Different fans either side of radiator - disadvantages?

J

joxang

Limp Gawd
Joined
Oct 30, 2010
Messages
279
Is there any disdavantage to a push pull set up where you have different makes of fan on either side of a radiator?

E.g. Yate loon slim fans pushing, and GTs pulling.

I'd like a set up like this because I can't fit normal sized fans in front of the rad where I've modded the case.
 
As long as one fan isn't too powerful over the other one should be fined.
 
Shouldn't cause any problems at all. Blowing air through a radiator isn't exactly a precision process that requires balanced fans. ;) Just as long as air is moving, you're good.
 
i have different fans on my 360 rad. 3 Noiseblockers and 3 Thermaltakes.

not sure if this is correct but i've put the more powerful fans (noise blockers) on back of rad (pull).
i believe it's probably better to have the stronger fans in the 'pull' config so as not to create too much 'back pressure'?

again this isn't a scientific approach and could be wrong, just seems logical to me.
 
aphasia said:
i have different fans on my 360 rad. 3 Noiseblockers and 3 Thermaltakes.

not sure if this is correct but i've put the more powerful fans (noise blockers) on back of rad (pull).
i believe it's probably better to have the stronger fans in the 'pull' config so as not to create too much 'back pressure'?

again this isn't a scientific approach and could be wrong, just seems logical to me.
Click to expand...

Yes, you are probably correct in assuming pull is better than push (i.e. negative pressure is more efficient at moving air through a radiator than positive pressure.) But it's negligible unless the fans are rated significantly different. Even still it doesn't make much of a difference. You're good to go.
 
Considering a fan is mostly open, I don't think you can really get a pressure build up on either side...not with PC fans at least. You should be good either way, but I'm not sure how much you gain from the slim fans.
 
I checked on this a few weeks ago, found some solid numbers here http://www.xtremesystems.org/forums/showthread.php?t=189402

These tests are a bit more extreme with at least one of the fans being 3k rpm, but the numbers are fairly solid and tend to scale for the lower ones as well. Basically, air is being forced into the radiator, where it slows down, so having a slightly slower pull fan is better than having a slower push fan. If you mismatch too much, one fan could cause more pressure resulting in poor performance, or the slow one could spin faster burning out the motor sooner. If you buy identical fans, the pull fan will spin a little faster. In the long run, you want them close, but if one is a few hundred rpm slower, put it on the pull side since the air has slowed down from being forced through the radiator. As aphasia said above, this is not an exact science, as there are more factors to consider (static pressure for example) but the general consensus is to keep them close to reduce chop noise and maintain performance without burning out fans too quickly.
 
mhenley said:
I checked on this a few weeks ago, found some solid numbers here http://www.xtremesystems.org/forums/showthread.php?t=189402

These tests are a bit more extreme with at least one of the fans being 3k rpm, but the numbers are fairly solid and tend to scale for the lower ones as well. Basically, air is being forced into the radiator, where it slows down, so having a slightly slower pull fan is better than having a slower push fan. If you mismatch too much, one fan could cause more pressure resulting in poor performance, or the slow one could spin faster burning out the motor sooner. If you buy identical fans, the pull fan will spin a little faster. In the long run, you want them close, but if one is a few hundred rpm slower, put it on the pull side since the air has slowed down from being forced through the radiator. As aphasia said above, this is not an exact science, as there are more factors to consider (static pressure for example) but the general consensus is to keep them close to reduce chop noise and maintain performance without burning out fans too quickly.
Click to expand...

That makes sense. Though, I'd still say the margin is so minute that for the OP it's null.
 
As long as the fans move a similar amount of air, you should be fine. I had 2 different fans on my H70 RAD, one of my stock case fans and one of the corsair fans that came with it. With both fans on, I found it to be a lot nosier than just using one of either fan.

Of course, it wouldn't hurt anything to try it any way you want. The worst that could happen is it wont work as well or be a bit noisier.
 
Well... if you want to use different fans... make sure you install the fan rated with higher CFM as PULL ... but either way, your airflow will be handicap ... but nothing like trying ;)
 
IMO have your stronger fans pushing, maybe its just me though but I'd think it would move a bit better.
 
hiodie said:
Considering a fan is mostly open, I don't think you can really get a pressure build up on either side...not with PC fans at least. You should be good either way, but I'm not sure how much you gain from the slim fans.
Click to expand...

There is always static pressure in any setup, including inside a PC. The fact the ends of the fan are open is irrelevant (even for case fans that have nothign up against them). Static air pressure is the pressure exerted by air when it is not moving. A fans static pressure rating is how much static air pressure it can overcome to get air flowing properly (few PC fan makers publish their static pressure ratings though :mad: )
 
ever take a fan and put it flat against the ground? You notice it especially with 38mm Deltas--they spin incredibly fast because they don't have as much resistance, because there is no air (or, at least, a very insignificant amount of air) going through them.

Taking that case to dual fans of different speeds, if you put the lower speed pushing and the higher speed pulling, there will be less pressure difference between the front/back of the faster due to the slower "helper" fan. Less pressure means that the fan will spin faster for a given voltage because there is less resistance=more air flow.
 
Thanks for all the info in the thread. I'll go with the slim YLs and the GTs and test both configs for noise and temps.
 
mtb2005 said:
ever take a fan and put it flat against the ground? You notice it especially with 38mm Deltas--they spin incredibly fast because they don't have as much resistance, because there is no air (or, at least, a very insignificant amount of air) going through them.

Taking that case to dual fans of different speeds, if you put the lower speed pushing and the higher speed pulling, there will be less pressure difference between the front/back of the faster due to the slower "helper" fan. Less pressure means that the fan will spin faster for a given voltage because there is less resistance=more air flow.
Click to expand...

Aye, but spinning faster will burn the motor out and wear the bearing(s) faster than under normal conditions. To each their own, but if I'm dropping some bucks for fans, I don't want them burning out in a few months.

OP: As long as you're comfortable with performance and noise level, that's what really matters. Obviously, as this thread shows, there are different opinions, theories and techniques. Good luck with your setup, and if you wouldn't mind, post some numbers back as to what your load temps are and which orientation you chose.
 
You must log in or register to reply here.
Back
Top