Bill:

From your graph then going from 2-3GPM lowers temps roughly 0.5C for a 60W heat source. Seems hardly worth the effort. I would have expected the flow to be a good bit less than 2GPM with the 1048 though; guess I am not too accustomed to these "high flow" blocks.

nikhsub1
from a testing perspective I can say that you cannot draw a conclusion from a single trial
the TIM joint variability is certainly larger than the difference due the pump change with that particular wb
- so you are not going to see the pump difference until you average many VERY carefully controlled wb mounts
-- how many ?, 10 of each for starters, then critically evaluate the range
- then there’s the CPU loading, the temp measurement, and on, and on

bigben2k
no, that whole post was for you Ben

labyrinth, as in channeled flow: -> a Spir@l is indeed a labyrinth too
its only the hype that swirls round and round

I have an article 'in the works' on wb testing
perhaps Dave Smith would want to collaborate with you on wb design ?
(and if you read the thread I linked to you could infer I'm more than a bit beyond the present products)

have YOU installed such a valve Ben ?
no "proof" do I see, I see words; where are your numbers ??

pHaestus
sorry, its not stated; the load was 70W, ~95W with Radiate

did I miss something ?
2gpm with a 1048 ?
seems a bit high, but note the absence of elbows, big rad, etc

I totally realize this! That is what I was saying in my previous post! But to the average joe blow, his results will likely be the same as mine with a similar set up.

I don't think nikhsub1 was out to prove a point, I think he was out for better performance, based on what he's seen/heard/read.

I agree that a spiral is essentially a labyrinth, but I like to seperate those because the channels aren't square restrictions, which are more restrictive. I'll make it a sub category of labyrinth type, how's that?

No, I've never installed such a valve, but I'm thinking that it would be an interesting experiment, albeit at nikhsub1's expense, to prove that the problem that he's encountering (if this problem in fact exists) is due to the rad flow rate being too high. As with all experiments, it is based on a theory, and my theory is that by lowering the flow rate through the rad, nikhsub1 will recover the performance that he (seemingly) lost. It's a shame that the block had to be re-mounted, in the process of changing the pump, because it alters the results of the pump swap.

Nikhsub1: if you're still reading this, I'll send you the valve and Ts, if you want to try it. I've got 3-4$ to spare...

There's a lot of spare parts in the typical o/cer and watercooler's closet. If you "upgrade" to the part of the day you'll go broke. Bill's comment on total system performance is well noted, and I will add my (anecdotal) test results here. They differ from Bill's in that:

1)My flow rates are +/- 6%
2)My temperatures are less precise
3)I was not isolating the waterblock so there is a heatercore for heat exchange with air rather than a chiller.

Take the numbers as illustrative rather than quantitative, please.

http://phaestus.procooling.com/gpmvary.jpg

The test setup was a Maze2 (newer rev) 1975 Caprice heatercore with 2 Panaflo H1A fans, Eheim 1250, 1/2" silicone, and a ball valve to adjust flow rate. Overall conclusion was that you must keep flow rates over 1 GPM; with the pressure drop of the flowmeter and the 1250 I couldn't get to the higher flow rates where Bill sees no improvement. I would suspect, however, that if the wb performance isn't improving but the radiator's efficiency is decreasing with ever higher GPM, then the delta T may actually rise again.

Thanks for that pHaestus, I think your results fall within BillAs, if one look pretty close up...

What do you think about adding a bypass to the rad?

Ya'll know that we talked about pump efficiency, but we didn't say the words: if you're shooting for high GPH, you should get a higher pressure rated pump, so that the pump runs in an efficient range. What I'm having an issue with is that there are few, if any centrifugal pumps that seem to have those specs, so maybe we should review the whole big pump thing, and start looking at other pump types.

The Eheim 1250 is not all that great for pressure, but no one questions it, and since Eheim won't put out P-Q curves for them, then this thing starts falling the way of the rumors with statements like "get an Eheim, it's the best". Shame!

"efficiency'' is being used a bit loosely (and several different items possibly confused)

other than for several round-tube radiators (graphs here),
gross dissipation will always increase as the flow increases (remember both wbs and rads are heat exchangers)
[invert a rad curve - guess what ? its just like a wb curve with different units)

rad efficiency has to do with the dissipation/in.^3/°

nikhsub1
posing an 'intellectual' question to ponder -

could not the thread have been titled 'Swapped pumps and a crappy wb install boosted my temps' ?
- using exactly the same data

all I'm saying is that what 'seems obvious' may not be the case

Ben
I had (for 2 days !) a 1060, and it had a P-Q curve on the side of the box
do not the others ?

Bigben you are right about Eheims being "the best". Although I do think they are the best in terms of failure rate and leakage. Although your valve idea sounds interesting, I don't really want to be the guinea pig. All I am after is the best possible temps with H20. Like I said, the 1250 "seems" to be the pump of choice and I figured there must be a good reason, seems I shouldn't go figuring. To add even more complexity to this issue, I swapped the Spiral for the TC-4 and I am seeing somewhat better results thus far. All I can say is that I will be putting the 1048 back in when I get some time, only this time, I WILL NOT remove the TC-4 during the process so temp differences HAVE to be based on the pump alone. Am I correct to assume this?

Iwaki (MD motors only, made in Japan)
much better
cost effective ? - here we go again

Is this the P-Q curve?

That Iwaki is one of the best pumps I've spec'ed. The reality is that most people will use a cheap pump, and it is going to be used inefficiently. Hey, that's watercooling... we gotta go with it, or stand alone.

Thanks nikhsub1, yes, that'll work. Just for kicks, you could try removing the turbulators in the TC-4, it seems that Viperman gets 2 or 3 deg C better without them. (I know, it's dissapointing to get the TC-4 and run it like a maze1).

Bill I've actually taken a liking to your crass attitude, and yes, I suppose that COULD have been the thread title. I may not have as much experience in testing as you but I DO know how to install a WB and thermal grease correctly, as a matter of fact, I reinstalled the WB 3 times to make sure.

Woot! there it is!

Thank you!!!

Can someone explain this P-Q curve to me? How does the 1250 stack up?

I like BillA too. You know though, some people really shoot themselves in the foot: if you know how to install a WB, why did you have to do it three times?:p

I got this one.

If you run the pump with no restriction, then it's giving out 100% of its effort to move water, and since this pump is centrifugal in nature, which means that it's about 70% efficient in converting electrical energy into a waterflow (which can be calculated), then you can easily see that if you achieve half of the max flow rate once this thing is installed, your efficiency (aka energy efficiency)is somewhere around 40%.

I didn't HAVE to, I wanted to be absolutely positively 100% sure the higher temps were NOT DUE TO a crap WB install. Needless to say I got the same result each time.:(

OK but how to read the chart I scanned? WTF are those #'s?

On the horizontal axis, you have the flow rate. On the vertical axis you have the head. Head can be converted to pressure. The higher the flow rate, the less head/pressure there is.

If you could measure your flow rate, you would be able to tell the pressure that the pump has to fight to get to that flow rate.

If your coolant is mixing together then you'll have warm water... the "cool" water returning from the rad would mix with the "hot" water returning from the block, and when they mix in the reservoir, voila, you have warm. This would hurt the effectiveness of both the block and the rad since you're lowering the delta T in both for no good reason. I could see this working in a two chamber reservoir setup, but then you'd have to match the flow in both loops or one reservoir would drain into the other. If I'm missing something, please set me straight folks.

Its just a thought, but with the pump upgrade , I see a reduction in tube size going to the vid block. I wonder if going to a larger sized pump would reduce the flow thrue the smaller tubes (Hence the whole "Water will always take the path of least resistance" there for introducing warmer water that does excape the vid card loop. Just a thought. Also having the pump at a higher location would increase the heat output due to it having to lift the water higher. maybe im totally off base....


Also I want to note that I am running a very small rio pump, and I can still get temps in the low 40`s C

Well, you're right about one res draining into the other one, that's for sure.

We covered this in another thread here

I suggested sticking the rad loop outlet into the CPU loop inlet. It'd be near impossible to match the flow rates though, they're always going to be different.

That's the exact same thing as having two pumps in series (i.e. it's one loop, not two, unless I misunderstand).

This one is specifically for Ben, but for all to consider.

It is a myth that radiators have a sweet spot. Perhaps "myth" is too strong a term. Maybe misunderstanding is more accurate.

When you're considering fluid flow through a radiator you are concerned with convection from a fluid to a solid. Sound familiar? It's the same concern with a water block. And just like a water block, higher velocity will always improve heat transfer.

Take a gander at the equation for convection again. Q = h * A * delta-T. Both "h" and "delta-T" are continuous functions that vary throughout the radiator. Nonethless, "h" is largely a function of velocity with higher velocity increasing "h". For a fixed "Q" and "A", this means higher velocity equates with lower delta-T.

So why the misunderstanding? Just like with waterblocks, pushing more flow through a radiator requires more pump power. Power tends to go up as flow^3. When flow and power are both low, it doesn't take a whole lot of power to increase flow rate "significantly". As a result you get better results from a flow increase. Once you get to a certain point, it requires a greater increase in power to generate more flow than the improved "h" can compensate.

There's a double-whammy here, too. As "h" gets better, delta-T drops toward zero. You start getting delta-T too small and it requires massively more flow to make a dent toward yet lower delta-T values.

So practically, yeah, if you get beyond a certain flow (which varies by radiator) then you'll see a drop in "performance" versus increased flow. This drop is largely imaginary, as the radiator is really dissipating more and more energy as the flowrate goes up. The only way to truly judge this is to decrease heat input from a CPU (or simulator) as the power to the pump goes up such that total power input remains constant. Even this is a crapshoot, however, as pump efficiency varies according to flow rate.

Anyway, more flow will always make a radiator more effective. It just won't always make your fluid temperatures better.

Should also note that water flow is only a part of the overall picture. Airflow is every bit if not more important.