water loop with 2 pumps, does order matter?

[sveniat]

Sp I'm thinking about doing a dual res/pump combo, probably 2x EK-XRES 140 Revo D5s. I kind of like the look of the dual res (and i'll be removing all drive bays so I need to fill some space), and I'll be doing 2 420mm radiators so I want a double pump system. My question is: do I need to spread the pumps out to get the benefit?

 

I have 2 lines of thought: 

 

1) it's about water pressure, so the positioning of the pumps relative to each other won't matter since both would be adding pressure to the loop no matter where they are.

 

2) another possibility is that I have no idea how fluid dynamics work and the above makes 0 sense, and I should really split the pumps up in order to get any effectiveness.

 

 

[manikyath]

is there the possibility of splitting the loops?

[Guest]

I would think it either doesn't matter or seperating them helps (but makes minimal difference), but I actually know almost nothing about watercooling so don't listen to me lol.

[pyrojoe34]

Well if you're doing res>pump>res>pump then the first pump is basically useless. The reservoir equalizes the pressure back to atmospheric (unless it's a pressurized reservoir which, as far as I know, they are not), so all the first pump is doing is pumping water into the second reservoir. If the second pump goes out then the only pressure in the system is basically gravity from the second reservoir. If in the other hand, you do res+res>pump>pump, then the pumps work together and have redundancy if one goes out.

 

Look at how this guy does it, the pumps are in series but only after the reservoirs. Also, make sure your reservoirs are either at the same height, or your second reservoir is lower than your first, otherwise it will be fighting gravity to fill the second one and put extra stress on the system.

[PrimeSonic]

7 minutes ago, pyrojoe34 said:

Well if you're doing res>pump>res>pump then the first pump is basically useless. The reservoir equalizes the pressure back to atmospheric (unless it's a pressurized reservoir which, as far as I know, they are not), so all the first pump is doing is pumping water into the second reservoir. If the second pump goes out then the only pressure in the system is basically gravity from the second reservoir. If in the other hand, you do res+res>pump>pump, then the pumps work together and have redundancy if one goes out.

With that in mind, what if OP did something like this?

res > pump > block > rad > res > pump > block > rad > ...

 

 

[pyrojoe34]

Just now, PrimeSonic said:

With that in mind, what if OP did something like this?

res > pump > block > rad > res > pump > block > rad > ...

 

 

That would work but defeat the purpose of redundant pumps since if one fails it will not really compensate for the other one (again, unless you have a pressurized reservoir). In that case it would be better to just make two separate loops.

[sveniat]

6 minutes ago, pyrojoe34 said:

That would work but defeat the purpose of redundant pumps since if one fails it will not really compensate for the other one (again, unless you have a pressurized reservoir). In that case it would be better to just make two separate loops.

I thought a single loop was preferable, as 840mm of rad space for 3 components can be more effective than 420mm for cpu and 420mm for gpus. For example, if your gpus were running hot and your cpu wasn't getting very much use, the 420mm rad on your cpu would be a lot less utilized than the 420mm gpu rad, and having them in the same loop could make that usage more dispersed over the whole 840mm system.

 

Granted, I realize that 420mm is overkill for 1 cpu, and overkill for 2 gpus, but it's about optimization. I'd still like to be as optimized in my overkill as possible

[pyrojoe34]

Just now, sveniat said:

I thought a single loop was preferable, as 840mm of rad space for 3 components can be more effective than 420mm for cpu and 420mm for gpus. For example, if your gpus were running hot and your cpu wasn't getting very much use, the 420mm rad on your cpu would be a lot less utilized than the 420mm gpu rad, and having them in the same loop could make that usage more dispersed over the whole 840mm system.

 

Granted, I realize that 420mm is overkill for 1 cpu, and overkill for 2 gpus, but it's about optimization. I'd still like to be as optimized in my overkill as possible

Yes, a single loop would be better IMO but you should have the pumps in series and not separated by reservoirs. My point is that if you want to do a dual res/pump loop you should not get the res/pump combos. Get two reservoirs and get two pumps then do res>res>pump>pump.

[sveniat]

16 minutes ago, pyrojoe34 said:

Yes, a single loop would be better IMO but you should have the pumps in series and not separated by reservoirs. My point is that if you want to do a dual res/pump loop you should not get the res/pump combos. Get two reservoirs and get two pumps then do res>res>pump>pump.

how do you fill the loop with the second pump not having a dedicated res feeding into it? just don't plug that pump in until the pump before it is sending liquid into it?

[pyrojoe34]

8 minutes ago, sveniat said:

how do you fill the loop with the second pump not having a dedicated res feeding into it? just don't plug that pump in until the pump before it is sending liquid into it?

Gravity does the job at first. As long as both pumps are just after the reservoir AND the pumps are below the reservoirs, then the pumps will be wet. If you're worried about it then just start the first one first and the second one after.

[sveniat]

5 minutes ago, pyrojoe34 said:

Gravity does the job at first. As long as both pumps are just after the reservoir AND the pumps are below the reservoirs, then the pumps will be wet. If you're worried about it then just start the first one first and the second one after.

I guess if the pumps are back to back then the super brief period between when the first pump starts and the second pump gets wet isn't really an issue.

[W-L]

2 hours ago, sveniat said:

-SNIP-

It would be better to have separate res and pump units then, where having two pumps in series together can give you redundancy and extra head pressure but you won't have any issues with the entire loop even on a single D5.

https://www.ekwb.com/shop/ek-xtop-revo-dual-d5-pwm-serial-incl-pump