rad's in parallel vs serie

I've been reading on parallel radiator setups lately, but after talking about it with my dad I am now wondering if a serie setup won't be better?

In serie the water cool's down in stages rather then splitting the water in half for both radiators. thus, the water enters the first radiator and get's cooled down and then enters the second radiator and get's cooled down even more.
basically you could use even more radiators to cool even more!

the idea behind this is that my dad is a electro engineer who works for the local power supply company and they use radiators the size of men height and up to 6 radiators in serie to cool down water.

has anyone ever did this, or are there articles I could read about the differnce between parallel and serie?
at this very moment I would rather choose a serie setup then a parellel setup because it gives me the idea that it cools better then a parallel setup.

thanks in advance!

im sure the water will get cooled better in series if your pump can provide the pressure necessary to go through 2 heatercore.. but the problem lies with flow.. a heatercore is very very restrictive. Having a pump run through 2 heatercores in series will seriously hurt the flow and in the end give you poorer results then than you would get in parallel..

when you run 2 heatercores in parallel.. you actually increase the flow because a heatercore is so very restrictive.. Water gets spilt and goes through both heatercore at once.. this gives less back pressure to the pump.

btw having 2 heatercores in series will usually lower the life of the pump a great deal.. we're not talking about industrial pumps with like huge heads.. we're talking about a small fish tank pump..

Yep it would need a hefty pump, I'ld imagine the power station probably has some extremely powerful pumps to keep the water circulating!

ok, but now you are talking about a heatercore. what about a normal non-heatercore radiator? would that make any difference?.

are there any technical articles on heatercores used for computers and have nice pictures? it would be easier to understand for me as the technical talk will probably be to much for me

I can agree on the pump part. and industrial pump can be made for very heavy duty pumping, while a fish tank pump is made just to pump water around and don't really care about that much pressure.

I'd imagine that a non-heatercore radiator would be even more restrictive than a heatercore radiator. A single long tube making a number of 180° curves. Not to mention that a tubular shape is one of the worst shapes for surface area/volume ratios (which is important for heat dissipation).

A heatercore has a number of thin, wide channels in parallel and only one 180° turn (usually).

JasonKosi: a heatercore will also have at least 2 180 degree turns because of it's in/out put ;-)

cherryp00t: well, talked it over with my dad and we can't really agree with you 100%.
when water is spliced from 1/2" to 2 times 1/2" using a Y part the water will indeed increase it's flow. but... when it get's out of the heatercore and join together you will have 2 high speed flows coming together in 1 1/2" tube. thus, you will have a blockade! that doesn't sound good too us neither.

we also can not believe that heatercores in serie will need a lot more pump power. in parallel it needs more pressure when the 2 flows come together again after getting out of the heatercores. this means it will need a constant higer pressure because of it.
when in serie it will only have a higer pressure when the pump is started and the water cycle get's started. this shouldn't take too long.

I hope you understand my explanation here. doing this in English is rather difficult since I am Dutch and English is not my native language ;-)

JasonKosi said:

I'd imagine that a non-heatercore radiator would be even more restrictive than a heatercore radiator. A single long tube making a number of 180° curves. Not to mention that a tubular shape is one of the worst shapes for surface area/volume ratios (which is important for heat dissipation).

A heatercore has a number of thin, wide channels in parallel and only one 180° turn (usually).

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do you have schematics or url's with schematics on heatercores?

I can only report what I've seen from personal experience, as I've often found that people receive differing results dependent upon their setups.

For me, parallel won out by a noticable margin. My temps were some 2~3 degrees lower with the parallel setup, and flow was noticably better when compared to the same components tested with the heatercores in serial.

Although I wasn't too exacting in my testing methods, and it was some time ago, in serial an empty container only filled to around 2/3~3/4, while in the same amount of time the setup in parallel filled it completely.

Again, I'm just reporting what results I had, yours might very well be different. I'd suggest trying it both ways and finding which method works best for you in your conditions. It really doesn't take much time, effort, or money to try it both ways...Besides, once you have your results, you could share the information you record with others here who could benefit from it

rmonster: that is very interresting. that would mean that the 2 water flow coming from the heatercores aren't so blocked as I thought it would be.

since the water is spliced but the tube diameters stay the same you would create vacuum, and that will be the blockade when the 2 water flows come together again.
very strange to see that parallel wins.......

offcourse I will try both setups and report them here

A few things here. Running 2 rads in parallel will give you a higher flow rate than running just one rad. Rads are most efficient when the water/air temp differential is high, ie. the hotter the water the more efficient a rad is, the lower the temp of the water the less efficient. When running in series (Cathar says he gets better temps in series but he is using an Iwaki MD-30RZT) the water will be hotter at the first rad, hence it will be more efficient. By the time the water gets to the second rad, efficiency is going to drop as the water will have already been cooled by rad 1. Plus in series you really hurt flow so be prepared for a serious pump.

nikhsub1 said:

A few things here. Running 2 rads in parallel will give you a higher flow rate than running just one rad. Rads are most efficient when the water/air temp differential is high, ie. the hotter the water the more efficient a rad is, the lower the temp of the water the less efficient. When running in series (Cathar says he gets better temps in series but he is using an Iwaki MD-30RZT) the water will be hotter at the first rad, hence it will be more efficient. By the time the water gets to the second rad, efficiency is going to drop as the water will have already been cooled by rad 1. Plus in series you really hurt flow so be prepared for a serious pump.

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I don't believe that. say for instance the water is 50C when it enters the first rad in serie of 2, and get's cooled down to about 30C and then enters the second rad. in the second rad it won'r drop as much as in the first rad, but will be cooled down to about 20C.
when in parallel the water get's spliced in half and both parts are cooled down to 25C. when the flows get combined again the water will still be 25C.

the part about needing to use a high pressure pump for a serie setup is nonsence too. like I said earlier, in the beginning of the cycle you may need more pressure. but when the cycle runs there is not as much pressure anymore. with a parallel setup the pump will need more work to do to get the two flows of water from the two 1/2" tubes into one 1/2" tube because of the vacuum created when the flow get's seperated before it enters the two rad's.
you push one flow of water through two tubes of the same diamter as the originating tube thus creating a vacuum. it's simple, the tubes must be filles up with something, right?
that is why the pump must do a big job in getting the two flows back into one flow because it has to push out the vacuum too.
this is something you will not have with a serie setup because there is one flow of water all the time.

Well let's see some testing then

IMHO I think he is correct given that he is using an inline pump VRS a submerged pump...lets start @ the outlet of the pump....it is pushine the water out and thru all your blocks and hoses then it feeds it under (some) preasure back into its inlet....inital startup would be the majority of the load, but one rolling it's 1 pump acting as 2 like a push pull setup....this what ya talking about freshy?

FizzledFiend, if I correctly understand what you are saying then yes indeed.
the pump will be inline without a reservoir. I will be using a T-line.

don't really understand the part about push pull though. could you be more clear on that? might be me being Dutch though ;-)

you have 1 heatercore with 2 fans.. 1 infront 1 behind it.. so 1 fan pushes through the heatercore the other one pulls through it.. increasing air flow

freshy98 said:

I don't believe that. say for instance the water is 50C when it enters the first rad in serie of 2, and get's cooled down to about 30C and then enters the second rad. in the second rad it won'r drop as much as in the first rad, but will be cooled down to about 20C.
when in parallel the water get's spliced in half and both parts are cooled down to 25C. when the flows get combined again the water will still be 25C.

the part about needing to use a high pressure pump for a serie setup is nonsence too.

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Do you have any hard numbers to back up your theory? It is a fact that rad 2 in a series setup is less efficient than rad 1. How did you arrive that 2 rads in series = 5C lower water temps? Now, when you run 2 rads in series, you double the head loss, if each rad has a pressure drop of .5m then you created 1m of head loss running 2 in series. Now, if you run the same 2 rads in parallel, your pressure drop would be a bit more than half of running the one rad, so we'll say .3m for running 2 in parallel.

As always, test them both ways and see which way works out better in your system.

nikhsub1 said:

As always, test them both ways and see which way works out better in your system.

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agreed the best way to find out the best setup is test it out yourself ;p then report back how you did =p

nikhsub1, the numbers I used were no actuall numbers. off course I will be testing it as soon as I have my stuff. that will takes weeks or maybe even a few months. depends on how fast I can sell my old case.

freshy98 said:

nikhsub1, the numbers I used were no actuall numbers. off course I will be testing it as soon as I have my stuff. that will takes weeks or maybe even a few months. depends on how fast I can sell my old case.

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It was just that you said after you quoted me, "I don't believe that". I was just wondering why you don't believe it? I stated no hard numbers, just facts of running rads series vs. parallel. Most users see better results in parallel rather than series with rads. Why create unnecessary head loss?

err, ok.it's not that I don't believe you but the thought that parallel is better then serie is hard to believe.
I'm just gonna test it myself and report my findings here. will take some time though.

I appologize for not believing you.