam. The fan could be directly mounted onto a ceiling hook and does not necessarily need a junction box. A porcelain or rubber grommet is used to reduce vibration and to electrically isolate the fan from the ceiling hook. Such mounting is typical for the ceiling fans, which were developed antiquely, and for those intended for industrial purposes in general. One variation of this system is in heavy-duty ceiling fans that have electrically reversible motors, using a U-bracket secured to the ceiling by means of lag bolts, thereby minimizing the risk of a fan unscrewing itself from the ceiling while running clockwise. Such a mount is perfectly suited for an RC flat roof with metal hooks and has become ubiquitous in South Asia, including Bangladesh, India, Pakistan, etc.
Flush mount (also called “low profile” or “hugger” ceiling fans). These are specially designed fans with no downrod or canopy like a traditional mount fan. The motor housing appears directly to be attached to the ceiling, that is where the name “hugger” comes from. They are ideal for rooms having low ceilings ranging in height between 2.286 m and 2.5908 m. One downside to this design is that because the blades are mounted so close to the ceiling, air movement is greatly reduced.
Some ball-and-socket fans can also be installed with the help of a low-ceiling adapter, that can be purchased specifically with the fan brand. This would allow the same design to be used in both high and low ceiling environments, effectively simplifying the buy decision at the hands of the consumer. In the past few years, it has become very common for a ball-and-socket fan to be designed such that the canopy (ceiling cover piece) is optionally screwed directly into the top of the motor housing, thus eliminating the use of a downrod. The whole fan can simply be secured directly onto the ceiling mounting bracket; this is often referred to as a dual-mount or tri-mount. Other components may include and vary by model and style:
A downrod—a metal pipe that allows the fan to be suspended from the ceiling. Downroads come in many lengths and widths depending on the fan type.
A decorative encasement for the motor known as the “motor housing”.

Switch housing: This is a normally metal or plastic cylinder mounted below, and centered on, the motor of the fan. It can help to enclose and protect a variety of components from view, such as wires, capacitors, and switches; on fans that require oiling, it usually covers the oil reservoir lubricating the bearings. The switch housing also provides a convenient place to mount a light kit.
Blade badges: these are small, usually decorative, items attached to the visible underside of the blades to hide the screws attaching the blades to the blade irons.
There are several switches for fan on-off, fan speed, blade rotation direction and separate lamp operation, if fitted. Some fans have remote controls to adjust speed and turn the light off and on.
Lamps
Uplights, mounted atop the fan’s motor housing, shine light upwards onto the ceiling, for aesthetic purposes — “to create ambience”
Downlights, sometimes called a “light kit” provide ambient light to a room and can serve to replace any lamps that were mounted on the ceiling that were displaced by the installation of a ceiling fan
This would include decorative lights mounted inside the motor housing — in this kind of setup, glass or acrylic panel sections are often added to the motor housing side-band, which lets light shine through.

Operation

How a fan is controlled depends upon the manufacturer, style, and era of the fan. Some common control methods include:

Pull-chain/pull-cord control. This method of control uses a metal-bead chain or cloth cord pulled to cycle the fan through its operational speed(s) and then off. These fans usually come with one to four speeds. Many fans with lights often have an extra pull chain to turn the light on and off, and it’s usually on/off, but some are three-way; some lights, other lights, all lights, and off. Some, typically outdoor rated or Canadian, have a further pull chain to change direction.

Variable-speed control. In the 1970s and into the mid-1980s, fans were often made 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, it continuously changed the speed at which the blades rotate—similar to a dimmer switch for a light fixture. Some fans substituted a rotary click-type switch instead of the infinite-speed dial for a set number of set speeds, usually ranging from four to ten.

Different fan manufacturers used variable-speed controls in different ways:

The variable-speed dial controls the fan entirely; to turn the fan on, the user turns the knob until it clicks out of the “off” position, and can then choose the fan’s speed.

Variable speed pull-chain. This setup is similar to the variable-speed dial discussed above, except that a “dual chain” setup is used to turn the potentiometer shaft.

A pull-chain present along with the variable-speed control; the dial can be set in one place and left there, with the pull-chain serving only to turn the fan on and off. Many of these fans have an option to wire an optional light kit to this pull-chain in order to control both the fan and the light with one chain. This method will let the user turn on either the fan or the light individually, or both together, and also turn them off.

Vari-Lo. A pull-chain and variable-speed control are fitted. This kind of fan has two speeds, both controlled by a pull-chain: high (full power, independent of the position of the variable-speed control) and “Vari-Lo” where the speed selected by the variable-speed control governs the speed. In some instances, maximum speed on the Vari-Lo setting is slower than high.

Old-style choke and new-style capacitor based wall control

Wall mount control. Some fans have their control(s) mounted on the wall instead of on the fans themselves, these are very common with industrial and HVLS fans. Such controls are usually proprietary and/or specialised switches.

Mechanical wall control. This style of switch takes varying physical forms. The wall control houses a motor speed regulator of some description, controlling how much juice gets fed to the fan, hence how fast it spins. Older such controls used to use a choke ; these controls tended to be quite big and boxy and surface mounted on the wall. They were usually between four and eight speeds. Modern designs for this type of control avoid the choke as such, using much smaller capacitors and/or solid-state circuitry, all installed in a standard in-wall gang box with a mounted switch. The old one is called an electrical fan regulator that works on the principle of reducing voltage and the new one is called an electronic fan regulator that works on the principle of switching that controls the time duration of the power supply. The new electronic fan regulator is more power efficient.

Digital wall control. This type of control maintains all functions of the fan—on/off status, speed, direction of rotation, and any light fixtures attached—through computerised wall control, which typically doesn’t require any special wiring but just uses the normal house wiring to send coded electrical pulses to the fan, which decodes and acts on them using a built-in set of electronics. This type of control usually has three to seven speeds.

Wireless remote control. In recent years, remote controls have dropped in price to become cost-effective for controlling ceiling fans. They may be supplied with fans or fitted to an existing fan. The hand-held remote transmits radio frequency or infrared control signals to a receiver unit installed in the fan. However, these may not be ideal for commercial installations as the controllers require batteries. They can also get misplaced, especially in instals with many fans.

Directional Switch Most ceiling fans typically include a small slide switch on the motor body of the fan itself that controls the direction in which the fan rotates. In one position it causes the fan to rotate clockwise; in the other, counterclockwise. Since the fan blades are typically angled, this results in air either being drawn upwards or downwards. While the user can select which they prefer, typically air is blown downwards in summer and lifted upwards in winter. The downwards blowing is experienced as “cooling” in summer, while the upwards convection brings ceiling-hugging warm air back down throughout the room in winter.

Classifications

Ceiling fans can broadly be categorised into three types according to application and utility. Each type has some unique advantages over others and hence is suitable for a specific application. They are household, industrial, and large-diameter fans.

Household fans normally have 4 or 5 wooden blades and a decorative motor housing; moreover, it also contains a standard three speed motor with pull-chain switch control. Depending on price and consumer preference, the fan comes in two types, one with a light kit and one without.

Commercial or industrial ceiling fans are usually applied in stores, schools, churches, offices, factories, and warehouses. Such a fan is designed to be more cost-effective and energy-efficient than its household counterpart. An industrial or commercial ceiling fan comes with either three or four blades, normally steel or aluminium in make, and driven at high speed. These energy-efficient ceiling fans aim to push massive amounts of air across large, wide open spaces. Thus, metal-bladed industrial ceiling fans were in demand from the late 1970s to the mid-1980s probably because of their lower price compared to a wood-bladed model in lower-income American households. In Asia and the Middle East, an industrial style ceiling fan is very popular in household applications.

5-blade ceiling fan in a restaurant.

Large-diameter ceiling fans intended for large spaces, such as large warehouses, hangars, shopping malls, railway platforms and gymnasiums are known as HVLS fans. These generally operate at a rather low velocity but because of their tremendously large diameter – usually between 7′ and 24′ in diameter – they are able to move a large amount of air, creating a gentle breeze across a large area. More advanced HVLS fans utilise airfoil-style blades that optimise the movement of air while reducing the energy required to do so. One of the largest manufacturers of HVLS fans is Big Ass Fans.

A High-volume low-speed fan

Indoor/outdoor ceiling fans are mostly designed for partially enclosed or open outdoor spaces. The bodies and the blades are made with materials and finishes which will be less drastically affected by moisture, temperature swings, or humidity than traditional materials and finishes. UL damp-rated fans can be installed in areas such as covered patios and porches where there is no direct rainwater exposure from above, and in bathrooms or laundry rooms where high moisture is anticipated. The open places where the fan might get in contact with water require a fan that is wet-rated. The motor in a UL wet-rated fan is hermetically sealed and will not be damaged by rainwater, snow, or even being washed off with a garden hose. Residential and industrial fans are available in dry-rated as well as damp-rated and wet-rated versions.