Stephen's Blog

I’ve been using a very small immersion chiller that was designed for stove-top 2.5 gallon batches. Since I’ve been doing 10-15 gallon batches, it’s needless to say that this was very ineffective. Initially I wanted to design acounterflow chiller (you’ll find no shortage of designs for these on your favorite search engine). However, a local homebrewer raised a good point which dissuaded me.

While a counterflow chiller may chill very effectively, it will only chill a small amount of wort at a time, leaving the rest unchilled. This becomes increasingly deficient as batch size increases. By contrast, an immersion chiller will cool the entire batch evenly.

I set off to the hardware store and ended up getting fifty feet of 5/8″ O.D. copper. I also grabbed a couple copper elbows, expecting that I’d take the opportunity to brush up on my soldering skills. I decided to make a coil diameter slightly larger than the conventional ~7″ made from utilizing a corney keg to wrap the coil around. I had a turkey fryer basket laying around which was suitable diameter and began wrapping the copper around it.

This turned out to be a mistake, as the basket was not tall enough and put up a real fight when I tried to compensate. I might also add that having a second helper is extremely advantageous; I would not recommend coiling such large diameter copper by oneself. In the end, I managed to induce a couple kinks that I couldn’t work with.

Not wanting to uncoil what I’d done, and optimizing around the kinked locations, I decided to cut the copper in half and join two separate coils. The second coil I wrapped around a corney keg and set inside the other coil. I returned to the hardware store for two more elbows and joined these together. At the other end, I used the other elbows to join the end pieces at a sharp angle. I fitted 5/8″ I.D. hose on top of these ends and secured with hose clamps. In one end, I inserted a 3/4″ garden hose to 5/8″ barb.

The result was not my most attractive work, but is very effective. In my most recent brew, I was able to watch the dial drop from boiling (211 F here in Texas) to about 120 in around ten minutes. The same temperature drop would have taken nearly an hour with my previous chiller.

I see two potential advantages to my design. First, the two series of coil may help distribute the surface area of the copper which comes in contact with the wort. Second, this relieves the need for a long vertical return piece from the bottom to the top. I recommend sticking with simpler designs though.