Does a fan cool a room?


Old 06-07-06, 04:27 PM
mjd2k's Avatar
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Does a fan cool a room?

Having a discussion with dissenting relatives. I suggested there is no value in running a fan if no one is in the room. The air is not cooler because of the just feels cooler because of air movement....which is the same effect as turning the fan on when you enter the room.

My brother wants to forgo installing AC by installing overhead fans in each room with thermostats so the rooms will be cooler when they get home.

.....Fans in each room...I've done that. .....leaving fans running all day when no one is home......doesnt' make sense to me. ....Just turn them on when you get home.

PS: I leave my overhead fans in reverse during he day whem when my AC is on so cold air is drawn upwards.

What do you people think?

Hope I'm right
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Old 06-07-06, 04:57 PM
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A fan moves air. It does not cool it.

If you want to get really technical a fan actually heats the room. All the electricity consumed by the fan eventually becomes heat. The motor gets warm/hot at it runs and the friction of the moving air makes heat.

Hot air rises and cold air sinks. A fan will stirr up the air helping to keep a more uniform temperature from ceiling to floor meaning the fan generally keeps the floor warmer and the ceiling cooler. This is why running a ceiling fan slowly during the winter is a good idea (you set it to blow up so it stirs the air but you are less likely to feel a draft).

Moving air takes the heat away from your skin much faster than still air. Water evaporating from your skin increases this effect. So if the air is blowing on you you feel cooler even though the fan is ever so slightly heating the room. So, use the fan when you are in the room and can feel it's cooling breeze, otherwise you are just wasting electricity and actually making things warmer.
Old 06-07-06, 06:37 PM
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Pilot Dane is 100% absolutely right.
Old 06-07-06, 06:43 PM
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Running a fan with a fresh air source may lowwer tempatures but really only helps if it is drawing air from a cooler location [possibly a shaded side of the home]
Old 06-07-06, 06:57 PM
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If you want the fan to cool a room install a ceiling fan to blow the hot air down then use a fan in the window to blow the hot air out.

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