Subject: Re: Which direction for ceiling fan?

From: [email-masked] (Nick Pine)
Date: 27 May 1996 05:22:25 -0400

Anna Bordelon <[email-masked]> wrote:

>We have always used portable box fans (the $20 ones from Woolworth)

Or $12 from K-Mart...

>set right in the window and blowing towards us to keep the room cool. 

Better to close the window during the day and put it on the floor?

>Is there an advantage to using a ceiling fan?

Well, it's more out of the way, and the efficiency of a fan is roughly
proportional to the blade diameter, so big slow fans are more efficient.

>Which kind of fan has the best "electricity used to air moved" ratio?

A $12 Holmes 20" box fan moves about 1,000 cubic feet per minute at 100 watts.
Grainger's $61 4C688 10" circular fan moves 560 CFM at 36 Watts, and has a
nice upper temperature limit of 149 F, which might make it useful in a sauna,
or something like that :-) Their $200 30" 3C686 industrial air circulator
delivers 6,000 CFM at 180 Watts, and their $168 4C721 60" ceiling fan moves
43,700 CFM whilst consuming 130 Watts, but they suggest 20-45 foot ceilings.
You might use this in an apartment, with some paperweights, and their $16.02
5C343 motor speed control, which has a manual low-speed trim adjustment for 
proper restart after a power interruption, to prevent motor overheating. 

Human beings have a thermal conductance of about 2 + V/2 Btu/hr-F-ft^2 in
air moving at V mph. Perspiration can help a lot more. Don't forget concrete
furniture. Does anyone make waterbed sofas or beanbag chairs? Hats with fins?

One of those floating pool chairs, inflated with water?

We need more human heat sinks.

Especially if we are fat.

Nick