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Hey everyone!

I’m trying to rework a 1/2” copper immersion chiller to use as a counter flow.

It’s about a 32.5 ft long coil with a diameter of 12” so it’s gonna be some tight turns to get a pipe on over it.

I initially looked at using pex as the outer piping. I’m trying to source 1” pex somewhere and try and feed that over the copper.

I’ve worked with pex for a number of years but never 1” and I can’t make a call on if I’ll be able to get that around that tight of a radius.

I wanna stay away from cheap garden hose and some of the other piping I’ve looked at has been insanely expensive.

Any thoughts?


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The idea sounds awesome. If you are concerned about the PEX kinking making the turn, why not try a heat gun...heck, even a good hair dryer would probably be enough to make it workable.

Would love to see the finished product, as I'm using the same and would like to move to CFC.

get some rad hose at princess auto

PEX would be clean and nice, but based on the following link, I think you are out of luck for bend radius, etc.

https://www.pexuniverse.com/pex-tubing-technical-specs

Maybe heating up like Shaun said would allow a slightly tighter bend, but you could be hard pressed to get what you want.
Hot water bath could heat a whole roll up, make it more pliable and then a hair dryer or heat gun for reheating smaller spots.

I made a pex counterflow chiller using 3/4" pex. I think my diameter was about 12". Getting it tighter than that would have been pretty difficult. As an aside, one issue I ran into was that the copper tubing does not sit squarely within the pex, reducing the contact with the water, and reducing efficiency.

See here: http://www.brewnosers.org/forums/viewto ... low#p41616

Thanks! I’m gonna look into the rad hose. The pex sounds like some trouble especially 1”.

I didn’t pay anything for the immersion chiller (thanks Dan) so even if I fork over a bit of cash for the hose I’m good.


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Be careful , you don’t want a big difference between the inner pipe and the outer pipe , the key for effective cooling is cold water temp and high flow rate, to demonstrate , my grainfather counterflow chiller will cool boiled wart down to 14c with my tap running at wide open , I can adjust the output temp by throttling the water flow. I would try a 3/4 inch garden hose , they are flexible enough and easy to slip on the copper pipe. Plus the amount of water used is a lot less.


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MacMan wrote:Be careful , you don’t want a big difference between the inner pipe and the outer pipe , the key for effective cooling is cold water temp and high flow rate, to demonstrate , my grainfather counterflow chiller will cool boiled wart down to 14c with my tap running at wide open , I can adjust the output temp by throttling the water flow. I would try a 3/4 inch garden hose , they are flexible enough and easy to slip on the copper pipe. Plus the amount of water used is a lot less.


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I’m confused. Could you clarify why having a big difference between the outer pipe and inner pipe will affect the heat transfer? The more water that’s transferred the more heat transfer correct?

Obviously with diminishing returns and wasted water at some point.


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Laminar flow

Interesting. I can see this being an issue when you have unobstructed/non mixing flow. But in a counterflow chiller where those two lines are oriented in an immeasurable amount of ways throughout its length, disrupting that flow. Would that really still apply?

I picture this principle at play in a tube where things are perfect and the flow is steady, even, and the inner pipe remains consistently in the middle somewhere with flow around it. Then the layering affect is possible. But would turbulence not become a disrupting factor in this principle?

If so, I can picture coiling some high gauge wire around the inner tube to create even more turbulence.

But I do not know anything about fluid dynamics.


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oceanic_brew wrote:Laminar flow

If so, I can picture coiling some high gauge wire around the inner tube to create even more turbulence.

But I do not know anything about fluid dynamics.

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When I made my first counterflow chiller, that's exactly what I did - I had some 2/0 copper so I took the strands of that and tacked it in a spiral configuration around the 30 feet of 3/8" interior copper. I used a high temp rubber hose from PA if I recall correctly. It was a great little chiller that I eventually replaced with a plate chiller and then the Chillzilla counterflow chiller.

I can't say if the spiral of copper helped, but it certainly didn't hurt and was fun to make.

I’m confused. Could you clarify why having a big difference between the outer pipe and inner pipe will affect the heat transfer? The more water that’s transferred the more heat transfer correct?

Obviously with diminishing returns and wasted water at some point.

Sorry for the delayed response.

My thought would be is as long as the output temperature is lower than the input ( near boiling i would assume) then your getting maximum efficiency ish, if the outside pipe is too large you lose much of the control of the output temp by changing the water flow as it will have less effect on the heat transfer. In reality, its the surface area of the inner copper pipe that will limit the heat transfer along with thickness etc etc, the more water you pass over that surface area , the better the heat transfer , so for optimal efficiency you would want to flow it faster and keep the temperature lower for longer along the path IMHO. My brother ( Physicist) and I discussed this at length when trying to figure out a pool heater and his one comment was , the higher the flow rate across the medium, and the more surface area in contact with that, the better the efficiency to a point. You don't want the cooling water to ever reach the same temperature as the wort its cooling because then there is no heat transfer. Interestingly enough, he said maximum efficiency is reached when you barely increase the temperature of the cooling liquid, IE the temp at the output is only a few degrees higher than the input which of course means huge volumes of water but then we were trying to heat a pool with solar piping and copper.

I am not sure how much efficiency gain you would get by introducing turbulance as that will ultimately reduce water flow and increasing pressure requried to flow the water.