I'm going to make an assumption that since you are here reading about a wort chiller you are involved in, or know something about home brewing of beer. So I'm not going to go into any detail about actually brewing beer, and instead I'm just going to focus on the the process of chilling wort. If that does not make any sense to you you should probably read some instructables on brewing beer before you read this instructable.
Anyone who has home brewed beer before will know that a wort chiller is pretty handy. The common wort chiller is basically made of a bunch of loops of copper tubing that is suspended in the wort. Then cold water is run through the copper tubing which in turn cools the wort making it ready to put in the final fermentation bucket and pitch the yeast right away. If you don't have a wort chiller you generally need to let the wort cool overnight before it is at a safe temperature to pitch the yeast. This instructable shows how to make a common wort chiller:
I have never been a fan of this type of cooler. First you either need sanitize the chiller very well, or put it in the wort during the boil to sanitize it. So you either need to work around the chiller during the boil, or add a sanitizing step to the brewing process. Either way you are making more work for yourself and potentially adding another way to introduce a contamination into the wort. Additionally, when all is said and done you need to clean the wort chiller which is more work.
Another downside is the cost - copper tubing is not cheep. Copper tubing at the local big box store runs about $1 or more per foot. The 15-20 meters of tubing suggested in the instructable above would run you about $50 alone, and that does not include all the suggested fittings. Lets just say it it costs more than the free wort chiller I'm about to present.
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Step 1: Items You Will Need
To make this wort chiller you are going to need a sink and faucet with a side sprayer. Most older kitchens like mine come with this type of faucet. If you don't have a side sprayer you may have to get creative to make this wort chilling method work for you.
You will also need a brew kettle and a plastic bucket. The brew kettle needs to fit into the plastic bucket, and must have handles large enough that it can not fall completely into the plastic bucket. Ideally the plastic bucket should only be about 1" larger in diameter than the brew kettle. It just so happens that my bottling bucket is just the right size to hold my brew kettle. If you don't have a bucket that fits your brew kettle, you will either need to find a bucket that fits, or buy a new brew kettle that fits a bucket you have. In this case I'm afraid your wort chiller won't be free, but it should still be cheaper than a traditional chiller, and you will still get all the benefits this wort chiller has to offer!
Step 2: Wort Chiller Setup
First pull out your sprayer hose all the way. Then unscrew the sprayer head from the hose. Next put the hose as far into the bucket as it can go. Now use a twist tie or zip tie to attach the hose to the bucket handle so that the hose won't fall out during the chilling process. You could drill a small hole in the top of the bucket to attach the hose if your bucket doesn't have a handle.
VERY IMPORTANT: water is going to spill out of the top of the bucket so make sure the hose exits well above the rim of the bucket. If not water could follow the hose back and flood the area under your sink.
Fill the bucket about 3/4 full of cool water.
Step 3: Let's Chill!
Once your boil is done carry your brew kettle over to the sink and slowly place it into the bucket until the handles rest on the top of the bucket. If you filled the bucket 3/4 full as described earlier, water will spill out over the top of the bucket as you put the pot all the way in. Now turn on the faucet and let the water pour out over the top of the bucket. The goal is to get water flowing out evenly around the top of the bucket. You can usually get this to happen by slowly nudging the bucket around in the sink. If water only flows out on one side you will not be cooling the wart as fast as you could be.
Once you have the water flowing out evenly around the bucket, adjust the flow rate until the water is just warm to the touch as it pours out . If the water feels hot then the flow is too slow and you are not cooling the wart as fast as you could. If the water is cold, then the water is exiting faster than it can cool and you are basically throwing water away.
I usually leave the brew kettle top on during the chill to minimize the possibility of introducing a contaminant. I do take the top off occasionally and give the wort a quick stir as that helps the cooling process. Be sure to have a sanitized place to put the spoon between stirring though.
Using this method I can chill the wart down to about 100F in about 15 minutes. Once you pour the wort into the final fermentation container and add a couple gallons of cool filtered water, the wort combination will be at about 80F, which is fine for pitching the yeast.
Step 4: Results and Comparison to Traditional Wort Chiller
When it comes to immersion cooling it's all about surface area. In the case of my brew kettle cooling system, it is how much kettle area is in contact with the water in the bucket. The kettle I use is about 10" in diameter and the handles are about 8" up from the bottom. So the total surface area is:
Total Area Kettle = side area + bottom area = 8" * 10" * pi + pi * (5")^2 = 330 sq inches
So how much copper tubing does this equate to? For 3/8" diameter pipe we have:
Length 3/8" tubing = 330 sq inches / (3/8" * pi) = 280" or about 23 feet or 7 meters
This is about 1/2 the total area of most immersion chillers. So a good estimate is that it will take about twice as long using the kettle chilling method over the pipe immersion method.
Admittedly I'm simplifying things quite a bit. I'm sure whole college thesis's could be done on pipe vs plastic bucket efficiency, but I'm an engineer so a first order approximation is good enough for me. Using the kettle chilling method I can chill the wort in about 15 minutes. How much faster is a copper tubing chiller going to be? Maybe 5-10 minutes? Anything faster than that and you are using too much pipe! Even if the copper tubing chiller saves 10 minutes of chill time, when you are done you still need to clean the copper tubing. To me that is worth waiting an extra 10 minutes for the wart to chill.
Also as I pointed out earlier, the introduction of an immersion chiller into your wort brings with it the possibility of introducing contamination. The kettle chill method presented here introduces nothing to wort that you would not have to add already.
So hopefully I've presented a good case for using the kettle chill method, but what ever method you decide to use remember the immortal words of Charlie Papazian, "Relax and have a homebrew."