Friday, 25 July 2014

Immersion Wort Chiller with DIY instructions

As I previously posted, I have started brewing beers using the Brew In A Bag (BIAB) technique. A key component of making beer is being able to cool the wort (unfermented beer) down quickly to get a "cold break" and reduce the risk of infection.

Initially I thought I would simply use an ice bath but when you end up having over 16 litres of liquid in a pot of 39cm diameter pot it is not the easiest to manoeuvre. There are a number of alternative options commonly used for cooling down wort with the two key ones for home-brewers being immersion chillers and counterflow chillers.

Counterflow chillers adopt a tube in a tube design where you flow the wort through a (usually copper) inner pipe while cold water flows through the outer pipe in the opposite direction. Whilst this is more effective than an immersion chiller, it was going to be more complex to get this working with my setup and it does come with higher sanitation requirements due to the wort travelling inside the tube.

Immersion chillers adopt a simpler approach whereby you flow cold water through a coiled (usually copper) pipe that is placed in the wort. I decided to go with this approach.

I looked around to buy a pre-made wort chiller, but in New Zealand there weren't too many available and those that were I thought were overpriced for the 15 metre length I decided I wanted. I therefore opted to make one myself.

Finding copper pipe turned out to be harder than I thought, but I ended up buying 15 metres of 9.52mm (3/8 inch) copper coil from TradeMe (New Zealand's equivalent of eBay). The seller offered to coil this into a diameter of my choosing to send it (which was great), and so I opted for a 25cm diameter since this was a good size for my 39cm pot.

I pretty much followed the instructions in this YouTube clip to bend the copper tube and attach the hose and fittings:

I bought two 2 metre lengths of garden hose, two hose clips for attaching the hose to the copper pipe and connectors to attach one of the hoses to another hose connected to the tap. The hose clips were just big enough for the hose and this proved challenging in terms of them initially slipping when trying to tighten them but I finally got there with perseverance and some pliers. In terms of the hose connectors there wasn't one connector that alone had a suitable attachment for connecting to the hose attached to the tap so I had to get two different ones (no biggie). I've also attached the cold water to the pipe that goes to the top coil. My chiller doesn't look as elegant as the one in the YouTube clip but it does the job.

When running water through the chiller you don't need the tap on full, in fact you need significantly less than that; I probably have about a half full pipe when I'm running it. As the water runs through I have the other hose sitting in the sink for the hot water run off. The temperature does reduce rapidly; my experiences so far:
  • First brew: 16.5 litres - 18 mins to get from boiling to 22 degrees Celsius
  • Second brew: 18 litres - 29 mins to get from boiling to 22 degrees Celsius (I did however note at one point that not much water was flowing through so had to turn it up)
When I did my first brew I found the wort chiller did leak quite a bit, but after tightening up the connectors some more prior to my second brew I got no leakage most of the time until I did increase the water flow significantly and then a little bit came out.

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