Ceiling Fans

Ceiling Fan Inspection

by Nick Gromicko

A fan attached to a room’s ceiling is known as a ceiling fan. Like other  fans, they are used to provide comfort for building occupants by circulating air  within a room.

Fun Facts About Ceiling FansMost household ceiling fans have four or five blades.

  • An adult human cannot be decapitated by a ceiling fan, according to the TV  show “MythBusters.” A powerful, industrial-strength fan might be able to damage  a skull or slice a person’s neck, however.
  • Ceiling fans were first used in the United States in the 1860s. They were  powered by a system of belts driven by a stream of running water.
  • Unlike air conditioners, fans do not actually cool the air, which is why  they merely waste electricity when they circulate air in an unoccupied  room.

Ceiling Fan Components

  • electric motor:  varies with the size of the fan and its application;
  • blades:  typically, two to six spinning, precision-weighted blades  made from metal, wood or plastic; industrial fans typically have three blades,  while residential models have four or five;
  • blade irons:  connect the blades to the motor;
  • safety cable: on heavy fans, these are required to hold the fan in place in  case the support housing fails;
  • flywheel:  connects the blade irons to the motor;
  • ceiling mount:  designs include ball-in-socket and J-hook;
  • downrod:  used where ceiling fans are suspended from high ceilings;
  • motor housing:  protects the fan motor from dust and its surroundings;  may also be decorative; and
  • lamps: may be installed above, below or inside the motor housing.

Common Fan Defects

  • The fan falls. A ceiling fan that breaks free from its ceiling mount can be  deadly. Fans must be supported by an electrical junction box listed for that  use, according to the National Electric Code, and a fan brace box will need to  be installed. While a particular junction box might support a fully assembled  fan, during operation, it will exert additional forces (notably, torsion)  that can cause the support to fail. Homeowners often overlook this distinction  by carelessly replacing light fixtures with ceiling fans without upgrading the  junction box, which should clearly state whether it’s rated to hold a ceiling  fan.
  • The fan wobbles. This is a common and distracting defect that is usually  caused when fan blades are misaligned from one another. Specific problems stem  from minute differences in the size or weight of individual blades, warping,  bent blade irons, or blades or blade irons that are not screwed in  tightly enough. The ceiling mount may also be loose. Wobbling is not caused by  the ceiling or the particular way that the fan was mounted. Wobbling will not  cause the fan to fall, and there have been no such reports. Wobbling  can, however, cause light fixture covers or shades to loosen and potentially  fall. These items should be securely attached, with all screws tightly set  in place. An easy way to tell if the blades are not on the same plane  is to hold a yardstick or ruler against the ceiling and measure the distance  that the tip of each blade is from the ceiling by manually pushing the  blades. A homeowner can carefully bend the misaligned blade back into place.  Blades can also be corrected in this way if measurement reveals that they are  not equidistant from one another.
  • There is inadequate floor-to-ceiling blade clearance. No part of the fan  blades may be closer than 7 feet from the floor in order to prevent  inadvertent contact with the blades. Downward air movement is maximized when the  fan blades are around 8 or 9 feet from the floor. For high ceilings,  the fan may be hung to a desired height. Low-profile fan models are available  for ceilings that are lower than 8 feet from the floor. Also, fan blades  should be at least 18 inches from walls.
  • Blades are turning in the wrong direction. In the winter months, the leading  edge of the fan blades should be lower than the trailing edge to produce a  gentle updraft, which forces warm air near the ceiling down into the  occupied space below. In the summer, the leading edge of the fans blades should  be higher as the fan spins counter-clockwise to cool occupants with a wind-chill  effect. On most models, fan direction can be reversed with an electric switch  located on the outside of the metal housing, but the same effect can be achieved  on other models by unscrewing and remounting the fan blades.
  • An indoor fan is not designed for exterior use. Ordinary indoor ceiling fans  are unsafe to use outdoors or in humid environments, such as bathrooms.   They will wear out quickly. Fans that are rated “damp” are safe for humid  environments, but they, too, should never be used where they might come into  contact with liquid water. Only fans that are rated “wet” are safe for such use,  as they incorporate features such as all-weather, UV-resistant blades, sealed  motors, rust-resistant housing, and stainless steel hardware.
In summary, properly installed and maintained ceiling fans can  inexpensively cool or warm building occupants.

From  Ceiling Fan Inspection – InterNACHI http://www.nachi.org/ceiling-fan-inspection.htm#ixzz2eVItwC00