What is the correct direction to spin a ceiling fan to get the best
airflow in a small appartment bedroom?

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Clarification of Question by philsown-ga on 15 Nov 2002 17:30 PST

In particular I'm interested in the angle of the blades vs. the direction.

Hi,

If the specific angle is your focus. This site provides advice:
"Opt for the optimal angle.
For a ceiling fan to move the right amount of air, its blades should
be set at a 14 degree angle. Blades set at a 10 degree angle will
simply slice the air, while blades at a 20-degree angle will meet so
much resistance that the motor may burn out."
http://www.lightingwholesalers.com/ceilingfantips.htm
 
This advice from a hotel management tips site:
http://www.ihei.org/HOTELIER/hotelier.nsf/content/b1c2g3c4.html
Some ceiling fans have a switch that changes the direction of the
blade rotation and are known as reversible ceiling fans. In theory,
reverse fan rotation is good for winter climates, because the fan
blows air upwards, reducing room stratification by forcing hot air
downwards. However, for normal eight-foot ceilings, reversible
operation of ceiling fans is not recommended.

Regency Ceiling Fan talks about reversing the rotation for the same
reason.
http://www.regencyfan.com/press/pdf/comfort.pdf

How do you know which rotation pulls air up and which pushes down?
A simple answer is provided on this page by the Ponca City News -
about three quarters of the way down - past the obituaries...
An easy way to determine whether the fan airflow is up or down is to
look at the fan blades as they rotate. The blades are installed on a
slight angle. If the leading edge of the blade (the edge facing the
direction of rotation) is up, the airflow will be down. And when the
leading edge is down, the airflow will be up.
http://www.poncacitynews.com/NewsArchives/1099folder/lo100699.html

This brochure from Berkomeh concentrates on industrial fans, but the
graphs, charts and drawing explain much about the physics of how a fan
works.
http://www.berkomeh.com/prod_pdf/bulsub/ZDA-LEFTG.pdf

A very technical paper on the OVERVIEW OF FAN DESIGN AND
PERFORMANCE...
"SECTION 1 - BASICS AERODYNAMIC PERFORMANCE OF FANS AND BLOWERS
Volumetric Flow Rate is the volume rate of flow through an area Q = AV
and is expressed in units of cubic feet per minute of air through the
blower or flow passage.
Mass Flow rate is the product of density and volume flow rate W = PAV
= PQ. It may be expressed as pounds per hour. Cooling heat transfer
effect is a function of mass flow rate."
There is no indication that the specific angle of the blades is
something that needs to be accounted for in performance, but that's
probably because the focus is enclosed fans - for elecrical appliances
or furnaces.
http://www.oem.co.uk/Thermal_Division/thermalappnotes(pdf)/EN%20-%20Overview%20of%20Fan%20Design%20and%20Performance.pdf

search terms: ceiling fan blades angle 

Hope this helps you to stay cool :-)
bcguide-ga

Thank you. Your comments regarding the position of the leading edge
being up or down was what I was most currious about, but I did not
know how to explain things. Your answer covered all the bases.