Installed some fans

[StirCrazy]

well i went down to radioshack and picked up a couple AC fans, they push 65 Cu/Ft each and run at 38 decibles .. so you can barly hear them.

I cut a hole in the top of my stand and mounted a fan there that pushes air down into the stand over the lights and onto the surface of the water. her is a couple pics of that one.
http://members.shaw.ca/stircrazy/stand/fans/topfan.jpg

http://members.shaw.ca/stircrazy/stand/fans/topfan1.jpg

the second one is high up in the riser part of the cabnet and it is to pull hot air out of the cabnet.. heres the pic
http://members.shaw.ca/stircrazy/stand/fans/insidefan.jpg

I plant on installing one more fan pushing into the stand above the other end of the light rack yet, and I still have a bunch of sealing to do to help creat a directional air flow through the stand. Once this is done the top fan that pulls air out will run all the time and the other two will be staged to come on when the MH is on or when it gets to a preset temp.

Steve

[StirCrazy]

well I thought about that but no it doesent.. the average temp has benn lowered more than when I had the external fans going..

if you look at the heat capacity of air it is 1/2 that of water.. so in effect the increased evaporation has more of a effect than the brief time the hot air is blowen at the water.

oh, thermal engineering is also part of my Job :D : D

Steve

[ 04 September 2002, 17:06: Message edited by: StirCrazy ]

[FishGeek]

And here I was trying to sound all smart!!!!! tongue.gif

[FishGeek]

Hi there! If you push the air past the MH lights and onto the surface of your water, isn't that going to have a heating effect on your water? All your doing is pushing hot air to the waters surface. And if heat travels from hot to cold, it should heat your water. Just a thought! Any thermal engineers here have any thoughts on this?

Simon

[Delphinus]

Actually I was kind of wondering if the warmed air might actually have an effect to increase the water evaporation and thus actually cool the water faster. Seems counter-intuitive almost, until you realize just how effective evaporation is at cooling the "evaporatee." (So long as the air has somewhere to go, quickly, after it contacts the water surface.) Thanks for asking the question, Simon; and thanks for answering, Steve; that was a very interesting point to ponder and it kind of confirms that theory! smile.gif

(PS. Great, now I think I've learned something. No wonder my head hurts! ;) )

[ 05 September 2002, 08:48: Message edited by: delphinus ]

[Dez]

Question Steve, Isn't 38 db pretty loud? I got a fan from radio shack (in fact you saw it when you came over), and the fan is the loudest thing on my tank right now, and that fan is rated at 32 db (it's only the 3" fan). I'm looking for 2 for inch fans now. Anybody know how to run DC fans into AC? I heard that DC fans are a lot quieter. I need these fans pretty quickly. Thanks.

Des

[canadawest]

Check out this thread from a couple months back when I outfitted my hood with a pair of DC fans.

DC Canopy Fans (http://www.canreef.com/ubb6/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=7;t=000122)

Should answer many of your questions about adding quiet DC fans to your system. Mine work excellent to cool the tank, have increased evaporation (which improves cooling) are adjustable in speed and most importantly are DEAD QUIET

[StirCrazy]

Originally posted by Dez:
Question Steve, Isn't 38 db pretty loud? I got a fan from radio shack (in fact you saw it when you came over), and the fan is the loudest thing on my tank right now, and that fan is rated at 32 db (it's only the 3" fan). I'm looking for 2 for inch fans now. Anybody know how to run DC fans into AC? I heard that DC fans are a lot quieter. I need these fans pretty quickly. Thanks.

Des<font size="2" face="Verdana, Helvetica, sans-serif">hey Des, my skimmer is louder than my fans.. well about the same I guess but the trickeling of water i have going down to my sump is louder so I don't even hear the fans at all. if you are interested about 1/2 way down this PAGE (http://www.glenbrook.k12.il.us/gbssci/phys/Class/sound/u11l2b.html) there are some good examples of what kinda noise compares to what db levels.. your 32 db fans should barly be able (if at all) to hear them across your room.

I chose AC fans because of the power, DC fans are quiet but the move less air and the ones that do move this much air are louder *Usaly* there are some expensive DC fans out there that are quite.. one word of caution about computer fans is that they will start to fail quicker than AC fans and become loud. *unless you have one of the expensive ones* also a big reason I chose the AC fans was simplicity.. I just put the wires in series with say my MH and when the MH comes on the fan will come on..

Steve

[Delphinus]

You'll need a DC power supply aka "wall wart." You can get them pretty much about anywhere that sells electronics. I've generally found good deals at "Princess Auto" (I think there's one of these up your way -- check www.princessauto.com) (http://www.princessauto.com))

[reefburnaby]

Hi,

38dB is loud ? Well, that's about as quiet as a quiet library or office.

Low noise fans are usually the low RPM ones and you can try the ones from computer stores (the mom/pop kind...not future shop). As an example, www.ncix.com (http://www.ncix.com) sells a couple of case fans.

- Victor.

[Delphinus]

Actually Steve I want to jump in here and second what you say about DC fans failing. My other mental illness ... er ... hobby is growing orchids and one particular interest I had are pleurothallid alliance which require very cool temps and VERY high humidity. Thus, over the years I've made various attempts at terrariums. But basically because of the high humidity in these terrariums, I found myself burning through 12VDC fans like kleenex. I remember at one point I was replacing them every 3-4 months. Not that they were very expensive to begin with, but, what a nuisance. And potentially bad, when high temps are very bad.

My AC fans over my 50g, they may be loud, but, they move a TON of air and they are rock-solid-bulletproof. That said, I have loud fans because I cheaped out. I think I paid $5 each for them at Princess Auto. There are others that you can get at hydroponics outfits, etc. for a little bit more that don't make as much noise. But I live with the noise for the peace of mind that the temps are under control.

Over my 75g I sprung and bought myself some Icecap fans. They're quiet, but .... they were $75 each. Ouch. (Mind you, they come with a thermostat controller that sets the fans to one of three speeds depending on temperature. So that's supposed to be a nice feature. That said, I've only ever noticed my fans running at one speed. I must have my thermosensors located poorly. But I digress..)

[Dez]

Thanks for all the responses. I found some 4 inch DC fans which push 74 CF of air. I hooked them up to that adapter and you can vary the speed of it as well according to voltage. They are actually quite quiet. I was thinking of making an enclosed hood to avoid moisture in basically everything. Or what else I could do is run open tops and have both fans blowing in with ventilation slats on the top of my hood. What do you guys think? Or is there a way to vary the speed of AC fans with maybe some sort of dimmer?

Des

[Delphinus]

Supposedly you use something called a "rheostat" to vary the speed of an AC fan. Whether this is the exact same thing as a light dimmer, or not, is something I have not been able to get a straight answer on. Would sure love someone to answer that one! smile.gif