Does anyone have any idea on how much heat these can disapate. I realize there are numerous variables but if they are at all efficent then I may be interested in building one.

An early plan would be have it 8ft long(3/4"ID) with 3ft tall(1/2"ID) parallel channels every 3inches on center. Its capacity would be about 1.4gallons. In my theoretical system at 2GPM that gives the water about 40 seconds to cool off. It would be mounted on a wall. The other idea would be to build one to hang from a ceiling accompanied by a ceiling fan.

I had a Thoroughbred AthlonXP running at 2300MHz (200MHz *11.5) cooled by 20ft of 3/4th copper pipe that I ran along a wall behind my desk. Under load my cpu was 45-49c. The pipes (and water) were noticeably warm. I have since changed my cpu to a Barton at the same speed, and use a large single pass heatercore in a box with a 120mm fan at 5v. Under load the barton now stays under 38c. Passive cooling is nice because you don't have to worry about dust and is dead silent, but to get good performance it has to be HUGE or be in a cool place (which miami is not ;) ). The 15 $us heater core I am using now performs MUCH better, is cheaper and smaller, and a panaflo fan at 5v is nearly silent.

Here are some pics of the passive setup I had:

Can't say thats what I wanted to here, although after doing the math your radiator had about 4 sq ft of surface area while the theortetical one I mentioned had over 16 sq ft. A small heatercore 6x6.5x2 has roughly 12 sq ft of surface area.

Does anyone remember a while back when someone posted a link to pipe that was meant for cooling, had both fins on the outside and a rough interior surface to increase heat transfer.

I threw the scraps of the failed gerwin radiator on top of the pipes and saw a temp drop of 2c. :p I think something about twice the size of what I had would work great. Make sure you get type m (red) pipes. They are thinner so they have less thermal mass and are cheaper.

If the core has 15 tubes then the answer should be about 2.5 sq ft.
Your rad should perform much better than mogwai's, 16sq/ft is huge. :)

My math was...

Each fin is 2x6, since its 2 sided that 24 sq in a pice, the heatercores I have each have 68 fins. so 68 x 24 / 144 is about 11.33.

A gerwin rad and a normal heatercore are apples and oranges. In a normal heatercore heat must travel through both solder and thin fins to get to the air. In a gerwin rad it must only travle through the wall or the pipe. However a downside to the gerwin rad is the water may flow to evenly and the center not cool off as much as the slower moving exterior.

Red? I've never seen those, in my corner of the continent. Are they dyed red or is the printing red...?

They are not acctually red, just the printing.
Type M == thinner walled, code printed in red
Type L == thicker walled, code printed in blue

I think there is also a type k which is even thicker, but I never seen it before.

yea.. i had to cut three little pieces of the blue lettered 3/4" pipe, since i ran out of red.

man that was a real pain in the ass...

my tube cutter's blade was doing fine up until then

So it is in Canada, I checked, but hadn't noticed before! Thank you!

heres an update.. i'm taking my time with this obviously.. i need to buy more fittings

http://phile.net/07-29-04_2336.jpg

I understand that normal copper tubing is cheap and widely available, but why hasn't anyone used (as far as I know) finned copper tubing instead?

Manufacturer

I have seen someone use finned tubing. They put in in a wood chiminy like box so the heat would rise inside it from convection. It looked interesting...I think it was posted in this forum. Let me know if you find it.

If passive, a lot of fins may not help much because they'd insulate the rad like hair does (I think). Sparse or short fins would help though (I guess).

***

I began to make a finned radiator once, just to try a manufacturing idea: This was interference fit fins put on parallel copper pipes. I used strips of sheet copper, drilled with rows of holes smaller than the pipes. I whacked all the holes with a large centerpunch, so they had a flare that seated over the pipe ends. Then I used a plywood scrap drilled with slightly oversized, matching holes, as a tapping block. The fins tapped down tight, with a temporary 1/8" shim between for the gap. I quit at two fins.

Sheet copper is easily available through up-market roofing companies. They'll even give away their off-cuts on a good day.

halfway done

http://phile.net/cr.jpg

Man, I hate stickers on pipe and fittings. I'm scrubbing with xylene just to take the goo off else it wrecks my pipe joint; some check-out clerk saved three seconds. :mad:

Besides the eyesore, it looks good tofu.