Cool your wort when the weather is HOT!

I recently put together a DIY counterflow wort chiller, and I was just about to put my 50’ immersion chiller up for sale, but…

Then I stepped outside and remembered how HOT it gets in North Carolina in the summertime!  And when it gets hot, my tap water just doesn’t get cold enough to cool my wort to pitching temperatures.  What’s a home brewer to do when he wants to chill his beer to below 70 degrees, but the water in the counterflow (or immersion) chiller is a stifling 80 degrees!?

I realized the answer to my problems would be to create a pre-chiller.

What is a Pre-Chiller?

A Pre-chiller allows you to cool down your cooling water before it enters your chiller (immersion, counterflow, or plate).  This can be done several different ways.  Here are a few examples that I have found:

1) Copper coil in an ice chest:


Image from

The easiest way to cool off that tap water is to first run it through a copper coil that is submerged in ice water.  This is basically the opposite of an immersion chiller.  Well…it IS an immersion chiller really!

Just create a coil as you would for an immersion chiller (though it doesn’t have to be as long, since you don’t need to cool it as many degrees as you do your wort), and then connect one end to your garden hose, and the other end leading to your wort chiller water input.  Then just put it in a bucket of ice water.  This should lower your tap water by a noticeable amount.



2) Recirculating using a submersible aquarium pump.

Another easy method that can be even more affective would be to first begin cooling your beer as normal, until it gets down to about 100-120 degrees.  You should be able to do this fairly easily with your normal tap water no matter how warm it is.

While that is cooling, fill a bucket with ice water (adding rock salt will make it even colder!).  You will then drop in a submersible aquarium pump and hook this up to your chiller. By doing this, you can send near freezing (or below freezing, if you use rock salt) water straight through your chiller.  This will help you cool your wort down from 120 to pitching temperature in a snap.

Though it does require purchasing and hooking up a submersible pump, it is not really any more difficult than option #1, and it can definitely send colder water through your chiller.

There is some good info on the various methods listed above (as well as some others) on HomeBrewtalk, so if you are interested in building one of these check it out!

I plan on using my old immersion chiller and using method #1 above, since this tap water is getting pretty warm here in Chapel Hill in August!  I’ll be sure to post some pics and let you know how it works once we get it built and running!

If anyone is currently using a pre-chiller, let me know which method you are using and how it works?  Are you noticing a dramatic difference in the amount of time it takes to chill your beer?


Jason Austin

Would you worry at all about using the rock salt with the immersion pump with regards to corrosion of the inner workings of the pump? Mine specifically says only use water, although I had thought about the rock salt route before…


I know several people who do this successfully. I think the biggest thing is going to be to make sure that you clean it well after every use. Since you’re already cleaning all of your brewing equipment anyway, it shouldn’t be too big of a deal to run some cleaner and sanitizer through it, but it is going to be one more thing to do.

If it worries you though, ice water works really well. The rock salt can make for colder ice water, but probably isn’t giving you a TON more temperature differential. So stick to ice water and you don’t have to be as careful about cleaning it after every use and it probably isn’t adding more than a few minutes to your overall chilling time.

In other words – relax, don’t worry, have a homebrew, and do whatever works for you!

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