Airflow direction through a case fan ?

[Spankbot-5000]

I'm doing a system overhaul and replacing the stock fans in my P180 with a bunch of Yate Loons. This is surprisingly the first time I've ever installed 3rd party case fans, and this is a completely embarrassing question. How do you tell which way the airflow moves through a case fan? From what I gather, they pull air in through the "open" side, and blow it out the side with the crossbars holding the blade assembly in place.

Is this a hard and fast rule that I can rely on when installing fans? Are there any other obvious signs I'm missing of which way the airflow goes?


Alright, now you can laugh and point.

 

[rhagz]

Well, you could plug it in and put your hand over it and see which side is pushing more air. Or you can take a piece of paper and put it on the fan to see which side has suction. A lot of fans will have an arrow on them that shows which way air goes as well.

 

[Eulogy]

I'm doing a system overhaul and replacing the stock fans in my P180 with a bunch of Yate Loons. This is surprisingly the first time I've ever installed 3rd party case fans, and this is a completely embarrassing question. How do you tell which way the airflow moves through a case fan? From what I gather, they pull air in through the "open" side, and blow it out the side with the crossbars holding the blade assembly in place.

Is this a hard and fast rule that I can rely on when installing fans? Are there any other obvious signs I'm missing of which way the airflow goes?


Alright, now you can laugh and point.

90% of fans I've seen do flow that way.
Not to embarrass you even further, but I think Yate Loon's have a little diagram for blade rotation and air direction on one of the sides (all 4 of mine have it on the side the 3 pin comes out of).

 

[Spankbot-5000]

90% of fans I've seen do flow that way.
Not to embarrass you even further, but I think Yate Loon's have a little diagram for blade rotation and air direction on one of the sides (all 4 of mine have it on the side the 3 pin comes out of).

Good to know! Don't have the fans yet, but I'll keep an eye out of for the arrows when my package arrives.

 

[Sphere]

No worries, I've had the same problems for years. I always have to plug them in before I can tell which way they blow

 

[Kett]

You can also just examine the blades.... They are concave on the side that air comes out, and convex on the suction side.

 

[CrazyJ]

I've had a problem knowing which way the fan blew as well.

Normally I spin it really fast with my hand and see if I feel any air coming toward it

 

[Spankbot-5000]

You can also just examine the blades.... They are concave on the side that air comes out, and convex on the suction side.

Interesting...

I knew there must be a way to tell just from the shape of the blades, but I couldn't find any relevant info on the web. Good find!

 

[wjogert]

Call me obsessive, but I always power-up any fan before mounting it in a case, even if it's new.

I've had brand-new fans with bad bushings, lighted fans with dim or bad LED, etc.

Most fans come with CFM and dB specs, but it's just nice to physically verify the noise level, airflow, and visual effects before burying into a case.

 

[Nenu]

Most fans dont have flat blades but are curved.
Where the blade curve is flattest with the fan face, that side draws air in.
Where the curve is more angled is where the air comes out.

I dont use that method to check though as all the fans I have ever come across flow the way you initially said, the open side draws air in.