Friday, November 18, 2011

DIY Counterflow Chiller

After years of being somewhat satisfied with my immersion chiller, I decided to move up to a  counterflow wort chiller. As you probably know, counterflow chillers get their name because the cooling stream of water is flowing counter (in the opposite direction) to the hot wort. According to John Palmer, "Counterflow chillers use more water to cool a smaller volume of wort faster than an immersion chiller so you get a better cold break and clearer beer."

I built my counterflow chiller out an old garden-hose, some flexible 3/8″copper tubing and various odds and ends. I already had the hose, the pipe and some of the fittings laying around. The major purchase for me was the 3/8″copper tubing. If you have a copper immersion chiller you could scavenge the tubing to convert it into a counterflow. You're going to find most of the other parts and supplies you need on the plumbing aisle.

NOTE: I used 1/2" copper pipe and fittings. You could substitute  1/2"PVC and it would work just as well. It's cheaper and you won't need to solder anything.

25' garden hose
25' of 3/8" ″OD copper tubing.
1' of 1/2" copper pipe
2ea. 1/2" copper tee fittings.
2ea. 1/2" copper female
2ea. Brass compression fittings for 3/8" copper tubing
4ea. Hose Clamps
Teflon tape
Tie Wraps (AKA Zip Ties)

Fine Sandpaper
Hacksaw or Tube cutter
Propane Torch
3/8" Drill Bit

I started by building the two end assemblies. Cut six pieces of 1/2" copper pipe about 1 1/2" long using a hacksaw or tube cutter. The pieces can be a bit longer or shorter, you don't need to be precise. Use the sandpaper to 'shine' the inside of the fittings and the outside of the pipe sections. Home Depot will be happy to sell you special little tools to do this, and they're not expensive. After you've shined the surfaces to remove oxidation, apply flux and sweat (solder) the joints.

End Assemblies

The copper compression fittings are the standard pieces you may have under your sink. When they're used in your house, the 3/8" tubing goes only part way into the fitting. We're going to want the tubing to go all the way through, so we need to use the 3/8" drill to remove the internal stop. Please, DO USE a vise to hold these little parts while you're drilling. Things can get rather unpleasant when your holding small parts with pliers if the drill bit binds.

Drilled out on the left, original on the right.

Cut the last several inches off both ends of the garden hose. The flexible 3/8″copper tubing is probably in a coil. Straighten it out as much as possible and shove it inside the garden hose. Slide one of the hose clamps over each end of the hose, then slide one assembly over each end 3/8″tubing until you can shove an inch of the copper pipe from that assembly inside the hose. Secure with a hose clamp, and tighten the compression fitting around the 3/8″copper tubing. Wrap the whole thing around something round. I used a Corny Keg. Tie-wrap the layers together to prevent your wort chiller from acting like a Slinky when you lift it. Slide one of the hose clamps over each of the little end pieces of the hose, jam the hose over the copper pipe coming from the sides of the two copper tees, and secure the hose clamps. You're done!

When your wort chiller is complete, connect it to your garden hose, and slide 3/8″ ID flexible tubing over the 3/8″ copper tubing tubing in a line between your boil and your fermenter. Hook it up so that the assembly that has the outgoing wort is on the same end as incoming cold water.

I added a thermometer to mine so I could monitor the outgoing wort temperature. I had to add a bunch of brass compression fittings on the end to make that work. Normally, the cool wort would come out where the thermometer is, rather than out of a tee'd connection.


  1. I am going to make one of these this week. I know where to get 20ft length of copper tubing but not 25ft, does it matter?

    For a chiller this length, can I use gravity to feed the wort through?

    I have seen other designs that have a copper wire around the outside of the copper tubing to breakup the flow of water and increase the cooling of the wort. Is this useful?

    1. I'm really crappy at following up on comments. Sorry about that.

      RE Length: Yes, gravity feed should work for you, it works for me.

      RE Wire: It should increase the turbulence in the water which should make the cooler somewhat more efficient. It may also promote more even spacing between the tube and the hose, which may also help.

  2. Hey, are you Bob the builder? You definitely know your way around things. Is it okay if I use brass pipes and fittings instead of copper? I learned that combining different elements can cause chemical reactions. One more thing, what type of thermometer did you use: digital or mercury laboratory? Well, for what it’s worth, I think the brass compression fittings will work nicely to prevent leaks or unwanted air passage.Gayle Manning

    1. As far as I know, brass fittings would be just fine for you, the brass compression fittings I'm using work just fine for me. I don't see brass pipes being malleable enough to bend into the shape you want, so I'm not clear on how you might use brass pipes for this.

      I used a digital thermometer, but analog should work just fine.

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