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Do you push or pull with your fans?

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Do you push or pull with your fans?

  • Push

    Votes: 53 25.1%
  • Pull

    Votes: 36 17.1%
  • Push + Pull

    Votes: 106 50.2%
  • I make both sides face each other

    Votes: 16 7.6%

  • Total voters
    211

BachOn

Member
Joined
Aug 4, 2011
-------------------------------------
I plan to get a new 120x3 radiator soon. Using a combination of 6 fans in a push-pull arrangement is probably the option for the best cooling. But it adds to the cost and could create more noise.

If I start with just 3 fans then I have to make a choice of pushing the air into the radiator or pulling the air through the radiator. I can see merits in both methods.

I thought I'd try to pick the brains of the people here. Planning the construction for the housing of my radiator can start before I buy it. But the fan arrangement may determine some factors in this construction. I'm trying to look ahead.

Which arrangement have you found works best on your systems? Or does it vary depending on the radiator and/or the fans?

Bach On:p
 
Why don't you add a poll to this thread? Just throwing it out there. When I had my single rad I had push pull. My new setup will have the fans pushing the air threw the top mounted rad(exhausting case air) and the back will be the same:D
 
Hoy crap that was the fastest response I have ever seen in my life. :rofl: you replies and added a poll in less than 3 minutes. Way to go. LMAO
 
If you get a MCR 320, no need for push/pull: with low FPI, the airflow finds its way easily.
 
What Manu said. I had an MCR320 and will have 2 more next week. The only reason I did push pull is because I had the exta fans laying around:) the QP series are only 12-13fpi and XP series 20fpi IIRC.
 
You should add a push AND pull option for the poll so some of us that have that setup would be selecting that :p
 
I use pull. Low FPI thick rads, Yates mediums before, now GT AP15's. My TC rad has a shroud (uneeded buy because I saw others said it was needed long ago). My XSPC RX has no shroud.

Martins tests showed better temps at low FPI and RPM for my rads. I have filters on the rads.

Filter/rad/fan, exhaust blows over my PC. Not a lot of air, but why not use what I have. No dust problems, I dust every 6 months, I don't have a dusty environment. I also use a tech station, so less airflow over the mobo and other parts.
 
Has anyone tried three fans on push without a shroud and one fan on pull with a shroud?

I've wondered if three fans pushing at low speed would force the air in and through, then a single fan pulling at a higher speed within a shroud might move that warmer air away from the radiator area.

Too much filtering can cut way down on the amount of air going through the radiator. I use electrostatic foam from a whole-house heating and air conditioning filter. It's thin, but the material is effective for removing very small molecules the cause smells. That includes dust. And it is easily washable. I found it at a home improvement store with the regular heating/AC filters. Seems like it was in a 24x30 size. And the plastic frame can be cut to fit different size needs. Not real cheap, but will last a very long time.

BTW, the filter is a reason I'd think a shroud might be a plus for pushing.

Bach On
 
Pull for my rad setup... for the same reason Conundrum listed. I have that same rad (+ a PA120.2) and Yate Loon High fans. No filters (vacuum FTW!).
 
From Martins Archive:

http://martinsliquidlab.petrastech.com/Radiator-Fan-Orientation-And-Shroud-Testing-Review.html

"While I didn't complete the full series of tests, this was enough for me to see there is some emerging trends going on. The push vs. pull question appears to really depend on the fan power. I believe the gains in the 38mm showing more benefit in push is due to pressure and turbulence. At these stronger speeds, the added pressure compressing the air along with higher turbulence across the radiator in push is providing the best benefit. This appears to change however for the lower speed fan where pull actually does better. I believe at this slower speed pressure and air flow is so slow that it's simply not turbulent enough to show gain in push and the radiator performs better with the more evenly distributed air flow over the radiator that's provided in a pull condition."
 
OK. I did a few calculations on a spreadsheet.

The surface area of a radiator covered by a 120 mm fan is roughly 14,400 mm. (Yes, the corners are usually slightly rounded, but this is still pretty close.)

Most fans of that size will have blades that are maybe 110 mm wide. (See below). They will cover an area of roughly 9,503 mm.

But the hub where the motor is located will probably have a diameter of maybe 50 mm. That is an area of roughly 1,963 mm.

So the actual area where the blades are moving air (minus the motor area) is roughly 7,540 mm.

So I figure the actual cooling portion of the fan is only 7,540 mm of the 14,400 mm area of the radiator. That's only 52.4%.

Please check me on my math. But if it is correct, having the fans in direct contact with the radiator surface is going to greatly reduce the area where the air is being blown through that radiator.

So putting the blades maybe an inch or so from the surface of the radiator would probably increase the actual percentage of the radiator in which the air will flow.

Thus, it would appear that a shroud could help increase the actual cooling area of the radiator in a push configuration. And the same factors could also come into play in a push-pull configuration.

So, is my thinking flawed?

Bach On
 
Yes, Martin discusses it in the link. He said about 30mm was pretty good if I remember right.

Have you seen picks of dust buildup on rads yet? A high speed 38mm with no shroud has a distinctive dust 'bald spot'. The larger (many 38mm) hub of a 38mm fan has little airflow at the hub, since it pushes. Adding a shroud for push/38mm/2000 RPM helps quite a bit, spreads the flow better. It's a moot fact though if your raddage is large, your % gains are very small, so why bother.

In pull/25mm/1000 RPM the air is 'pulled' through more channels on the rad initially, kinda like the turbulence Martin was talking about. So me having a shroud on my PA 120.3 is actually a waste, really. But I got it, so might as well leave it eh?

Edit:

Some rads have a larger gap on one side than the other, forget which one. Still, there 'is' a gap to start with. If your going push and high speed (dunno why some want a loud PC anyway) then yep, a shroud would help.
 
I use 3 low-speed (Noctua) pull fans with a custom fiberglass triple shroud on my MCR320-QP-RES.
My rad is also filtered using an AC filter from a BlueBird bus (I worked at the factory). 3/8" thick open cell foam, washable.

**BTW I did a test with fans on the rad, and using a shroud while building this system. The shrouds are quieter (no meter, just good ears ;)).
 
Last edited:
Martin has tested push/pull and with/without shrouds with accurate equipment, and also different fans, link above and his newer test with new improved testing bench....and has shown it depends on fans you use and whether push or pull for how shrouds help or not.

His testing is here. pic from martins testing, push/pull was best not surprising, but shrouds benefited GT's in pull, but push was better without shroud:
 

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