[Znth]

Hi,

was wondering if it's possible to have two pumps in the same loop to increase performance? I have two laincg ddc pumps, ones an older revision with less flow than the other, but I thought maybe I could put two together for some benefit?

 

[Mootsfox]

Dual.

Yes it is possible to run two pumps in series.

 

[iampoor]

Yes you could.

2 seperate loops might be better althought because if there flow in't matched it might cause turbulence cavicating...

Its not ideal if the flow is different but i BELIEVE it will be better

 

[Apollo4g]

you need 2 of the same flow rate pump, Ira has 2 ddc-1's i believe in a series, it increases head

 

[Skullzaflare]

sell me the older

, the one that pumps stronger would probably force the older to run faster decreasing its life. the only benifet(sp) i can see to running dual pump is if one goes out the other might be able to keep things going long enough for you to notice

 

[iampoor]

Quote:

Originally Posted by Skullzaflare sell me the older , the one that pumps stronger would probably force the older to run faster decreasing its life. the only benifet(sp) i can see to running dual pump is if one goes out the other might be able to keep things going long enough for you to notice

OFFTOPIC: you should stop requesting things like this. You will be infracted for it

 

[Martinm210]

Yeah, two identical pumps in series will increase the pressure head. It essentially stacks the two PQ curves to give you twice the head power per flow rate, maximum flow rate remains the same. The end result rule of thumb is around a 30% increase in system flow rate.

The only time running them in serial is an advatage is extremely free flow low pressure conditions where you can take advantage of the low end of the curve and stack the flow rates together but that really never happens in a PC cooling system.

Also keep in mind that it also adds a small amount of heat dump from the additional pump.

 

[Apollo4g]

hey artin, my MCR320 is doing a really good job cooling my MOSFETs,NB and 8800. With yate loons on them. How are yours doing?

 

[Martinm210]

It does just fine with the loons, the most I've ever seen my water temps is 2-3C above ambient and that's typically when I'm not getting good fresh intake air.

I've got an MCW30 I'm going to add to my GPU loop to cool the northbridge. Later I might make a third loop (NB, SB, Small Rad, DB-1), but this is all I could afford this month. Decided to buy vista(I know..bad idea..) and a few minor WC goods...the MCW30, a UV yate loon, some mcmaster tubing, and G11 blue dye...going to run one loop blue and the other green..

 

[ira-k]

Quote:

Originally Posted by Martinm210 Yeah, two identical pumps in series will increase the pressure head. It essentially stacks the two PQ curves to give you twice the head power per flow rate, maximum flow rate remains the same. The end result rule of thumb is around a 30% increase in system flow rate. The only time running them in serial is an advatage is extremely free flow low pressure conditions where you can take advantage of the low end of the curve and stack the flow rates together but that really never happens in a PC cooling system. Also keep in mind that it also adds a small amount of heat dump from the additional pump.

I doubled my flow with 2 18W DDC's in series....I went from 5 psi to almost 11psi..That converted is 1.5gpm to 3gpm..I only dropped 2C by adding a second pump, but thats with just a CPU in the loop...If I had more blocks I'm sure it would of been more...I mostly did it for redundancy....

Take a look at Petra's results...DDC Top & Pump Performance Comparison (Petra's, Radiical, Alphacool, etc.)

Hey I like Vista I've had it since it first came out...I don't game though thats the main complaint I hear from people that is legitimate...

 

[CL3P20]

Ira- any differenc in the positioning of the two pumps for series operation?

ie- pump1->pump2->rad->cpu-> back to pump....
or...pump1->rad->pump2->cpu-> back to pump1

 

[ira-k]

Quote:

Originally Posted by CL3P20 Ira- any differenc in the positioning of the two pumps for series operation? ie- pump1->pump2->rad->cpu-> back to pump.... or...pump1->rad->pump2->cpu-> back to pump1

I ran mine res-pump-pump-rad-cpu...You need to use 2 identical pumps or the flow will be limited to whatever the smaller pumps out-put is...

That way the extra pump heat dump will hit the rad also before the cpu...

 

[Martinm210]

Quote:

Originally Posted by ira-k I doubled my flow with 2 18W DDC's in series....I went from 5 psi to almost 11psi..That converted is 1.5gpm to 3gpm..I only dropped 2C by adding a second pump, but thats with just a CPU in the loop...If I had more blocks I'm sure it would of been more...I mostly did it for redundancy.... Take a look at Petra's results...DDC Top & Pump Performance Comparison (Petra's, Radiical, Alphacool, etc.) Hey I like Vista I've had it since it first came out...I don't game though thats the main complaint I hear from people that is legitimate...

Really, that's great, I know theoretically series is like stacking the pump PQ curves in the head or y direction which is great and yes redundancy is good. I even thought about trying a single loop again with both pumps just to try it.

Good to know on vista..

I game now and then, so I'm aware of the 10% performace cut I'll get there, but as long as it's a good stable platform I figured I gave the drivers enough time to mature now to make the switch. I installed it on my mother inlaws computer when I last did a major hardware upgrage (I always give her my old stuff), and the install was easy and it sure does look nice. I've got a hal.dll error with a storage HD right now that needs a OS install so I figured it would be a good time.

 

[born2killU]

Quote:

Originally Posted by Apollo4g you need 2 of the same flow rate pump, Ira has 2 ddc-1's i believe in a series, it increases head

if you put one before the other yes you do , if you put it like this you will be fine

Newer Pump - Rad - Block - old pump - Block - Newer pump

 

[Sideburns]

Quote:

Originally Posted by ira-k I doubled my flow with 2 18W DDC's in series....I went from 5 psi to almost 11psi..That converted is 1.5gpm to 3gpm..I only dropped 2C by adding a second pump, but thats with just a CPU in the loop...If I had more blocks I'm sure it would of been more...I mostly did it for redundancy.... Take a look at Petra's results...DDC Top & Pump Performance Comparison (Petra's, Radiical, Alphacool, etc.) Hey I like Vista I've had it since it first came out...I don't game though thats the main complaint I hear from people that is legitimate...

redundancy? lol...if one pump were to stop, it would block the flow anyways....

 

[ira-k]

Quote:

Originally Posted by Martinm210 Really, that's great, I know theoretically series is like stacking the pump PQ curves in the head or y direction which is great and yes redundancy is good. I even thought about trying a single loop again with both pumps just to try it. Good to know on vista.. I game now and then, so I'm aware of the 10% performace cut I'll get there, but as long as it's a good stable platform I figured I gave the drivers enough time to mature now to make the switch. I installed it on my mother inlaws computer when I last did a major hardware upgrage (I always give her my old stuff), and the install was easy and it sure does look nice. I've got a hal.dll error with a storage HD right now that needs a OS install so I figured it would be a good time.

Thats one of the things where theory doesn't carry over to our WC applications...You basically double the head and the flow...2 18W DDC have more head and flow then the Iwaki RD 30 running at 18W....

..Just a tiny bit more heat dump though.

I got the Vista home premium and I really like it...I just had a few very minor driver problems but thats when it first came out....I like it a whole lot better the XP when it first came out...That thing was pretty buggy....

^^^^No Man water runs right through a pump when its off...

 

[Martinm210]

Quote:

Originally Posted by ira-k Thats one of the things where theory doesn't carry over to our WC applications...You basically double the head and the flow...2 18W DDC have more head and flow then the Iwaki RD 30 running at 18W.... ..Just a tiny bit more heat dump though.

Are you sure you're getting twice the flow rate though?

From what I understand double the pressure does not mean double the flow rate.

Here is just a hypothetical system flow rate curve plotted on a single vs. a double DDC2 w/ Petra top system in series:

I used an assumed system with three D-tek fuzions, probably equivalent to a rad, a pair of blocks, tubing and reservoir. You do double the pressure with two pumps in series, should look something like this:

The net result is only about 35% increase in flow rate though. That's consistent with what I've heard on XS.

And for comparison sake this is how two pumps in parallel should look:

Only 17% increase at high pressure conditions, two pumps in parallel would be the better choice only in very low restriction. At that point your way on the right hand of the curve where you're adding flow rates, probably never a condition we would see in water cooling.

Petra did a series test on this thread:
http://www.xtremesystems.org/forums/...d.php?t=117215

Average restrictions:
Single pump @ 12v = 2.32gpm
Dual pumps in series @12V = 2.78 gpm
That's a 20% increase in flow rate

High restrictions:
Single pump @ 12v = 1.36gpm
Dual pumps in series @12V = 1.84 gpm
That's a 35% increase in flow rate

So that's a good real world test to show the theory is reasonable, but I screw up all the time and could be wrong....lots to learn still..

 

[ira-k]

I haven't flow tested it with the 2 pumps...1 was 1.5gpm when I did it in a bucket at 5psi...If you look at Petra's testing the pumps in series actually have more flow then the pumps in parallel not less...If I'm getting 1.5gpm at 5psi thats 0.3gpm for 1psi...So I would think 10psi would translate into 3gpm...I don't see how it wouldn't....

I would break it down and do it in a bucket but its a pain with the Pelt in the loop...

Take a look for some of nicksub1's testing there also...I think he came to the same double conclusion also...

EDIT: I forgot you like visuals....

5psi with single DDC.... Close up Side

10psi...I was still bleeding it in this pic, it went on up to 10psi...I'm back down to 9psi since I put a 480 GTX in the loop...10psi was with a 240 BIX...

.... Dual Pumps

 

[aquavortex1]

Quote:

Originally Posted by Sideburns redundancy? lol...if one pump were to stop, it would block the flow anyways....

Actually it dosnt totally block it. I have tried this in my test bucket with my 2 ddc-1's. You still get decent flow rates, defiantly enough to save your computer from overheating.

 

[ira-k]

Quote:

Originally Posted by aquavortex1 Actually it dosnt totally block it. I have tried this in my test bucket with my 2 ddc-1's. You still get decent flow rates, defiantly enough to save your computer from overheating.

Yeah I just run one of mine when I'm bleeding...Seems to bleed faster and it doesn't foam up as much and it doesn't splash out of my res as much either...