AC V Ceiling Fan?

[dani]

Probably a silly question but is a ceiling fan cheaper to run all night than an AC Inverter Unit ?

[Keithcaley]

Yes, by a factor of about 100....

[Panchocat]

We use the inverter a/c for a couple of hours before we go to bed and then switch it off and use a ceiling fan over the bed. On a couple of nights during the hot spell recently the a/c has been switched on again during the night.....

[Deniz1]

Cheaper to run yes but it only blows the hot air around. If you want to be cool then its ac

[Keithcaley]

Cheaper to run yes but it only blows the hot air around. If you want to be cool then its ac

Wrong! (Sorry Deniz )

A ceiling fan cools you by using 'Latent Heat of Evaporation' - remember that from your General Science class at school?

As evaporation from a surface is proportional to (amongst many other things) the speed of the airflow over that surface, and uses heat from the surface in the process, the surface of your body is cooled by the evaporation of moisture from your skin.

There are Wine Coolers which use this exact effect to chill wine - they are made from a porous material, you soak them in water, and then place them in a breezy spot out of direct sunlight, and voila! - cooler wine!

[Panchocat]

Also if you use the A/C first for a couple of hours the fan is moving the cooled air around.

[Deniz1]

My ceiling fanjis quite big and quite new but does hardly anything to cool the room. floor standing fan works better for me plus ac for half an hour before bedtime.

[Keithcaley]

My ceiling fanjis quite big and quite new but does hardly anything to cool the room. floor standing fan works better for me plus ac for half an hour before bedtime.

Yeah, they don't actually cool the room - they will only cool surfaces like skin that have some moisture available to be evaporated.

A few weeks ago, I noticed that the ceiling fan over my bed didn't seem to be cooling me anymore, and when I looked at it closely, I realised that it was running in reverse! - it was sucking air UP from the room towards the ceiling, not blowing air down at me!

It turned out that my cleaner had accidentally moved the small switch on the side of the motor housing when she was cleaning the fan, and left it running the wrong way

It may be worth checking that your fan is actually 'blowing' and not 'sucking'...

Of course you do need to be in a more-or-less straight line with the fan pointing at you, so that the air from the fan does flow over your body, because it won't cool anything else that doesn't have any moisture content - it will just move the air about, as you say.

[sophie]

Despite having installed 3 new inverters for last winter I don't think any of them have been on more than twice all summer. I hate the idea of having windows and doors closed and much prefer fans. Insects don't like the fans and they can't cope with such "strong winds". Keith has explained in much more scientific terms why fans are better. On top which the A/c used to dry my throat and eyes. I always feel that if you have A/c going, it just makes going outside seem even hotter.

[Deniz1]

It is in downward mode.

[Keithcaley]

Ah well, 'each to his own' as they say!

Chill...........