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Would this WC Layout impede water flow?

Last response: in Overclocking
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June 26, 2011 5:03:07 AM

I have recently taken an interest in WC while planning for a new computer system that i'll be getting at the end of the year.
I've been planning my WC layout but cannot seem to find anyone promoting or demoting the use of a y splitter for radiators. (not entire loops)

This is what i had in mind:

............................................Dual 120mm Radiator
Reservoir>Pump>Y-Splitter>.................................>Y-Splitter>CPU>GPU>GPU>Loop back to Reservoir.
............................................Dual 120mm Radiator


As far as i have researched, Your loop order dosen't make much of a difference since the heat is dispersed almost evenly across the entire body of water.
There also seems to be suggested that cooling your CPU and GPUs in parallel will not be effective due to the reduced flow rate.
Further research also suggested that placing radiators in serial could cause increase in resistance of flow.

My question is, would placing the radiators in parallel increase the surface area:volume ratio of the water passing through and thus cool the water down more?
At the same time, would using the Y splitters reduce the FLOW RATE TO THE CPU and onwards? And if so will this outweigh any possible benefits on placing the radiators in parallel?

Thanks for taking the time to answer, and i do apologize if this question has been asked before or is common sense. I could not find any information on it through scouring the forum and google.
a c 190 K Overclocking
June 26, 2011 11:16:27 AM

Yes splitting through a y-piece will adversely affect flow, I'm currently building my first loop and I had the idea of splitting my line until a more informed member of the watercooling club pointed me away from the idea :) 
This is the thread I posted, its in there somewhere :) 
http://www.tomshardware.co.uk/forum/forum2.php?config=t...
hope this helps and good luck with your loop man, pics when your done please :) 
Moto
June 26, 2011 12:43:36 PM

Thanks for the reply Moto.
I have not studied any fluid mechanics so my process of rationalization may be flawed.

Am i right to say that by placing a Y-Splitter after the pump (1/2" to 1/4"), the result would be an increased water velocity, but a lower volume of liquid resulting in overall lower CFM?
-What effect would this have on heat dissipation in the radiatior?
-What difference would it make if the Split was made from a 1/2" tubing to 1/2" tubings instead.

Now if i converge the two lanes back into 1 with another Y-splitter (1/4" to 1/2"), would i continue to have a decreased CFM? or would it go back to the rate it was at between the pump and the first Y-splitter?
[In my mind, since the two lanes converge back into one. The pressure and volume reverts to normal and thus the CFM should as well, excluding the energy lost to friction]
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a c 190 K Overclocking
June 26, 2011 2:15:10 PM
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I'm no expert myself but basic physics tells me,
a y-splitter will lower pressure,even with the change to a smaller bore hose, therefore the fluid in both lines would be under less force and move slower, meaning the heat isn't taken away as quickly as it could be, increasing the temp of the fluid more than it would ordinarily
and at the point where it went back to a single 1/2 the pressure change would result in a kind of nullspot with not much inclination to flow anywhere until forced to
you would possibly end up with a huge airlock in there which you dont want at all
I'd vote for keeping the same bore throughout the loop and if you need two rads place them in series,
Moto
June 26, 2011 2:47:54 PM

Best answer selected by silenciaco.
June 26, 2011 2:52:23 PM

Thanks, that clears uo alot. Looks like i'll be sticking to the tried and true serial layout.

Left with an unrelated question.
How do i go about calculating the heat output of my setup? (in Watts)

Related info:
Asrock z68 Extreme4 MB
i7 2600k 3.4GHz processor
2x Radeon HD 6950 Xfire'd

Planning to overclock CPU to ~4.5Ghz
a c 324 K Overclocking
June 26, 2011 10:48:22 PM

Moto is correct: keep your loop serial...splitting with 'Y's will drop your flows and will be a detriment to your flow and temps...aka...drop in delta. Keep it serial, it will perform better.
June 27, 2011 6:50:39 AM

Actually, from a person that works with pipes and water, what would happen with parallel radiators is the flow rate (velocity) through the radiators would halve, reducing friction loss (the higher the velocity the higher the friction loss) and cause the water to spend longer in the radiators to cool down. Once the pipes converge again the velocity will go back up the full speed to travel through the rest of the system. Running 2 is serial would mean that the full velocity has to travel through both radiators and I would assume they are the biggest source of friction or flow reduction on the system and possibly cause the rest of the loop (through the cooling blocks of the cpu/gpu) to be slower. If there is minimal friction loss through the radiator the both ways would run almost identically, high friction loss and the parallel system will run much better. If you tried both ways under a stress test it would be simple to see which way cools better. The more back pressure (whether it be through friction loss in radiators or tubes too small) the lower the flow rate that the pump will be able to move.
a c 324 K Overclocking
June 27, 2011 1:17:15 PM

This has been tried, parallel splits in a water loop causes a drop in flow. Drops in flow = drop in delta = reduced cooling by the loop. Watercooling pumps aren't as powerful as industrial or other pumps, so keeping a serial loop is a good idea. If you want to run dual loops, run dual loops...otherwise, you aren't gaining anything by splitting with a 'Y' connector...if you ran the same rads in series, you'd see better temps.
!