Liquid Cooling Can I run two pumps on a single loop?

[B L ! T Z]

Originally Posted by JD666 ♥ the second water pump will have to be installed in the opposite direction and switched off, and having enough freewheeling capability to send current back. Which generally does not happen, since water pumps have a different rotation mechanism.

So, are you saying that if I attach the second pump and keep it switched off in the normal direction, the freewheeling capability will be retained and the flow will be maintained?

[Man]

Originally Posted by JD666 ^^ When rotated in a particular direction ( opposite to the one the fan normally rotates in ), the fan motor being DC does send a current in the opposite direction, which causes the fan lights to glow. if led stands for 'light emitting diode, and the diode glows what does it say about the direction of current? In the case of water pumps, the second water pump will have to be installed in the opposite direction and switched off what happens if the pump remains on? , and having enough freewheeling capability to send current back. if air is a compressive fluid water is? And this will do what to freewheeling! Which generally does not happen, since water pumps have a different rotation mechanism.

What is this misterious different mechanism?

I really appreciate you guys taking the time to clarify, but explain assuming I have the understanding of a 5 year old :-) thanks

[B L ! T Z]

Originally Posted by Man When rotated in a particular direction ( opposite to the one the fan normally rotates in ), the fan motor being DC does send a current in the opposite direction, which causes the fan lights to glow. if led stands for 'light emitting diode, and the diode glows what does it say about the direction of current? In the case of water pumps, the second water pump will have to be installed in the opposite direction and switched off what happens if the pump remains on? , and having enough freewheeling capability to send current back. if air is a compressive fluid water is? And this will do what to freewheeling! Which generally does not happen, since water pumps have a different rotation mechanism.

Since the second pump is attached in the opposite direction of the first pump and both are turned on, then its like two cars pushing each other full front and one is more powerful from the other one. So, the second pump should die much sooner.

[JD666]

^^ no offense but then i wont be discussing watercooling with a 5 year old

If the LED is glowing, its getting the current from the DC motor of the fan instead of the power socket of the fan. Thats about it. A DC motor is a generator as well. You can either apply a voltage to it, to rotate it or rotate it and get a voltage/current from it.

Its the mechanism of the fan that lets it rotate freely, causing the back current.

With water as the fluid, and the mechanism needed to propel it ( in the case of a water pump ), the scenario changes.

Read up on pumps, and how they operate. you will realise that they are harder to rotate freely ( freewheeling ), by pumping water thru them. You can blow onto a fan and make it rotate , but not the same for a pump when you push water to it ( atleast not within normal levels ).

[Man]

Originally Posted by B L ! T Z Since the second pump is attached in the opposite direction of the first pump and both are turned on, then its like two cars pushing each other full front and one is more powerful from the other one. So, the second pump should die much sooner.

I don't know if pump dying was a subject, but instead of internal combustion cars, use golf carts and make sure both the cars have the same battery source.

Originally Posted by JD666 ^^ no offense but then i wont be discussing watercooling with a 5 year old Don't discuss, just explain If the LED is glowing, its getting the current from the DC motor of the fan instead of the power socket of the fan. Thats about it. Question was about the direction of current thats about it, come on dude don't sound like a 5 year old A DC motor is a generator as well. You can either apply a voltage to it, to rotate it or rotate it and get a voltage/current from it. Finally something we both agree on Its the mechanism of the fan that lets it rotate freely, causing the back current. With water as the fluid, and the mechanism needed to propel it ( in the case of a water pump ), the scenario changes. I know it's not a reciprocatory pump, so Read up on pumps, and how they operate. you will realise that they are harder to rotate freely ( freewheeling ), by pumping water thru them. You can blow onto a fan and make it rotate , but not the same for a pump when you push water to it ( atleast not within normal levels ).

Harder, may be, but will it rotate?
And what happens when the levels are not normal? Xspc is 750 l/hr pump and D5 streaches its legs upto 1500l/hr and produces 3 times the head. What do you think will happen?

---------- Post added at 01:29 AM ---------- Previous post was at 01:17 AM ----------

Originally Posted by JD666 In the case of water pumps, the second water pump will have to be installed in the opposite direction and switched off,

Are you sure?

[JD666]

^^ Yup, coz it would have to be installed in the opposite direction to actually send a reverse current.

And i really dont wanna know what would happen, since it would be illogical to install em together in the same loop. Unless you are gonna link me to some google article or video of such 2 pumps lined up together.


Besides that, enough said on the topic.

[Man]

Originally Posted by JD666 ^^ Yup, coz it would have to be installed in the opposite direction to actually send a reverse current. And i really dont wanna know what would happen, since it would be illogical to install em together in the same loop. Unless you are gonna link me to some google article or video of such 2 pumps lined up together. Besides that, enough said on the topic.

It was assumed the pumps will remain in the same loop and after an hr of healthy discussion you think it would by illogical to put them in the same loop
And what will happen after i give you a link to such a video? You could have said that you won't accept any thing logical or not unless you saw a video before we got into this discussion

[mav2000]

Man..,.now your just being obstinate.

For the pump to send back any current it HAS TO BE INSTALLED IN THE OPPOSITE DIRECTION OF THE OTHER PUMP.

Anyway the extra flow and head pressure will kill the pump quite soon if both run in the same direction. If they run in opposite directions be sure that the pump will die out sooner.

If you want to try it out, do so at your own risk.

[JD666]

Im gonna stop feeding the troll now, I commented on what i said before, that your arguments are based on installing them in the same loop, which is illogical in my opinion.

And eventually such discussions will be backed up with a link or a video.

Because if you knew the outcome, why would you still wanna debate over it?

[Man]

Originally Posted by mav2000 Man..,.now your just being obstinate. For the pump to send back any current it HAS TO BE INSTALLED IN THE OPPOSITE DIRECTION OF THE OTHER PUMP. Anyway the extra flow and head pressure will kill the pump quite soon if both run in the same direction. If they run in opposite directions be sure that the pump will die out sooner. If you want to try it out, do so at your own risk.

First of all this is a public forum and mod or not I suggest you be carefull with your choice of words. Up until now the discussion has been kept healthy in the right spirit and you are most welcome to participate as long as you keep it that way.

And regarding your logic of opposite direction of the other pump, makes no sense. You rotate it forward the polarity remains same, you rotate it back words the polarity is reversed. It will create a potential difference you like it or not. And I have been hinting it with the diode in LED,

Originally Posted by JD666 Im gonna stop feeding the troll now, I commented on what i said before, that your arguments are based on installing them in the same loop, which is illogical in my opinion. And eventually such discussions will be backed up with a link or a video. Because if you knew the outcome, why would you still wanna debate over it?

Yes I have said before(look again) that keeping two pumps is not the best way to go but the guy wanted a solution with those limitations.
Let me ask you again what will happen with a video?
I was happy giving an opinion till some one jumped on saying no no this does not happening.unfortunately logic or physics is not intimidated, you like it or not.

[rakesh_sharma23]

This is a buildlog.. if you want to continue discussion about using two pumps pls use this thread.. http://www.erodov.com/forums/why-can...oop/50301.html

Any suggestions about the build is welcome here...

[mav2000]

Originally Posted by Man First of all this is a public forum and mod or not I suggest you be carefull with your choice of words. Up until now the discussion has been kept healthy in the right spirit and you are most welcome to participate as long as you keep it that way. And regarding your logic of opposite direction of the other pump, makes no sense. You rotate it forward the polarity remains same, you rotate it back words the polarity is reversed. It will create a potential difference you like it or not. And I have been hinting it with the diode in LED, Yes I have said before(look again) that keeping two pumps is not the best way to go but the guy wanted a solution with those limitations. Let me ask you again what will happen with a video? I was happy giving an opinion till some one jumped on saying no no this does not happening.unfortunately logic or physics is not intimidated, you like it or not.

I only said you are obstinate....obstinate is not a bad word..I would ask you to re read the post and then get back with your thoughts. I would like to say a lot more, but I am not going to reply to this topic anymore, since my words are being misinterpreted.

[Man]

Originally Posted by mav2000 You cant run two dis similar pumps together as the stronger pump will kill the weaker one with the flow. So keep that in mind. If you want to use a stronger pump, then remove the weaker one.

Originally Posted by rakesh_sharma23 No No.. weaker pump will not act as generator and start burning circuits.... Stronger pump will apply more pressure on the impeller of the weaker pump and more wear-and-tear will happen to the weaker pump...and it will die too soon..

Originally Posted by B L ! T Z Since the second pump is attached in the opposite direction of the first pump and both are turned on, then its like two cars pushing each other full front and one is more powerful from the other one. So, the second pump should die much sooner.

Originally Posted by JD666 ♥ And i really dont wanna know what would happen, since it would be illogical to install em together in the same loop. Unless you are gonna link me to some google article or video of such 2 pumps lined up together.

Thanks to @napster this was brought to my attention.

[JD666]

^^ does he mention anywhere that both the pumps were in the same loop?

And he states himself that the flow rate was same for both. It dont matter if you have a bigger but slower rotating pump, or a smaller but faster rotating pump, as long as the net system flow rate is the same and does not exceed any one of the pumps.

[mav2000]

1. So where does it say that it acts like a generator?

2. The MCP series pump used in that test has been beefed up with DIY INHK, so the head pressure on both the pumps should be close together. Therefore, will not cause any of the pumps to go bad really quickly. We are talking of two pumps in this thread which have a huge difference in performance.

3. Most dual pump setups use the exact same pump, so as not to have the issue of one pump killing the other.

4. That test must have run for around a couple of hours/days. I bet if its run long enough one of the pumps will die as the rotor will be running faster than the 4000-4400 rpm its supposed to run.

5. Once the pump dies, it will only add as a restriction in the loop, and a major one at that as the rotors now have to be turned without electrical power by the other pump. Same as what it shows in the page you linked. It will not become a power generator.

6. If you blow into a pump, the impeller/rotor will not move. I have opened up quite a few DDC 325's and I can assure you its not possible to move them by blowing on them. I dont know about EK pumps (Jigway), as they seem to be a bit weaker.

Give you a simple experiment. Run a 2200-2500 rpm fan in a sandwiched together with a 1200-1400 rpm fan and see what happens. Over a period of time the slower fan will start burning out as the blades are moving faster than what it should be running at. Thats why, on rads, we normally use fans of the same type in a push pull situation. In case of mismatched fans, we can expect some issues with the fan motor after a couple of months of use.

EDIT: And finally and most importantly, this test is for pumps in series and not in parallel, which is what we have been discussing. Please take a look at the pump setup in the first pic and confirm it. This is a far more easier solution for pumps which do not match each other, "almost" like making two different loops. Serial is a whole other ball game.