Pumps in Series Vs. Parallel Graph

[Martinm210]

I know this has been talked about and explained before, but I got bored and wanted to make a new one to hopefully explain this a little better to newer folks in the forum.

This is why you want to run pumps in series over parallel. Most water cooling systems are fairly restrictive (and getting worse as designs continue to get more restrictive to squeeze every last drop out of the waterblock), so that's where series and the stacking of pressure comes in favor.

Parallel is only really better when you're talking extremely low restriction setups, pretty hard to do actually. And in that case, you're already moving plenty of flow with the single pump.

Anyhow, hope this helps someone...I was bored...

The single pump curve was one that I tested with an XSPC regular top. The two series/parallel curves are theoretical. Parallel = 2X Flow rate numbers. Series = 2X pressure numbers. I can't remember the exact gear for the High and low pressure drop curves, but they were pretty extreme examples if I remember right. Regardless, it gives you the idea. We have high restriction systems and that's where series is the better option...

[JOCKTHEGLIDE]

thx martin for the graph setup.....very very much appreciative.

[Sly Fox]

Awesome information Martin, thank you.

Waterlogged had given me a rough explanation in the other thread, but the graph helps understand.

[Petra]

Martin, I think this just goes to show that your real talent is being able to clearly convey concepts through the use of illustration (more specifically, the use of Excel).

I'm fine with explaining things to people and occasionally drawing something freehand to illustrate my point, but I'm an utter failure when it comes to the use of spreadsheet software. As they say, a picture is worth a thousand words... and this one certainly saves some of us a lot of typing

[nikhsub1]

Nice Martin. In 'normal computer restriction loops' you gain about 33% flow rate with 2x pumps in series. Obviously the more restrictive the loop the better serial pumps scale.

[Sadasius]

So I was right and it does improve the flow and pressure performance then.

Ha, smoke that Vapor! You know I am joking....right?

***EDIT*** Actually now that I go back and read it again you agreed with me right?!? Damn it I am confused again!

[Vapor]

Sweet write-up Martin

Clear explanation and a GREAT chart! Also probably worth a mention that increases in flow with high-restriction parts *usually* net more performance than gains with low restriction parts. Not always the case of course

Regardless, it's awesome to see laid out so plainly.

So I was right and it does improve the flow and pressure performance then.

Ha, smoke that Vapor! You know I am joking....right?

***EDIT*** Actually now that I go back and read it again you agreed with me right?!? Damn it I am confused again!

I'm really not sure what you're alluding to

The loop order debate? That has very little to do with this

[Senater_Cache]

Nice Martin. In 'normal computer restriction loops' you gain about 33% flow rate with 2x pumps in series. Obviously the more restrictive the loop the better serial pumps scale.

Hey nikhsub1,

IS there a way you can get a hold of the deltaT "interactive chart" from procooling of back-in-the-day?

I would love to see someone with current test-methodologies that are on-point like martin's use that to make the FAQ section as robust as can be.
Maybe it can even be combined with data like this in a way.

[Sadasius]

I'm really not sure what you're alluding to

The loop order debate? That has very little to do with this

Nah not that...This-> http://www.xtremesystems.org/forums/...d.php?t=224966 Would have explained myself better but was pretty damn busy at work.

[Mech0z]

Now I just want to see the XSPC duel ddc res (the new thing) tested with the same conditions :p and see how well(bad) it does, but very nice info.

[Makubex_GB]

Very nice, thanks for the info, Martin.

[JOCKTHEGLIDE]

martin,
did the switch to series everything is better now vs what I had in parrell. Better as in one pump does not seem to overpower the other pump and send things back into the res from the Y splitter. I can now feel the flow of the water in my tubes vs before.

[Martinm210]

martin,
did the switch to series everything is better now vs what I had in parrell. Better as in one pump does not seem to overpower the other pump and send things back into the res from the Y splitter. I can now feel the flow of the water in my tubes vs before.

Awesome, I hoped that would take care of the problem, glad it did..

[HESmelaugh]

Great illustration! I can imagine this will be a much linked thread when questions about dual pumps pop up.

[defect9]

sticky this somebody

[dreamaxx]

Awesome, thanks for that info

[JOCKTHEGLIDE]

sticky this somebody

I agree alot f martions OPings should be stickied in general instead of doing a damn search for them all the time....STICKIE THIS NOW PLEASE

[tuanster1119]

top notch as usual. Thanks for the info Martin.

[Bojamijams]

What about the whole "pump downflow will have its impeller burnt out due to pressure from pump 1" talk ?

[Boogerlad]

that is if you have mismatching pumps iirc.

[Darth_Penguin]

that is if you have mismatching pumps iirc.

Would the pumps be considered mismatched if you used a xpsc Res top for one and a regular xpsc acrylic top for the other?

[eth0s]

For two pumps in series you should place the weaker pump feeding the stronger pump for maximum performance, otherwise the weaker pump would restrict the flow of the stronger pump. But as for a powerful pump "burning out" or overpowering a weaker second pump, I am not really sure that is possible, because the extra pressure will pass through the second pump (albeit reduced by the restriction of the pump). However, I suppose I can imagine a scenario, where if you had some kind of a super-powerful water-jet type pump, maybe you could do some physical damage to a weaker pump, but even then, I don't think so. To give you a real world analogy of what is happening when pumps are in series, suppose you have three pumps with 10 feet of head pressure each, and you need to get water out of a hole in the ground that is 25 feet deep. Now this hole is so deep that if you try to use any one of your pumps, there will not be enough head pressure to lift the water out of the hole (because each pump will lift the water only 10 feet). So what do you do? Put the pumps in parallel? No way, in parallel you will simply pump the water to a height of 10 feet, but three times faster. You need to add the pumps in series, thereby adding the head pressure of each additional pump, until you get enough pressure to get the water to a height of 25 feet in order to reach the top of the hole. With three pumps with 10 feet of head pressure each, in series, you should be able to pump the water out of a 25 foot deep hole. Imagine the first pump is at the bottom of the hole and, that each additional pump is mounted 10 feet above the other. The same principle will apply inside your computer case, except instead of overcoming gravity, you are overcoming restriction in your water blocks and the friction resistance of your tubing. And as Martin pointed out in his graph, the more restriction in your loop, the more you will benefit from pumps in series.

[DexNfX]

Guess it's time to change my loop around and put pumps in series. Oh well, it's time for a cleaning.

[HanMies]

The two series/parallel curves are theoretical. Parallel = 2X Flow rate numbers. Series = 2X pressure numbers.

At first this sentence looked really bad. However, the "theoretical" GPM gains from adding a second pump in series are in line with the real world observations that have been posted, so I guess it can be as simple as multiplying by two...

[Martinm210]

Glad you guys brought this back up. I'll do some actual testing onb this and see how real world compares with some stand alone pumps.

I'll also look at pump redundancy.