[MadZack]

I'm not to satisfied with the performance of my store-bought copper tube immersion chiller, and I'm planning to build my own.  After reading up on it, I'm planning to do a split-dual, i.e. inner and outer coils running in parallel, since that seems the most efficient and quickest-cooling approach.

So my questions is: what would happen if I set it up so that the two coils ran in different directions?  For example, running the inner clockwise, and the outer counter-clockwise?  Would this affect performance at all?  For better or worse?  Anyone actually tried this?

I'd also be curious what folks who have built similar systems might be using to stabilize the coils and keep them separated from each other?

I'd also-also like to hear from folks about bending tubing for the final bend that hooks over the rim of the boil kettle.  Should I heat up the tubing (with a propane torch or similar) before bending?  Will combining torch heat and also using a bending coil ease things further?

And finally, any thoughts on SS vs. copper?  Is SS much harder to work with?  Are the cooling properties much worse?

Thanks in advance for any constructive/helpful thoughts you can share!

[denny]

It would make no difference to have them running in different directions.  For example, the JaDeD Hydra uses 3 coils all connected to a single inlet and outlet, meaning that all flow in the same direction.  It is about the fastest chiller I've ever used, of any type.

[Stevie]

Use a tubing bender. You will kink the tubing if you do it by hand. Don't heat it. This stuff is thin wall and made to be manipulated by hand.

Stainless is cheaper, slightly less efficient, and slightly harder to bend. Depending on the price of copper, it can be much less expensive. If you plan on braising the pipe connections, copper is easier to work with and the fittings are more readily available. Also, use 3/8" as it is much less expensive than 1/2" and more efficient.

It doesn't matter if the coils touch. You can use cooper wire to hold stuff in place.

[apple]

I just made a dual coil chiller. It was not too hard to put together. Sourcing the parts was probably the most time consuming part.

I have only had a chance to use it once, but it performed amazingly well. I did a 20 minute whirlpool, then turned on the water. It got the temp down to 70 in less than 10 minutes! I use a pump to recirc while I'm chilling. I think that helps a lot.

My website is still a bit of a disaster, but if you want to check out some pics you should be able to see them here.

https://brewnanigans.wordpress.com/diy-2/diy/

To answer your question about the direction of flow. Mine introduces the cold water at the top for both coils. I can't say if one way is better than another. My thinking was that the warmest wort is at the top so put the cool water there. Also, running the coils counter to each other might tend to transfer some heat from the 'warm' side of one coil to the 'cold' side of the other coil. If they run in parallel they are more likely to take the heat from the wort and not from each other...I think.

[MadZack]

I just made a dual coil chiller. It was not too hard to put together. Sourcing the parts was probably the most time consuming part.

I have only had a chance to use it once, but it performed amazingly well. I did a 20 minute whirlpool, then turned on the water. It got the temp down to 70 in less than 10 minutes! I use a pump to recirc while I'm chilling. I think that helps a lot.

My website is still a bit of a disaster, but if you want to check out some pics you should be able to see them here.

https://brewnanigans.wordpress.com/diy-2/diy/

Noice!  Looks very well crafted!  I love the detailed breakdown of the U, if I can find the parts, I'm going to do a similar approach.  I had thought of doing a simple Y, but I think your U approach will actually lead to potentially less chance of uneven distribution.

I'm curious why you decided to place the U so low?  Looks like it would be submerged in the wort, and maybe I'm being paranoid, but the idea of soldered joints being in the wort worries me a bit (don't want heavy metals getting into my brew).  Had you considered instead running the 1/2" tubing farther up, and doing the U above the wort-line?

I'm also curious having the two lines interleaved makes much difference?  The approach I was going to take was to have two concentric chillers, one at 10" diameter, and one at 8" (or maybe 9" and 7").  I was thinking of using copper wire to both keep it rigid, space out the coils, and keep the two concentric chillers equally spaced from each other.

Also, got any advice on learning how to solder copper?  You clearly did a great job, so any advice you can give would be super-helpful.

To answer your question about the direction of flow. Mine introduces the cold water at the top for both coils. I can't say if one way is better than another. My thinking was that the warmest wort is at the top so put the cool water there. Also, running the coils counter to each other might tend to transfer some heat from the 'warm' side of one coil to the 'cold' side of the other coil. If they run in parallel they are more likely to take the heat from the wort and not from each other...I think.

I think I wasn't clear.  I agree that having the flow start at the top of the coil, and the return straight up from the bottom makes the most sense.  I was more asking if I should have them go opposite directions radially, i.e. the inner one clockwise and the outer one counter-clockwise.  Think that would make any difference?

Thanks again for the response!

[apple]

I hadn't considered moving the joints up. That might be a good idea if you are concerned about it. I'll have to look next time I brew, but I think they are actually out of the wort for a 5.5 gallon batch. I would guess the most important thing is to use lead free solder.

I actually didn't do that great of a job soldering! There are some messy ones that took a few tries to get to seal up. You can mask a lot of sins by cleaning up the copper afterward with a scotch pad and some PBW to get the tarnish and gunk off.

I would guess there are some good YouTube videos or web pages that cover it. I'm certainly no expert. My quick tips would be:

• Make sure you clean the copper really well. I use a clean sanding scotch brite pad. Then alcohol to remove any oils.
• Use lots and lots of flux! I use water based paste and smear it well on each side of the joint before I put them together. Sometimes if I'm having trouble getting the solder to flow I will dab some more flux over the hot joint and let it sizzle.
• When you heat the joints heat the female end first. Move the flame around so you are heating all sides of the pipe relatively equally. By heating the female side first you will tend to pull the solder into the joint. If you don't do this you can get the pipe hot enough, but the female connector might not quite be up to temperature.
• I test the joint by touching the solder to the joint quickly to see if it melts. If it does you know you are hot enough.
• When this happens remove the flame and run the tip of the solder gently around the crack in the joint. The trick to making it look neat is to use just enough to fill the joint but not enough to run out.
• Some people take a wet rag and wipe the joint quickly to remove excess solder. If found that for most of my applications this just jostles the joint and can lead to failure.
• When you are done just leave the joint sit and cool. Don't touch or move it until the solder solidifies.

Of all those tips, getting the joint clean and using lots of flux are the most important. And if that doesn't work...use lots of flux! If the joint is contaminated the solder will not flow into the joint. It's the most frustrating part of the whole process for me. Did I mention you can't use enough flux? lol

[MadZack]

My quick tips would be:

Wow, thanks for all the deets!


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[Visor]

   I made a single coil chiller last spring, the inlet side is at the bottom of the coil - same principle as the secondary heat exchanger on a high efficiency furnace. If your cooling water enters in the hottest part of the wort and heats up as it passes through the coil, by the time you get your wort temp down to around 80 or 90 the water at the bottom of the coil is about the same temp as the surrounding liquid. The greater the temperature change, the faster the cooling. I tried it both ways just for giggles and it definitely cools faster, especially once I'm below 100, if the inlet is on the bottom.
   As for keeping the coils separated and stable, I used 12 gauge copper wire braided around the coils. That was a major pain in the butt, and left a bunch of sharp wire ends which love to poke holes in rubber gloves. If I were to make another one I'd use narrow strips of copper sheet, it would be faster, much easier, and leave you with a much cleaner end result.
   

[MadZack]

   I made a single coil chiller last spring, the inlet side is at the bottom of the coil - same principle as the secondary heat exchanger on a high efficiency furnace. If your cooling water enters in the hottest part of the wort and heats up as it passes through the coil, by the time you get your wort temp down to around 80 or 90 the water at the bottom of the coil is about the same temp as the surrounding liquid. The greater the temperature change, the faster the cooling. I tried it both ways just for giggles and it definitely cools faster, especially once I'm below 100, if the inlet is on the bottom.

Interesting!  So far, all the conventional wisdom I've read suggests that you start the inflow at the top of the coil, then connect outflow to the bottom.  But your logic is compelling.  Thanks!

[Visor]

It might pay to remember that conventional wisdom once knew that the world was flat and at the center of the universe.

[MadZack]

Someone pointed out to me that by cooling the wort near the surface first, you create convection, as the cooler wort travels downwards and warmer travels up, only to be met by the upper coils of the chiller, and that overall that helps to cool it faster.  This makes a lot of sense to me...

Still, as we all know, the difference between theory and practice is that there is a difference...    And fortunately it is easy to try it both ways, and see for myself.


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