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Cooling a water-reservoir

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Senior Member
Mar 21, 2001
I'm still in the designing stage of my water cooling and I have a question about the temperature of the water.

Some bluepaper specs so far for the reservoir:
About 20x14x40cm (WxHxD), made from sheet-metal or some such.
It'll hold about 10~11 liters of water. 2xTemp sensors (LCD) & waterlevel-window made out of plexiglass. Attached with rails under my case (Antec SX1030).

Would that amount of water keep the water temp low enough for me to just recycle it thru the pump to the waterblock? My CPU pumps about 70W of heat currently... If not, could I attach a low-power peltier (30W?) to the back of the reservoir (outside) and cool the with a heatsink? The heatsink would be 97x130mm. Sideprofile of the HS attached as an image.

Oh, I could use my PEP66 without a fan also.
Somewhere I saw a thing about a guy who used a 5 gallon bucket with not radiator or pelts. It ran fine for several hours until the water got hot, then it crashed. I think you need something to loose the heat, probably a radiator would work better than a pelt.
Thanks for the info. A radiator is out of the question, as it includes fans... And the e-shop I'll be buying the stuff from has only one radiator which costs the same as the rest of the stuff. That would be about $200 combined.
If you are going for a silent water cooled system you might try coiling a lot of copper tubing and running the water through that. Why don't you want to use a radiator, is it noise? I am planning on doing a cheep watercooled rig myself. Try looking at www.aquastelth.com for ideas or very inexpensive parts.
The copper pipe idea sounds ok, you may wish to consider a larger water resovior, a plastic 20 litre Jerry can would be verry cheap.
The only problem with using just a large reservoir for cooling is that it doesn't do any cooling. At all. It makes the water take longer to reach an equilibrium temperature. You would definately have to add some form of cooling ability to the water for it to lose the heat. The TEC on the side might work...though I really don't know how much heat that would remove, nor do I know how hot it would get. The copper tubing idea does have merit...and you could consider a couple of ideas to go with it:

Get a low rpm fan (assuming it's the noise you don't want) or two and have it blowing (sucking, maybe?) on it

Get a whole lot of the tubing and run it out and around your case and everywhere so that it can just passivley cool off.

I hope this helps you out, and good luck with your ideas. :)
Thanks for the ideas, people!

I had actually tought about running tubing around my case originally, but now it's layered with bitume to reduce noise, so I cannot do that.

Here comes my newest idea:
I'll get two FOP32's (quite cheap without fans) and two peltiers, about 60W? I'll put the peltiers to the back of the reservoir and attach the FOPs. Then I'll put those Titan 80mm fans to good use, they're thermocontrolled.
And I'll run the tubing inside the reservoir. That could be a bad idea, though...

Tell me what you think.
Well, if you're cooling the reservoir then you don't really need to run the tubing in it at all, cause the water *should* already be cooled...since it came from the reservoir and all.

Also, I don't know how well the fop will cool the TECs...they might do a good job and they might not, I really don't know. You might look into that if you haven't.

Other wise sounds like a good plan! :)
Hmm... Maybe those FOPs could cool 36W/16V TECs? Smallest I know I can get, here in Finland. I'd be running them at 12V, though.
Well, I stopped to think for a second...

I think that the FOP would be up to cooling the 60's...though I don't know how cold the water would be getting. I came to this conclusion by comparing 60W TEC to 60W Tbird...keeps it at ~+20-25 (something like that anyway) C...so then the cold side would be whateve the change is from that. Of course, I really don't know the safe operating parameters of TECs, nor do I even know if you can compare the cooling ideas like this.

I really wish somebody that really knew their stuff would look in on this and help out...cause I'd really like to know if I'm right or not. :)
HI!! OK first you have to take into account the heat from the pump ,add that to the heat from the CPU and thats what youll need to deal with ,,The TEC's in the side of the tank will work as a radiator. but they will never reach maximum potential air cooled ,, youd better plan on at least 20-30% more watts than you think youll need, a good radiator will keep you about ambient , using a chiller and a rad is kind of iffy , cause the water always returns to ambient when it goes through the rad. as far as the coils go ,,they work fairly well but will restrict flow proportinatly to its length.. if you go that route , make sure you use tubing larger than the rest of the system to try and reduce back pressure,,,ALSO a large res with no rad. or fans (5gal plastic bucket) actually cools quite well just by radiating heat off the sides and surfae of the water, It wasnt great , but it kept up after it stabilized
Thanks, surlyjoe!

Some extra info: the pump would be a Sicce Nova.
Sicce's homepage.

So, if the pump generates about 30W (wild guess), the whole thing would be generating approx. 100W of heat... Holy mandung (<- ha ha). But having two pelts generating about 60W each, I should be safe with those FOPs.
There's a pelt (ICE-71) that is rated 80W@16,1v, so @12v, it would be 59W, if it's linear. The deltaT is 71C, so if I can keep the hotside about 40C, the coldside would be about -30C, if I'm not mistaken.

And the tubing... I don't know what to do with that. Maybe I'll have my friend inline the reservoir with copper, that should make the heat transfer faster away from the water and help the pelts distribute their cold more effectively around the whole thing.

I'm starting to think that I'm getting too ambitious with this whole reservoir thing. Grr. But it's such a neat idea.
if both pelts were running perfectly, you would be OK ,although that would be to keep it at ambient correct?? I would make sure I gave myself some head room!! Also, it takes a considerable amount of juice to run 2 pelts , its gonna run up your power bill if you leave it on 24/7 ,. something else to think about :p
Now that was a good thing to know.
Those pelts are out the question then, as I'm folding 24/7. I would've had a 230W PSU just for them. Bugger. The f@h server is down at the moment, grr...

It would have been to keep water at ambient or close enough. Now it's the tubing thing I'll do. Maybe drill holes to the back of the thing and have the tubes bent to a U rotated 90 degrees, so they'll come out some 8-9cm. Then I'll use those extra Titan fans to blow some air across them. Hows that sound?
I'd really think of going with a cheap rad. you can get a used heater core for less than 10$ and it will get you pretty close to ambient , I have 2 nidec blowers on one and its almost silent , the coils work , but not as well as a decent rad.
One of the reasons I've been planning this reservoir is the aesthetics, as my GF doesn't want any "ugly" things sitting around... If she didn't object, I'd already have water cooling, using a bong. I don't think I can hide a radiator so that it runs well enough, especially a cheap one.

I'll write about that tubing in approx. 3 hours, as I gotta go to work. It's 7.50am here.
Didn't have enough time on lunchbreak, so here we go:

Copper piping (better word), coiled like a spring, 4cm radius. Four of these: two atop each other and two side by side. Goes something like 20cm(?) inside the reservoir. Those thermocontrolled Titan 8cm fans blow cool air across the coils.

One possible addition is a lowpower peltier (must put one somewhere :)) between the coils. Cooled with the PEP66T using 2 stacked 60x60x10mm Titan thermocontrolled fans. Seems like I have those in abundance.
The intake for the waterblock would be touching (piece of CU pipe) the pelt, so it would cool it somewhat.

BTW, I ordered that watercooling kit on the lunchbreak, I'll propably get it on week 22. <need a new thread>
What size peltier are you looking for. Other wise try experimenting running different sizes at maybe 7volts. That would cutt the wattage down quit a bit. wouldnt running a 85w tec @ 7volts drop the wattage down to around 39watts? I'm not sure how much your looking to cool the water?
You could also check out this link on the homepage, A peltier Controller!

Just make sure (and i'm sure you already know this) that to keep the water at it's coldest before it hits the cpu, that you it touches the cpu block right after going thru the chiller. Or atleast after the copper coils. If you have the chiller before the copper coils it may bring the temp of the water closer to room temp again. But then again if thats all your looking for is to keep the water at ambient temp then it doesnt matter!