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Too much Suction?

post #1 of 10
Thread Starter 
Hello all. I put together my first WC loop this month and it went pretty smooth. Its comprised of a MCP35X pump w/res top, 240mm rad, 200mm rad, and two FC-6970 GPU blocks. All held together with Tygon tubing, the food grade clear kind. Everything seems to be working just fine, but I noticed something that I am unsure about. On the lest leg of my loop, from the last GPU block back to the reservoir, the tubing seems to be sucked in a bit when the pump is going more then 50% so that its not round anymore but oval. What I mean is the tube looks like too much suction is going through that segment of tube and the sides of the tube are a little squeezed in. The flow into the reservoir comes crashing in when I am above 50% too. So is this indicative of a problem?
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post #2 of 10
Hard to say atm, can you post a picture? There are ways to fix this problem. You can get some anti kink coils and that will fix it right up.
post #3 of 10
Thread Starter 
Quote:
Originally Posted by Timlander View Post
Hard to say atm, can you post a picture? There are ways to fix this problem. You can get some anti kink coils and that will fix it right up.
will post a shot in the evening. I do have some anti kink coils on hand but I wasn't crazy about their looks. I was worried that the tubing I got was a little too soft and the Hydrx coolant I used was a little too viscous. Should have mentioned earlier that instead of distilled water I decided to give the coolant Swiftech sells a shot. It looked promising as they claim if you make it double strength you only need to change the loop coolant every three years.
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post #4 of 10
I didn't think that these pumps were self priming, therefore there was only pressure moving the water out of the pump, no (extra) pressure from the pump pulling water in... I could be mistaken though.

Have you tried running with the res fill port open to see if that relieves some of this pressure?

*edit* saw that you describe the water as crashing into your res. Perhaps there isn't enough restriction in your loop to keep the pump in check when it is ramped up... The 35x is pretty powerful.

How are the temps below 50% power and then above? Any difference?

Honestly, I think martin should weigh in on this one
Edited by whiteslashasian - 5/23/11 at 9:56am
    
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post #5 of 10
Thread Starter 
Quote:
Originally Posted by whiteslashasian View Post
I didn't think that these pumps were self priming, therefore there was only pressure moving the water out of the pump, no (extra) pressure from the pump pulling water in... I could be mistaken though.

Have you tried running with the res fill port open to see if that relieves some of this pressure?

*edit* saw that you describe the water as crashing into your res. Perhaps there isn't enough restriction in your loop to keep the pump in check when it is ramped up... The 35x is pretty powerful.

How are the temps below 50% power and then above? Any difference?

Honestly, I think martin should weigh in on this one
I did read his review of the MCP35X, of course after I set up my loop and did not set up the reservoir as he recommended (using the top inlet/3" tube inside the res pointing down). Not much difference in temps if I recollect running the pump over 30%. Thanks for the suggestion about running it with the fill port open, I will give that a shot too.
Edited by CesarNYC - 5/23/11 at 10:03am
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post #6 of 10
If you're getting an increase in flow and temps are ok, it's fine.

The only way your tube could cause an issue is if it completely kinked over, which is unlikely.

I would recommend getting thicker tubing (what size are you using) standard "thicker" tubings are 1/2" ID 3/4" OD or 3/8" ID 5/8" OD (the thinner being 5/8" OD and 1/2" OD respectively).

Or perhaps getting a right angle joint to take the stress of a bend that goes from your res to your pump.

I don't think you'll need to, but for your peace of mind...
    
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post #7 of 10
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Quote:
Originally Posted by Crabid View Post
If you're getting an increase in flow and temps are ok, it's fine.

The only way your tube could cause an issue is if it completely kinked over, which is unlikely.

I would recommend getting thicker tubing (what size are you using) standard "thicker" tubings are 1/2" ID 3/4" OD or 3/8" ID 5/8" OD (the thinner being 5/8" OD and 1/2" OD respectively).

Or perhaps getting a right angle joint to take the stress of a bend that goes from your res to your pump.

I don't think you'll need to, but for your peace of mind...
I am unfortunately locked into 1/2 ID * 5/8 OD tubing (So much money spent on Koolance compression fittings, and I didn't even know that Koolance made 3/4 OD when I filled up my shopping cart). Live and learn. But your idea about the right angle joint makes a lot of sense, I will five that a shot too. Thanks for your help.
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post #8 of 10
It's a closed loop. Suction is balanced by the output of the pump coming back around. Make sense? Reservoir should be right before pump pick up/inlet. Open the filport on the res and see if the tube changes shape. I predict it will not.

Use some cable ties around the outside of the tubing where it is out of shape to keep it round.
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post #9 of 10
Quote:
Originally Posted by CyberDruid View Post
It's a closed loop. Suction is balanced by the output of the pump coming back around. Make sense? Reservoir should be right before pump pick up/inlet. Open the filport on the res and see if the tube changes shape. I predict it will not.

Use some cable ties around the outside of the tubing where it is out of shape to keep it round.
And there you have it. Cable ties are a good idea.
post #10 of 10

Are you using the mcp35x reservoir? If so, is your inlet the top or bottom inlet port?

Some dude on here had the same problem.

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