The logic or illogic of ceiling fans

Logic may not always be correct when applied to different situations.

Ceiling fans are something that have always intrigued me. In their use. The idea is that the propellor blades hung from the ceiling (usually roofs) will drive the “cool” air on top, to the heads of the people sitting below.
That happens a lot where I live at the moment – in sunny Malaysia. I have given up telling friends who lunch with me at hot hot hawker centers. It’s amazing how it is that all one has to do is to move ones stool two feet away and test the temperature in order to be convinced about the real effect the fan has, in an environment with low ceilings and a battery of fans beating the hit air from the zinc roofs down onto tables underneath.

Yet, hot air rises. So, is it hot air that is being driven down onto the heads of the people sitting below, when it’s a hot day inside a hot food court?
Yet almost everyone declares that fans are supposed to cool us and so they choose to sit directly under a fan.

I think the height of the ceiling and the length of the fans arm has something to do with the cooling or heating effect.

Most of the fans I come across on the US have a little switch that you can flip to make the fan blades revolve the other way. Hence, in low ceilings and on a hot day, you can get the fan to pull the hot air up away from the top of your head (hopefully replacing it with cooler air from the surrounding). The reverse side of the switch can be used, on cold days, to push the warmer air that naturally rises to the top of the ceiling, down towards the person sitting beneath the fan. Quite logical.


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About Ed Simon

This is my user name as Editor of this blog. Some site visitors may already be acquainted with the different areas of my interest. I am uncertain how I should classify myself. I have lived studied and worked in Malaysia and in the UK for long periods. I have also travelled to many other countries for both work, pleasure, and just "wandering". I leave the postings to tell about my areas of work and interest, so as not to bore you with a lengthy (and probably embellished :-) recount of my triumphs and tribulations.

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