The information on this page has been awarded #1 answer at Yahoo! Answers on many occasions!
"OK...so the most common technical question that people ask regarding ceiling fans is "What direction should my fan spin during the summer and winter" and "Why?"
Quick Answer: I say quick answer, because this is a very generalized answer, which in many (or most) cases is not necessarily correct. But, I will state this answer first simply because it is what has been the industry answer for over 100 years.
"During the summer you want the fan to blow air straight down, so your ceiling fan needs to run in a counter clockwise direction as you look up at it. The warmer it is, the higher the speed should be. During the winter, your fan should run at a low speed in a clockwise direction." Read the more detailed answer below to really understand this answer as there are many exceptions to this rule.
Forward = Counter Clockwise = Summer mode
Reverse = Clockwise = Winter Mode
This is one of the most commonly asked questions we get from people who own lower quality ceiling fans that seem to make little or no difference in summer or winter regardless of the direction they are spinning. Such fans are poorly made and simply don't move much air in either direction. So if you cannot tell if your fan is in forward or reverse by just turning it on high speed and standing under it, maybe it's time to consider replacing your fan with one that actually moves a good amount of air.
During the summer you want lots of airflow, but you want to control it so that it is not too much during more mild days. You also want maximum control of lower speeds during the winter so the fan does not cool you off while drawing the warm air from the ceiling. And of course, you want to be able to conveniently reverse the fan without having to get on a ladder or fumble around for a switch hidden on top of the motor. The "Eco" fans below from Emerson are the ultimate answer because they are best designed for use in both summer and winter. These high performance fans have super efficient DC motors, which use very little electricity yet have the ability to generate a wide range of airflow from very low to very high. They all have 6 speeds, so you can really fine tune the airflow and they come with a remote control (or wall control), making them super convenient and easy to reverse direction. Since hot summer months require maximum airflow and cold winter months need maximum efficiency at low speeds, these fans are by far the ideal choice for those who wish to use their ceiling fans year around. They also run super quiet, so they are great fans for bedrooms and other sound sensitive rooms. Read more about the Emerson Eco Fans.
This video features a Casablanca Panama with the Inteli-Touch wall control, which is also available with a 6 Speed DC Motor. The Casablanca Panama is one of the highest quality ceiling fans on the market, and one of the best choices for fans that are used in both summer and winter. My only criticism of this video is the recommendation to use the fan on medium speed...I prefer higher speeds on very warm days...and the lowest speed during the winter. 6 speed fans like the Inteli-Touch Panama or the Emerson Eco fans shown above are advantageous because they give you the ability to fine tune the speed depending on how hot or cold it is. This video can be found directly on YouTube here: http://www.youtube.com/watch?v=3HZwG9zDiJA
During the summer, you want the air blowing directly on you so you will feel cooler from the wind chill effect (which is how fans cool you off). So stand under the fan and turn it up on high speed. If you "Do Not" feel the air very well, then turn the fan off and flick the reverse toggle switch. Turn it back on high speed. If you feel more air, you have it in the right position. So whichever position you feel the most air movement when standing directly under the fan is the correct position for summer. If you do not feel much air in either direction, then your fan has a very weak motor with a relatively flat pitch to the blade. Fans like this won't do much good for you in either direction during the summer. If this is this case, you may wish to consider visiting a specialty fan dealer online to get a more powerful fan than the ones they sell at the home centers.
During the winter, it is the opposite. You do not want to feel the air movement from the fan blowing directly on you since this will make you feel cooler from the wind chill effect. So, again...stand under the fan and turn it up on high speed. Whichever mode you feel the least amount of air is the correct mode for winter. However, you want to operate the fan at a low speed during the winter, otherwise, even in the correct mode, you will still get some wind chill effect, which you do not want.
To set the matter straight about how fans work during the winter and summer:
During winter (in the correct mode as described above), the fan will slowly draw the cooler air from floor level directly below the fan upwards to the ceiling where it mixes with the warmer air. The air is then kicked out across the ceiling towards the walls as it comes down. This circulates the air giving you the least amount of direct air movement, which minimizes the wind chill effect.
During the summer, you want the maximum wind chill effect, so the main column of air that rushes straight down from the fan is what you will feel the most. However, if your fan is not directly over the area where you want to feel coolest, say your room is rather large with a fan in the middle and your couch closer to an outer wall, you might find yourself more comfortable if you run the fan at a high speed in the wrong direction because the wind chill effect will be more prominent further away from the fan closer to the walls.
One customer told me how he determined the best direction to operate his fans. He turned on a bubble machine in his home and watched where the bubbles went. To this day, I think this is the most ingenious answer I’ve heard to the question."
Here are some exceptions to the rule as well as some great tips and tricks you can perform with your ceiling fan!
How about a card trick! OK, just kidding...but seriously, if you are playing cards at a table that is beneath a ceiling fan during the summer and you want the fan to cool you off without blowing the cards off the table, then turn your fan in reverse (clockwise) and run it on the highest speed. This will cause the fan to draw the air up from the table and blow it around your back side.
Dining Rooms: How about over a table when you are eating? Same thing as playing cards or doing anything else at your table. Running the fan in reverse will help keep the fan from cooling off your food while gently throwing a breeze towards the walls and backup toward your backside. You might notice that in many restaurants, the fans are running in clockwise motion. I don't know who told the restaurant owners to do this, but I amazingly find that more often than not, they are doing this correctly. This must be an inside secret in the restaurant business.
Bedrooms: Well, some people do not like the feeling of air blowing directly on them and cannot sleep, so my suggestion is to run the fan on a higher speed in reverse so you do not feel so much direct air movement. You will sleep better and get more comfort from your fan. I myself love to feel the air movement, so I blast mine in forward so the air blows right down on me.
Large Rooms: So you have a large room and wisely decided to install 2 ceiling fans. You might want to experiment with the fans during the summer by operating them on high speed in forward, reverse, and opposite directions. Depending on where your seating is in the room, a combination of directions may actually hit that spot the best by creating a unique vortex in the air flow. The bubble trick I mentioned previously is great for testing this!
Outdoors: OK, so you have your fan outdoors. I will assume that you are pretty much going to be using the fan only during the summer. So, all of the above rules apply...such as over a table when playing cards or doing paperwork. However, an additional benefit of having a ceiling fan outdoors over a table is that you can use the fan to keep bugs away by turning it up on high speed in forward (counter clockwise). The compromise here is that it will cool your food off. Keep in mind that for this to work, you need a ceiling fan that has a motor powerful enough to create a column of air strong enough to ward off those pesky flies and yellow jackets. Not all fans will do this well, so make sure to ask for a fan with a powerful motor if you wish for your outdoor fan to perform this task. You will be much more pleased with the comfort level the fan produces anyway, so it's worth spending a bit more for the best quality outdoor fan you can afford.
Here are links to several excellent outdoor fans that move a good amount of air:
Smokers: If you or someone in your family (or a guest) smokes inside your house...you need to run your ceiling fans in reverse (clockwise) to draw the smoke up towards the ceiling and out towards the walls away from you and your guests. Although the speed at which you should run your fan depends on how powerful the fan is as well as how large the room is, my suggestion for this application is medium speed for the average ceiling fan. This is a common application in cigar lounges where they use this technique combined with exhaust vents in the ceiling to pull the smoke out of the area.