ok need some help on these fans please

[Boar]

Just tried one of the computer fans an these things are way to flipping powerful, an I mean way! dose anyone have specifics on computer fans that ur using in ur perm. cause there is a jillion of them out there an dont know wat to use. the fn i got is a five inch fan but it could blow a sail boat agint the wind. Are u simply using the one that u take right out of a hard drive? which would be a like a 2.5 inch fan. Any help would be great. thanks

[CAMAN]

You could do that, or place a rheostat onto the positive wire and make the fan speed variable. It would also be much quieter and less buffeting of air than the smaller fan.

[Boar]

thanks caman, wat about a computer fan with three leeds, red, black an white, red is pos, black is neg, an white would be nuetral right just tape it off?

[CAMAN]

The white wire is a speed sensor telling the computer the fan speed. It can just be clipped short and capped.

[Boar]

Ok cool, beans, I understand the reostat, where could i get those, an would it slow the fan enough so it dosent cool the air but circulate?

[Rang64]

Radio Shack.And,Yes it will slow fan way down. I use a computer fan with a reostat in my portable.

[Boar]

Thanks rang, an welcome to the forum! Hers my next uestion, after doing some research onthem, itsobvious that there are diffeent sizes per application, my fans are 12v 2.78A would one the size u'd use for a dimmer on a kitchen light work? Hw dose one detrmine wat size to use?

[CAMAN]

You can use most any standard dimmer. A standard household dimmer is probably rated at 15 amps. Add the amp rating of all the fans you are planning to use and try not to go over that 15 amp rating. Also make sure the wiring is capable of handling 15amps. Also an inline fuse or circuit breaker rated at 15 amps is always a good idea.

[Boar]

Thanks alot! this helps so much, relly appriciate the help. As along as I dont go over the rated amps on the rheostat im good to go. thanks boar

[low277]

Wow, those fans must be rated at close to 200 cfm? How loud are they?

[ORGMaster]

You could simply add a resistor inline to knock down the speed. These fans require a minimum 5v to start. By calculating your amps it looks like around a 30ohm X 1/2 watts would be a good place to start. The resistor will get warm as it bleeds off the excess juice, so give it some space.

A house rheostat sound pretty bulky for your application.

Another idea is to use a $.50 potentiometer or "pot" from the radio place.

Then you can control the fan's speed.

[Boar]

a pottentiometer? is that the picture u have there? doing research looks just like a rheostat. Yeah the fans might be over kill, their not to loud I think they were rated for 180cfm i questoned that but since I didnt know where to begin with computerfans, an the little hard drive ones from PC's seem to small I figured these would be the ticket. thanks for all the help guys like learning this stuff.

[CAMAN]

From reading Boars replies, it sounded to me like he has a few fans and installing them in a permanent. A $.50 POT probably isn't built for that amount of current.

[Boar]

Ok so hears the deal, I decide to ruffly istall things to get a better idea of wat going on instead of just holding the fan in my hand and saying WOW thses things are to powerful, I hooked everything up an an mounted the about 2inches from the cieling, an fired them up. at first I thought to much power. So I turned on the heater to medium, now granted im in my back yard an not on the lake on over ice, but its still 26 degrees out but no wind. any way I put a thermomter on the floor after about an hour of the fans runnning an it the floor temp read 70 degrees, plus the fans seem to be pushing the same temperature air, when I first started them they pushing cool air but the air has equalized an circulated enough so that their pushing equal temps. I think its time to dance! Still gointo get a rheostat I like thae idea of controlling flow. Thanks for everyones help, Good luck fihing! Later , boar

[low277]

How many fans are you using?

[Boar]

Just two I have a 17 ft camper but thats a length from bumber to hitch. the inside space would be equivolent to probabley 6x8 maybe 6x9 house

[efgh]

I beleive AC. amps are not the same as DC. amps, I could be wrong though.

[skyhawk]

You're right sort of. Amps are amps, what changes is component ratings. A switch rated for 15 amps AC would not handle DC. Same with wire, a given size wire has 2 ratings, 1 for AC 1 for DC.