Passive water cooling (even for a Prescott)

From the beginning, I have to say that if you want to build anything like this or something out of the ordinary, eBay is the place to shop. High street shops won't stock what you need or be able to help you... at least that's what I found. Online shops weren't much better, though they do ask less questions about "why would you water cool your PC??? "

Parts used:
Eheim 1060
Mystery water block
1/2" hose
1 1/4" hose
1" hose
5/8" to 1/2" reducer (bought from frozencpu)
1 1/4" to 1/2" reducer (made out of steel by my dad on his lathe)
Lada radiator off a 1200CC engine

Yes, a car radiator.

First off, I bought the pump... this cost me £21.58 delivered. This is a fearsome pump with 2280LPH of flowing power, a bit overkill... and it even uses 50W of electricity in the process, adding heat to the water as it pumps. Still only enough to heat the water by about 1 degree C though, according to calculations done by people who know about this kind of thing. I tried it in the bath when I first got it, and it scared me a little as it managed to cause a whirlpool effect due to the amount of movement the water was being given, which scared me a bit with visions of pipes bursting off barbs and such.

The next thing was the block... Eheims in general don't like much back-pressure, but the "big" Eheims are almost allergic to it. For this reason a block using jet impingement was out of the question, so I went with something more "open" and less restrictive. The block I got is a mystery, the seller on eBay didn't know who made it and I can't find anything on the web that matches it. I have been told by someone it looks like an early Danger Den block, and I have to agree, but I still don't know... The pump seemed to like it, anyway.

Picture of the block:


Next up was the hardest part, choosing the correct radiator. I guess this is why you're reading this.... There are 3 basic things to look out for in a radiator for this use:

1) It has to be made of copper or brass (not aluminium, unless you want to use aluminium blocks, which you don't)
2) It has to have a filler cap on the top. This means you don't need a reservoir as filling it up is easy. Dead easy.
3) It has to be BIG!! The bigger the better

After a lot of searching, I found the perfect radiator, one off a 1200CC Lada. It was nearby so I could pick it up and not pay postage, which meant the actual rad cost me a grand total of 99p. Yes, 99p. Mmmmm. If you do plan on using an exact radiator like this to save yourself a lot of research into what is made of copper and what is aluminium, be aware the cap does NOT fully seal in the top, it merely covers it. In the car it must have had a "breather bottle" where extra water could spill into or get sucked out of when it gets cold... I didn't find this out until turning it on it's side and getting water over my feet. Nice.

Now my main concern with such a piece of choice equipment was that the water would not be able to flow through the radiator quickly enough to feed my insane pump. This is nothing to worry about. Water flows through it really easily, and by far quickly enough to feed your pump if you have a water block attached. I don't know about if you didn't have a block attached, but that would be stupid! The other problem, with the Lada radiator specifically, is that the bottom outlet (I used it as an outlet) points upwards. This makes getting hose to seal on it really quite difficult, and there is a lot of pressure at the bottom of the rad due to the weight of the water above it. Two jubilee clips have just about stopped it leaking, though I'm not sure if they've completely locked it off. The little gap between the end of the hose and the radiator outlet is permanently wet, but it doesn't drip, as the surface tension can hold it there.

So, with these things kept in mind, I simply used 1 1/4" ID hose to fit to both the inlet (top) and outlet (bottom) of the radiator, and reduced it through several steps to 1/2" for the block. AS I look at it now, the reducers go as follows:
1/4" to 1", the pump reduces 1" (its inlet) to 5/8" (its outlet), 5/8" to 1/2", and then a custom made 1/2" to 1 1/4" reducer for the inlet of the rad. I'm not sure how else you could do the final step as reducers just don't come in such big jumps.

My coolant is simply 90% water (tap water) and 10% anti-freeze... or maybe 15%. Something around there. Anti-freeze is nice because it inhibits corrosion and stops algae growth, and it's cheap.

I'm currently writing this on a Celeron D 315 (SL93Q) and folding at 100% for F@H, overclocked to 3.9GHz at 1.55v, and the temperature as shown by my onboard sensor is 41C. Obviously, the real temperature could be up or down by 10 degrees from this, but it's still cool enough for a Prescott core. The important thing about this, though, is that I have NO fans on the radiator. It is passive. If I open the window, it goes down to 38C with the slightest breeze. With fans, I'm sure just above ambient could be achieved.



Some pictures

Testing the radiator:
http://img171.imageshack.us/my.php?...dcp00278uj2.jpg

Testing the entire loop:
http://img359.imageshack.us/my.php?...dcp00277ja4.jpg

The whole system set up in my room:

i wanted to use a car radiator for my passive water cooling but i didnt cos you need to mount the radiator horizontally to make the most out of passive cooling - it would be an awesome passive cooler when horizontal, but even at an angle, say 45 degrees, it would still passively cool very well.

i used a ridiculously large reservoir to passively cool my water, approx 60 litres. the pump is submerged in the reservior/reserator, sitting on soft foam. the system is so quiet u cant hear it unless u put your ear near the reservoir.

that thing is fucking enormous!

but a good idea for my next build - the silent PC.

That sure seems like an excessive amount of tubing there snod, or are you gonna mount your rad pump like 5 feet from your rad and case. I could see it if it was the rad but the cpu block doesn't have much length to the rad and then you have like 5 feet to the pump, you said it worked better when you cut more hose off, why not take even more off of it.

I've taken a lot off since... it's about half as much now.

The radiator is leaning against the wall at, ooo, 30 degrees? Seems to be ok.... as I say, the cap doesn't actually seal on mine, so it needs to be stood up

The rad is still mounted a couple of feet away, though, so tubing is still a bit long...

Ok good, I was gonna say, I thought you had said you cut off some tubing, must say that is one ugly water cooler though.

I like the idea, and I probably would have done a similar thing, but I wanted my water cooling to be portable

Portability is a big problem... Icedragon suggested making some kind of bracket to hold it and attaching it to the side of a case, which I like the sound of... lots of trouble to make though. Also, the pump likes to be lower than the radiator, so I don't know how I'd do that. The pump sure won't fit in a case, it's too big.

I'll figure something out in time... if only I could weld...

get a full tower case

I was looking for one a while ago... they seem to be difficult to find in the UK (for cheap).

Sure sounds like the way to go, though... hmmm....

I think I'll mount the whole thing on wheels, too, so on cold days i can take it outside

im going to schucks auto right now to get me some of this shit. im totally in maybe you could give me some tips as to what to do/notdo

i had a broken radiator once, one of the brackets was cracked. i took the radiator out of the car and took it to a radiator repair/fitment place. they re-soldered the bracket on for like $10.
if u need something soldered on the radiator take it to a radiator shop.

you can solve the problem of the overflow outlet by getting an inch of overflow hose, or some hose the same size as the overflow hose, and blocking the end of the hose. u can use a fine threaded screw and secure the screw on with a hose clamp and use a hose clamp to secure the hose to the radiator. if the cap leaks, go get a new cap. u can then tilt the radiator further to improove passive airflow. u can experiment and see what temperatures are acheived at increased angles. just dont lie it flat on the floor cos that will block inlet airflow, worsening temps. it would have to be at least an inch or two off the floor i reckon.

Interesting... a radiator shop. I've never seen one but I know they exist

I've currently stuffed take off where the cap goes with tissue (where the pipe would go). I'm trying to stop the smell of the antifreeze escaping... it isn't working well though. In a room as small as mine, the smell of antifreeze seems really quite strong. For this reason I wouldn't recommend it...

Still passively cooled now though

And I'd be happy to help anyone else who attempts to do this

This thread really looks like a sticky, or at least it'd worth it.

Anyway, great job, Snod.

Yes, very thorough, we don't have enough wc info on this forum.