Unexpected results - higher flow = higher temps

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10-22-2006, 09:23 PM
virtualrain

5 Attachment(s)

Thinking dual DDC's? higher flow = higher temps

I have an interesting observation and I would like your thoughts...

My temps are higher at high flow rates and slightly lower (but certainly not worse) at lower flow rates.

Loop:

DDC Ultra w/mod /res > DDC Ultra (stock) > BI GTS 240 > BI GTS 240 > Apogee > MCW30 > Alphacool watercooled PSU

Note: I'm not yet watercooling my GPU.

I use a pair of 140mm SL Yate Loon fans on EACH rad (4 fans total). They run at 800 RPM.

I have an Aquaero and use that plus a couple of these circuits to vary the voltage to the pumps from 7V to 12V...
http://home.nc.rr.com/katyandrandy/pwm.htm

The following temps were noted after running dual Orthos Prime for 1hr. on separate days.

At 12V the flow is about 6lpm and temps are:
Room Temp: 21
Water in: 29.7
Water out: 29.5
IHS: 27.8 (thermal probe on side of IHS)
Core: 43 (as reported by Speedfan)
CPU: 44 (as reported by Spedfan)

At 7V the flow is about 3.5lpm and temps are:
Room Temp: 22
Water In: 29
Water Out: 29
IHS: 27.1
Core: 40
CPU: 43

Why would my temps be the same or lower with lower flow? I would have expected worse temps with lower flow.

I assume this means that the cooling effectiveness of my rad/fan combo cannot benefit from higher flow. Is it that the water is moving to quickly through the rads to be effectively cooled?

I assume more airflow and/or better rads would change this so that temps would decrease with higher flow?

I guess one other observation from this is given my system design, dual DDC's is really not helping.

When I get my graphics card in the loop, I suspect I should also look at upgrading my fans from 140mm SL's to ML's to move more air?

I'm interested in your thoughts.

EDIT/UPDATE: After input from a lot of people, I think the link in Post #30 provided by fairydust answers the question as to why more pump is not always better! Here's a review that anyone considering dual pumps should read!

Update: Added some photos.

Here's a few notes that will make the photos make a bit more sense...

- I originally fitted everything using a wooden MDF mockup of my mobo and expansion cards. At the time I was hoping to cool the GPU as well as the chipset but given the layout of the Mobo and other constraints of my design (namely the rads on the side door) could not cool both the GPU and chipset. Knowing I would soon be updating to a Conroe and G80, I decided to wait on the GPU cooling. At any rate, in one of the pics you can still see the wooden computer mockup with GPU block on it.

- All tubing is 7/16" Masterkleer with coolsleeves. The tubing connecting the rad to pump 2 at the top and the CPU block at the bottom obviously had to be given a lot of thought so the door could be opened and closed without kinking the tubing.

- Flow basically starts at the top of the chassis, flows through the rads and then works its way back to the top through the blocks.

- In the top of the chassis at the rear is the water cooled PSU which is the last water block in the chain. That feeds a small DD fillport res which then feeds the inline Remag flow meter before Pump 1 which has the Alphacool res which is mounted in the top front bays. Pump 1 then feeds Pump 2 which is mounted under the blowhole near the res. This then feeds the rad inlet.

- The DD Fillport res made bleeding a lot easier than useing a T. Trying to bleed using a T with dual DDC pumps is not practical. In fact, I had to glue some fish tank sponge to the top of the res to trap air so it would not get sucked back into the loop. I found that with dual pumps any air in the loop or the T will get sucked into the loop.
10-22-2006, 10:06 PM
mnewxcv

how long did you run the system with each setting?
10-22-2006, 11:12 PM
virtualrain

Quote:

Originally Posted by mnewxcv

how long did you run the system with each setting?

The temps were recorded after 1hr of running Orthos Prime on both cores... temps had stabilized long before.

Incidentally, idle temps also exhibit the same differences between running the pumps at 7V vs. 12v... that is, at 7V idle temps are a degree or so lower.
10-22-2006, 11:44 PM
Reinvented

Gee, I wonder why...

7v means less heat dump into the water, as opposed to 12v... get the picture?

Doesn't take a damn rocket scientist to figure that one out..
10-22-2006, 11:50 PM
Vikodemous

The lower Flow rate is giving the water more time to cool through the rad before it goes back to the CPU.
10-23-2006, 12:47 AM
L'enFer

Quote:

Originally Posted by virtualrain

I suspect I should also look at upgrading my fans

may be u should to upgrade wb's?
10-23-2006, 12:57 AM
MaxxxRacer

Quote:

Originally Posted by Vikodemous

The lower Flow rate is giving the water more time to cool through the rad before it goes back to the CPU.

Please go read the guides before you say such nonesense.
10-23-2006, 12:58 AM
Digz

Quote:

Originally Posted by Reinvented

Gee, I wonder why...

7v means less heat dump into the water, as opposed to 12v... get the picture?

Doesn't take a damn rocket scientist to figure that one out..

OOOOOOOOOoooooo (handbags at the ready)

:D
10-23-2006, 01:31 AM
Mord

Yep. Slower water = more heat absorbed from the WB's AND more heat dissipated by the RAD. Pretty simple. That's why I run my setup at about 400l/h. The max of the pump is 800l/h. It's SICCE NOVA.
10-23-2006, 01:39 AM
Herr Brun

Quote:

Originally Posted by Mord

Yep. Slower water = more heat absorbed from the WB's AND more heat dissipated by the RAD. Pretty simple. That's why I run my setup at about 400l/h. The max of the pump is 800l/h. It's SICCE NOVA.

You are wrong. Read the stickies please.
10-23-2006, 01:49 AM
exhausted mule

Quote:

Originally Posted by Herr Brun

You are wrong. Read the stickies please.

i'm sure that the performance curve of fan/flow/temp delta is not the same for both wb and rad.

everybodies setup will differ and its good to experiment to find your optimum setup.
10-23-2006, 01:51 AM
Mord

Could you please explain what's wrong. I think it's obvious. :)
10-23-2006, 02:08 AM
Hound53

Just out of curiosity how did you get your flowrates? Unless you took return line off and actualy measured the flow returning or have a small accurate inline flow meter I would bet you only flowing 3.5 LPM (or less) at the pumps designed head pressure at both voltages.

These are non positive discharge pumps. You could have the designed head with zero flow once it reaches it's designed head pressure, then the water just sit's there and spins (slippage) and builds up heat energy. I once saw a pump hooked up to PVC build up enough heat in the water to soften the PVC to the point where it swelled up and burst because someone turned off #1 pump and shut #2's discharge valve when switching pumps. It was a lot larger pump granted but still the same theory.

If you were to put a ampmeter, a flowmeter, a pressure gauge and a thermometer on a pump then slowly shut down on a discharge valve the pressure would rise to x with y flow and z amps. Keep shutting down on the valve and x and z would reach a point where they remained constant but y would continue to decrease until it hit zero. Study Newton's law of energy conservation look at the thermometer in that discharge line and you will see where the energy( x timesz) went.
10-23-2006, 02:20 AM
Mord

Don't know about the others. I measure it the dummy way - start the pump and see how much water gets out the other way in the bucket for 5mins. Measure it and divide by 5. This way I know its flowrate with a good approximation.
10-23-2006, 02:28 AM
v0dka

The pump dumps more heat?

Hound53 seems to be on to somthing but I dont understand a word of it lol :D
10-23-2006, 03:01 AM
Radical_53

Strange behaviour. Still, the loop itself is somewhat strange to me (performance in total is not that good I'd say). If you are willing to, try a loop with just one rad and just the modded DDC. To me, the second pump and rad doesn't make too much sense on this kind of setup.
10-23-2006, 03:11 AM
Hound53

Quote:

Originally Posted by Mord

Don't know about the others. I measure it the dummy way - start the pump and see how much water gets out the other way in the bucket for 5mins. Measure it and divide by 5. This way I know its flowrate with a good approximation.

Hey that works, and is a heck of a lot cheaper than a flowmeter that you would use once in a blue moon.

Quote:

Originally Posted by v0dka

Hound53 seems to be on to somthing but I dont understand a word of it lol :D

Centrifugal pump theory and physics 101. In every day terms. Bigger is not necessarily better. Once one of these pumps reaches it's designed maximum head pressure that is the maximum it will flow. It could be rated at 10000 gpm but if the loop only flows 1 gpm at whatever the pumps max head is 9999 gpm 's worth of energy is wasted even though it weill be doiing it's best to move that 10000 gpm somewhere.
10-23-2006, 04:28 AM
ChongL

I think we need Marci in here to school everyone
10-23-2006, 04:57 AM
L'enFer

Quote:

Originally Posted by aznblueeboi

I think we need Marci in here to school everyone

or creidiki...
10-23-2006, 05:07 AM
Hound53

An alternative way of setting the pump to max efficiency would be use a speed control with a flow meter, once the flow peaks that pump is moving as much water as it can through the loop.

A sensitive pressure gage and a bypass valve back to the pumps suction would acomplish the same thing. Put the gage in the branch that leads to the water blocks, open the bypass back to the pump suction until pressure started to drop. That would give you max flow to the block(s).
10-23-2006, 05:18 AM
voigts

I wonder if running those rads in parallel instead of in series would make a difference, but I must say that dual pumps and dual 240 rads is total overkill.
10-23-2006, 06:23 AM
Modzilla

Have we figured this one out yet? Im not the sharpest knife in the drawer but I think I have the answer. Inline pumps produce heat during operation and discharge this heat into the water. This heat comes from the power source and friction (friction of impeller against the impeller housing and the water). More volts equals more heat, and faster impeller speed equals more friction which equals more heat. At the higher flow, the pump is fed by 12v and the impeller speed is higher, thus more heat dump than at 7v and slower impeller speed. The speed of the water through the waterblocks and radiators does not affect cooling (not counting friction). All systems will, with time, reach a steady state of heat absorbtion and discharge, thats why temps must be read after the system has been running for an hour or more.
And we are assuming that speedfan and your temp probe are accurate and precise, and that .7 degree is a significant difference for this system. Anyway, I saw the same with my system: i switched out the danner mag 350 gph model for the danner mag 250 gph model and got lower temps. The 250 model uses less power to run and the impeller spins slower. The pumps are identical in all other respects.
10-23-2006, 08:55 AM
virtualrain

Wow, lots of input here.

To answer some comments:

- I agree the system is overkill as it stands. As noted, I intend to add the GPU to the loop when I get an 8800 in the next couple of months and perhaps switch to a Storm when I upgrade to a Conroe however, I want to understand this first before I go to the Storm.

- I could definitely try using only one rad and one pump instead of dual pumps and rads at some point, but I'm too busy to rip the loop apart right now to try that. Alternatively, when I redo the loop, I could try two separate loops but the added tubing complexity in my rig may not be feasible.

- As for flow, I have a Remag flow meter in-line... http://www.remag.ch/vision.php?language=4&sub=1&tab=2 I am having some problems with this however... more on that in the next message.

I also tested the flow of the loop using buckets before I started using it and it flowed 6lpm.

- Someone said the performance wasn't all that great... I'm not sure what that's based on, but my temps are now 15 degrees lower than they were on air and the system is a hell of a lot quieter so in my mind: mission accomplished.

- Is there simply not enough restriction in the loop? When both pumps are running at full, the second pump does "clack" a bit... as Marci and others have reported when running Dual DDC's without enough restriction in the loop.

- I'm curious about the merits of the heat-dump theory?
10-23-2006, 09:10 AM
virtualrain

Quote:

Originally Posted by Hound53

An alternative way of setting the pump to max efficiency would be use a speed control with a flow meter, once the flow peaks that pump is moving as much water as it can through the loop.

A sensitive pressure gage and a bypass valve back to the pumps suction would acomplish the same thing. Put the gage in the branch that leads to the water blocks, open the bypass back to the pump suction until pressure started to drop. That would give you max flow to the block(s).

So here is the problem with my flow meter that may or may not be related to this issue... Keep in mind this could be a red-herring as it could be a faulty flow meter or the Aquaero mis-behaving.

According to spec, the Remag flow meter generates 700 imp/l. I have noticed that if I set the Aquaero to this value and then run the pumps at full speed, the flow reported is way off... it's 0.6lpm. If I run the pumps at lower voltage, the flow meter seems more accurate...

However, if i set the imp/l on the Aquaero to 70 imp/l, I get what seem like more accurate flow ratings of 6lpm at full speed and 3lpm at 7V.

Here's the flow meter output at different pump speeds for the rated 700imp/l. Note that 0% = 7V and 100% = 12V due to the voltage divider I'm using...

10% = 1.5lpm
20% = 1.9lpm
30% = 2.2lpm
40% = 2.6lpm
50% = 2.9lpm
60% = 0.1lpm (very erratic)
70% = 0.4lpm (now it's off by about an order of magnitude!)
80% = 0.6lpm
90% = 0.6lpm (no change)
100% = 0.6lpm

Note that I tested the loop with buckets and both pumps running at max and the flow was 6lpm! So again, I say this may be a red-herring and it could be a faulty flow meter or Aquaero.

Update: I confirmed on the Aquacomputer forums that the Aquaero can only manage flow readings up to 3lpm which explains the findings above. So this had absolutely nothing to do with the temperature problem at higher flow rates. Unfortunately, I can only extrapolate my maximum flow which according the to rate of increase of flow with pump voltage would put the max flow at 100% at about 4.5lpm.
10-23-2006, 09:22 AM
thunderstruck!

Quote:

Originally Posted by aznblueeboi

I think we need Marci in here to school everyone

....waits patiently....
10-23-2006, 10:06 AM
Vikodemous

Quote:

Originally Posted by MaxxxRacer

Please go read the guides before you say such nonesense.

Thats your explanation Mr. Darth Water? With him running Dual rads let's hear your Brilliant Deduction then...

P.S. It's spelled nonsense.
10-23-2006, 10:10 AM
Hound53

Quote:

Originally Posted by virtualrain

So here is the problem with my flow meter that may or may not be related to this issue... Keep in mind this could be a red-herring as it could be a faulty flow meter or the Aquaero mis-behaving.

According to spec, the Remag flow meter generates 700 imp/l. I have noticed that if I set the Aquaero to this value and then run the pumps at full speed, the flow reported is way off... it's 0.6lpm. If I run the pumps at lower voltage, the flow meter seems more accurate...

However, if i set the imp/l on the Aquaero to 70 imp/l, I get what seem like more accurate flow ratings of 6lpm at full speed and 3lpm at 7V.

Here's the flow meter output at different pump speeds for the rated 700imp/l. Note that 0% = 7V and 100% = 12V due to the voltage divider I'm using...

10% = 1.5lpm
20% = 1.9lpm
30% = 2.2lpm
40% = 2.6lpm
50% = 2.9lpm
60% = 0.1lpm (very erratic)
70% = 0.4lpm (now it's off by about an order of magnitude!)
80% = 0.6lpm
90% = 0.6lpm (no change)
100% = 0.6lpm

Note that I tested the loop with buckets and both pumps running at max and the flow was 6lpm! So again, I say this may be a red-herring and it could be a faulty flow meter or Aquaero.

No I think I swas suffering from a case of anal cranial inversion and forgot all about efficiency curves. Most pumps operate most efficiently between 70%and 90% of their rated head. 90% being at the top of the scale and 70% being a cheap pond pump. Keep in mind that I am just a shade tree mechanic, and we really need to get a real engineer in here to settle this.
10-23-2006, 10:40 AM
Reinvented

Quote:

Originally Posted by Vikodemous

Thats your explanation Mr. Darth Water? With him running Dual rads let's hear your Brilliant Deduction then...

P.S. It's spelled nonsense.

Please, do US ALL a favor and THINK before you post...
10-23-2006, 10:47 AM
Fairydust

Check out this brilliant pump review, it explains a lot of the basics (horrible robotranslation sorry). You see the improved block/radiator performance from increased flowrate is often not enough to offset the increased water temperature from higher heatdump of the more powerfull pump.
10-23-2006, 11:39 AM
Firelord-OCHW

Why have you got the rads infront of the cpu block? Surely the Apogee would benefit from being right after the pump for max flow and then the rad after before it hits back round
10-23-2006, 11:40 AM
virtualrain

Quote:

Originally Posted by Fairydust

Check out this brilliant pump review, it explains a lot of the basics (horrible robotranslation sorry). You see the improved block/radiator performance from increased flowrate is often not enough to offset the increased water temperature from higher heatdump of the more powerfull pump.

Interesting find!!! At first glance, their findings with dual DDC's vs. a single DDC is consistent with my own. I gather that running both my DDC's at 7V is equivalent to just a bit more than a single DDC at 12V.

I guess I have a few options...
1. Get rid of one pump and run the other at full speed for the same results.
2. Keep both pumps as is running at 7V (they are very quiet at 7V)
3. Add more restriction (i.e. my GPU and possibly a Storm) to take advantage of the over-kill in pump power.

I'm obviusly leaning towards #3 and possibly using #2 during idle periods. Since I've already invested in the extra pump (which I purchased also for redundancy and to eliminate down-time in the event of an RMA) I may as well just keep it as is... no real point to ripping it out of the loop.

What do you think?

Question... would I benefit much from higher flow fans?
10-23-2006, 11:41 AM
virtualrain

Quote:

Originally Posted by Firelord-OCHW

Why have you got the rads infront of the cpu block? Surely the Apogee would benefit from being right after the pump for max flow and then the rad after before it hits back round

I think common lore is to have the CPU block directly after the rads for coolest water. Flow is the same at all points throughout the loop.
10-23-2006, 11:43 AM
Vikodemous

Quote:

Originally Posted by Reinvented

Gee, I wonder why...

7v means less heat dump into the water, as opposed to 12v... get the picture?

Doesn't take a damn rocket scientist to figure that one out..

Your right, I should have said something charming Like you did. You reply to his post like it's a burden. Lord forbid I try to give someone some sort of explanation to his having lower temps with lower flow rate.

And your absolutely right, "water that is no longer under constant heat won't cool"<-- I hope this statement makes you feel better.
10-23-2006, 11:54 AM
Senater_Cache

Quote:

Originally Posted by Vikodemous

The lower Flow rate is giving the water more time to cool through the rad before it goes back to the CPU.

better run and hide man.

Quote:

Originally Posted by Vikodemous

Lord forbid I try to give someone some sort of explanation to his having lower temps with lower flow rate.

you did nothing but spread misinformation. You did more harm to his grasp on watercooling than you did good.

Quote:

Originally Posted by Vikodemous

"water that is no longer under constant heat won't cool"

thats not quite the idea behind a radiator nor a block...think about convection rate and how its better at higher temperature differences between 2 materials.
10-23-2006, 11:56 AM
[XC]Atomicpineapple

Quote:

Originally Posted by Vikodemous

The lower Flow rate is giving the water more time to cool through the rad before it goes back to the CPU.

Small problem there. The water takes a time t to traverse the waterblock. During that time its temperature increases as it absorbs heat energy from the CPU. As its temperature increases the temperature difference (or 'delta') between the CPU and the water inside the block decreases, thus heat transfer rates drop.

If the flow rate is increased time t taken to traverse the block is decreased. Therefore each unit (molecule) of water absorbs less heat energy so its temperature remains lower. Thus the temperature differential is maintained and the heat transfer rates stay as high as possible. Now youre thinking 'ah-ha less heat transfered to water, means higher CPU temps at higher flow'. Um, no, because the higher flow rate will mean that more water molecules traverse the block in a given time period.

However as others have pointed out this increase in flowrate means more heat energy is dumped into the water by the pump(s). This can raise temperatures.

Thinking aloud now because I'm not sure where this will go........ The smaller time t also applies to the radiator. This means that the water has less time to remove its heat energy across a temperature delta, but as heat transfer rates grow exponentialy with temperature difference the decrease in t will perhaps have little to no effect on the radiator exit water temp as the decrease in time t would, in effect, be removing the section of the heat energy removal graph that relates to low temperature deltas, thus being the section of the graph where temperatures are least affected.
10-23-2006, 11:57 AM
Nanometer

:horse: I never understood what this smiley meant. Anyone want to explain?
10-23-2006, 11:57 AM
Reinvented

Quote:

Originally Posted by Vikodemous

Your right, I should have said something charming Like you did. You reply to his post like it's a burden. Lord forbid I try to give someone some sort of explanation to his having lower temps with lower flow rate.

And your absolutely right, "water that is no longer under constant heat won't cool"<-- I hope this statement makes you feel better.

Actually, maybe you should. And while your at it bud, read the stickies, and educate yourself a bit more...
10-23-2006, 12:01 PM
Modzilla

radiator placement is less important than some people think, if using a radiator that is about the size of a heater core (like most watercooling rads). what really matters is the heat absorbtion and dispersion capacity of the system as a whole. with a decent flowrate, the temperature of the water at any given point in the loop will be within a couple degrees F of the temp at any other point in the loop. it takes time for the water to absorb the heat and disperse it to the rad, and for the rad to disperse it to the air. its that steady state achieved by the system, after accounting for heat input and heat dispersion.
10-23-2006, 12:04 PM
virtualrain

Quote:

Originally Posted by Modzilla

radiator placement is less important than some people think, if using a radiator that is about the size of a heater core (like most watercooling rads). what really matters is the heat absorbtion and dispersion capacity of the system as a whole. with a decent flowrate, the temperature of the water at any given point in the loop will be within a couple degrees F of the temp at any other point in the loop. it takes time for the water to absorb the heat and disperse it to the rad, and for the rad to disperse it to the air. its that steady state achieved by the system, after accounting for heat input and heat dispersion.

In my case, the water temperature as measured just before the rads is often only 0.3 degrees C warmer than the water temp after the rads.
10-23-2006, 12:06 PM
Senater_Cache

Quote:

Originally Posted by Nanometer

:horse: I never understood what this smiley meant. Anyone want to explain?

lol...yep.

But it will never end. and with chaps like vikedemous running rampant spreading the gospel its only gonna get worse.
watercooling, soon to be mainstream and completely misunderstood.
10-23-2006, 12:25 PM
nikhsub1

Quote:

Originally Posted by virtualrain

I think common lore is to have the CPU block directly after the rads for coolest water. Flow is the same at all points throughout the loop.

Careful how you word that. While overall system flowrate is constant, PRESSURE IS NOT. You will get the greatest pressure right after the pump, pressure goes down as it goes through each piece in the loop.
10-23-2006, 12:34 PM
Radical_53

Quote:

Originally Posted by Modzilla

radiator placement is less important than some people think, if using a radiator that is about the size of a heater core (like most watercooling rads). what really matters is the heat absorbtion and dispersion capacity of the system as a whole. with a decent flowrate, the temperature of the water at any given point in the loop will be within a couple degrees F of the temp at any other point in the loop. it takes time for the water to absorb the heat and disperse it to the rad, and for the rad to disperse it to the air. its that steady state achieved by the system, after accounting for heat input and heat dispersion.

Depends on what you mean with "radiator placement". Where it is on the loop, you're right. Where it is in your case, definitely not. Makes a huge difference if there's not enough space for the air to get in or out.

@fairydust: You're right about that review, there was something from Cathar on a topic like that too:

http://forums.procooling.com/vbb/sho...light=storm+g7

Generally spoken, a too small pump will give you low performance because the flow rate is low, but a too big pump will give low performance too, as the heat dump is too high.
Somewhere in the middle you'd find the "perfect pump" for your setup. One reason why I dumped the second DDC+ on my loop, as it doubled pump heat dump but only gave me ~15-25% higher flow rates. It didn't show a real improvement, so why hassle around with it.
10-23-2006, 12:35 PM
Fairydust

Quote:

Originally Posted by virtualrain

Question... would I benefit much from higher flow fans?

If your radiator performance increases and °C/W drops (more powerfull fans or radiator, bigger area) the impact on water temperature of the raised heatdump of a more powerfull pump will shrink. If the impact of the heatdump is smaller than the increase in block performance due to increased flowrate, temps will drop. If this will happen in your particular setup I do not know.
10-23-2006, 12:36 PM
Modzilla

I meant where the rad is in the loop. For my posts, Im assuming that the rad has adequate air-flow.
10-23-2006, 12:39 PM
Radical_53

Ok, my fault ;) Then I totally agree with you. I've seen differences of up to 1°C before and after the rad, but that depends a lot on the rad used and how much air is going through the rad. On a "good" setup, definitely nothing to even think about.
10-23-2006, 12:40 PM
nikhsub1

Quote:

Originally Posted by Radical_53

One reason why I dumped the second DDC+ on my loop, as it doubled pump heat dump but only gave me ~15-25% higher flow rates. It didn't show a real improvement, so why hassle around with it.

Actually it will give you ~35% improvement in flowrate.
10-23-2006, 12:46 PM
Herr Brun

Quote:

Originally Posted by nikhsub1

Careful how you word that. While overall system flowrate is constant, PRESSURE IS NOT. You will get the greatest pressure right after the pump, pressure goes down as it goes through each piece in the loop.

But that doesn't matter, if I understand correctly? Pressure does not matter, flowrate does? Or is it different with impingement (sp) style blocks?
10-23-2006, 12:54 PM
nikhsub1

Quote:

Originally Posted by Herr Brun

But that doesn't matter, if I understand correctly? Pressure does not matter, flowrate does? Or is it different with impingement (sp) style blocks?

There is no way to correctly answer that question. Yes sometimes it does matter, how much? Another guess. If pressure didn't matter we'd all be running pumps with 1 inch of max head...
10-23-2006, 12:55 PM
JoeBar

And Tt would be the king of wc'ing... :lol2:
10-23-2006, 12:59 PM
[XC]Atomicpineapple

Quote:

Originally Posted by Herr Brun

But that doesn't matter, if I understand correctly? Pressure does not matter, flowrate does? Or is it different with impingement (sp) style blocks?

Flowrate is what matters, but pressure leads to flow rate (to a certain extent). As pressure allows the water to overcome obstruction. Ie a pump with 30000l/h max flow and 6" max head is useless, but 1000l/h max flow and say 16' max head is useful.
10-23-2006, 12:59 PM
Nanometer

No1 answered my question :(
10-23-2006, 01:02 PM
Modzilla

beating a dead horse.

Beating a dead horse
From Wikipedia, the free encyclopedia

In American English, "beating a dead horse" is an idiom which is most often used as a retort used to make clear that a particular request or line of conversation is already foreclosed, mooted, or otherwise resolved.

The linguistic roots of this phrase draw on an allusion to literally "whipping" or "beating" a deceased horse in order to make it get up and go. Figuratively, when one is "beating a dead horse", one is flailing at a dead or useless idea.
10-23-2006, 01:08 PM
Herr Brun

Quote:

Originally Posted by nikhsub1

There is no way to correctly answer that question. Yes sometimes it does matter, how much? Another guess. If pressure didn't matter we'd all be running pumps with 1 inch of max head...

Yeah, but I thought more pressure at the start = more flow, but I'm probably all wrong. Really new to wc (just read my thread about the dead mobo and gpu :stick: ), and still doing my first year of physics in high school.
10-23-2006, 01:09 PM
Herr Brun

Quote:

Originally Posted by Atomicpineapple

Flowrate is what matters, but pressure leads to flow rate (to a certain extent). As pressure allows the water to overcome obstruction. Ie a pump with 30000l/h max flow and 6" max head is useless, but 1000l/h max flow and say 16' max head is useful.

That's exactly what I thought. Logic seems to work to some extent ^^
10-23-2006, 01:37 PM
Tero

It depends on how much pressure and how much flow you're dealing with since these pumps are not positive displacement.

For example you have a pump with 10000gph and 16' of head. Now imagine what happens when that pump gets restricted by 50%. A 50% restriction on a centrifugial pump means ~50% of it's energy gets transfered into the water through friction or whatnot.

That's a lot of energy being thrown away and more importantly being put into the water. Now logically one would think "but hey we still have ALL that flow" well the amount of heat the pump puts into the loop becomes more than the radiator can dissapate and heats up the loop. This works on a smaller scale in a similar way i'm just not sure of the actual impact. It would probably be calculated by the amount of force needed to move the amount of water head the pump loses a certain distance in a given time.

Seems we need some positive displacement pumps to make WC a lot less annoying.
10-23-2006, 01:48 PM
[XC]Atomicpineapple

Tero, sure, but then you get into pump design, which I know naff all about. With my example above I wasnt thinking about including the thermodynamics/ fluid mechanics of the pump into the equation, just using a mysterious force on the water to explain my point about head leading to flow.
10-23-2006, 02:03 PM
Fairydust

Quote:

Originally Posted by Tero

...For example you have a pump with 10000gph and 16' of head. Now imagine what happens when that pump gets restricted by 50%. A 50% restriction on a centrifugial pump means ~50% of it's energy gets transfered into the water through friction or whatnot...

I am not sure I understood you correctly, are you saying a restriction leading to 50% less flow, would increase heatdump ~50%? Lots of the the electric energy is still converted into kinetic energy, the water is just pumped inside the housing instead of entering the loop and with increased restriction the pump's rpm will drop (up to 100% restriction where all the water is pumped inside the housing), reducing power consumption.
10-23-2006, 02:06 PM
Radical_53

@nik: Well, if you use two individual (modded) tops, yes. I don't have enough space for that, so I had to use the one piece design tops, which don't give an improvement of 35%.
10-23-2006, 02:15 PM
NickS

Quote:

Originally Posted by L'enFer

or creidiki...

No, no way. Maxxxracer.
10-23-2006, 02:24 PM
[XC] leviathan18

Quote:

Originally Posted by Vikodemous

Thats your explanation Mr. Darth Water? With him running Dual rads let's hear your Brilliant Deduction then...

P.S. It's spelled nonsense.

oh god, you are going to try to correct maxxxracer? :rolleyes: have you seen who is the guy that made most of the stickys here? if he says the water should be black for better cooling is because he knows it :stick:

now please use some logic here we dont buy better pumps with more flow or head preasure because we want to sound cool its because it improves temps.... so like maxxx said go and read the stickies before you spit out more nonsense
10-23-2006, 02:24 PM
eXa

Quote:

Originally Posted by Vikodemous

Your right, I should have said something charming Like you did. You reply to his post like it's a burden. Lord forbid I try to give someone some sort of explanation to his having lower temps with lower flow rate.

And your absolutely right, "water that is no longer under constant heat won't cool"<-- I hope this statement makes you feel better.

But you explanation is bogus(or whatever they say in english) and you obviolsly dont understand waht is happening in the loop...

I dont mean to be harsh, man we all started out knowing nothing. just read a bit more and dont be so ":banana::banana::banana::banana:y" when coming with thoose false statement.
10-23-2006, 02:48 PM
Digz

I cant see how virtualrain running the pumps at 7v then at 12v is going
to cause a 3deg temp swing as adding a northbridge block in the loop will
dump more heat than that in the water.

You never hear of people saying that they have had a 3deg temp increase
when adding a chipset block as the rads can dump 100's of watts of heat.

?
10-23-2006, 03:55 PM
Tero

Quote:

Originally Posted by Fairydust

I am not sure I understood you correctly, are you saying a restriction leading to 50% less flow, would increase heatdump ~50%? Lots of the the electric energy is still converted into kinetic energy, the water is just pumped inside the housing instead of entering the loop and with increased restriction the pump's rpm will drop (up to 100% restriction where all the water is pumped inside the housing), reducing power consumption.

That's not what i said. I said that the friction of the impeller would result in the kinetic energy of the moving water being changed into heat. It has to go somewhere. This has nothing to do with with the amount of electricity the pumps motor uses to achieve the kinetic energy. The only way to figure that out is to figure out how much power the pump converts to physical energy(its efficeincy) then figure out how much of that energy is lost.

The rpm drops due to friction and if the pump is being fed power to the motor at the same rate that power has to go somewhere. Meaning that when the rpm drops it either drops because energy is being changed into heat or the efficiency of the motor drops.

What do you suppose that water inside the housing is doing? I'm sure it isn't cooling down.

It's not as direct as i'm probably making it sound but, it does happen. This is just the reason why head is better than flow for WC.
10-23-2006, 04:01 PM
Hound53

I spent half the afternoon reading the HVAC Pump Handbook by James B Rishel and still cannot wrap my head around some of the concepts.

A couple of things I did discover though was never dump excess flow back to the suction without sending it to the radiator first, and yes there is a such a thing as excess flow or churn which is water just spinning in the pump building up heat and not going anywhere.
10-23-2006, 04:01 PM
Tero

Quote:

Originally Posted by Vikodemous

Thats your explanation Mr. Darth Water? With him running Dual rads let's hear your Brilliant Deduction then...

P.S. It's spelled nonsense.

It's just a forum stop taking things so personally. You were wrong deal with it.
10-23-2006, 07:35 PM
MaxxxRacer

Ok this is going to be a long post.

In response to Reinvented, Hound53, Fairydust, and Tero

As I will mention below, the heat dump into the water from the pump is mostly not from the impeller friction but rather the electronics and stator.

Next up, the effeciency of a pump is pretty easy to calculate if you know the delta P (pressure), flow and input wattage of the pump. With the pressure and flow you can calculate the hydaulic pumping power the pump is exerting on the water. This is the amount of work the pump is doing check out this review of the MCP655 by Robotech for more info on hydraulic pumping power. (Hydraulic Pumping Power ) . Now that we have the amount of work the pump is doing we just divide that by the input wattage which can be measured with any good digital multimeter. Equation goes as follows.
Effeciency = HPP/Wx100
HPP = Hydraulic Pumping Power and W = Input wattage.

In Response to virtualrain:
1.
Please let us know which flowmeter (the exact model #). Looking at the models you linked two, the only useful ones would have a pressure drop of 1.6 to 4.5 feet of head (depending on model, and at 5litre per min which is 1.3gpm). that is ALOT for just a little flow meter and the pressure drop gets logrithmically (i cant spell so sue me) higher as flowrate increases. This might partially explain the issues you have been experience. My reccomendation is to remove the flowmeter

2.
I am not entirely sure what you meant by "heat dump theory", but it is a fact that the pumps input a good portion of their heat into the water. BUT the heat is, for the most part, NOT from friction (KE) of the impeller and water inside of the impeller housing. Most of the heat comes from the electronics and stator. A perfect example is the Iwaki pumps. Their design insulates the impeller housing from the stator, thus keeping the heat dump in the ~50% range. The DDC, and D5 on the other hand have the stator housing in direct contact with the water and their heat dump percentage is 80+ (dont have the exact numbers off hand).

3.

Quote:

In my case, the water temperature as measured just before the rads is often only 0.3 degrees C warmer than the water temp after the rads.

If I remember some correctly some relatively high accuracy tests were done with calibrated platinum RTD probes with 0.01C resolution and the deltaT (difference in temp) between waterblock inlet and outlet on an 80watt source. the deltaT on that setup was between .5C and .15C depending on flowrate. So you .3C is probably relatively accurate although I am unaware of what sort of temperature measurement equipment you are using. Check out the info here

4.
As you pointed out as well as others, it is very likely that your system is just mismatched. The incredibly high pressure of the dual DDC's combined with a relatively low restriction system may be leading to bizarre issues with the DDC's. My suggestion is to try the loop with one rad (you can keep both in if your lazy) and one pump, with the inline temp and flow meters removed. Your system will probably work alot better like this. Also, some pictures of how you have your rig set up would be very beneficial in determining the cause of your issues as well as enabling us to help you redesign your loop for maximum effeciency.

In Response to Firelord-OCHW:
Loop Order does not affect flow so long as your reservoir is right before the pump. Other than that the loop order does not affect flow so long as all other things are kept constant (ie: tube bends and tubing length)

In Response to Vikodemous
I said it once and I will say it again.. Go read the guides. The "information" you are providing is a complete reversal of the truth and has no basis in reality. cooling effeciency in radiators and waterblocks increases per molecule of water as flow rate increases up to a certain point (much higher than any normal watercooler will achieve) and then will stay relativley constant or slowly drop off. The very smart, but rude Bill Adams demonstrated this property to the watercooling community in his radiator tests. If you like I can dig up some links to show you.

In Response to Herr Brun & Atomicpineapple

Quote:

But that [pressure] doesn't matter, if I understand correctly? Pressure does not matter, flowrate does? Or is it different with impingement (sp) style blocks?

The actual pressure of the water in the block does NOT matter so long as its not negative, which to be frank is not really possible in a watercooling loop (barring the pump inlet). To add some more detail to that statement; the closest thing to the pump gets the highest water pressure and the pressure keeps dropping off until it hits the end of the loop (the reservoir) where it then becomes the same pressure as standing water (assuming the reservoir is open to the air). But while this is true, it does not play any role in the performance of the system, its just a little useless factoid (well almost useless ;) ) because the flow will remain constant at any point in the loop (sure water velocity changes but now overall flow).

Now head pressure of the pump on the other hand is VERY important. We are not talking about water pressure here, but rather how much pressure can the pump exert on the system. As long as you stay within the confines of Cathars guidelines for pumps (located HERE), looking for a pump with the highest head pressure is an excelent idea, and is the reason why the DDC is so popular. You just have to make sure that the pump has a properly proportioned PQ curve so you dont end up with a pump like a fuel pump for a car (insane pressure but very low flow).

OK. I think I covered everything that needed addressing. And if you want to complain about my spelling, go right ahead and post it in the official complaint deparment located HERE
10-23-2006, 08:34 PM
virtualrain

Quote:

Originally Posted by MaxxxRacer

In Response to virtualrain:
1.
Please let us know which flowmeter (the exact model #). Looking at the models you linked two, the only useful ones would have a pressure drop of 1.6 to 4.5 feet of head (depending on model, and at 5litre per min which is 1.3gpm). that is ALOT for just a little flow meter and the pressure drop gets logrithmically (i cant spell so sue me) higher as flowrate increases. This might partially explain the issues you have been experience. My reccomendation is to remove the flowmeter

Hi, first of all thanks again to everyone for their interest and input!

The flow meter I'm using is the 46500-164-4F16,5 (it's the one that produces 700imp/l and is rated for 2-35 lpm and has minimal pressure drop below 10lpm. I doubt that it affects flow significantly... probably less than a block since it has an ID of 8.5mm which is reasonable and the turbine is very streamlined. Never the less, it is a novelty and although I like it, I may remove it (more on that below).

The link again for reference... http://www.remag.ch/vision.php?language=4&sub=1&tab=2

Quote:

Originally Posted by MaxxxRacer

2.
I am not entirely sure what you meant by "heat dump theory", but it is a fact that the pumps input a good portion of their heat into the water. BUT the heat is, for the most part, NOT from friction (KE) of the impeller and water inside of the impeller housing. Most of the heat comes from the electronics and stator. A perfect example is the Iwaki pumps. Their design insulates the impeller housing from the stator, thus keeping the heat dump in the ~50% range. The DDC, and D5 on the other hand have the stator housing in direct contact with the water and their heat dump percentage is 80+ (dont have the exact numbers off hand).

Thanks... no further comment.

Quote:

Originally Posted by MaxxxRacer

3.
If I remember some correctly some relatively high accuracy tests were done with calibrated platinum RTD probes with 0.01C resolution and the deltaT (difference in temp) between waterblock inlet and outlet on an 80watt source. the deltaT on that setup was between .5C and .15C depending on flowrate. So you .3C is probably relatively accurate although I am unaware of what sort of temperature measurement equipment you are using. Check out the info here

In my case, I'm using Innovatek thermal probes like these...
http://www.highspeedpc.com/Merchant2...de=FanTempFlow

One probe is in the unused inlet port of Pump #2 to measure the temperature before the rads. The second one is actually epoxied into a hole I drilled in the outlet area of the second rad.

They are connected to an Aquaero which was used to calibrate the probes.

Both probes were calibrated at a variety of water temperatures on the bench before being used in the loop.

Quote:

Originally Posted by MaxxxRacer

4.
As you pointed out as well as others, it is very likely that your system is just mismatched. The incredibly high pressure of the dual DDC's combined with a relatively low restriction system may be leading to bizarre issues with the DDC's. My suggestion is to try the loop with one rad (you can keep both in if your lazy) and one pump, with the inline temp and flow meters removed. Your system will probably work alot better like this. Also, some pictures of how you have your rig set up would be very beneficial in determining the cause of your issues as well as enabling us to help you redesign your loop for maximum effeciency.

I agree. Please note that being busy is different from being lazy! Hence, I won't be making any changes to my loop in the near future other than just running both pumps at 7V. When I have time, I will likely start by adding my GPU and a Storm to the loop. Hopefully that alone will address the mismatch. If there is still a mismatch then again, I'll probably just run the pumps at lower speeds.

Next time I have the loop apart, I will use some buckets to assess the impact the flow meter has on the loop and also to test it's accuracy which I was unable to do before assempling my current loop. If I find it is negatively impacting the loop in a significant way, I will remove it.

For me, at least, this thread has been helpful, and I'm not sure what more can be done.

I'll try to post some more pictures and update my blog soon.
10-23-2006, 08:53 PM
Vapor

Going out on a limb here....if it weren't the added heat dump or some funny stuff with the pumps, could it be the TIM?

If it were a new setup, AS5/Ceramique would show that progression of temps as they break in. Even with the lower performance of the pump, the broken-in TIM could easily outperform fresh TIM. On top of that....the true difference between 12V and 7V may not be more than a fraction of a degree with your loop.
10-23-2006, 09:19 PM
embeejay

virtualrain: when you add your gpu block, you could also consider doing two seperate loops with one pump/rad for each loop - I have read a few places that two seperate loops can give better performance, tho i am truely a newb and havn't got any experience myself to back it up.
10-23-2006, 10:32 PM
MaxxxRacer

Quote:

In my case, I'm using Innovatek thermal probes like these...
http://www.highspeedpc.com/Merchant2...de=FanTempFlow

One probe is in the unused inlet port of Pump #2 to measure the temperature before the rads. The second one is actually epoxied into a hole I drilled in the outlet area of the second rad.

They are connected to an Aquaero which was used to calibrate the probes.

Both probes were calibrated at a variety of water temperatures on the bench before being used in the loop.

well then. you got that pretty well figured out. Most people run those innovatek probes with tin little T shaped compression barbs which kills the flow. Nice to see you thought ahead on this one and didnt restrict the flow.

Based on the specs of that flow meter, you appear to be correct; It has very little flow restriction in the 5-6lpm which you are working in.

As to the wierd results you obtained with the flow meter, it is probable that the hardware you are using to read the pulses cant read the high pulse count of the meter at higher flow rates which causes it to give crazy results. you can pick up a pulse counter on ebay for around 20 -40 dollars that has high accuracy and a very wide range. Such an item might be of some use to you.
10-23-2006, 11:08 PM
exhausted mule

Quote:

Originally Posted by Hound53

An alternative way of setting the pump to max efficiency would be use a speed control with a flow meter, once the flow peaks that pump is moving as much water as it can through the loop.

A sensitive pressure gage and a bypass valve back to the pumps suction would acomplish the same thing. Put the gage in the branch that leads to the water blocks, open the bypass back to the pump suction until pressure started to drop. That would give you max flow to the block(s).

100% aggree.

is like resistance after a while is just gets exponential and you get so little for so much...
10-23-2006, 11:30 PM
virtualrain

For those interested, I added some pics to the OP. I also updated the blog tonight with more pics on how the rads were mounted to the fans and side door... (click the link in my sig)
10-24-2006, 01:43 AM
Hound53

MaxxRacer thanks for the info. Excellent link, I may actually get a decent grip on this stuff one of these days. A big maybe there but still possible I suppose.

exhasted mule - the part about dumping back to the pump suction was bad advice on my part, any dumps would have to be back to the radiator or a heat build up would occur according to Rishel. But if Maxxracer is correct, and I have no doubt that he is, the heat issue from restriction is moot anyway.
10-24-2006, 02:18 AM
Digz

Wonder if the leading edge of Diamond shaped pins of the apogee at
high flow push the water to the outside edges of the block and cause
a dead spot at the back of the pins. ?

Abit like the front of a ship pushing through water.

Just a thought.
10-24-2006, 07:35 AM
nikhsub1

Quote:

Originally Posted by virtualrain

The following temps were noted after running dual Orthos Prime for 1hr. on separate days.

I'm gonna look at the most logical explanation for this difference. First, how many days went by between test 1 and test 2? Was ANYTHING in the loop touched between first and second test? Was the CPU block remounted? Was tubing knocked? You see, if you even bump the tubing near the cpu block you could throw the block off and get different results - sounds crazy but true. I would bet that if you reran this test ON THE SAME DAY the results would be different. IDK why you have not done that - one test is meaningless without more tests to back it up.
10-24-2006, 08:32 AM
virtualrain

Quote:

Originally Posted by nikhsub1

I'm gonna look at the most logical explanation for this difference. First, how many days went by between test 1 and test 2? Was ANYTHING in the loop touched between first and second test? Was the CPU block remounted? Was tubing knocked? You see, if you even bump the tubing near the cpu block you could throw the block off and get different results - sounds crazy but true. I would bet that if you reran this test ON THE SAME DAY the results would be different. IDK why you have not done that - one test is meaningless without more tests to back it up.

Nothing was changed between tests. I ran the test at 12V on Sat. and I ran the test at 7V on Sunday. I started by leaving the computer idle all day while I was out running errands then I started the Orthos dual core test and noted the temps after 1hr. Same thing on Sunday except at 7V.

Incidentally, the reason I decided to do this more formal test is that last week I was experimenting less formally with the speed of the pumps and noticed that the temps in general (at idle or while gaming) were lower when the pumps were at 7V and higher when at 12V. Hence, I don't think there needs to be a retest... the observations I've made are consistent from day to day.
10-24-2006, 09:03 AM
Modzilla

where's that beating the dead horse smiley?
10-24-2006, 01:18 PM
Hound53

Quote:

Originally Posted by Modzilla

where's that beating the dead horse smiley?

dead horse or not I have gotten quite a bit of info from it. I realize it might have pushed a " which block is best" post off the 1st page but too bad.
10-24-2006, 11:13 PM
virtualrain

Quote:

Originally Posted by Hound53

dead horse or not I have gotten quite a bit of info from it. I realize it might have pushed a " which block is best" post off the 1st page but too bad.

LOL!!! I definitely appreciate all the input as well!

BTW, I found out from someone on the Aquacomputer forums that the Aquaero can only handle flow up to 3lpm... that explains why I get stupid readings beyond that. I'm not impressed! :slapass:
10-25-2006, 12:55 AM
Radical_53

But only if you use an old firmware version. The older Innovatek controllers had just the same problem.
Both of them are fine if you use the most actual firmware.
10-25-2006, 08:37 AM
virtualrain

Quote:

Originally Posted by Radical_53

But only if you use an old firmware version. The older Innovatek controllers had just the same problem.
Both of them are fine if you use the most actual firmware.

I'm running the most current firmware... 4.10a.
10-25-2006, 08:42 AM
Radical_53

Then there shoulnd't be any problems normally. How high did you have to set the pulse/liter settings?
10-25-2006, 08:59 AM
Tero

Quote:

Originally Posted by MaxxxRacer

Ok this is going to be a long post.

In response to Reinvented, Hound53, Fairydust, and Tero

As I will mention below, the heat dump into the water from the pump is mostly not from the impeller friction but rather the electronics and stator.

Is there any calculation you know offhand that will calculate that? I'm very interested in just how much heat impeller friction causes since all i've seen posted on it has said it causes some friction and it's the main cause of heat.

Thinking about it, it would be quite difficult to figure it out since every pump would have a different resistance coefficient based on the impeller and the housing the water is traveling through.
10-25-2006, 09:15 AM
Modzilla

by asking about the dead horse smiley in my last post I only meant to imply that we have answered the original question posed in the thread, not to discount the value of everybody's post or the information contained in the thread.

I didnt say the main cause of the higher temps was friction, I said it was a cause of higher temps, and by listing 2 causes (pump input power and friction) and listing friction second, I meant to imply that the pump input power contributes more to the higher temps, and that friction contributes less to the higher temps.
10-25-2006, 10:15 AM
virtualrain

Quote:

Originally Posted by Radical_53

Then there shoulnd't be any problems normally. How high did you have to set the pulse/liter settings?

The flow meter outputs 700 imp/l which is what I set the flow meter setting to on the Aquaero.

Here's a link to the Aqua Computer forum where the discussion is unfolding...
http://www.aqua-computer-systeme.de/e_forum-index.htm
10-26-2006, 02:18 AM
Marci

Some references...

Pump Data: http://forums.procooling.com/vbb/showthread.php?t=10825 (pre-D5 / DDC+ hence ommitted)
CPU Block Performance vs Pumping (Hydraulic) Power: http://forums.procooling.com/vbb/sho...5&postcount=41
Radiator Analysis (Efficiency): http://www.swiftnets.com/Technical/A...erformance.pdf
Radiator Testing (the original baseline): http://thermal-management-testing.com/ThermoChill.htm

If monitoring flow with meters, ensure system is piped with tubing that's as close a match to the bore of the flow meter to minimise losses of that flow meter. Same goes for fittings. Suggest you repipe your system in 8mm ID 10mm OD tubing (5/16" ID) to make your flowmeter's results more "valid" without the pressure drop issues.
10-26-2006, 02:59 AM
Hound53

thanks for the links Marci
10-26-2006, 08:54 AM
virtualrain

Quote:

Originally Posted by Marci

Some references...

Pump Data: http://forums.procooling.com/vbb/showthread.php?t=10825 (pre-D5 / DDC+ hence ommitted)
CPU Block Performance vs Pumping (Hydraulic) Power: http://forums.procooling.com/vbb/sho...5&postcount=41
Radiator Analysis (Efficiency): http://www.swiftnets.com/Technical/A...erformance.pdf
Radiator Testing (the original baseline): http://thermal-management-testing.com/ThermoChill.htm

If monitoring flow with meters, ensure system is piped with tubing that's as close a match to the bore of the flow meter to minimise losses of that flow meter. Same goes for fittings. Suggest you repipe your system in 8mm ID 10mm OD tubing (5/16" ID) to make your flowmeter's results more "valid" without the pressure drop issues.

Given the problems I'm having with the flow meter providing accurate readings above 3lpm, its going to come out during my next loop rebuild.
11-14-2007, 06:35 PM
Serpentarius

high flow cuts the time taken travelling from point waterblock to point rad .... well, maybe the rad is unable to dissipate the amount of heat effeciently before its recirculated back into the loop, ultimately back to the processer block

or maybe the rad is being repainted and the paint gets into the rad fins which is vital for dissipating heat?
11-14-2007, 11:50 PM
welshtom

Quote:

Originally Posted by Serpentarius

high flow cuts the time taken travelling from point waterblock to point rad .... well, maybe the rad is unable to dissipate the amount of heat effeciently before its recirculated back into the loop, ultimately back to the processer block

this has been covered already.
If the water goes twice as fast, it goes through the rad twice as often.

thus the overall time a water molecule spends in the radiator/block is the same, whatever the flowrate over a set time
11-15-2007, 05:31 AM
Xilikon

Without considering it's a stupid thread ressurection...

But to add my grain of salt, if water get 2x more time in the rad, it also get 2x more time in the blocks collecting more heat so it even out.
11-15-2007, 06:35 AM
initialised

Heat dissipation in the radiator is a function of water flow rate and air flow rate. If you increase the water flow beyond the capabilities of the fans then you wont transfer all the heat so dT (inlet temp-outlet temp) will increase.
11-15-2007, 10:15 AM
Jedda

Quote:

Originally Posted by initialised

Heat dissipation in the radiator is a function of water flow rate and air flow rate. If you increase the water flow beyond the capabilities of the fans then you wont transfer all the heat so dT (inlet temp-outlet temp) will increase.

Do you want to look closely at what you just wrote?
11-15-2007, 10:28 AM
sbinh

He watercooled PSU ???? More temp. cuz more power draws from PSU ?

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