Hello,
I switched to a 10 gallon pot a while back for my 5-6 gallon batches. I had a 20 foot immersion chiller that I haven’t even bothered to use with the new pot. Currently, I let the wort sit over night to get down to temperature (no issues yet). However, I’d like to get to pitching more quickly and I’ve had a 50 foot coil of 1/2 inch copper refrigerator tubing for a while now.
My question: Is it better to make just one coil, or should I make an inner and outer coil? For example, input water goes down inner coil and comes back up outer coil to exit? Basically, I’d like to know if you all think there is a cooling advantage in an inner and outer coil?
I do believe it will help if you have your cold water start from the top and down. Then, straight up to discharge. At least, it makes sense to me, since most of the heat would be at the top op the wort. That’s how I coiled mine, anyways. :-\
That what I was thinking, but there are plenty of people that do it the fancy way and before I got all bendy I wanted to check here (i.e. I am not a thermodynamics expert). It will be much easier to keep it one coil. I was planning on the ‘top down’ approach due its ubiquity among homebrewers.
Check out the JZ (Jamil Zainasheff) chiller design if you have a pump in your brewing ensemble… There’s a couple of Youtube videos about the chilling efficiency you can get from combining a whirlpool with the chiller.
I used 50 ft of copper tubing wrapped around a corny keg to make my IC.
I typically brew 10 gallon batches in a 20 gallon SS kettle.
The top of my coil tends to stick above the wort (no big deal) by an inch or so.
Regardless, it still chills 10+ gallons in under 15 minutes to ambient temps.
If I had wanted more of my copper tubing immersed in the wort, I could have used a cylinder with a larger diameter (e.g., a 5 gallon Homer bucket). However, when I was contemplating my design options, I was thinking that, long-term, I might like to use this IC as my “pre-chiller” and be able to place it inside a bucket or cooler of ice water–hence the tighter coil.
I made a handle out of PVC pipe, wooden dowel fillers, and black electrical tape to avoid burns. It makes manipulating the IC (i.e., whirlpooling) and lifting it out effortless and safe.
No regrets.
Having an inner and outer coil vs. a single coil makes no difference if the coil is totally submerged either way and the wort is not agitated (i.e. no stirring or whirlpooling). If you do stir or whirlpool, then the coil that’s in the slow moving wort in a double coil system will only chill about 60% as well as the other, though perhaps you could whirlpool by introducing wort in between the inner and outer coil and keep both coils performing as well as a single coil. What I mean is that if you agitate by, say, stirring with a spoon inside the inner coil, then the outer coil will not perform as well as the inner coil. The opposite happens if you whirlpool and introduce the circulating wort outside the outer coil. All this as opposed to a single coil that’s as long as the inner and outer coil combined.
I made mine using 50’ of 1/4 inch od copper tube and made it a double coil cooling from the bottom up. Spaced the coils about 3/4 inch apart form the inner and outer coil sets with a stagger of about half an inch between each loop set as it comes up. Silver soldered a piece of tube between them to hold them apart and to keep spacing from deforming as it comes up. 1/4" tube has a thinner wall than the normal 3/8" I have seen a lot of people using so there is a better heat transfer. The spacing helps make for a larger cooling surface as compared to a traditional setup as the cooling threshold ( don’t know the tech term) over laps each other and in effect covers more volume. I can take 6 gallons of wort at boiling and drop it to 70 degrees in about 15 minuets with just tap water at 52 degrees. I plan to add a secondary coil in an ice bath to lower my water temp even farther later down the road but for now it is working fantastic. You can almost watch the cold brake drop out of suspension as it cools.
I don’t know if this is typical, but the 1/4" tubing I have is the same thickness as the 3/8" tubing I use in my chillers. In any case, the heat transfer you gain from any change in thickness between 1/4" and 3/8" will be wiped out and then some due to the lower coolant flow rate and lower heat transfer coefficient of a 1/4" v. a 3/8" coil. But do what works for you, of course.
I doubt there’s any measureable effect, unless your’re using a REALLY slow coolant flow rate, but if there is, you would want the coolant to enter at the bottom and leave at the top. You may get some counterflow effect that way. That’s how my coil is arranged, though again, I doubt it makes any appreciable difference.
I went with a double coil (plastic bucket - outer & coffee can - inner) primarily so it would be totally submerged in the pot, especially if I made a 5 gallon batch which I do once in a while. Not sayin’ it’s perfect but it gets the job done. Here are a couple pics. Cheers!!!
there will be some but still little temperature stratification in the kettle. and simply lifting and placing the chiller up and down a few times during cooling or giving the wort a stir will eliminate this further. the faster the flow rate in the chiller, the colder the inlet water, and the more the chiller surface area will make the biggest impacts
[quote]I don’t know if this is typical, but the 1/4" tubing I have is the same thickness as the 3/8" tubing I use in my chillers. In any case, the heat transfer you gain from any change in thickness between 1/4" and 3/8" will be wiped out and then some due to the lower coolant flow rate and lower heat transfer coefficient of a 1/4" v. a 3/8" coil. But do what works for you, of course.
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I’m not sure if it’s typical or not, it just may be a cheaper brand of tube but I have a piece of 3/8 and 1/2 I used for my manifold and wall thickness is defiantly thinner on the 1/4 inch. I don’t see what it would matter if the cooling started from the top or the bottom other than the fact that cooler liquid will sink to the bottom but I don’t think the brew pot is big enough for that to happen. I just went that way because everything I looked at the inlet water went to the bottom first so that’s how I set it up. It’s basically a single coil I just staggered the loops in and out form the bottom up to increase the coverage. The small size was based more on price rather than efficiency but it works very well. 50’ of 3/4 or 1/2 was about three times as much as the 1/4 at the time. After getting a fridge for lagering it kept the wife happy. ;D
Two separate coils in parallel are much superior to two coils in series or to a single coil as you can run a faster flowrate of cooling water. To maximize natural convection which speeds up chilling and reduces need for mixing do the following: 1. Have water come in at top of coil is better. 2. The coils should stick out above the top of the wort. 3. Have more coils at the top than in the bottom. 4. The coils should occupy as much of the kettle as possible (2 overlapping coils that occupy nearly the diameter of the kettle works well). The above recommendations may not be best for whirlpooling.
For number 1, while heat stratification is very real (try touching the top half and bottom half of your kettle while chilling, there’s a HUGE difference, with mine anyway), I doubt that the direction of flow will matter at decent flow rates, and Denny has tried it both ways ( ;D) with no apparent difference. But if you run your coolant so slow that flow direction does makes a difference, then if you run from the top, you’ll actually be doing some heat redistribution, rather than just heat removal. Imagine a partially chilled kettle, still 100F at the top of the coil and say 70F at the bottom of the coil. The coolant enters from the top and, let’s say half way down the coil, has reached 80F, say at the same level in the kettle where the wort is 80F. For the remaining length of the coil, as the coolant continues lower, it will be warmer than the wort and will actually add heat back to the wort until the coolant exits the coil. If the coolant enters from the bottom, it has the opportunity to cool over the whole length of the coil.
For number 2, I’m just confused. Coils outside the wort won’t do anything useful…
I am happy that the post generated discussion. I just went with the simple single coil option. I the immersion chiller from my previous 5 gallon boil setup that I plan on using as a pre-chiller.
Interesting. I’ve only tried it my way. I guess I was just assuming that heat rises, so the majority of the heat would find it’s way to the top of the wort. But, based on what you said, I got to thinking about it. Perhaps because the thick bottoms of the kettle hold so much heat, there is a constant heaating of the wort at the bottom. Then again, I was just making an educated guess based on what I know about air flow. Knowledge is a dangerous thing! ;D
