Why use radiators with both intake and exhaust fans in the same system?

[zarg]

I have seen people doing this, but haven't been able to find any explanation for it. Here is an example of what I mean:

(from: http://www.overclock.net/t/1239875/worklog-800d-white-black-and-red)

All three radiators have the same water passing through them. It seems that heat will be transferred from the water to case air through the intake radiators, then from case air back to the water through the exhaust radiator, resulting in no additional cooling than if both intake fans + radiators were removed (plus allowing more warm air to pass over the motherboard).

Am I missing something? If this actually does help, how does it work?

 

[Arondayot]

I have 10 Fans in total, as follows:

Intake:::
2-SP120 High PErformance as Front Intake;
1-AF120 LED Series High Airflow located at Front but less constraint;
2-AF120 LED Series High Airflow located at the Bottom near the Front; and,
2-AF120 LED Series High Airflow located at the Left-Side Panel.

Exhaust::
2-SP120 LED Series High Static Pressure located at Top-Rear, attached with the Radiator. in other word, my Radiator is also serve as exhaust; and,
1-AF140 LED Series High Airflow lcoated at the Top-Rear.


Room Tempearture: Always Air-Conditioned.

Chassis: Full Tower Colossus Bitfenix

CPU: Intel Core i7-4960x
Graphics Card: ASUS GTX 780ti DCUII OC 3GB
MoBo: MSI Extreme Big Bang 2
RAM: 8-8GB Mushkin 1600

Only my CPU whish is watercooled though i'm planning to but another Closed-loop Watercooling kit for my GPU.

 

[zarg]

I have 10 Fans in total, as follows:

Intake:::
2-SP120 High PErformance as Front Intake;
1-AF120 LED Series High Airflow located at Front but less constraint;
2-AF120 LED Series High Airflow located at the Bottom near the Front; and,
2-AF120 LED Series High Airflow located at the Left-Side Panel.

Exhaust::
2-SP120 LED Series High Static Pressure located at Top-Rear, attached with the Radiator. in other word, my Radiator is also serve as exhaust; and,
1-AF140 LED Series High Airflow lcoated at the Top-Rear.


Room Tempearture: Always Air-Conditioned.

Chassis: Full Tower Colossus Bitfenix

CPU: Intel Core i7-4960x
Graphics Card: ASUS GTX 780ti DCUII OC 3GB
MoBo: MSI Extreme Big Bang 2
RAM: 8-8GB Mushkin 1600

Only my CPU whish is watercooled though i'm planning to but another Closed-loop Watercooling kit for my GPU.

Your system doesn't have a radiator on both the intake and exhaust, so it doesn't apply to my question...



I read this thread again and I have to say, I'm still as confused as I was when I asked this a year and a half ago. I understand that there could be some performance gain because some of the heat will disperse elsewhere or stay in the radiator, but I still don't see how this could work better than putting the second radiator somewhere else other than directly inside the airflow of the first radiator. If we put it at the bottom of the case, even without additional directed air over it, wouldn't heat transferred to it disperse more evenly throughout the case without affecting the main supply of cool air as much?

 

[rubix_1011]

The theory used in this thread assumes that 1) your heat load on your radiators determines that you have far too much load to be effectively removed and the delta-T of the loop is much higher than it should be, and 2), that your case is 100% air tight and there is never any lossless air transfer between internal case and ambient, which isn't ever possible in a normal case...and it never should be.

I don't see the case in which you're arguing these points so adamantly without having ever watercooled before. The concepts (while they do have merit) don't necessarily apply to a watercooling loop, especially one where there are multiple heat exchangers (radiators) and in which airflow inside the case is not an independent ecosystem from the room ambient.


Edit: why was this thread resurrected 1.5 years after the last post?

 

[zarg]

The theory used in this thread assumes that 1) your heat load on your radiators determines that you have far too much load to be effectively removed and the delta-T of the loop is much higher than it should be

How so? I don't see how the heat load has anything to do with it. It isn't a question of whether it's "effectively removed", it's a question of whether it's more or less effective than the alternatives.

and 2), that your case is 100% air tight and there is never any lossless air transfer between internal case and ambient, which isn't ever possible in a normal case...and it never should be.

No, I'm not assuming that either. The fact that the case is not airtight simply means that the results are slightly better than they would be if it was airtight. What has this to do with the relative efficiency of this method versus alternatives?

I don't see the case in which you're arguing these points so adamantly without having ever watercooled before.

What's even more amazing is that none of the supposed watercooling veterans who replied have supplied either a) an explanation as to how this is more efficient, or b) any hard data supporting the assumption that it is. My goal here was to learn how this works, one way or the other. Condescension and hand waving isn't helping anyone.

 

[rubix_1011]

Seems rather hypocritical that you're calling us out, yet you do not offer any form of explicit explanation that supports your statements.

1) Thermal load has EVERYTHING to do with it. Given that radiators are more effective at removing heat from a source when the delta to the ambient temperature aids in convection based on the thermal load they can effectively dissipate. Take for instance - the likelihood that your car will overheat in the summer while stuck in traffic is much more so than it will in the arctic winter is the same principle; heat transfer is much less effective the closer the temperatures are to one another. But, in the same vein, if you have too much thermal load for a heat exchanger to process, you have effectively created a system where more thermal energy is contained, rather than expelled...like filling a swimming pool with a fire hose and draining it with a garden hose.

A watercooling radiator should really never put out air from the fan exhaust more than lukewarm or slightly warmer. If so, your loop delta is higher than it should be (+15C or more).

2) Which alternatives?

3) Yes, we're all 'supposed' veterans, and thank you for the underhanded comment response. What 'hard data' are you looking for? Cooler air is always better when it comes to cooling radiators; this is widely accepted and understood under any circumstance. The main issue you are debating comes down to overall case airflow within the case, and one which varies widely depending on hardware being used in the loop, the hardware in the system and the case itself...including fans.

Also, the initial diagram in the first post depicts more radiator(s) in the loop than are needed to cool the components being cooled. This lends the loop to have a lower delta-T, which means the difference in thermal load carried by the total volume of water in the loop as a function of flow rate, fan speed, radiator surface area and thermal exchange of the CPU & GPU blocks to the liquid as well as the thermal exchange of the liquid to the radiator tubes/fins. The overall cooling system (the loop) has a great efficiency to dissipate the same amount of heat in watts (CPU + GPU) with that configuration than attempting to do so via the single 360 rad, or any combinations of the radiators in lesser surface area.

 

[zarg]

Seems rather hypocritical that you're calling us out, yet you do not offer any form of explicit explanation that supports your statements.

...What statements? I'm the skeptic here. I'm asking for evidence and reasoning. I'm not saying "this is how it is". I'm saying "if this is how it is, prove it." All the answers I got were either logically inconsistent, or irrelevant to the question. For instance, everything you said about thermal load is an example of the latter (the question still applies, whether the exhaust is lukewarm or "too hot").

What 'hard data' are you looking for?

A comparison that shows that this is a better use of resources. So for example in the OP, we have the main radiator on the top, and another one in the rear. My expectation is that the one in the rear would be better placed elsewhere because this is the primary source of air for the top one. But apparently everyone thinks I'm wrong. So show me data for this setup versus the same setup with the rear radiator on the bottom (or anywhere other than over the rear fan).

The overall cooling system (the loop) has a great efficiency to dissipate the same amount of heat in watts (CPU + GPU) with that configuration than attempting to do so via the single 360 rad, or any combinations of the radiators in lesser surface area.

I do see that we're better off leaving all the rads there than removing them. But my main confusion still remains, as to why this configuration should be chosen.

 

[rubix_1011]

Evidence? There isn't anywhere that is going to define exactly what you are looking for in this question. The simplicity of it is that the cooling ability of the loop is defined in the calculation of delta-T against your ambient room temperature. The rest is up to the specific airflow, layout and components in your case. There isn't a single scenario that covers anything that specific. Coolest air to the radiators is beneficial, but your misunderstanding of how the fundamentals of watercooling work makes this incredibly difficult to get across to you.

'THIS' configuration is merely a specific layout concept that works for this person (in your image). Why? Because that user has defined that airflow for their case would seem to indicate that this is a good layout, maybe from their own experience, maybe from something they have found on the web or maybe they don't know if it is for certain.

You are only a 'skeptic' because you are questioning and rejecting information and data from people who have done this for years who are trying to tell you and explain to you (the one who has not done this for years) what is done and why. Perhaps you should purchase your own loop and do your own research and let us know what you find. If we are so grossly incorrect, do your own research and return with details as to why you're right and we're incorrect.

Given that you've been given fairly specific details on many responses and not only from me, but also others, it is clear that you're only here to be told that you are correct and we are all incorrect. If you wish you demand that specific details be given to you in order to prove you being incorrect, I would ask that you prove to me to your detailed arguments as to why you are correct and I am in error.

I am finished with this thread.

 

[Arondayot]

I have 10 Fans in total, as follows:

Intake:::
2-SP120 High PErformance as Front Intake;
1-AF120 LED Series High Airflow located at Front but less constraint;
2-AF120 LED Series High Airflow located at the Bottom near the Front; and,
2-AF120 LED Series High Airflow located at the Left-Side Panel.

Exhaust::
2-SP120 LED Series High Static Pressure located at Top-Rear, attached with the Radiator. in other word, my Radiator is also serve as exhaust; and,
1-AF140 LED Series High Airflow lcoated at the Top-Rear.


Room Tempearture: Always Air-Conditioned.

Chassis: Full Tower Colossus Bitfenix

CPU: Intel Core i7-4960x
Graphics Card: ASUS GTX 780ti DCUII OC 3GB
MoBo: MSI Extreme Big Bang 2
RAM: 8-8GB Mushkin 1600

Only my CPU whish is watercooled though i'm planning to but another Closed-loop Watercooling kit for my GPU.

Your system doesn't have a radiator on both the intake and exhaust, so it doesn't apply to my question...



I read this thread again and I have to say, I'm still as confused as I was when I asked this a year and a half ago. I understand that there could be some performance gain because some of the heat will disperse elsewhere or stay in the radiator, but I still don't see how this could work better than putting the second radiator somewhere else other than directly inside the airflow of the first radiator. If we put it at the bottom of the case, even without additional directed air over it, wouldn't heat transferred to it disperse more evenly throughout the case without affecting the main supply of cool air as much?

Sorry!
Actually, I am maintaining a Positive Pressure inside my Chassis with More Intakes or to be exact 7 Intake Fans while 2 Fans on the Radiator on my CPU which also serve as Exhaust... Lately, My Rear Exhaust I am also planning to fix other Radiator the 140mm for my GPU. in other words, in my opinion I don't recommend to make some Radiators as Intake but as Exhaust unless otherwise you are in a Air-Conditioned Room. are you? Even so, CPU and GPU are not my only concern for cooling but also my MoBo and its important parts that produces heat and of course Ram. Making some of the Radiators as Intake, will likely cool the compoment you want to keep cool even when overclocked but you might as well jeopardise your other important components.

Lastly, with regards to your questions.... could be their chassis doesn't have enough slots to add another Chassis's Fans as Intakes so they've took advantage of their radiators instead regardless what might be the effect to their MoBo in the long run....

 

[Arondayot]

I have seen people doing this, but haven't been able to find any explanation for it. Here is an example of what I mean:

(from: http://www.overclock.net/t/1239875/worklog-800d-white-black-and-red)

All three radiators have the same water passing through them. It seems that heat will be transferred from the water to case air through the intake radiators, then from case air back to the water through the exhaust radiator, resulting in no additional cooling than if both intake fans + radiators were removed (plus allowing more warm air to pass over the motherboard).

Am I missing something? If this actually does help, how does it work?

I have 10 Fans in total, as follows:

Intake:::
2-SP120 High PErformance as Front Intake;
1-AF120 LED Series High Airflow located at Front but less constraint;
2-AF120 LED Series High Airflow located at the Bottom near the Front; and,
2-AF120 LED Series High Airflow located at the Left-Side Panel.

Exhaust::
2-SP120 LED Series High Static Pressure located at Top-Rear, attached with the Radiator. in other word, my Radiator is also serve as exhaust; and,
1-AF140 LED Series High Airflow lcoated at the Top-Rear.


Room Tempearture: Always Air-Conditioned.

Chassis: Full Tower Colossus Bitfenix

CPU: Intel Core i7-4960x
Graphics Card: ASUS GTX 780ti DCUII OC 3GB
MoBo: MSI Extreme Big Bang 2
RAM: 8-8GB Mushkin 1600

Only my CPU whish is watercooled though i'm planning to but another Closed-loop Watercooling kit for my GPU.

Your system doesn't have a radiator on both the intake and exhaust, so it doesn't apply to my question...



I read this thread again and I have to say, I'm still as confused as I was when I asked this a year and a half ago. I understand that there could be some performance gain because some of the heat will disperse elsewhere or stay in the radiator, but I still don't see how this could work better than putting the second radiator somewhere else other than directly inside the airflow of the first radiator. If we put it at the bottom of the case, even without additional directed air over it, wouldn't heat transferred to it disperse more evenly throughout the case without affecting the main supply of cool air as much?

Hi! This is only my opinion and im not quite sure whether mine is correct or best.
I've got your point but in my case, All Radiators attached with fans are all exhaust instead of as Intake since I do not want warm air to come in but to blow out.

Photo attached herein is for your perusal.]http://[/url]

 

[rubix_1011]

Thread is almost 2 years old. I'm going to close it out. If someone needs this re-opened, send me a PM.

Thanks.