Building a Counterflow Wort Chiller

If you don’t have plumbing skills, or experience with fluid mechanics this project can seem a bit daunting. Rest assured if you are methodical and confident this is not so hard.
A Counterflow chiller was described to me in relation to an immersion chiller as the difference between a Ducati and a bicycle. I have never used the immersion chiller, so I don’t know, but the logic is sound.

What we are doing is rapidly going through cold break, which can be a pivotal time in a worts life for infection and chemical reasons. The biggest difference is surface area. Immersion chillers run a small surface area of cold tubing in a large amount of hot liquid. So heat transfer is slower. A counter flow is the opposite, large surface area of cold on a small amount of hot liquid. Cold break in seconds.

So here is how I built mine and you need some stuff:

1. 20′ copper tubing the kind you use to hook up a refrigerator water line. I got 3/8th ID. mainly because it works best with the reducer coupling.

2. A 25 foot garden hose 5/8ths diameter.

3. Two 1/2″ copper T’s

4. 2′ of 1/2″ copper pipe

5. Two 1/2″ to 3/8″ copper reducer

6. A ton of large zip ties

7. 4 tube clamps

8. A 3/8th dual barbed ball valve (this regulates wort flow)

9. Garden hose on off valve
I soldiered mine, so for tools, torch, flux, soldier, (kits have all you need) sharp utility knife, drill, 3/8 th drill bit, pipe cutter, channel lock pliers, and a ton of dish soap (washing up liquid).

Here is the step by step.

Cut the ends off the garden hose, leaving about 10″ of hose attached to each. Keep these. Check the inside of the hose, be sure it is smooth. My first hose had a thin rubber bead in the inside, I could not push the copper in, so I had to buy a new hose. Lay the garden hose in the sun using weights to straighten it. Also straighten the copper pipe carefully not to kink it.

Next cut the copper pipe I made 2 @ 4 inch and 4 @ 6 inch.

Using the drill and bit, drill the stop out of the 3/8 reducing collar. What this means is there is a small ring of metal in the collar to stop a 3/8 pipe from sliding in freely. It stops the pipe. We want our copper tube to slide right through so the stop needs to be removed. I just slid the collar up and down the drill bit holding with channel locks in a very mechanically erotic way. Check and make sure the copper tube freely slides through the collar. If your tube is not perfectly round then cut a inch or so off until it is.

Building the T is pretty simple, if you understand the mechanics. The top of the T is where the copper tube will pass, on the right the long hose will attach. The bottom of the T is where the water will flow in and out. 4″ on the copper tube in or out side, 6″ on the other two where one is the bottom of the T.

Assemble, ensuring the reducer is on the 4″ end, and the 4″ pipe is on the Top of the T, flux, soldier, wipe away excess gunk. If you don’t have soldier experience it is very easy, just watch a YouTube video. If you accidentally get soldier in the reducer like I did, more drill-sterbation, clean it out.

With T’s built the grunt work begins. Using a remarkable amount of soap, and water, and a friend, feed the copper tube into the hose. I wore some ruberized gloves I had, just for grip. This is not easy work, the outer dimension (OD) of the copper is close to the inner dimension (ID) of the hose. It’s a lot of wriggling, forcing and in Tampa, sweating. Eventually you will have a tube in a tube.

Make sure about 12″ of copper tube stick out the end, and cut the garden hose on  other endso about 12″ stick out as well.  Pull the un used hose off.  You can obviously pre cut as well, I didn’t might have made it easier.

Next is the cool part. Get a bucket (Home Depot or brewing bucket without a spigot) and gently coil the hose around the bucket, taking care to not kink it, not bend the copper that protrudes from the end, and that there is a smooth gravity flow to the coil.

Zip band the coil, then zip band it more, finally zip band it between the zip bands.

Installing the T”s is pretty easy, slide a hose clamp on the garden hose, then slide the T on, and force the 1/2″ pipe inside the hose as far as you can. Pipe clamp it. Repeat on the other side.

Flux inside the collar, and soldier it onto the copper tube, both sides of the chiller.

Now grab those hose ends, it is a Counterflow, keep this in mind, hot wort in the top, cold water in the bottom. Put the water “in” end (the one you would screw into a spigot) on the lowest T, water out on the highest T. Stuff the copper pipe into the hose ends and pipe clamp.

Screw the garden hose shut off on the “in” side.

You are done, except for quality control. Hook it up to a hose and see if it leaks if it does, then crap, you have to resoldier. But I’m sure you did it right. There is a liquid welding compound you can use called “JB WELD” I think. If you have confidence with that, it just needs a day to dry. Pick one or the other, can’t fix bad soldier with JB Weld as far as I know.

Now to use the Ducati of chillers, use gravity from your Boil Kettle, attach a hot line to the top copper tube and the kettle ball valve. Attach a 4″ tube to the bottom copper tube where wort will flow out and feed it into the brass barbed 3/8 ball valve, and attach a final line to the fermenter. Fill the chiller with hot wort, boil kettle valve full open, turn the water hose on, and gently open the brass ball valve and what flows out is cold wort. Adjust the brass valve to the optimum flow for cold wort. All of my wort lines are pipe clamped.
I sanitize my chiller with boiling water, during the wort boil, I boil the remaining water in the liquor tank. Running about a quart of 212 F water through, then I close the brass valve at the bottom to hold it full of water. Simply then clamp off the top with a small clamp pull it from the tank. When I’m ready to chill, I drain, run a small amount of sanitizer through it, then fill with boiling wort, closing it in with the brass flow valve. Clean up is the same process.

Good luck, and stay cool you crazy cats.


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