Question about dual fans on radiator

r00t · 05-23-2003, 06:27 PM

Correct me if I'm wrong, but wouldn't having two fans on a radiator with two different CFM ratings be a bad idea? What I mean is putting say an 80 CFM fan on the front side of the radiator (pushing air through) and a 70 CFM fan on the rear (pulling air through). To me that just seems like the slower fan will either restrict the airflow of the faster, or it will be forced to work harder to keep up. Am I wrong?

Since87 · 05-23-2003, 07:24 PM

Fans don't deliver their rated CFM when they have to move air through anything which restricts airflow. The rated CFM is a maximum rating in open air.

The actual CFM you would get with this two fan system, would most likely be substantially below 70 CFM.

pHaestus linked an excellent article on fan usage recently. It would be worth searching for.

r00t · 05-24-2003, 07:30 AM

So is that saying I'll be fine with two different fans because neither will reach their rated CFM?

Since87 · 05-24-2003, 07:57 AM

Yes it will be fine.

Two fans in series will increase the pressure differential that can be developed across the rad. That will get the actual airflow closer to 70 CFM than it would be with a single fan.

JCYC5 · 05-24-2003, 08:06 AM

Quote:

Originally posted by Since87
Fans don't deliver their rated CFM when they have to move air through anything which restricts airflow. The rated CFM is a maximum rating in open air.

The actual CFM you would get with this two fan system, would most likely be substantially below 70 CFM.

pHaestus linked an excellent article on fan usage recently. It would be worth searching for.

I can't find it? :shrug:

Since87 · 05-24-2003, 08:25 AM

Here it is.

tot31 · 05-25-2003, 12:41 PM

I've tried using 2 fans on my heatercore..the front is pulling and the back is pushing...still there's no difference in temp...

Tweety · 05-28-2003, 06:37 AM

Then possibly the rad isn't the weak point of your system...? ie it already dissapates enough heat, and the performance limiting part in your system is something else...

05-23-2003, 06:27 PM	#1
r00t Cooling Neophyte Join Date: Sep 2002 Location: Ohio Posts: 16	Question about dual fans on radiator Correct me if I'm wrong, but wouldn't having two fans on a radiator with two different CFM ratings be a bad idea? What I mean is putting say an 80 CFM fan on the front side of the radiator (pushing air through) and a 70 CFM fan on the rear (pulling air through). To me that just seems like the slower fan will either restrict the airflow of the faster, or it will be forced to work harder to keep up. Am I wrong?

05-23-2003, 07:24 PM	#2
Since87 Pro/Guru - Uber Mod Join Date: Sep 2002 Location: Indiana Posts: 834	Fans don't deliver their rated CFM when they have to move air through anything which restricts airflow. The rated CFM is a maximum rating in open air. The actual CFM you would get with this two fan system, would most likely be substantially below 70 CFM. pHaestus linked an excellent article on fan usage recently. It would be worth searching for.

05-24-2003, 07:30 AM	#3
r00t Cooling Neophyte Join Date: Sep 2002 Location: Ohio Posts: 16	So is that saying I'll be fine with two different fans because neither will reach their rated CFM?

05-24-2003, 07:57 AM	#4
Since87 Pro/Guru - Uber Mod Join Date: Sep 2002 Location: Indiana Posts: 834	Yes it will be fine. Two fans in series will increase the pressure differential that can be developed across the rad. That will get the actual airflow closer to 70 CFM than it would be with a single fan.

05-24-2003, 08:25 AM	#6
Since87 Pro/Guru - Uber Mod Join Date: Sep 2002 Location: Indiana Posts: 834	Here it is.

05-25-2003, 12:41 PM	#7
tot31 Cooling Neophyte Join Date: Apr 2003 Location: Malaysia Posts: 8	I've tried using 2 fans on my heatercore..the front is pulling and the back is pushing...still there's no difference in temp...

05-28-2003, 06:37 AM	#8
Tweety Cooling Neophyte Join Date: Mar 2003 Location: Sweden Posts: 11	Then possibly the rad isn't the weak point of your system...? ie it already dissapates enough heat, and the performance limiting part in your system is something else...

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