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I am thinking on buying an immersion chiller and from other threads I've thought of using the post-chiller hot water for cleanup, and I've also heard of using the water (after it starts to cool down) to water the garden.

How much water does a wort chiller use to cool a 5 gallon batch of beer down to pitch temp? Does any one kind use significantly more/less than the others?

EDIT

Sorry, I worded the question poorly. I started this question thinking about immersion chillers only, but as I was typing I wanted to open it up to other chiller types. Based on the answers by Brewchez and Room3, I'm figuring that an immersion chiller takes somewhere around 50 gallons to bring a batch to pitch temp.

What is the approximate water use of Counterflow, Plate, and Whirlpool chillers?

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From the title I was hoping this would be a tongue twister... –  C4H5As Jul 22 '11 at 13:29
    
Our immersion chiller recycles ice water because it uses a pump and not just the faucet. You could go that route and you would only be using about 4 gallons of water probably. We keep some ice stocked and throw the ice in there to cool the water back down to freezing. Works like a charm but you have to put in a small amount of cost up front for the pump. –  Joe Philllips Jul 27 '11 at 15:56
    
Drop a cheap 12 volt bilge pump in a cooler with fed with hose water at the start thru to your cleaning bin. Then switch to recirculating with ice at the end. This will save a lot of water. –  Dale Mar 17 '12 at 12:54
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6 Answers

up vote 10 down vote accepted

First off, you're going to want to figure out the immersion chiller's flow rate. Depending on your water pressure, tube length, and tube diameter, I think it could range anywhere from 1 gallon a minute to 10 gallons a minute.

You can approximate it's output by timing how long it takes you to fill your carboy with a garden hose or sink, whichever applies to your chiller. Your gallons per minute = the size of your carboy (in gallons) divided by the elapsed time to fill it (in seconds), multiplied by 60, so:

(CarboySize/FillTime)*60 = GallonsPerMinute

Once you have this, you'll have to scale down to compensate for the area difference between the hose and the tubing. Remember area=Pi*radius^2? I always wondered when I'd put it to use :-)

Lets say you have a 5/8 inch hose, so the area would be:

Pi * (.625 / 2)^2 = ~.3068

Lets say you have a 3/8 inch, 25 ft chiller (this seems to be a popular one), so the area would be:

Pi * (.375 / 2)^2 = ~.1104

So I would guess it would have about a third of the throughput:

NewGallonsPerMinute = GallonsPerMinute / 3

So assuming your hose and chiller are the sizes indicated above and your hose can put out about 10 gallons per minute, your looking at about 3 gallons per minute for your chiller.

Your cool-down time will depend on whether you just sit the chiller in the pot or you agitate your wort a lot, as well as your cold water temperature and your copper coil surface area. But if you go by previous posts on this site it sounds like times of 20 minutes seem to be average, costing you about 60 gallons of water.

If you really want to you could apply Newton's law of cooling to calculate how fast it will cool. Basically the more surface area (the longer and wider your tubing), higher temperature difference, and faster water flow you have, the faster your wort will cool.

Note that temperature difference is only the temperature of the water and wort touching the tube walls, not the other wort sitting around, so a great deal depends on liquid turbulence. This isn't a big deal inside the tube, since the flowing water is very turbulent, but if you just sit your chiller in your wort and don't disturb it, you'll notice cold water coming out of your chiller while your wort remains hot.

As for which ones use less water than others, doubling your tube length doubles your surface area, but actually only gives you about a 50% increase in efficiency. That's because the surface area you gain by lengthening the tube doesn't have an affect at the beginning, but gradually increases efficiency as you chill. The temperature difference at the beginning is just too great for it to matter. Doubling the tube width, actually gives you better efficiency than lengthening, but that's do to the fact that you're increasing the flow rate as well as the surface area.

So if by efficiency you are referring to the speed you can chill, the more length and diameter, the better.

If you're wanting to save as much water as possible while also cooling quickly, go for a chiller with more length.

I've also seen chillers that have the coils all bound or soldered together. This won't be as efficient as an unbound chiller of the same length due to the decreased surface area.

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I deleted my answer cuz this one is WAY better –  hookedonwinter May 11 '10 at 14:58
    
I added your comment in about water temp, since I left that one out –  Room3 May 11 '10 at 15:00
    
But you don't run your chiller at full bore for most of the chill process. So while these calculations are accurate for calculating restriction and flow rate, its not the best use of an IC. The questions about different types and efficiency of cooling aren't addressed. I down voted. –  brewchez May 11 '10 at 15:59
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I never change the flow rate through my chiller...isn't the whole point to get it down as quickly as possible? The two factors in efficiency are temperature difference (the temperature of the water in and wort outside of the tube) and surface area of your tubing, both of which I mentioned. I could've thrown in Newton's law of cooling, but since there are a lot of people that can give good approximations on cooling time, I figured it was a little overkill. If you noticed, my method correctly predicts both volume outputs stated in your own answer. –  Room3 May 11 '10 at 16:49
    
Uhhmmm I was told there would be no math in this brewing hobbey? –  Graham Jul 23 '11 at 20:10
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My immersion chiller spends about 30-35 gallons of water to chill down a five gallon batch. But the volume of water depends on the efficiency of your chiller. I used to use a 3/8ths 25 foot immersion chiller and I used more water. Closer to 60-70gallons. Now I have a 1/2inch 50foot chiller and its more efficient, i.e. less water consumed.

So the amount of water produced for clean up is going to be related to efficiency of the chiller.

The useful temp of such water is another issue. The first 5-10 gallons is very hot water. And the water gets progressively cooler as you chill. If you collect all the water in a large tub eventually you'll be cooling the "wash water" with chill water.

So even though your chiller may produce 30-70 gallons of run out water. Not all of it will be "hot" enough for your cleaning (depending on your preference for temp of wash water right?).

I tend to put PBW into the bottom of a large party tub, run the hot water into it and stir it up occasionally. Then as the water cools I pay attention. When the water is still hot but cool enough to touch, I start running out the cooler water to the ground so as to not over chill the cleaning water.

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My Therminator plate chiller gets hooked up to a utility sink that runs 3 gallons per minute. It chills an entire 5 gallon batch down to pitching temperature in 3-4 minutes. So, 9-12 gallons. If I was very concerned about saving water, I think I could get that down by using the Thrumometer, which would allow me to use the minimum possible flow rate to get the temperature I need.

If you're concerned about water usage, a plate chiller or other counterflow chiller is the best way to go.

As a side note, if I wasn't a light sleeper, I would sleep with this thing under my pillow every night. I lurve it.

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+1 for the Therminator and Thrumometer combo - I love mine and get about the same chill rate - starting with 60°F water I chill 10 gallons of post-boil wort down to ~70° in less than 10 minutes using about 20-30 gallons of water which I retain in the sink for cleanup. –  Jim Denmark May 12 '10 at 18:31
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Just a note to mention that you'll get a much faster cooling rate if you keep both liquids in motion in opposite directions. You get this for free with a plate or counter flow chiller. For an immersion chiller, this requires moving the wort in the kettle in the opposite direction of the water flow thrugh the coil. You can do this either by stirring by hand, or by recirculating the wort with a pump. There are lots of advantages of this teqhnique - improved control of final wort temperature, more hop flavour/aroma and less DMS. Whirpooling with an IM chiller is described in detail at http://www.mrmalty.com/chiller.php

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I too use a pump to recirculate water through my immersion chiller... without that I would use about 50 gallons or more... I'm not really sure...

Once I added a pump and used ice water to recirculate, I dumped about 5-6 gallons (the first time you run it the water is extremely hot), and then closed the system... so I guess I use 5-6 gallons and about 30 pounds of ice.

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I never have the tap running at anything like full, and it normally takes around 30 to 40 minutes (depending on time of year, and therefore tap water temperature). It's a 10m coil of 10mm copper pipe, so that's about 32 feet of 3/8 inch pipe.

I've never measured the exact amount I use, but I'd be very surprised if it was more than 50 litres (around 13 US gallons). After filling a bucket for cleaning, I return the rest of the cooling water to my 200 litre waterbutt, and it never seems to go up by even a quarter.

I'm not aiming to get it chilled as quickly as possible, just quickly enough, and since we're on a water meter I'm quite conscious of the water I'm using.

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