Changes

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 '''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 drawn upward (typically clockwise), takes cool air from lower levels in the room and pushes it upward towards the ceiling. The warm air, which had naturally risen 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 reverse rotation has the added advantages of not creating the wind-chill effect of the summer operation scheme, and of heating the air slightly by forcing it along the entire surface area of the ceiling which is typically hot due to risen hot air trapped on the other side in the attic.

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 drawn upward (typically clockwise), takes cool air from lower levels in the room and pushes it upward towards the ceiling. The warm air, which had naturally risen 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 reverse rotation has the added advantages of not creating the wind-chill effect of the summer operation scheme, and of heating the air slightly by forcing it along the entire surface area of the ceiling which is typically hot due to risen hot air trapped on the other side in the attic.

== Parts of a ceiling fan ==

== Parts of a ceiling fan ==

* '''[[Pull switch|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.

* '''[[Pull switch|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.

* '''Variable-speed control.''' During the 1970s and 1980s, fans were often produced with a [[Potentiometer|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. A few fans substituted a rotary click-type switch for the infinite-speed dial, providing a set number of speeds (usually five).

* '''Variable-speed control.''' During the 1970s and 1980s, fans were often produced with a [[Potentiometer|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. A few fans substituted a rotary click-type switch for the infinite-speed dial, providing a set number of speeds (usually five).

**Different fan manufacturers used the variable-speed control in different ways:

**Different fan manufacturers used the variable-speed control in different ways:

*** The variable-speed dial controlling 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.

*** The variable-speed dial controlling 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.

* '''Wall-mounted control.''' Some fans have their control(s) mounted the wall instead of on the fans themselves; such controls and are usually proprietary and/or specialized switches.

* '''Wall-mounted control.''' Some fans have their control(s) mounted the wall instead of on the fans themselves; such controls and are usually proprietary and/or specialized switches.

** ''Digital control'': 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, which typically does not require any special wiring. Instead, it 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 style of control typically has anywhere from three to six speeds.

** ''Digital control'': 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, which typically does not require any special wiring. Instead, it 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 style of control typically has anywhere from three to six speeds.

** ''Choke''. This style of switch takes varying physical forms. The wall control, which contains a resistor of some sort, determines how much power is delivered to the fan 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 had 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.

** ''Choke''. This style of switch takes varying physical forms. The wall control, which contains a resistor of some sort, determines how much power is delivered to the fan 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 had 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.

==Safety concerns with installation==

==Safety concerns with installation==

A typical ceiling fan weighs between 15 and 35 pounds when fully assembled. While many junction boxes can support that weight while the fan is hanging still, a fan ''in operation'' exerts many additional stresses--notably [[Torsion (mechanics)|torsion]]--on the object from which it is hung; this can cause an improper junction box to fail. For this reason, in the United States the [[National Electric Code]] (document [[NFPA]] 70, Article 314) states that ceiling fans must be supported by an electrical junction box listed for that use. It is a common mistake for homeowners to replace a light fixture with a ceiling fan without upgrading to a proper junction box.

A typical ceiling fan weighs between 15 and 35 pounds when fully assembled. While many junction boxes can support that weight while the fan is hanging still, a fan ''in operation'' exerts many additional stresses—notably [[Torsion (mechanics)|torsion]]—on the object from which it is hung; this can cause an improper junction box to fail. For this reason, in the United States the [[National Electric Code]] (document [[NFPA]] 70, Article 314) states that ceiling fans must be supported by an electrical junction box listed for that use. It is a common mistake for homeowners to replace a light fixture with a ceiling fan without upgrading to a proper junction box.

Another concern with installing a ceiling fan relates to the height of the blades relative to the floor. American law states that no fan can be mounted with its blades closer than seven feet from the floor; this often proves, however, to not be high enough. If a person fully extends his or her arms into the air--as sometimes happens during normal tasks such as stretching, changing bedsheets, or recreation--he/she may become seriously injured if there is an operating ceiling fan mounted too close. Also, if one is carrying a ladder, long [[Lumber|wooden board]], [[Pipe (material)|pipe]], or some other long and awkward object, one end may inadvertently enter the path of rotation of a ceiling fan's blades; this can be very dangerous if the fan is operating at the time, and can cause damage to the fan regardless.

Another concern with installing a ceiling fan relates to the height of the blades relative to the floor. American law states that no fan can be mounted with its blades closer than seven feet from the floor; this often proves, however, to not be high enough. If a person fully extends his or her arms into the air—as sometimes happens during normal tasks such as stretching, changing bedsheets, or recreation—he/she may become seriously injured if there is an operating ceiling fan mounted too close. Also, if one is carrying a ladder, long [[Lumber|wooden board]], [[Pipe (material)|pipe]], or some other long and awkward object, one end may inadvertently enter the path of rotation of a ceiling fan's blades; this can be very dangerous if the fan is operating at the time, and can cause damage to the fan regardless.

==Notes==

==Notes==

==References==

==References==

{{cite book |last=Scharff |first=Robert |coauthors=Casablanca Fan Co. |title=The Fan Book |origyear=1983 |publisher=Reston Publishing Co, Inc. |location=Reston, VA 22090 |language=English |isbn=0-8359-1855-6 |pages=128}}

{{cite book |last=Scharff |first=Robert |coauthors=Casablanca Fan Co. |title=The Fan Book |year=1983 |publisher=Reston Publishing Co, Inc. |location=Reston, VA 22090 |language=English |isbn=0-8359-1855-6 |pages=128}}

==External links==

==External links==