Why rez before pump?

[Herr Brun]

Hello there.
I just wondered here the other day, why does res/t-line have to be before the pump?

[Mankz_91]

so that there is always water going into the pump....

[Herr Brun]

so that there is always water going into the pump....
Huh? There is always water going into the pump at any given point in the loop? If not, your cpu would definately die from the sudden temperature rises/drops that would happen when the cpu block didn't get water.

[Maviryk]

Because it makes it easier to prime the pump when you initially fill up the loop with coolant. If you didn't do this, the pump would cavitate due to lack of water.

Also, depending on the design, a reservior right before the pump feeds water better than a T-line, and also bleeds air out of the loop a lot faster.

[virtualrain]

Honestly, I don't think the order of the res in the loop matters so much but I'm also interested in why some folks think it needs to be before the pump. It's job is to bleed and fill so as long as when you fill your res, coolant will trickle into your pump, I don't think the order matters at all. It definitely needs to be the highest thing in the loop to be most effective.

In terms of filling/bleeding I was able to fill my loop almost completely before turning the pump on by pouring coolant into the res, moving the case around allowing the coolant to get into and through pumps, blocks and rads and repeating until there was very little air left in the loop. Only then did I turn on the pumps for a few seconds at a time, top the res, and repeat for a few cycles. Within a few minutes the loop was completely full and after letting it run for a few hours, it was completely free of air.

[ChongL]

res goes before the pump because it's the logical thing to do.

[Maviryk]

The process you described to me sounded like the process for bleeding a system which uses a T-line. A proper reservior bleeds in minutes, not hours.

And you would never route the outlet of the pump right into the reservior. This is the only occasion where order does matter.

[Mankz_91]

took me like 5 mns to blled the loop with my Res...

[thunderstruck!]

Took me 10 seconds to bleed with res. Took my 1.5 hours to bleed with t-line.

[eXa]

only reason to put it before pump is when filling the loop, cus then the water goes right into the pump and ensuring that it dont just run on air wich will damage 12v pumps really fast!

[bball4ever39]

It would actually put a little less strain on your pump as well, if you had extra components after the reservoir then your pump is not only trying to push the water through say your rad and your cpu block and then it would also be trying to pull the water through the gpu block. You lose all your pressure and flow rate then when the water enters the reservoir, so its making your pump work both ways instead of just feeding the pump with a gradual stream of water letting it do what it is supposed to do. A pump is going to be more efficient pumping water through a set up rather then trying to pull it through.

[freecableguy]

A resovoir is usually located right before a pump, with a height difference (ie. above the pump) in order to provide additional suction head. NPSH (net positive suction head) is defined as the minimum pressure required at the eye of the pump's impeller in order to prevent pump cavitation. The weight of the column of water in the resevoir provides this extra pressure. This is usually of no concern for watercooling since the pumps we use have such redicuously low minimum NPSH requirements.

Additionally, as some others have mentioned, this can sometimes make it easier to fill and bleed the systems and this insures that an water added to the system is immediately available to prime the pump (don't ever run a pump dry that is lubricated by water as this can cause damage right away).

Hope this helps.

-FCG

[Herr Brun]

A resovoir is usually located right before a pump, with a height difference (ie. above the pump) in order to provide additional suction head. NPSH (net positive suction head) is defined as the minimum pressure required at the eye of the pump's impeller in order to prevent pump cavitation. The weight of the column of water in the resevoir provides this extra pressure. This is usually of no concern for watercooling since the pumps we use have such redicuously low minimum NPSH requirements.

Additionally, as some others have mentioned, this can sometimes make it easier to fill and bleed the systems and this insures that an water added to the system is immediately available to prime the pump (don't ever run a pump dry that is lubricated by water as this can cause damage right away).

Hope this helps.

-FCG
That was the answer I was looking for. I had read something like this somewhere on the forums earlier, but I couldn't remember. I was also afraid that someone would shout "go read the stickies" at me, but I have read the first post in all of them. Maybe put this in the pump sticky?

[snowwie]

Took me 10 seconds to bleed with res. Took my 1.5 hours to bleed with t-line.
exactly. if you change your system a lot it makes a huge difference. yes, you can just put a t line at the top of the loop, and say "gravity will fill it", but in my experience, that way just gets you a lot of air bubbles which take a long time to get out. I always have a res that can hold the capacity of the water system right before the pump. That way, I can build and mount the water system, then add water (only once!) to the res, then turn on the pump. never any water bubbles, never have to move or shake components to get the gurgling sound out, and it's all ready to go. takes 5-10 mins to mount the system dry, 10 secs to fill the res, and half a second to turn on the pump. I saw an online guide about bulding the system outside the computer, filling and bleeding, leak testing for 24+ hours, and then mounting the system, full of water, into the case. talk about a pita!

[virtualrain]

The process you described to me sounded like the process for bleeding a system which uses a T-line. A proper reservior bleeds in minutes, not hours.

And you would never route the outlet of the pump right into the reservior. This is the only occasion where order does matter.

Agreed... In my situation, I have dual DDC pumps in series and found it impossible to bleed even over night with a T-line so switched to a res and found it was still very difficult to bleed due to air getting sucked into the lines from the res. I quickly learned to just bleed with one pump for a while to get all the tiny micro bubbles out that got in as a result of the dual pumps frothing things up. It seems once you get tiny microbubbles in your loop it can take hours or days before those all bleed out.

I suspect if you just have a single pump and a decent res, bleeding should be fairly painless and quick.

[Maviryk]

Micro bubbles depend on your coolant. I generally use distilled first, bleed, then add in additives. No frothing, a little aeration, but nothing visible to the naked eye.

[fhpchris]

The process you described to me sounded like the process for bleeding a system which uses a T-line. A proper reservior bleeds in minutes, not hours.

And you would never route the outlet of the pump right into the reservior. This is the only occasion where order does matter.

if you do not put res before pump, your pump can be partially filled with air, and it will not move water around in the loop, so it will not ever work....

Put your res before the pump :)

[nikhsub1]

Micro bubbles depend on your coolant. I generally use distilled first, bleed, then add in additives. No frothing, a little aeration, but nothing visible to the naked eye.
QFT :fact: Unfortunately since it is not a long post, most will just ignore it. The above 3 sentences would reduce bleeding time problems of tee lines and res' alike.

[virtualrain]

Micro bubbles depend on your coolant. I generally use distilled first, bleed, then add in additives. No frothing, a little aeration, but nothing visible to the naked eye.

Agreed! Good piece of wisdom!

[MaxxxRacer]

additives? what additives?

[NickS]

Ya know, the pretty colorful ones :)

[badhabit]

Micro bubbles depend on your coolant. I generally use distilled first, bleed, then add in additives. No frothing, a little aeration, but nothing visible to the naked eye.

So it's not important to premix additives (say, Zerex) before filling? I don't necessarily want to invite another theoretical discussion, but would the additive dissolve evenly into the distilled water if it were just added at one point in the loop (the reservoir) and not stirred in prior?

[Cupcake]

I have my pump before my res

It just fits in my case 10x better that way

never had a problem and I havent noticed any difference in temps than when I had it the other way around

[thunderstruck!]

So it's not important to premix additives (say, Zerex) before filling? I don't necessarily want to invite another theoretical discussion, but would the additive dissolve evenly into the distilled water if it were just added at one point in the loop (the reservoir) and not stirred in prior?
Yes. The pump is circulating liquid from the res throughout the system. This method of adding additives wouldn't be used if it wasn't effective.

[Maviryk]

So it's not important to premix additives (say, Zerex) before filling? I don't necessarily want to invite another theoretical discussion, but would the additive dissolve evenly into the distilled water if it were just added at one point in the loop (the reservoir) and not stirred in prior?

Did you ever have that experiment in chemistry class where you put a few drops of dye in a glass of water. By natural diffusion the dye will go from areas of high concentration to low concentration.

Inside a water loop, even a few drops of additives added to the top of the T-line will find its way into the rest of the loop due to the turbulence caused by flowing water.

[voigts]

A resovoir is usually located right before a pump, with a height difference (ie. above the pump) in order to provide additional suction head. NPSH (net positive suction head) is defined as the minimum pressure required at the eye of the pump's impeller in order to prevent pump cavitation. The weight of the column of water in the resevoir provides this extra pressure. This is usually of no concern for watercooling since the pumps we use have such redicuously low minimum NPSH requirements.

Additionally, as some others have mentioned, this can sometimes make it easier to fill and bleed the systems and this insures that an water added to the system is immediately available to prime the pump (don't ever run a pump dry that is lubricated by water as this can cause damage right away).

Hope this helps.

-FCG

My understanding of why is the idea that the res before the pump helps eliminate pump cavitation by having some gravity fed pressure to help counteract any negative pressure at the pump intake.