Build your own counterflow chiller

Here's one I made earlier!

For a long time we used an immersion chiller for our homebrewing and that worked pretty well. However when we upgraded to a 56L kettle the chiller no longer neatly sat over the side of the kettle and into the wort. As such we needed to drop the immersion chiller into the wort on its side. And then there’s the stirring. That’s a pain too!

Furthermore we have been seriously contemplating a hop rocket and this needs to have hot wort go through it, and then for the wort to be chilled after which would be a pain using immersion.

Anyhow, flicking through the hallowed pages of John Palmer’s How to Brew I turned to the section on building your own counterflow chiller and set to work.

What is a counterflow chiller? With the more common immersion chiller the cold water pipe goes into the hot wort. With a counterflow the hot wort is run through a pipe which in turn is inside a pipe with cold water running through it. This has the massive advantage of having the cold water moving over the surface of the hot wort, thus cooling far more rapidly.

The first issue is that here in the UK we use ½” garden hose as standard and not ¾” as they do in America. So that took a bit of tracking down, eBay is your friend here. You could use a ½” hose, but the chilling effect would be seriously diminished (again refer to How to Brew).

Stuff you’ll need:

3/4" hose and 10mm copper pipe

• 10m of ¾” hose

• 10m of 10mm micro bore copper pipe

• 6 short lengths of 15mm copper pipe (no more than 4cm each)

• 2 x 15mm copper tees

• 2 x 15mm copper ends

• 2 x 15mm copper connectors

• 2 plastic 15mm to ½” hose adaptors

Plus: Various jubilee clips, PTFE tape, 10mm drill (which I didn’t have!), silicon sealer, gas torch, files, abrasive pads, solder, flux etc.

Step 1

Prepare the copper: This bit had me stumped for a while, but once I got me head around it things fell into place. You need to build two ends that allow the cooling water in and out around the 10mm wort pipe.

Firstly you need to drill a 10mm hole in the copper ends. Be careful to get this central, so use a punch to mark it and then drill a pilot hole with a smaller drill bit. This wants to be a nice tight fit around the 10mm pipe.

Two ends, one finshed and one yet to be assembled

Cut your short lengths of 15mm copper pipe, three for each tee and then get to soldering. You’ll see my handy work and already have worked out I’m not a plumber! But it works. The 2 x 15mm copper connectors are there to make the pipe closer in diameter to the ¾” hose.

Yes, my soldering is that bad

Step 2

Insert the copper pipe into the hose

Note I've already put the jubilee clips on!

You’ll want your ¾” hose slightly shorter than your 10mm pipe to leave circa 15-20cm of pipe extending from the hose. Tempting as it seems, with the both the pipe and hose coming in coils, you’ll need to make both as straight as possible, or you simply won’t get the copper pipe down the hose. A good squirt of washing up liquid helps here.

Once that’s done you’ll want to coil it back up and what easier way than use one of your empty cornies!

Step 3

Putting it all together

Do this first: put two jubilee clips over your ¾” hose – you don’t want to be doing that after the fact! Wrap plenty of PTFE around the part of the tee that’s going inside the ¾” hose (i.e. the 15mm copper connectors). Push the 10mm copper pipe through the tee you made and solder the part that is poking through to make it water tight.

Tighten the jubilee clips and apply some sealant so that your ¾” hose doesn’t leak. Add the two 15mm to ½” connectors ready to attach to your regular hose for cooling and your pretty much done.

NOTE: I’ve left the 10mm pipe as is because I’ll connect to my kettle with vinyl hose. You may want to add something more permanent and I may do in the future.