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Sakthitharan
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Direction of Fan

09/12/2011 1:02 AM

Table fan and ceiling fan rotates in opposite direction-why?

Is it true ?
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dvmdsc
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#1

Re: Direction of Fan

09/12/2011 2:16 AM

Not necessarely.

A table fan must run according the pitch of the blades, must "spoon" the air.

A ceiling fan mostly has a reverse switch and can run both ways.

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JRaef
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#2

Re: Direction of Fan

09/12/2011 2:31 AM

I have two table fans that run in opposite directions. It means absolutely nothing.

Fans either suck or blow. The direction of rotation is relevant only to the blade pitch and the suck or blow decision.

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kvsubramanyam
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#3

Re: Direction of Fan

09/12/2011 2:38 AM

I think there is no hard and fast rule. It depends on blade design.

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rockraiden
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#4

Re: Direction of Fan

09/12/2011 2:46 AM

if your fan is single-phase then it must be the blades that are interchanged..

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PWSlack
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#5

Re: Direction of Fan

09/12/2011 6:55 AM

Doesn't it depend upon the direction the fan is viewed from?

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Usbport
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#6
In reply to #5

Re: Direction of Fan

09/12/2011 8:03 AM

In a general sense, yes. But the rotation of the fan blades with respect to the air flow can be either left handed or right handed.

(I bet you knew that.)

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PWSlack
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#9
In reply to #6

Re: Direction of Fan

09/12/2011 9:23 AM
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KJK/USA
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#7

Re: Direction of Fan

09/12/2011 8:56 AM

One fan was purchased in the southern hemisphere, the other in the northern hemisphere.

Mystery solved

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Sakthitharan
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#8
In reply to #7

Re: Direction of Fan

09/12/2011 9:12 AM

I love your comment - Thanks
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cuba_pete
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#10

Re: Direction of Fan

09/12/2011 11:44 AM

This would depend on which end of the motor that the drive shaft was fixed to. I never really compared them before, but it is interesting.

I don't buy that it depends on the fan blades per se, I would say that the fan blades and motor were designed to the desires of the person who makes it and puts it all together. Someone somewhere made the conscious decision to say that the fan would rotate clockwise/counter clockwise.

Also, if you look at the fan blade from a physicist's perspective the blade is not "scooping" the air. The curve of the blade creates a positive pressure zone on the forward facing blade and a negative pressure zone on the obverse, thus creating the breeze.

A sailboat is not pushed by the wind, but is pulled forward into the negative pressure area created by the sail. A wing does not "lift" an aircraft, it is pulled into the negative pressure created by the wings shape (which is not flat in any direction).
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cuba_pete (1); dvmdsc (1); JRaef (1); KJK/USA (1); kvsubramanyam (1); PWSlack (2); rockraiden (1); Sakthitharan (1); Usbport (1)

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