Alphacool Eisdecke Plexi / Noise on test

[acresflood]

Hello there,

This is my first watercooled rig, so please bear with me. Now I understand this is not how you build a w-cooled system, but I'm here so that's it.

I mounted the Alphacool Eisdecke Plexi vertically.
I am using the jumper to run a test only with the pumps.

1) First issue is that the pumps are generating a very annoying, uneven vibration. Is that normal? I understand they're at full speed, but is really annoying.

2) Then, the problem is that the pumps are never full with water, no matter what I do. I tried everything, tilting the case, pumping more water, it's simple physics, there will always be air on the 1/3 top of the pump.
Can you please advise?

3) Lastly, after 5-10m of running, there is a very high pitch and very powerful sound coming from the first pump from right to left (flow order), like metal running on metal. I guess somehow the pump is running low of water. I stop the test immediately, I tilt the case a few times, and the noise is gone, only to reappear again.

I tried everything: to tilt the case, to pressure-pump coolant (with and without releasing air) but the physics is clear: there will always be air on the 1/3 top of the pumps, because the intake and outtake are halfway, and the top will remain filled with air.

I'm looking forward to your feedback.
thanks

 

[Eddy]

1. If you don't decouple the setup and run two pumps at full speed, you'll get strong vibrations that can lead to annoying noise. Especially with two pumps that never run 100% in sync (there are always slight fluctuations between pumps), this can create unfavorable vibration patterns.

2. That’s due to your setup. Since you're going in and out from the bottom, it's extremely difficult to bleed the system properly. It takes a lot of time, and you'll probably have to flip the whole thing upside down at some point so the air can escape through the lower port.

3. I can’t say anything specific about that. A metallic noise definitely shouldn’t be there. I have no idea where it’s coming from. The only thing that helps is to take it apart and carefully check if something is rubbing or scraping somewhere.

 

[acresflood]

Many thanks for replying, Eddy. Don't know how much this means to me.
I am alone in this, I have no one to talk to, and between balancing a difficult job, a family and this project, this forum is my breath of fresh air.

1) I don't understand. Do you suggest running only a single pump? Or to run them at different speeds? I understand that they should always run at the same speed. Otherwise, the slow one would only induce drag. Please advise.


2)
I have turned the case upside down already - again, the air is always filling in somehow.
I could make some changes to the setup, but I'm unsure if moving the inlet to the side or to the front will make any difference: the "link" between the two pumps is in the middle. The water will flow from pump 1 to pump 2 through that channel and only that.
My understanding of physics (see pic1) tells me that the first pump will always create bubbles/vortex/suck air and then the superior half of the first pump will always be air filled, as the air has no where to escape through.

The issue is that I can get rid of that air through manual pumping, but 5-10m after running, the air is back, no matter what I do. I can spend time changing the inlet, but can you please guarantee that it is not in vain and that the issue will be solved by doing so?
So, even if I get rid of all air and change the inlet (and/or the outlet) due to this design, I will always end up with any air in my system trapped there. Running the system for longer doesn't resolve things; it only adds more air.
Making changes to my design involves a considerable time investment from my side, and that's something I lack. If I make another effort, I'd like to be in the right direction and finalise.

Can you or someone else please help with a real-life example of where this setup ran fine and how?

Please advise.


3) Maybe because it's running with so little water? As you can see, there is a filter ahead. There is nothing in the filter - it is immaculate. I thought I would have more impurities, but it is ok for now.

Looking forward to your reply.

 

[Eddy]

I wasn’t trying to suggest anything directly — I simply wanted to explain why using two pumps in a dual pump top can lead to increased vibrations, and why that happens. What conclusions you draw from that is entirely up to you. Personally, I don’t see much reason to run a dual pump setup at all.

The biggest issue with your setup is that the water does not flow freely and unobstructed to the pump top. Starting from the reservoir, there are bends, kinks, and even a filter in between. This is a design that should generally be avoided when using separate pump tops. Pumps cannot draw water — they only push it. That’s why it’s important that water can flow freely and without resistance to the pump top.

To put it very plainly: this part of your setup is extremely poorly designed. That’s likely the main reason you’re having trouble getting the loop properly bled.
If you were able to fully bleed it once, the system would probably run fine long term — but getting to that point with this setup is extremely difficult. A direct connection from the reservoir to the pump top without all those bends would be the best solution. The filter would also have to go in that case.

You definitely do not have too little water in the system. That’s not a concern — there’s more than enough water in the reservoir.