Illustration by Eric Diotte

How to Make a Wort Chiller

I like beer, plain and simple. I enjoy brewing it, reading about it and, of course, drinking it. The process of brewing beer has been around for thousands of years, and the science and history behind it incredibly fascinating. For those of you who are not familiar, you should still be able to enjoy the topic of this blog post. However, after this, you should head over to Wikipedia and do some reading.


In its simplest form, brewing will contain the following steps:


1. Steep your grain to extract your fermentable sugars.

2. Remove grain, bring the solution to a boil. This solution is known as wort.

3. Boil wort for 60 minutes, occasionally adding hops for flavors and aromas.

4. Remove from heat and cool to approximately 70-80°F.

5. Place the cooled wort into a sanitized fermentation container.

6. Add brewing yeast, known as pitching the yeast.

7. Place in a dark, preferably temp controlled, environment for 10-14 days.


After step 7, if the yeast have done their jobs correctly, the fermentable sugars obtained from the grain will have been turned into alcohol, and you will have beer. However, this beer is currently flat and probably room temperature. So, at this point, you can either place the beer into a keg and force carbonation with a tank of CO2 or place the beer into bottles with some additional sugar and let the yeast do the carbonation for you.


I wanted to take some time to talk about step 4, chilling the wort. Traditionally, this is done with something called an immersion wort chiller. This is a length of copper tubing which is coiled in such a way that it will fit into the pot with the hot wort with the two ends protruding outside the pot, so you can attach hoses for inlet and outlet water.

One end of the tube is connected to a water source, usually a hose in your backyard. The other end is connected to a free length of hose you use to guide the outlet water flow. As cold water flows through the chiller, it pulls heat from the hot wort and leaves the chiller at roughly the same temperature as the wort. You run this process until the wort has reached the desired temp, 70-80°F.  I have a crude drawing of what this looks like below. I couldn’t find any diagrams that I liked so you will have to settle for my hand drawn images. I hope you find them clear and cute, as opposed to confusing and sad.


This process works extremely well assuming you have plenty of water and/or a yard to water. Living in the California Bay Area, both of these things are coming at a premium these days. So I came up with a slightly different solution when I was living in an apartment in Mountain View. Instead of circulating hose water through the immersion chiller, I bought a submersible pump and a 5-gallon bucket to recirculate a reservoir of water. The problem with this is, if the reservoir reaches equilibrium with the wort before we get to our desired 80°F, it can’t cool the wort any further. I would offset this issue by buying large sacks of ice from the store before I would brew.


This solution worked well, however, this still seemed a bit wasteful to me. I figured there should be a solution within the spectrum of hose/yard on the speedy/wasteful end and “no chill brewing” on the slow/conservative end. “No chill brewing” is a thing I just discovered during research for this blog post, and I will leave subsequent reading to the reader (basically you leave the wort out to cool with nothing but ambient air).

So what I wanted to do was to take my pump and bucket+ice solution and modify it to use a small car radiator. As the outlet water leaves the immersion chiller, it is passed through a radiator before returning to the reservoir in the 5-gallon bucket.


Before actually purchasing a radiator, it was my original plan to calculate the amount of heat that needed to be removed from the wort.

So 6 Megajoules, it sounds like a lot, but I thought I would throw it into Wolfram Alpha to see what else has about that much energy. I found some interesting but not really relatable energy comparisons.

While I now know a boiling pot of water has enough energy to run my phone for 6 months, it is interesting to know that this is also equivalent to roughly 1400 kCal. That is 70% of the 2000 kCal recommended diet we all come to despise.

Now equipped with mildly interesting energy comparisons, I set out to actually build something and see how well it would work. I was able to locate a $20 transmission fluid cooler on Ebay.

The white bucket was used as the cold water reservoir, the sump pump was located inside.

A final picture of the setup in action can be found below. I quickly began to lose patience while rigging the whole thing up so the whole setup may seem a little hackish. However, I like to think it made me look like more of a mad scientist.

So did it work? The short answer is yes, I was able to get my wort down to my desired 80 degrees Fahrenheit. It took roughly 3 hours after removing the kettle from the heat to get the wort down to temp. From the pictures above, I think we can all agree that this solution leaves room for improvement. For my next batch, I would like to tackle the following:

  1. Channel more air flow through the radiator

  2. Collect temperature data over time of…

  1. Wort

  2. Coolant water (inlet and outlet)

  3. Air Flow (inlet and outlet)

I think I can gain a large improvement from the first item – anything would be an improvement over dangling the radiator over the fan. The data collection is mostly to satisfy my technical curiosity to see where the bottleneck in the process is. Hope to have some improvements for my next post.