Ceiling Fan System Components:Based on our class definition of a system, (" Individual components with specific functions integrated to achieve an overall objective"), the ceiling fan system is composed of these individual components that work together to create a cooling affect on the occupants of a room [2]:
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System Description:Ceiling fans were first invented in 1882 by Philip Diehl who adapted his motor from Singer sewing machines along with a fan blade he suspended from the ceiling [1]. Obviously the ceiling fans of today have many advancements & optional features from the ones Diehl first created in 1882, but they still hold the same principles. The physical mechanics is simple, a blade or series of blades are attached to a motor which rotates the blades. As these blades rotate they circulate the air around. The fan does not actually increase or decrease the temperature in a space, but creates the feeling of cooling through the evaporative cooling effect.
A ceiling fan system really only has an affect on the perceived air temperature through the use of increasing the velocity of air flow. It does not have an impact on the true temperature of a room or the gas or particulate content or the pressure of a room. The ceiling fan creates the cooling effect through using circulating air that helps the evaporation of perspiration from the bodies skin. In essence it almost acts as a support system to your own bodies natural cooling system. Since ceiling fans are not actually impacting the heating or cooling of a room they are often used in conjunction with other systems like window or central air conditioning or heating units and help to more efficiently distribute the air within a space. In such a case they can be viewed more as a secondary system, but in the event where such measures are not available like in poorer countries where the cost of a unit and the draw on electric power is too great these systems would act as primary units. It is important to note that fans cool people and not rooms. Ceiling fans should be turned off when not in use. According to the department of energy by using a ceiling fan, which uses less energy than a air conditioner, you can raise the air conditioner thermostat 4 deg Fahrenheit without a reduction in comfort [3]. If you live in a temperate zone you may be able to not use your AC unit at all which would be a significant decrease in energy usage since the typical air condition unit uses 3,500 watts of energy, while a ceiling fan uses about 60 watts running on high [4]. Also to increase efficiency the ceiling fan blades should be at an angle minimum of 12 degrees. This way the air will be most efficiently moved throughout the space. |
Typical Uses:Ceiling Fans can be used in a variety of spaces, but often are not the primary HVAC system since they do not control temperature, humidity, particulate matter, or pressure.
The most common use of ceiling fans is in residential structures. It is common that these fans are used in conjunction with a light fixture and are often there for aesthetics as much as for actual cooling. Another use of fans is in commercial buildings. You may see them in restaurants, office buildings and gyms. Ceiling fans are also common in older institutional buildings such as elementary and middle schools which were not built or retrofitted with central HVAC systems. The cost of installing fans versus retrofitting HVAC systems is drastically lower so some schools without the needed funds will install fans instead. The use of ceiling fans in most industrial and manufacturing spaces is limited since often times the ceiling spaces are occupied with assembly lines or the ceiling heights are to great to efficiently install ceiling fans. Also most times specific ventilation or temperature needs are to great to consider the installation of ceiling fans. |
System Limitations:
Ceiling fans have a limited use because of their simplistic design and functionality. They are good at what they do which is circulate air, but not much beyond that. As previously mentioned, fans cool people, not rooms. In order to have a room at a set temperature you will need to use another system that has the ability to control temperature. Likewise if you need particulate, gas, pressure or any other controls you will need to use another system or combine the ceiling fan with this system.
The size of the room can also be a limitation on the system. Fans need to be appropriately sized for the room, too small a fan or one placed too high in a space will be inefficient in providing the cooling affect needed. See the figure to the right for sizing. Ceiling fans should also be a minimum of 7 feet from the floor, so in older homes that were built with smaller rooms and ceiling heights fans are not a good option. |
Typical Materials:Fan motors are typically made of durable metal components such as aluminum while the fan blades can range in materials such as wood, iron, aluminum, or plastic [2].
The cost of the fan can range from around $40 to several hundred depending on the quality and materials used [7]. |
Construction Issues:As stated above, ceiling fans should be installed 7 to 9 feet above the floor with 10 to 12 inches of clearance from the ceiling [3]. In addition the fan blades should have a minimum of 8 inches of clearance from the ceiling and 18 inches from the walls [3].
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References:
[1] http://home.howstuffworks.com/ceiling-fan.htm
[2] http://en.wikipedia.org/wiki/Ceiling_fan
[3] http://energy.gov/energysaver/articles/fans-cooling
[4] http://www.thesimpledollar.com/ceiling-fan-hacks-save-big-on-energy-use/
[5] http://www.build.com/how-to-choose-a-ceiling-fan/a192
[6] http://www.nivasa.lk/wp-content/uploads/2012/11/ceiling_fan_parts_diagram.gif
[7] http://www.hometips.com/buying-guides/ceiling-fans.html
[8] http://blog.studiosmw.com/wp-content/uploads/2014/08/Fans_After-8.jpg
[9] http://www.bowmanelectricsa.com/images/ceiling-fans-gfi-plugs.jpg
[2] http://en.wikipedia.org/wiki/Ceiling_fan
[3] http://energy.gov/energysaver/articles/fans-cooling
[4] http://www.thesimpledollar.com/ceiling-fan-hacks-save-big-on-energy-use/
[5] http://www.build.com/how-to-choose-a-ceiling-fan/a192
[6] http://www.nivasa.lk/wp-content/uploads/2012/11/ceiling_fan_parts_diagram.gif
[7] http://www.hometips.com/buying-guides/ceiling-fans.html
[8] http://blog.studiosmw.com/wp-content/uploads/2014/08/Fans_After-8.jpg
[9] http://www.bowmanelectricsa.com/images/ceiling-fans-gfi-plugs.jpg