Intake, Exhaust or Both?

[Stephen73ta]

I have two 4 inch computer fans that i am going to install in my stand, should i have them bringing air in(intake) or bringing air out(exhaust)? or possibly one going in and the other going out.. i'm looking to maximize airflow to reduce temperatures.

The fans will be mounted on the back of the cabinet.

 

[x2uranium]

one each way, also, I hear that one on each End is better than the back.

 

[Henry Bowman]

Both blowing air IN....with some vent or way to exhaust. Running fans under a hood or in a stand will suck water and humidity through them thereby causing them to rust quicker.

Point them in, set and forget....

 

[ravedood]

The best way is if you have the fans blow cool air into the hood from the sides and have the hot air naturally escape out of holes on the top. Hot air naturally rises also your fans will last a lot longer since they will not be sucking out hot, moist, salted air.

 

[Entropy]

IMO pulling air out and placed in the top of the canopy is the best setup. Hot air rises so if you vent it from the top you get the hottest air. I agree with Henry on the wear on the fan, but a good CPU fan costs about $4 for a 28db (silent) fan, so I just consider it a consumable item. If it lasts six months and then dies, oh well. I buy them five at a time so no biggie.

 

[Stephen73ta]

ok, but this isn't for a canopy! my light fixture is free hanging and open..

I'm putting the fans in my cabinet for the sump! there will be only a small compact light for the fuge, other than that i'm just trying to decrease temp.

If I point both fans inward, I guess I should cut some hole for ventilation?

 

[Henry Bowman]

Yup,

Cut / drill some holes along the top (be careful not to degrade the integrity or strenght of the stand). I'd drill sevral 1/2" holes around the top 4-5" apart.

 

[james3370]

here is what i am gonna do in my stand (take a look at the build thread to see it)

since my stand will be all enclosed, in the bottom of the door on the skimmer side, i am installing (2) 120mm pc fans. there will be one of these ac vent covers. the side door on the opposite end of the stand will have just the cover & holes. the louvers facing down should allow the air to circulate pretty well, but cut down on the light creep

additionally, since the stand was designed to encompass all the rear plumbing, there are a few holes in the very top for the plumbing, so rising hot air will be able to escape there as well

 

[Stephen73ta]

yeah i think i will get a vent cover to cover the fans and to cover the ventilation holes

 

[Entropy]

You will have to tell us how that works out. I have been thinking about enclosing the back of mine to cut down on the skimmer noise in the still of the night. I am worried about moisture and heat though.

 

[strayvoltage]

I agree with Entropy, the fans are cheap enough that you can call them consumable items. I use the fans to pull the hot air out. If you push air in then you are also going to push dust and other particles in. Here is how I am using the fans.
I had one of the ones like james3370 put the link to but it was only until I made the wooden one.
Entropy, my stand is completly closed in and it was so hot in there with the doors on is why I vented it.

DIY vent

Fans mounted inside with velcro. Makes for easy removal to clean and or replace.

 

[rickh]

strayvoltage

I am afraid you need more or larger holes in you grill for the fans to perform properly.

I always have my fans blowing air into a canopy. After replacing several fans blowing out of the canopy I tried blowing air in and the fans lasted much longer. R

 

[strayvoltage]

rickh, thanks for the heads up but the fans are doing a fine job at keeping the enclosed stand cool. I can feel the air on the outside through the holes at least 12" away. I agree that the fans will last longer if they are not pulling the hot air through them. But the air from under the stand it not nearly as hot as the air in a canopy.

I don't worry about the fans going out, I have about 50 of them laying around and will replace them as needed.