A ceiling fan doesn't change the actual temperature in the room
(watch your thermometer).

It can certainly change the temperature at the lower part of the room.
Hot air rises and a fan blowing down will push hot air down.

You might see a difference when the fan is first turned on, but once the
air is mixed up it shouldn't change. The fan itself doesn't warm or cool
the air in the room.

I have watched my thermometer (digital thermostat directly beneath the
ceiling fan), and there is no change in temperature whether the fan is
turned on or not. But the gentle breeze still "feels" cooler on a hot day.

It makes a big difference, because with the air blowing up, there is
little direct breeze on you. With it down, there is a direct breeze.

I tried having my fan blow upwards, and could feel a nice breeze along the
walls where the air is being pushed down. But I don't spend a lot of time
up against the walls, and it's still a lot more disperse than directly
under a down blowing fan.

Anthony Watson
www.mountainsoftware.com
www.watsondiy.com