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-   -   fans vs a/c, and diminishing returns? (http://www.houserepairtalk.com/f8/fans-vs-c-diminishing-returns-4446/)

Philphine 06-17-2008 08:29 PM

fans vs a/c, and diminishing returns?
 
at my last house i got into the habit of sticking a fan in front of the back door and letting cool air from the shady backyard in in the morning. once the a/c kicked on i just shut the door and let the a/c work. it kept the air off a little longer in the mornings.

now in my new home i do the same with one fan in a kitchen window. here though, i have two bed rooms that have a jack and jill halfbath bettween them, and if i keep all the doors open i can kind of get a circular draft going. i can barely tell, but if i burn an incence stick the smoke moves very slowly following the path. there's also a ceiling fan on pretty much all the time, a/c or fan, in the den (part of the circle), and i'm planning on adding one in each of two bed rooms (one is in this circle)

the question is, i could get this to work better with more fans along the pathway of this circle, but at what point am i losing the benifit of keeping the a/c off?

i mean, i know the a/c pulls more wattage than a fan, but i'm sure if i have a bunch of fans going it will add up to the same or more wattage (not to mention the noise of a bunch of fans running).

partially, i just like playing with a breeze in my house, but not if it actually costs me more than just running the a/c. thanks for any help.

should have added it's central air. i don't know what size it is but it's cooling a smallish 3br one level ranch style house so i guess it's not real big.

glennjanie 06-19-2008 11:51 AM

Hello Philphine:
Fans work very well when they are blowing on you; they can lower the temperature as much as 7*. They can also work well to draw in cool air from a shaded area. The key is to watch the humidity which your ari conditioner handles real well. With the humidity lowered to around 59% and a fan blowing on you can be very comfortable.
I wonder how much humdity you are taking in the house in the morning; since I live down the Ohio River from you, I'm sure you get plenty. You might want to try running your air conditioner temperature up to around 75* and using a fan to blow right on you. That should keep you chilled even if you're working.
Louisville Gas and Electric says that raising the air conditioning temp by 2* can save as much as 10% on your bill. Average billing also makes it easier to budget your electric cost. It stays the same the year around and they settle up in July; sometimes we get a credit for half or more that month and sometimes we have to pay $50 or so.
Glenn

Philphine 06-21-2008 07:24 AM

the t-stat setting is something i have going for me right now. my wife is away and i don't like being that cold, so it's set at 80.

that's one reason i can play with this right now. i can fool around with fan positions and which windows to try and see how cool the house can be with less a/c.

so far it seems like three fans do pretty good. two in windows on opposite sides of the circle and one in a hallway kind of opposite of the den (that kind of accelerates the breeze and being away from the den where i am most of the time, isn't as noisy).

i kind of forgot about that the fans run constantly, more or less, and the a/c kicks on and off. i guess that would be a factor too.

glennjanie 06-21-2008 12:33 PM

Hello Philphine:
Your 80* setting will save you even more. Your fans running constantly will not use as much power as the compressor in the A/C, even if it does run intermitently. As long as your A/C keeps the humidity down the fans will do a wonderful job.
Glenn


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