Two different pumps in series?

Tyler Durden

Tyler Durden

Tyler Durden

Associate
Joined
28 Oct 2002
Posts
444
Hi,

I have two loops running in my external cooling tower - one powered by an Iwaki (for the CPU and GFX) and one by a dual DDC pump arrangement (for the SCSI, chipset, voltage regulators and RAM).
The dual DDCs seem not to generate enough pressure to push the coolant through the multiple radiators and the blocks and I am thinking of adding a D5 vario pump to correct this.

My question is - would I be best served removing the dual DDC and replacing with the more powerful D5 or adding the D5 in series?

It would be a pain to remove the DDCs as they are mounted in the tower, but if their presence would hinder performance I would be forced to reconsider.

THANKS
 
Water-cooling is very like electrical circuits. Think of a pump as a battery. Blocks and rads are resistors. If you add 2 12v batteries in series to a circuit it doesn't change the amount of voltage but it changes the amount of current. Two pumps may not change flow-rates but may preserve flowrates for a given resistance.

Imagine the D5 chucking water out at 3gpm. It enters the DDC which also runs at 3gpm. The water doesn't come out at 6gpm but the second pump helps to deal with additional blocks/rads by adding force to the water.
 
MikeTimbers said:
. If you add 2 12v batteries in series to a circuit it doesn't change the amount of voltage but it changes the amount of current.
Click to expand...

No, it changes both, lol.

The point you made afterwards is correct, that the flow rate won't incrase, but adding another battery in a circuit changes both the current and the voltage.

V=IR
you can't change I without changing V if R stays the same
two 12V batteries in series give 24V.
 
how about putting the second pump into the loop after water blocks or before the rad? its hard to say without knowing more about your loop
 
Ben M said:
No, it changes both, lol.

The point you made afterwards is correct, that the flow rate won't incrase, but adding another battery in a circuit changes both the current and the voltage.

V=IR
you can't change I without changing V if R stays the same
two 12V batteries in series give 24V.
Click to expand...

Correct :) You can't argue with Ohms's Law.

AndyOcUK
(Spark) :D

Modern pumps are designed to cope with multiple blocks so I'd be tempted to put two separate loops in if you have room in your case.
 
Thanks guys.

Both loops are housed in an external tower - old Lian Li PC70 converted to the purpose a few years back when liquid cooling was more in vogue. Now seems overkill. but as I have it.....

The main loop (two triple rads and three doubles) is running well with the Iwaki.

The secondary loop has four rads (three singles and a triple - all for silence with minimal 5V fans, hence the multiple rads) and is intended to cool the chipset, SCSI drives (four) and the voltage regulator and Flex RAM. As you can tell, that is a considerable restriction and it would seem the dual DDC pumps do not have the juice to pump the coolant through such a complex loop.
As the D5 is more powerful, I hope it will add the pressure I need, but I worry that the presence of the other less powerful pumps will be detrimental....

Should I remove the DDC pumps or not?
 
Last edited:
Looong time since I played with electricity circuits but my point remains true. Extra pumps maintain flow but with modern systems flowrate is no longer king. Was a time when all anyone was worried about was calculating flow-rates but that was before specialist water-cooling rads arrived.
 
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