When brewing beer, its critical to quickly cool your brew before adding yeast to minimize the chance of infection.  Today we look at the advantages of rapidly cooling your wort after boiling, and also how to build a simple immersion chiller using copper tubing purchased from your local hardware store.

Rapidly cooling your wort after boiling can significantly improve your finished beer’s clarity and flavor.

Some of the advantages include:

• Reducing the chance of infection – your wort is vulnerable to bacterial infection when it is warm and has no yeast added. You want to minimize the chance of infection by cooling rapidly and pitching the yeast as soon as practical.
• Improved clarity – When you rapidly cool hot wort, many of the heavy proteins and tannins will no longer be soluble and will fall out of the wort. Siphoning the wort off of this “cold break” will result in a improved clarity and improve taste as well.
• Reduction of volatile compounds – Dimethyl Sulfide (DMS) which gives beer a strong “”sweet corn” flavor can continue to break down after boiling and may be carried forward into the finished beer unless you rapidly cool the beer (Ref: Brewers Handbook by Goldhammer).

Quickly cooling 5-10 gallons of boiling hot wort does present some problems for the home brewer.  Ideally you would like to reach fermentation temperature as quickly as possible, though something in the 10-20 minute range is acceptable.  Commercial brewers use elaborate two-stage heat exchangers with a glycol coolant to achieve the final fermentation temperature.

Home brewers often choose something a bit less elaborate.  Some popular wort cooling systems include:

Ice Bath

Often beginners immerse their entire boiling pot into a tub full of ice water.  This can be an effective method, but it typically takes longer than the methods listed below, since heat can only be transferred through the hot pot itself.

Immersion Chillers

The simplest solution for most homebrewers, an immersion chiller (pictured above) is a coil of 30-50 feet of copper tubing that is immersed in the hot wort in the pot.  The tubing is connected to a sink or garden hose and cool water is continuously run through the chiller to cool the wort.  Since 50 feet of copper tubing has a large surface area, 5-10 gallons of wort can be chilled rapidly using this method.

Immersion chillers may also include a second stage, consisting of an additional coil before the main coil that is immersed in a ice water bath to lower the temperature of the water as it goes into the wort.  A two stage immersion chiller cools even more quickly and helps in cases where the tap water going into the chiller might be at or near the desired fermentation temperature.

Immersion chillers are also very easy to make, as described below, and also easy to clean since the outside of the coil simply needs to be wiped down and washed after use.

Counter-flow Chillers

A counter-flow chiller is a coil that contains two tubes of different diameters, one placed inside of the other.  Cold water is pumped through the outer tube while the wort is siphoned or pumped in the opposite direction in the inner tube.   Counter-flow chillers are extremely efficient and can cool wort very quickly.

The only downside for homebrewers is that they can be more difficult to clean and sterilize.  As soon as you finish using a counter-flow chiller, you need to flush it rapidly with hot water and run cleaning fluid through it.  Also it is a bit harder to construct a counter-flow chiller at home.

Building an Immersion Chiller

An immersion chiller (shown in the picture above) is simple for the average brewer to construct and maintain.  The basic materials can be bought at the local hardware store and assembled in about 30 minutes.

Materials Needed:

• 50 feet of 3/8″ outer diameter copper tubing
• 20 feet of 3/8″ inner diameter plastic tubing
• 4-6 3/8″ hose clamps
• Garden hose adapter (female)
• Compression fittings/adapters to mate garden hose adapter to the 3/8″ copper tubing

Start by making a large diameter coil from the copper tubing.  Make the coil small enough to fit in your boil pot.  The best way to form the coil is to wrap the tubing around a large coffee can, bottom of a corney keg, or other large cylinder.

Leave both ends of the copper tubing sticking up above the height of your pot, and bend them 90 degrees so they extend horizontally over the edges.  On one end, attach the fittings to the garden hose adapter, and to the other attach your plastic hose with clamps.  Attach the garden hose and run water through it to check for leaks.

For a two stage cooler, attach a second smaller coil to one end and place the garden hose fitting on it.  Join the two coils with a length of plastic tubing.  When operating, place the first coil into a cold bath of ice water and the second into your wort.  This will cool the water going into the wort, making your system more efficient.

I hope you enjoyed this week’s article on wort chilling.  Thank you for joining us on the BeerSmith Home Brewing Blog.  Subscribe for weekly delivery or visit our BrewPoll news site to see other brewing and beer news.  Have a great brewing week!

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