Look this pump

[Marvin]

What do you think about this pump ?

[murray13]

That is a powerful pump. Even the smallest one. One thing to consider, the smallest one (if I'm reading it correctly) is .25hp that is about 180W. Even if that is input power there will be about 90W of heat put into the water from the pump. Your CPU might just be there maybe. So the pump will induce about as much heat as the CPU.

[Cathar]

WAY too overpowered for computer water-cooling use.

For centrifugal pumps you want to be looking at a maximuk motor power draw of less than 40W to prevent excessive pump heat being the major factor.

[Blackeagle]

Cathar,

How did you come up with a 40W max. pump size?

I'm not disagreeing with you on this pump. But I am interested in how or why this is what you feel the max size should be.

This question of max pump size is one I've wondered about for some time.

Thanks

[#Rotor]

those pumps are awesome.... and they have a magnetic coupling between the pump assembly and the electric motor, They are not for submersion. they do not dump all that heat into the water. That is why it's important to have good air ventilation on the motor.



a tad on the big side for one pc, Yes.... But for some clustering action, or for some sub zero liquid manuvers.. just right....

[Volenti]

Yea their a similar setup to the Iwaki pumps.

[Cathar]

Originally posted by Blackeagle
Cathar,

How did you come up with a 40W max. pump size?

I'm not disagreeing with you on this pump. But I am interested in how or why this is what you feel the max size should be.

This question of max pump size is one I've wondered about for some time.

Thanks

It's just an arbitrary figure that I've slowly decided upon over much time playing with different pumps.

As you all know, the more powerful the pump, the more heat that is dumped into the water, whether that be through direct pump heat, or frictional heat caused by the impeller spinning trying to push the water. Either way, quite a substantial portion of the pump's heat will make it into the water.

I have dual Nippon-Denso Camry cores (22cm x 14cm x 3.2cm with 24FPI) mounted in a large box I made with a household mains-power exhaust fan pushing through them.

I also have an Iwaki MD-30RZ pump, which draws 80W.

I also run my T'Bred B at 2500MHz/1.95v, and run BurnK7 on it.

I also have an Eheim 1250 which I use for priming the Iwaki pump, and an external reservoir. This is useful because the Eheim draws 28W, and can be used to circulate the water even if the Iwaki is turned off, and it acts as a filter. Typically the Eheim 1250 is turned off.

Now under full CPU load (BurnK7) with the Iwaki pump, my water temps are climbing to 3.1C above the fan intake temperature.

If I turn the computer off and leave the fan/Iwaki running, the water temps stabilise at 1.9C above the fan intake temperature.

If I turn the Iwaki off and the Eheim on, the water temps sit at 1.2C above the fan intake. This 1.2C is due to the heat of the (submsered) Eheim pump, and the heat from the fan's motor (rated at 50W).

Now if we say that the fan + pump = 78W, which equates to a 1.2C rise in water temps, then the radiator setup has a C/W of 0.015.

If the Iwaki + fan = 130W, and equates to a 1.9C water rise, we also have a correlational C/W of 0.0146 (close enough to 0.015 given the margins of error). Note that the Iwaki pump sits in the box, so all of its 80W of energy will either be going into the water or through the radiators via the heat that radiates off its body.

That fan really should be sucking rather than blowing eh?

From this, we can roughly predict the CPU wattage being transferred into the water-cooling loop, and it works out to around 80W, which is about what I'd expect.

So what does all that mess tell us? It tells us that even given a good radiator setup that a powerful pump has a very real impact on the water temperatures, and that a very hot CPU is dumping around 80W of heat into the loop that needs to be cooled by the radiator.

So this is where I get max 40W pump recommendation from. If 40W of heat is coming from the pump, then it's going to be contributing to at least 1/3 of the total system heat. As the pump's power is increased, it can become the major heat source.

Now let's look at some block PQ curves.

The Eheim 1250 will push around 6.5lpm through my setup.

The Iwaki MD-30RZ pushes around 11.0lpm through the setup.

Looking at the flow vs C/W graph of the White Water, this corresponds to about a 0.01C/W difference in terms of waterblock performance. For an 80W CPU, that's 0.8C.

For the extra 52W that the Iwaki uses over the Eheim 1250, the CPU is 0.8C cooler, but the water is 52 * 0.015 = 0.78C warmer.

ie. the very good radiator setup is only just able to overcome the extra pump heat. A lesser radiator setup (and I won't lie, almost every single radiator setup out there is going to cool way worse than mine) will actually result in higher CPU temps with the pump. I've gained nothing, others will lose.

Given a radiator setup that's cooling 3x worse than mine (ie. something like D-Tek Pro core with 2 x 100+ CFM 12cm fans mounted on either side), then a 80W pump is total overkill. Let's assume the D-Tek setup described will have a C/W of around 0.045, which is probably about right looking at BillA's data in the simulator discussion forum.

Let's assume a 40W pump like an Aussie spec (50Hz) Iwaki MD20-RZ. About the best 40W pump you'll get. It'll push about 9.5lpm through a WW setup like mine, for about a 0.008C/W difference, or about 0.6C difference on the CPU compared to an Eheim 1250.

Given a D-Tek pro core, the extra 12W of the Iwaki MD-20RZ will result in 0.55C warmer water, so it alone can barely give any benefit with the more powerful heat dumping MD-20RZ.

ie. for the typical computer water-cooling user, looking at anything more than a 40W pump is totally futile. Heck, even for me it's basically a no-win situation.

40W maximum, and even then, only if you're buying an MD-20RZ

A 10-20W pump is ideal. That 12V 11W "March" brand pump that was looked at here in another thread would probably be close to "ideal", as it gave a PQ curve about the same as a US spec Iwaki MD-15, but at 11W, it's extremely efficient.

So long as the pump is pushing more than 4lpm in your system and is sucking down less than 40W, you'd got the right pump for you. In fact I'd go so far as to say that the right pump for anyone is one that gives about 6lpm (1.5gpm) for the lowest wattage.

As a general rule for most any waterblock you can buy, don't bother chasing more than 6lpm unless it comes very easy, it's simply not worth it.

[Marvin]

Sorry i post the wrong pump. look a this.
80 W.
corrected first image

[BillA]

nice description Cathar

BTW, I just installed a 14W Hydor L20

[Blackeagle]

A question for Cathar &/or BillA.

I have in mind to use the 2-342 rad that BillA just tested. While it did well in BillA's testing I don't really know how it compares to yours Cathar. It will be mounted to have air flowing through rad and into the case with 4 120mm in push/pull, 2 on each side. CFM of the 120mm fans used on rad will be somewhere from 80 to 100 CFM connected to a reobus.

I also want to use CPU, NB & Gfx blocks in series which would lead to higher heat load and resistences. The CPU block would be of one of two types. 1. micro channel of the WW design if they don't mess them up altering them for mass production, or 2. May see if I can work out a deal with Morphling 1 on one of his in copper. The NB will be a Morphling block if I go with his CPU block and Danger Den's Z block if I use the WW commercial design. Not sure of what Gfx to use yet.

Lines will be 1/2" up to 5/8" depending on pump used. May also use a mix of sizes but nothing under 1/2". I hope to keep total line length to 30" or less.

Res will be a DIY of my own making, about 2.5" cylinder shaped one closely connected to the pump.

System total CFM will be high enough to insure pump heat to be removed fast, so radiated heat off the motor as should not be a problem as Rotor said.

Pumps I'm considering are all Iwaki's.

1) MD-15 which has 11.1 feet of head and 300 gph of flow rate @ 0 head. I like the fact this would be much easier to locate in a case.

2) MD-20Z Like the higher head rate, but I'll need to pull a hard drive cage to make room for it.

3) MD-30Z Would offer highest flow and head rate in a system. Takes no more space in case than a MD-20. I like the idea of it insuring high flow even with 3 blocks.

Question is would the MD-30 be to much? If the MD-30 is to much, how much more flow would the MD-15 offer vs. the MD-20 in a system like I want to put togather?

Thanks

BE

[BillA]

what ? WHAT ?
you're not WCing the hdds and psu ?
- and why not ?

seriously, that's a lot of stuff
the 30 is way out
with the 20RLZ you should get 2.5gpm easy, and the pump is operating efficiently

but it is big, hot, and not so silent (and expensive ?)
if the WCing setup is in another box - fine

if in the case, I'd experiment a bit with 'too small' pumps 'till I found one that was just adequate
(and I suspect adequate might be below the 20RLZ)

[Blackeagle]

Hdd & power supply....hhmmmm. LOL

Yeah, I'm planning a last socket A system that I want to be pretty top shelf.

Cost and heat of the larger pumps I was aware of, but not the noise factor. Thanks for the warning there. Space was also a issue with them as well. Thoughts on the MD-15?

Or it might be a whole lot faster if I just asked this. What pump would you suggest as the best for the type of multi block set up I'd like to have? Cost isn't as important to me as is it's being dependable above all, reasonably low noise and good flow with up to 3 blocks?

edit: Case will be a full tower/server type.

Thanks

BE

[Marvin]

billA, what do you think abou thos pump ?
cheers

[Cathar]

BlackEagle, I would say that the MD-15 is definitely the pump you want out of those three.

Unless you have a very specific need for the higher pressure pumps like the 20/30-RZ models, you will be worse off with them. Too much heat/noise for little real benefit at the block, and a net loss once the radiator has to try to remove that heat.

I'm somewhat familiar with the heater-core you're looking at and it is a "rough" equivalent to a single one of the cores that I use in terms of cooling performance, based on the experience of one person I know who has had both in a setup and switched between the two.

[Cathar]

Originally posted by Marvin
billA, what do you think abou thos pump ?
cheers

It's about the same as the Iwaki MD-30RZ. Unless you literally had a car radiator (not a heater-core) cooling your setup, you'd be worse off.

[Marvin]

Yes, thats completely right. totally overkill.
i borrowed my uncle this 1\4 hp pump and the temp raised 5 C with the dtek+2 shrouds, that became extremely hot....
completely useless.
back to maxi 1200

[Gizmologist]

Extreme:

a : existing in a very high degree <extreme poverty> b : going to great or exaggerated lengths : RADICAL <went on an extreme diet> c : exceeding the ordinary, usual, or expected <extreme weather conditions>


It seems like all the responses have been by naysayers..

A lesser radiator setup (and I won't lie, almost every single radiator setup out there is going to cool way worse than mine)

That's a pretty bold statement...I don't care who you are...

Anyway...good luck Marvin...with whatever you decide to go with..

_Giz

[Cathar]

Originally posted by Gizmologist
That's a pretty bold statement...I don't care who you are...

Please note that I said almost.

Unless dual large and high efficiency heatercores flowed by a 400CFM rated mains-powered house exhuast fan in a purpose built shroud box has become the standard issue for the majority of radiator-based water-cooling setups, I stand by the statement that the radiator setup that I use will offer better cooling than almost every other radiator-based setup used for computer water cooling.