suck or blow

[woppy101]

is it better to suck or blow through a rad at the min i have 2 fans blowing through but have two more which i can put on

 

[Aqua-Pc's]

errrmmm nice title

where is the fan in the case, top?

 

[woppy101]

the fan is on top of the rad on top of my case blowing through the rad into the case

i thought the title would get everyones attention lol

 

[Aqua-Pc's]

Mine blows the air into the case from the top - but the best thing to do is try both ways of doing it and see what works for you

 

[Yeungster]

I've got a top mounted rad, and I've tried it in both configurations, including the top case fan, and it makes minimal difference for me ie 1c

 

[limqareb]

i love it when they suck

no rly it should be a blow effect

 

[Allsorts]

Yeah I don't think there's a big performance difference between the two. Maybe add a poll to see which way is most common? If you have extra fans then you could add them to the other side of the rad and have them suck air through for a bit extra airflow.

 

[Mr. Smith]

There is a performance diff, its always better to get them to suck

Also known as 'pull'.

Pulling cold air in from outside the case is better than using warm air in the case

 

[Marci]

"Minimal difference" is a term used a lot for push vs pull. Realistically, in radiator performance terms that 1 degree is a HUGE amount of difference when you're talking temp changes in the regions of hundredths of a degree per watt of heat, which means that the setup with 1 degree colder temps could be able to remove up to an extra 50watts of heatload (if asked to) over the warmer setup.

Pull (suck) provides more even airflow which generally results in better performance over the same fan on the same radiator in push...

Will also compare shrouded, unshrouded, suck (pull), and blow (push) air-flows.

Was just messing with the equipment a bit last night, putting a Yate-Loon on a PA120.1 radiator with a shroud, in suck or blow arrangement. I was able to position the anemometer on the other side of the radiator to get an idea of the evenness of the air-flow through the radiator. Used the tachometer to measure the fan speeds, and the noise meter the fan noise levels. I haven't calibrated the fan noise levels yet to any base reference point, so I won't report the absolute values I got, just the relative values.

Free-air: +0dBA noise, 1480rpm speed

Shroud Suck: -2.7dBA noise (i.e. quieter), 1350rpm speed

Shroud Blow: -3.0dBA noise (i.e. quieter), 1460rpm speed

I found the noise level differences, and the fan speed differences to be quite intriguing. If the fan is spinning faster, it's pushing more air-flow in the blow-mode.

However, using the anemometer on the other side found that with the shroud, in blow mode, the air coming out the edges of the radiator had about an 80% higher velocity than the air coming out the dead-center. In suck mode, the overall air-velocity appeared lower (will need to measure properly later on full-testbed), but it was more even, with only about a 25% variation between the edges (higher) and the dead-center (lower).

So yeah - this throws a cloud over the general suck/blow debate. The fan appears to like to blow much better than to suck, but the air-flow is less even, even though it's of a higher velocity. The fan is also quieter in blow-mode.

It would appear (without further testing) that putting a fan into blow-mode on a radiator with a really deep shroud (60cm) to straighten out the air-flow would be the best way to go, but that's not terribly practical.

*snip*

It seems to be a scenario of while blow creates more air-flow, the unevenness of the flow through the core hurts performance. Performance does not scale linearly with air-flow, and so it's always better to have even air-flow over the entire core area, rather than some areas receiving twice the air-velocity of other areas.

Source: http://www.xtremesystems.org/forums/showthread.php?t=150261&highlight=fan-pull

 

[Mullet]

How does the pull/suck configuration compare to the push method where a thermochill performance shroud is fitted between fans and radiator?

 

[Marci]

No extensive testing has been done yet with shroud in either format to be able to give any conclusive results. The only definitive statement is that noise levels are decreased... there's anecdotal evidence out there for performance increases with low CFM fans, but pinning it to anything solid isn't possible as no testing has been done on a qualified calibrated testbed.

 

[HarryB]

Ide say suck and blow lol if u can get one on one side of the rad and one on the other or close enough it should be effective

 

[ichiban]

I have mine on suck mode and having shrouds will helps too.