2nd pump location

Distracted · 12 Jan 2019 at 20:11

I'm planning and building my loop and I have an issue where i don't think I'm going to have enough flow with just a single d5.

I have 3m of tube running to a MO-RA3 and then 3m running back to my PC where there's another rad plus all my blocks etc.

I have on hand a DDC pump which can be PWM controlled and I'm told that while they can be noisy, lowering the speed via PWM makes this a non issue.

My question: if i add the DDC to the loop should I be putting it on the MO-RA3 or can I add it anywhere in the loop to increase the flow of the liquid?

Jokester · 12 Jan 2019 at 20:14

The single D5 will be adequate, but if you are going to add the 2nd pump, it doesn't matter where it goes, but it does need to be in parallel with the 1st pump.

Distracted · 12 Jan 2019 at 22:05

Thanks, I didn't know that.

fornowagain · 12 Jan 2019 at 23:42

Is it head you want or flow rate? Long pipes and restrictions (friction head) and difference in mounting height (static head), gives total head.

Massive simplification, but pumps in series add their head, pumps in parallel add their flow rate.

D5 have good flow, not so good head.
DDC have better head, not so much flow.

So generalising, run D5 in series to bump the head up with good flow. Or DDC in parallel keeps their head but increases flow. Assuming identical pumps. Watch out for parallel pumps, if one fails it can create a short loop and drop a lot of the main flow.

Mixed pumps is more fun as you can't just add the curves.
https://martinsliquidlab.wordpress.com/2011/04/26/pump-setup-series-vs-parallel/

You could have course discharge the D5 into a DDC pump/res combo at the MO-RA3 end. That would act as two loops, with different head values depending on the mounting point.

Distracted · 13 Jan 2019 at 00:57

Thank you very much for your input both of you, it has really helped.

I've put it together with just the d5 running at max. I have over 6m of tubing in total (3m to and 3m from the MO-RA then the stuff in the pc) plus the MO-RA3, an xspc tx 360, gpu and cpu block, vrm block, 3 quick disconnects and a flow rate thing that spins or in this case doesn't spin very much.

I think the QDCs are causing a lot of restriction but I also know that while the MO-RA is supposed to be not that restrictive, the thermalbench review (iirc) found it did restrict flow quite a bit.

I was thinking I could add the DDC at the MO-RA end to help; I do have a res for it if needed. But it would be easier in terms of wiring to have both pumps in the PC case or as close as possible.

However, I am liking the idea of having the D5 push fluid out to the MO-RA and then the DDC pushing it back to the PC with reservoirs on both.

I'd love to hear any suggestions and feedback.

Radox-0 · 13 Jan 2019 at 01:16

I use a very similar setup in that I have a large external radiator on the floor then use a pump to push the water through the system on the desk, so in addition to all the tubing and blocks (3 GPU's and CPU) I found EK's D5 Serial pump to be great. A normal D5 pump lacks the pressure vs a DDC, but in series your double the pressure and get the benefits of a massive flow rate. Even at 60% on both pumps, have no issues with a relatively complex loop and pump on the floor plus there is still reasonable enough flow in the event one fails.

This is what I use, but can likely just grab a single pump and the head separately I imagine: https://www.overclockers.co.uk/ek-w...al-d5-pwm-serial-incl.-2x-pump-wc-945-ek.html

With that said if your looking to use what you already have, I found moving from quick disconnects to ball valves helped.

In regards to your comment, I would probebrly put the DDC pump before the Mo-RA to be honest and D5 after it to leverage the DDC's pump head pressure through the Mo-Ra 3 which is somewhat restrictive.

Distracted · 13 Jan 2019 at 02:25

Thanks! I was thinking along these lines.

Res+D5 - cpu - vrm - gpu - 3m - res+ddc - mora3 - 3m - tx360 - back to start.

This is because of case space and trying to use components i have rather than buying another D5.

Smffy · 13 Jan 2019 at 08:34

I would simply do pump to other pump then out, no need for another res then really... same effect.

Distracted · 13 Jan 2019 at 10:29

Smffy said:
I would simply do pump to other pump then out, no need for another res then really... same effect.

I have the pump and pump top, but I also have a res that will fit the DDC so I can do either. Without the res would be my preference for space and ease of moving the rad (making it less bulky), as well as making it easier to mount the DDC on the MO-RA.

But if i were doing it without the res wouldn't that mean the pumps are in series? That's something @Jokester said I shouldn't do, unless I'm reading it incorrectly.

Smffy · 13 Jan 2019 at 11:58

Distracted said:
I have the pump and pump top, but I also have a res that will fit the DDC so I can do either. Without the res would be my preference for space and ease of moving the rad (making it less bulky), as well as making it easier to mount the DDC on the MO-RA.

But if i were doing it without the res wouldn't that mean the pumps are in series? That's something @Jokester said I shouldn't do, unless I'm reading it incorrectly.

Well I think you will fine with more flow on that amount of tube, it’s going to be in series unless you split the fluid and then combine it back together regardless. If you put 5 things in between them it’s still a series... Usually people just stack the pumps as it scales well.

Jokester · 13 Jan 2019 at 14:38

fornowagain said:
Mixed pumps is more fun as you can't just add the curves.
https://martinsliquidlab.wordpress.com/2011/04/26/pump-setup-series-vs-parallel/

I think I'm going senile, I was sure it was parallel = more flow, series = redundancy.

pastymuncher · 13 Jan 2019 at 14:40

I have around 9m of tubing (Mayhems 10/16mm and 12mm copper pipe externally, 14mm hardline internally) to connect to my pair of windowsill mounted radiators and only use a single Alphacool VPP655P (D5 Vario) and have no problems at all with flow. That's with a very restrictive Alphacool XPX cpu block and a big inline filter in the loop as well.

Distracted · 13 Jan 2019 at 16:13

pastymuncher said:
I have around 9m of tubing (Mayhems 10/16mm and 12mm copper pipe externally, 14mm hardline internally) to connect to my pair of windowsill mounted radiators and only use a single Alphacool VPP655P (D5 Vario) and have no problems at all with flow. That's with a very restrictive Alphacool XPX cpu block and a big inline filter in the loop as well.

I think it may be the 3 QDCs plus the MO-RA that is causing my flow issues.

Primarily the QDCs in fact. I'm going to have a look at possibly replacing them.

Jokester · 13 Jan 2019 at 16:15

Distracted said:
I think it may be the 3 QDCs plus the MO-RA that is causing my flow issues.

Primarily the QDCs in fact. I'm going to have a look at possibly replacing them.

Which model of QDCs are you using?

Most are very restrictive sadly.

Distracted · 13 Jan 2019 at 16:20

Barrow. One seems fine, the other two slow the flow considerably but holding them together increases the flow a lot. It's as if the fit isn't tight enough on them. I'm going to see if I can get the low flow ones replaced.

MikeTimbers · 13 Jan 2019 at 20:36

I wouldn't have expected the length of tubing to be a factor unless it has loads of sharp bends. I'm surprised your D5 isn't enough so I doubt it's the MO-RA or the tubing length. Try changing the QDC for standard fittings and see what happens before you start adding components.

Bugbait · 14 Jan 2019 at 10:17

Jokester said:
I think I'm going senile, I was sure it was parallel = more flow, series = redundancy.

Parallel = More flow but huge pressure loss when one pump fails.
Serial = More pressure and same flow but minimal pressure loss when one pump fails.

Jokester · 14 Jan 2019 at 11:53

Bugbait said:
Parallel = More flow but huge pressure loss when one pump fails.
Serial = More pressure and same flow but minimal pressure loss when one pump fails.

That’s what I thought, but the martin’s liquid lab testing of it says otherwise.

Bugbait · 14 Jan 2019 at 12:02

Jokester said:
That’s what I thought, but the martin’s liquid lab testing of it says otherwise.

Selected quotes from MLL testing:

(Parallel: Higher flow) When you run two pumps in parallel, the curves somewhat get stacked in the X or flow rate direction with an averaging of pressure.
(Parallel: Lower pressure from failed pump) That’s bad new for parallel loops, as you lose not only the one pump that quit, but you also loose about 83% of the remaining pump’s power.
(Serial: More pressure) It is as simple as adding the two pump curves in the Y or pressure direction. While this does double the pressure of two like pumps, it should be noted that it does not double your flow rate.
(Serial: Low loss from failed pump) While you do lose the power of the second pump that was turned off, the restriction of the still pump is is very small. On average you will only see about a 2% loss in pumping power vs. a single pump setup. Series setups retain nearly full pumping power of single pump setup and therefore pass the redundancy check with flying colors.

Seems to be consistent with above.

Jokester · 14 Jan 2019 at 16:26

Heh, completely misread it