Is sucking air through a heatercore better than blowing through it?

Mark Larson · 04-06-2003, 07:17 PM

I tried using a fan and shroud on my AX-7, thinking i would get the same results as people who build shrouds for heatercores. I didn't - my temps were up to 6-7°C higher than using the default layout.

Now i'm curious - does sucking air through a heatercore really work better than blowing air at it? Are heatercores designed to have air sucked through them instead of blown?

Any concrete results with people who decided to do this with good measuring equipment?

redleader · 04-06-2003, 09:19 PM

If it blows through, it leaves a big dead spot in the middle under the fan motor, if it sucks through its less of a dead spot.

At least thats how I look at it.

psychofunk · 04-06-2003, 09:53 PM

I know very little but maybe your fan is wasting time sucking air throught the connection seams, take a feel around maybe you might want to use something to seal so that the fan can only get air from the shroud and the shroud can only get air from the opposite side of the rad. Just an idea.

nOv1c3 · 04-06-2003, 11:23 PM

I run a swiftech daul 120 mm fan Rad and i tried it both ways pulling and pushing and didnt see a bit of deferent with my temps ...... I,m pushing the air through now just so i can run filters on my fans

Mark Larson · 04-08-2003, 09:26 AM

More answers and experiences?

bigben2k · 04-08-2003, 09:42 AM

Suck, don't blow. Eliminating the deadspot can actually gain you a degree.

A shroud is a must, preferably one for each fan (there have been some reports of better performance).

Of course it shouldn't really make a difference, if there's a fair distance between the fan and rad/core, but that should be more than one inch, for sure.

DigitalChaos · 04-08-2003, 09:42 AM

try it out yourself.. post results

imo, sucking > blowing

hara · 04-08-2003, 10:01 AM

A fan blows in a turbulent fashion but airflow is sucked in a laminar fashion.

Therefore, Sucking is better

Mark Larson · 04-08-2003, 10:03 AM

But with low airflow, such as a 7-volted L1A, isn't there a lot of airflow loss due to friction from a big shroud? I purposedly made mine around 1" tall because i felt making it taller would increase airflow loss due to friction...

redleader · 04-08-2003, 03:55 PM

Friction with what?

babyeater · 04-08-2003, 04:07 PM

I noticed a one degree temp diference for the better going from sucking to blowing.

04-06-2003, 07:17 PM	#1
Mark Larson Cooling Neophyte Join Date: Feb 2003 Location: MN Posts: 67	Is sucking air through a heatercore better than blowing through it? I tried using a fan and shroud on my AX-7, thinking i would get the same results as people who build shrouds for heatercores. I didn't - my temps were up to 6-7°C higher than using the default layout. Now i'm curious - does sucking air through a heatercore really work better than blowing air at it? Are heatercores designed to have air sucked through them instead of blown? Any concrete results with people who decided to do this with good measuring equipment? __________________ AMD Fanboy.

04-08-2003, 09:26 AM	#5
Mark Larson Cooling Neophyte Join Date: Feb 2003 Location: MN Posts: 67	More answers and experiences? __________________ AMD Fanboy.

04-08-2003, 09:42 AM	#6
bigben2k Responsible for 2% of all the posts here. Join Date: May 2002 Location: Texas, U.S.A. Posts: 8,302	Suck, don't blow. Eliminating the deadspot can actually gain you a degree. A shroud is a must, preferably one for each fan (there have been some reports of better performance). Of course it shouldn't really make a difference, if there's a fair distance between the fan and rad/core, but that should be more than one inch, for sure. __________________ WBTA (Water Block Testing Alliance) Nordic Hardware WC 101

04-08-2003, 09:42 AM	#7
DigitalChaos Cooling Savant Join Date: Jan 2002 Location: Waukesha, Wi Posts: 698	try it out yourself.. post results imo, sucking > blowing __________________ http://www.digitalsimplicity.com/eatme/

04-08-2003, 10:01 AM	#8
hara Cooling Savant Join Date: Oct 2002 Location: Malta, Mediterranean Posts: 662	A fan blows in a turbulent fashion but airflow is sucked in a laminar fashion. Therefore, Sucking is better __________________ - Every great HD crash day is the day before back-up day. - My Past System - "Better to reign in Hell than serve in Heaven." - Milton, Paradise Lost. - FMZ

04-06-2003, 09:19 PM	#2
redleader Thermophile Join Date: Jun 2001 Location: The deserts of Tucson, Az Posts: 1,264	If it blows through, it leaves a big dead spot in the middle under the fan motor, if it sucks through its less of a dead spot. At least thats how I look at it.

04-06-2003, 09:53 PM	#3
psychofunk Cooling Savant Join Date: Jan 2003 Location: Los Angeles Posts: 365	I know very little but maybe your fan is wasting time sucking air throught the connection seams, take a feel around maybe you might want to use something to seal so that the fan can only get air from the shroud and the shroud can only get air from the opposite side of the rad. Just an idea.

04-06-2003, 11:23 PM	#4
nOv1c3 Crazy Stupid Join Date: Nov 2002 Location: Dallas texas Posts: 149	I run a swiftech daul 120 mm fan Rad and i tried it both ways pulling and pushing and didnt see a bit of deferent with my temps ...... I,m pushing the air through now just so i can run filters on my fans

04-08-2003, 10:03 AM	#9
Mark Larson Cooling Neophyte Join Date: Feb 2003 Location: MN Posts: 67	But with low airflow, such as a 7-volted L1A, isn't there a lot of airflow loss due to friction from a big shroud? I purposedly made mine around 1" tall because i felt making it taller would increase airflow loss due to friction... __________________ AMD Fanboy.

04-08-2003, 03:55 PM	#10
redleader Thermophile Join Date: Jun 2001 Location: The deserts of Tucson, Az Posts: 1,264	Friction with what?

04-08-2003, 04:07 PM	#11
babyeater Cooling Neophyte Join Date: Sep 2002 Location: Ireland Posts: 42	I noticed a one degree temp diference for the better going from sucking to blowing.

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