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