Why does a ceiling-fan revolve clockwise and a table-fan anti/counter clockwise?

Question

I couldnot find any logic behind this fact!

Nope..there's no switch to reverse the direction!

One more thing....isn't it obvious that the blade direction remaining unchanged the air direction will reverse if the rotation reverses!!

It seems like fans in US have this direction switching facility.
Its not this way in India!

But no-body has answered the dilema of Table-fans till now.....

Answer 1

*It depends upon the side from where you are looking.
from motor side or fan side?
Another thing is that these fans are having axial flow blades. Reversing the direction will change the direction of flow.
Please read below:
Fans come with a forward and a reverse setting. When you click it to 'forward', the fan blows the air down. Standing under the fan, you will feel a breeze. When you click it to 'reverse', the fan reverses rotation and blows the air up. Now, when you stand under the fan, you won't feel a breeze.

So, during the winter, turn the fan to 'reverse' to circulate the warm air without blowing air down and cooling you in the process. Hot air rises and a ceiling fan, running in reverse, gently mixes the air.

During the summer, on the other hand, turn it to 'forward' to create a wind-chill effect as the air moves against your skin and cools you.

So far, what I've said holds true for rooms with standard 8-foot ceilings. Fan companies recommend this procedure.

"Some people with higher ceilings, like a stairwell, often do the opposite of this," Marcus of Lamp Depot says and explains their rationale. Cool air sinks to the floor, which causes the lower levels to be cooler and the upper levels hotter. So, in the summer, they run the fan in a blowing-up direction to keep cool air-conditioned air, which is coming out of their upstairs vents, upstairs where they want it.

In the winter, they run the fan in the blowing-down direction to move warm air into the lower levels of the house where they spend their time during the day. They feel no draft downstairs because they are too far away from the fan.
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*But all ceiling fans does not have reversible switch.
It depends upon the application.
For eg. exhaust fans are having the direction to expel the air/gases out.
[*You can get the same result if forward curved blades rotate in clockwise direction and backward vanes rotate in anticlockwise direction.
If there is any threded portion,then the direction matters.
So, depending upon direction ,RH/LH threads are selected.]

Answer 2

You are always standing under a ceiling fan looking up when you observe a (non-reversing) fan, however, you may stand in front of or behind a table fan to 'reverse' its rotation CW or CCW. However, the real reason that all (most?) table fans revolve in the same direction likely depends on the fact that most use similar (shaded pole) motors that govern the direction of rotation. The correct blades must be installed to direct (blow) the air in the direction the customer wishes. Using the same rotation likely avoids manufacturing and stocking both right-hand and left-hand screw fans. Convention also dictates that the cold water faucet is always on the right (as it was in early days when there was only cold water).

Answer 3

Ignoring the up downs of ceiling fans, as there is plenty on that...

Why Table Fans...

Well it is true that a table fan should generally blow forward, to keep you cool, but, whey does it go one way you say. That is because of your location. Fans in the Northern hemisphere spin counter clockwise and have the appropriate blade setting to blow forward, and fans in the southern hemisphere turn clockwise, and have the blades opposing the northern fans, to blow forward.

The reason for this is the way the motors start to spin when electricity is applied. It is no fluke that the magnetic coils can start the armature spinning the same way each time, and this is because of the inertial push of the earths magnetic field which kick starts the armature in the motor in the anticlockwise directoion in the North and the clockwise direction in the south. Use your right hand tarzan grip rule to determine the direction of field about the wire as current passes through it. Thumb to the pole, representing current, and bent fingers point in direction of rotation.

Answer 4

My speculation on why a table fan revolves in a counter clockwise direction is based on how the fan blades are attached to the motor shaft.

I assume that the the motor shaft has thread which the hub of the fan blade assembly screws into or by a threaded fastener.

If the fan need to be partially assembled by the user right hand threads are the most common and would be easiest to assemble by a novice. Most every one knows how to tighten a right hand thread.

To keep the fan from unthreading during use you would want the fan to spin in a direction which would naturally tighten the treads onto the shaft and prevent them from loosening.

Answer 5

re: table fans > they move in forward direction only, mean blow outward
in order for the table fan to be effective for suction or exhaust application, the sides would need to be sealed
enclosed in a cut-out i mean

first 6 answers received thumbs down > each was correct !
my guess is its a fellow indian, unfamiliar with bi-directional ceiling fans
< counting my ignorance too, twice over ! >

ceiling fans:
clockwise & anticlockwise is no issue, just a matter of local / regional practices rather than engineering issues
reversing the blade vane angle serves same purpose as reversing rotation
rotation is governed or restricted, more commonly with use of capacitor start / run induction motors, rather than shaded pole motors ... to my knowledge > & this part for both, ceiling & table fans

sure, a few good & informative answers before me
just to end any snuff of a myth !
__ __ __ __ __ __ __ __ __ __

i have posted just for records sake, that you stressed on table fans & would like to clearly state that i do not intend to undermine the efforts of jdsheth & kes , besides the other answerers, in any way
PERIOD

Answer 6

your ceiling fan can turn either clockwise or counter clock wise. the anti is to push the air out. where as clockwise will suck the air up. you put it on the clockwise setting during the winter time to help with the heat. there is a switch on the side of the ceiling fan that can change how it spins. so turn of your ceiling fan flip the switch or slide it and see it change the way it spins. hope i helped you. every winter we change it so the heat does not sit up by the ceiling. it helps save on the heating bills. as so for the summer where we pull the air from the floor and bring the heat to the ceiling so the room cools. if you stand on a ladder during the summer you will notice it is hot near the ceiling. do it this winter and you will see near the ceiling is cool.

Answer 7

If you look on the side of ceiling fans there is a switch that you can reverse the flow to pull up or push down the air, spinning in both directions.

Answer 8

Either way the fan turns it will bring the heat down. The trick is to have the heat come down without it blowing the air directly on you. Since most furniture is arranged around the edge of a room the fans are usually reversed in the winter to bring the heated air across the ceiling and down the walls. That works the best most of the time, but on occasion the other direction seems to circulate the heat better. There is no wrong answer here. My advice is to try both ways to see what works best in your situation.

Answer 9

actually there is a button on both fans. Check! If you press the button the fans will turn the other way. Depending on if you want the air to rotate up or down. Surprise!

Answer 10

i have two fans and they both have a switch to make it go in reverse .check your fan very closly it may be hard to see or if you still have the directions look at them.it will show you where it is at if it has one