Intake, Exhaust or Both?

Stephen73ta · 05/07/2009, 01:42 PM

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 · 05/07/2009, 02:14 PM

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

Henry Bowman · 05/07/2009, 02:15 PM

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 · 05/07/2009, 02:19 PM

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 · 05/07/2009, 02:20 PM

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 · 05/07/2009, 02:39 PM

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 · 05/07/2009, 03:00 PM

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 · 05/07/2009, 04:38 PM

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 · 05/07/2009, 05:37 PM

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

Entropy · 05/07/2009, 07:03 PM

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 · 05/10/2009, 10:53 PM

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 · 05/11/2009, 12:33 PM

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 · 05/11/2009, 06:51 PM

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.

05/07/2009, 01:42 PM	#1
Stephen73ta Registered Member Join Date: May 2009 Location: Austin, TX Posts: 178	Intake, Exhaust or Both? 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.

05/07/2009, 02:15 PM	#3
Henry Bowman Reefing since '87 Join Date: Jul 2006 Location: Allegheny Mountains of VA Posts: 2,162	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.... __________________ Have a good'un Current Tank Info: 90 gl SPS dominant / upgrade in the works

05/07/2009, 02:19 PM	#4
ravedood Registered Member Join Date: Apr 2008 Location: Pembroke Pines, FL Posts: 1,540	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. __________________ Florida Marine Aquarium Society Member --Ben

05/07/2009, 02:20 PM	#5
Entropy Texas Reefer Join Date: May 2003 Location: Round Rock, TX Posts: 13,656	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. __________________ Rich Overton 150G cube FOWLR, 30g sump, ReefKeeperII, 3x Koralia 1400's, QuiteOne 3000, Reef Octopus DNWB150, 4x 30w Par38 LED. Current Tank Info: 36x36x27 150g

05/07/2009, 02:39 PM	#6
Stephen73ta Registered Member Join Date: May 2009 Location: Austin, TX Posts: 178	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? __________________ 29 Gallon 20x13x15" Acrylic/Rimless, Coast2Coast overflow, Mag 5 return pump Current Tank Info: 40g Rimless Starfire Cube, external C2C Bean Animal Overflow

05/07/2009, 02:14 PM	#2
x2uranium Registered Member Join Date: Dec 2007 Location: Pittston, PA Posts: 1,257	one each way, also, I hear that one on each End is better than the back.

05/07/2009, 03:00 PM	#7
Henry Bowman Reefing since '87 Join Date: Jul 2006 Location: Allegheny Mountains of VA Posts: 2,162	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. __________________ Have a good'un Current Tank Info: 90 gl SPS dominant / upgrade in the works

05/07/2009, 04:38 PM	#8
james3370 Registered Member Join Date: Aug 2008 Location: US ARMY - El Paso TX Posts: 3,678	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 __________________ Yes I hear voices in my head, but they speak spanish so I can't understand anything they say. there's no place like 127.0.0.1 It's a shame that stupidity isn't painful.... Current Tank Info: currently tankless....but planning an AIO

05/07/2009, 05:37 PM	#9
Stephen73ta Registered Member Join Date: May 2009 Location: Austin, TX Posts: 178	yeah i think i will get a vent cover to cover the fans and to cover the ventilation holes __________________ 29 Gallon 20x13x15" Acrylic/Rimless, Coast2Coast overflow, Mag 5 return pump Current Tank Info: 40g Rimless Starfire Cube, external C2C Bean Animal Overflow

05/07/2009, 07:03 PM	#10
Entropy Texas Reefer Join Date: May 2003 Location: Round Rock, TX Posts: 13,656	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. __________________ Rich Overton 150G cube FOWLR, 30g sump, ReefKeeperII, 3x Koralia 1400's, QuiteOne 3000, Reef Octopus DNWB150, 4x 30w Par38 LED. Current Tank Info: 36x36x27 150g

05/10/2009, 10:53 PM	#11
strayvoltage Registered Member Join Date: Nov 2006 Location: Deming,N.M. Posts: 1,919	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.

05/11/2009, 12:33 PM	#12
rickh Registered Member Join Date: Aug 2005 Location: Lost_in_Michigan Posts: 1,306	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

05/11/2009, 06:51 PM	#13
strayvoltage Registered Member Join Date: Nov 2006 Location: Deming,N.M. Posts: 1,919	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.