Triple passive Mo-Ra3 experiment - advice?

DoubleTap

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I've been running a Mo-Ra 360 for about 6 months without any serious issues.

(it's cooling an 8700K and a 2080Ti that are often overclocked)

I read a while back that a single Mo-Ra3 (I think the 420) can dissipate 200W of heat passively.

These giant radiators can be hard to find, but I did locate two 420s and they are on their way to me.

My goal is to see if I can run all 3 of these radiators without using fans and whether the coolant will eventually heat up past 40C or not

I do have fans on my 360 so I can make them turn on if I need to.

Someone on another forum recommended that I run them all in parallel (on my single D5).

The flow through the radiators will be slowish, but flow through the blocks should be good (in theory)

Is that as simple as getting a 4 way connector and just running a 3 way in / out?

This is what I'm thinking:

1611677852379.png


I have 1L of Koolance 702 on hand and another 5L on the way. Will need more fittings and maybe another box of ZMT.

Willing to buy a second pump if needed.
 
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soulesschild

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Will a single D5 pump be able to push through all of them? I'd almost want to run dual pumps
 

termite

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The pump could certainly be an issue.

Orientation may also be key.

Radiators do better orientated horizontal with passive cooling.
 

Nenu

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I've been running a Mo-Ra 360 for about 6 months without any serious issues.

(it's cooling an 8700K and a 2080Ti that are often overclocked)

I read a while back that a single Mo-Ra3 (I think the 420) can dissipate 200W of heat passively.

These giant radiators can be hard to find, but I did locate two 420s and they are on their way to me.

My goal is to see if I can run all 3 of these radiators without using fans and whether the coolant will eventually heat up past 40C or not

I do have fans on my 360 so I can make them turn on if I need to.

Someone on another forum recommended that I run them all in parallel (on my single D5).

The flow through the radiators will be slowish, but flow through the blocks should be good (in theory)

Is that as simple as getting a 4 way connector and just running a 3 way in / out?

This is what I'm thinking:

View attachment 322879

I have 1L of Koolance 702 on hand and another 5L on the way. Will need more fittings and maybe another box of ZMT.

Willing to buy a second pump if needed.

Easily achieved if you place chimney(s) sealed over the top of the rads.
Heat rising has a lot of energy and the longer it is made use of, the more energy you get to tap, so the taller the chimney the better.
Place the radiator off the floor but flat, seal the chimney to the rad so hot air rising from it forces cool air up through the rad.
And with a steampunk theme it could look great.

I did it with a single radiator as a proof of concept and it works well.
But the rad ended up under a table so I didnt pursue it.
 
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Will a single D5 pump be able to push through all of them? I'd almost want to run dual pumps
A single D5 can handle a single MO-RA. I'm actually the guy on the other forum who suggested running the three in parallel! Three in parallel should present 1/3rd the restriction of one, so I believe a single D5 should be able to do this.

Of course, two D5s is better than one... 😂

Hi DoubleTap !
 

DoubleTap

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A single D5 can handle a single MO-RA. I'm actually the guy on the other forum who suggested running the three in parallel! Three in parallel should present 1/3rd the restriction of one, so I believe a single D5 should be able to do this.

Of course, two D5s is better than one... 😂

Hi DoubleTap !

Thanks man, small world lol.

I have a feeling I might go with that dual pump mount you're using...
 

Nobu

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A single D5 can handle a single MO-RA. I'm actually the guy on the other forum who suggested running the three in parallel! Three in parallel should present 1/3rd the restriction of one, so I believe a single D5 should be able to do this.

Of course, two D5s is better than one... 😂

Hi DoubleTap !

Unless I'm mathing wrong, shouldn't they have the same restriction (+/- a bit) as one, since net flow will be about the same, and flow through each rad will be about ⅓?
 
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Unless I'm mathing wrong, shouldn't they have the same restriction (+/- a bit) as one, since net flow will be about the same, and flow through each rad will be about ⅓?
You're correct that the portion of total flow through each rad will be about 1/3rd, but the overall restriction posed by the three of them in parallel will also be about 1/3rd the restriction of a single rad. It's the same principle that determines parallel resistance in electrical circuits.

Picture two barrels with corks in holes in the bottom. One barrel has a single cork and the other barrel has two. Fill both barrels to the same height and pull the corks: you know, intuitively, that the second barrel with two corks will empty nearly twice as fast. The motive force for the fluid is the same for both barrels (in this case it's head pressure or gravity), but two holes is less restrictive than one, so overall flow is higher.

That's super simplified, but I think the concept is more or less the same.
 

FrgMstr

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You're correct that the portion of total flow through each rad will be about 1/3rd, but the overall restriction posed by the three of them in parallel will also be about 1/3rd the restriction of a single rad. It's the same principle that determines parallel resistance in electrical circuits.

Picture two barrels with corks in holes in the bottom. One barrel has a single cork and the other barrel has two. Fill both barrels to the same height and pull the corks: you know, intuitively, that the second barrel with two corks will empty nearly twice as fast. The motive force for the fluid is the same for both barrels (in this case it's head pressure or gravity), but two holes is less restrictive than one, so overall flow is higher.

That's super simplified, but I think the concept is more or less the same.
Now have that two-hole barrel empty back into a single hole barrel...
 
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Nobu

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You're correct that the portion of total flow through each rad will be about 1/3rd, but the overall restriction posed by the three of them in parallel will also be about 1/3rd the restriction of a single rad. It's the same principle that determines parallel resistance in electrical circuits.

Picture two barrels with corks in holes in the bottom. One barrel has a single cork and the other barrel has two. Fill both barrels to the same height and pull the corks: you know, intuitively, that the second barrel with two corks will empty nearly twice as fast. The motive force for the fluid is the same for both barrels (in this case it's head pressure or gravity), but two holes is less restrictive than one, so overall flow is higher.

That's super simplified, but I think the concept is more or less the same.
Resistance of a component doesn't change when you add others in parallel, though. The voltage (pressure) drops, current (flow) drops, but resistance remains constant.

If you put components in series, the resistance of the whole circuit increases, but going from one to three in parallel doesn't change anything other than pressure and flow (through the parallel components, who are effectively acting as a single larger component with lower pressure and flow rate)
 

Nobu

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To use your anology: it's like taking a hose and splitting it into three buckets with a single hole, vs one bucket with a single hole, and then pumping that water back up through the hose into the buckets. Theoretically the three buckets would empty faster, but because it's a closed loop, the resistance of the water exiting the three buckets into the single hose prevents that from being the case.

Edit: yeah, I'm retarded. Resistance drops, or else the voltage drop across them would be the same. But because the resistance of the rest of the system is so high, it's unlikely to make much difference in flow (vs a single rad). It'll be much better than three in series, though, and should work just fine with one pump.
 
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Now have that two-hole barrel empty back into a single hole barrel...
Yeah, my analogy isn't great. But my point still stands.

It's the same reason why the overall flow in a parallel loop is greater than the overall flow in a serial loop with the same components. By putting three MO-RAs in parallel, you wind up with a flow path with three times the cross sectional area as a single MO-RA, which directly translates to a lower pressure drop and thus more flow.
 

FrgMstr

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Yeah, my analogy isn't great. But my point still stands.

It's the same reason why the overall flow in a parallel loop is greater than the overall flow in a serial loop with the same components. By putting three MO-RAs in parallel, you wind up with a flow path with three times the cross sectional area as a single MO-RA, which directly translates to a lower pressure drop and thus more flow.
1 pipe going into 3 pipes going into 1 pipe in a sealed system....
 

Nobu

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Yeah, my analogy isn't great. But my point still stands.

It's the same reason why the overall flow in a parallel loop is greater than the overall flow in a serial loop with the same components. By putting three MO-RAs in parallel, you wind up with a flow path with three times the cross sectional area as a single MO-RA, which directly translates to a lower pressure drop and thus more flow.
Yeah, you're right, but because that section is in series with other components (the water blocks) which are way more restrictive, the flow of the system shouldn't increase much vs a single rad. It should be much better than three series rads, though.
 

FrgMstr

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You're ignoring the huge pressure drop that the MO-RAs induce by just using "pipe."
Okie dokie. I only sold industrial hose and tubing for a decade into refineries, plastic plants, and the oil field.
 

BrotherMichigan

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Okie dokie. I only sold industrial hose and tubing for a decade into refineries, plastic plants, and the oil field.
He's actually right as far as the large pressure drop goes, if not the reason. The flow rate is the same because it's an incompressible fluid in a sealed loop, but the pressure drop is pretty large across a MO-RA. The pressure drop is actually reduced by its use of round tubing, but it's still really large because it's so big, and putting all three in parallel effectively reduces the total pressure drop to the same as a single radiator.

See here for reference: https://thermalbench.com/2016/09/12/watercool-heatkiller-mo-ra3-420-pro-radiator/3/
 

LukeTbk

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Do not know nearly enough if the slower liquid help hurt the pressure less by going parallel, but would the splitter and combiner introduce restriction that make the more complicated affair loose is interest (if it was significant in the first place) ? Or is splitting "free" ?

Would be curious if both solution get tried and compared.
 

Nobu

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Do not know nearly enough if the slower liquid help hurt the pressure less by going parallel, but would the splitter and combiner introduce restriction that make the more complicated affair loose is interest (if it was significant in the first place) ? Or is splitting "free" ?

Would be curious if both solution get tried and compared.
There's a thread somewhere in these forums discussing different tubing sizes and adaptors, and I think the consensus was "it doesn't make enough difference to matter in most cases." There may be a small efficiency loss, but other things have a greater influence.
 

BrotherMichigan

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Do not know nearly enough if the slower liquid help hurt the pressure less by going parallel, but would the splitter and combiner introduce restriction that make the more complicated affair loose is interest (if it was significant in the first place) ? Or is splitting "free" ?

Would be curious if both solution get tried and compared.

The splitting and combining essentially cancel each other out in terms of pressure. As for the slower flow through each radiator, the reduction in flow rate is actually what causes the pressure drop to be lower, so it's kind of two sides of the same coin.
 

LukeTbk

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The splitting and combining essentially cancel each other out in terms of pressure. As for the slower flow through each radiator, the reduction in flow rate is actually what causes the pressure drop to be lower, so it's kind of two sides of the same coin.
That what I was trying to say by slower liquid help hurt the pressure less (that was terrible phrasing)
 
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Okie dokie. I only sold industrial hose and tubing for a decade into refineries, plastic plants, and the oil field.
It's alright. I'll admit my understanding of fluid dynamics is not formally educated, but I am a process controls engineer and I work in a plant where I deal with this kind of thing. Plus I've seen the results of parallelizing flow in my own loop, so we can agree to disagree until OP sets up and finds out. I did get him to buy a flow meter; I wonder if we can bully him into trying it both ways - he'll have to be one of a handful of people on the planet with three MO-RAs hooked up to a single system!
 

FrgMstr

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It's alright. I'll admit my understanding of fluid dynamics is not formally educated, but I am a process controls engineer and I work in a plant where I deal with this kind of thing. Plus I've seen the results of parallelizing flow in my own loop, so we can agree to disagree until OP sets up and finds out. I did get him to buy a flow meter; I wonder if we can bully him into trying it both ways - he'll have to be one of a handful of people on the planet with three MO-RAs hooked up to a single system!
I get the flow across the rads. That is not the point that makes the issue as per having one pump or two.
 

DoubleTap

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It's alright. I'll admit my understanding of fluid dynamics is not formally educated, but I am a process controls engineer and I work in a plant where I deal with this kind of thing. Plus I've seen the results of parallelizing flow in my own loop, so we can agree to disagree until OP sets up and finds out. I did get him to buy a flow meter; I wonder if we can bully him into trying it both ways - he'll have to be one of a handful of people on the planet with three MO-RAs hooked up to a single system!

I'm open try whatever configs make sense - when you say both ways, do you mean also try them in serial?

I still need to order fittings and a flow meter and while I'm going to try one pump at first, I'm resigned to the idea that I will need two.
 

tunatime

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If you are going to try and be fancy to get as much flow as you can do 2 loops one for rads and one for blocks and combine them in the reservoir...or do everything in serial with one or 2 pumps
 

Nimisys

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I would think in a passive system, slower flow through the rads would be a good thing, as it would allow more thermal transfer from the liquid to the metal of the radiator which would be trying to stay in equilibrium with ambient.

Though in this setup, I'd suggest running the rads in parallel with the PC loop as well.
 
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