Ceiling fans provide year-round, energy efficient climate control. They also add beauty and interest to your home. Do You Need Additional Fan Hanging / Operating Accessories? Each fan comes with its own unique set of accessories. These may include downrods or remote / wall controls. Please see Product Specifications* to determine what accessories are included in the purchase price. Downrods are needed in order to bring the fan blades down to 8' or 9' above the floor so you can feel the air movement. If your ceiling fan has a light kit, reduce the length by 12". If downrods or controls are not included they can be purchased separately. Fan Installation Styles Low Ceilings For safety, all blades must be at least 7" above the floor, if you have low ceilings (7" to 7 1/2" high) look for hugger fans. Just Under 8' High Ceiling If your ceiling is 3" or 4" shy of 8' consider purchasing a fan with a "Low Ceiling Adapter". 8' to 9' Ceilings Most fans are designed for 8' or 9' ceilings. If this is your ceiling height, you don't need an additional downrod. Over 9' High If your ceiling is higher than 9', refer to the chart above for suggested downrod lengths. The mounting hardware that comes with the fan will attach directly to the downrod. Vaulted Ceilings If your ceiling is angled more than 30°, you will also need a sloped ceiling adapter or vaulted ceiling adapter purchased separately. Source: LightingShowplace
Source:
http://www.lightingshowplace.com/how-to-choose-your-ceiling-fan/c80854