Wort chillers provide several advantages, including reducing haze by precipitating cold break proteins, saving time, pitching yeast into proper wort temperature for better fermentation, and reducing the chances of infection.

There are two common types of wort chillers among homebrewers — immersion and counterflow. I chose tubular counterflow design for the speed at which it can chill large volumes of wort, ease of cleanup, simple design, and ease of construction. Counterflow chillers work by passing a cooling fluid (water in our case) in one direction over a tube of wort flowing in the opposite direction. This requires two concentric tubes, where the water flows in the outer tube, and the wort flows in the inner tube. Factors that affect the efficiency of these types of heat exchangers are the thermal conductivity of the inner tube material, surface area of the tube (diameter x length), wort and coolant flow rate, surface texture/shape, and the temperature difference between the cooling fluid and the wort. For our application, the most significant of these factors is the temperature difference between the water and the wort, known as ΔT. The cooler your tap water is, the greater the ΔT and the more efficient your chiller will be. The material most commonly chosen for the inner tube is copper for its flexibility and high conductivity. The length of copper tube you need will depend on its diameter and the temperature of your tap water. Copper can also be used for the outer jacket material, as can silicone and rubber garden hose. I used rubber hose for this build for the sake of simplicity and economy.

This project outlines an easy-to-use basic counterflow chiller designed for gravity flow wort. Using 3⁄8-inch copper refrigerator tubing, 25 feet (7.6 m) should work well with water temperatures up to 65 °F (18 °C). I added an extension on the end of my chiller to accommodate a thermometer to monitor the output wort temperature in real time. Knowing this, I can make adjustments to the flow rate of the cooling water and wort in order to achieve the desired temperature. A ball valve on your kettle is the easiest way to control the flow rate of your wort, but any in-line valve can be used. Sanitizing the chiller is as easy as siphoning some boiling water or sanitizer through the chiller prior to the end of the boil. Flush the chiller with hot water in reverse direction from normal flow (also known as “backflush”) to clean it after each use. A periodic cleaning with alkaline cleaner is recommended.

MATERIALS
25 ft. (7.6 m) of 3⁄8-inch copper refrigeration tubing (1⁄4-inch ID)
(4) 1⁄2-inch ID x 3⁄8-inch ID copper reducers. (Often labeled as 1⁄2-inch x 1⁄4-inch reducers)
~2 ft. (0.6 m) of 1⁄2-inch copper pipe
25 ft. (7.6 m) 5⁄8-inch high-temp
rubber garden hose.
(3) 1⁄2-inch copper tees
Rubber stopper size #00
Probe thermometer
Stainless hose clamps
Zip ties

TOOLS
Pipe cutter
Drill
Soldering kit (propane torch, flux,
lead-free solder)
Sand paper or wire brush
Bench vise or clamp

1. Cut to length and Feed The copper pipe into the hose
Carefully uncoil and measure 25 feet (7.6 m) of the copper tubing. Try not to bend or kink the copper, since that could weaken the material. Use a pipe cutter to cut the copper tubing to length, and save about a 1.5-inch (4-cm) section for later. Cut about 6 inches (15 cm) off the ends of the rubber garden hose and save them for later. The ends will be used for the cooling water input and output fittings on the chiller. Once everything is cut to length, feed the copper tube into the rubber hose. This can be difficult, but pouring a little bit of water and dish soap into the rubber hose can help coax the tube through.

2. Coil your tubing
Next we’ll wrap the tubing around a cylindrical object to form a coil. A corny keg, 20 pound CO2 cylinder, or any firm object with a similar diameter works well. It’s unlikely that the copper tube will kink while wrapping it around your object as long as it’s soft copper. However, if you want to be extra cautious, you can fill it with water first. The water will not compress, assuring consistent internal pressure on the tube while you wrap it. To do this, crimp one end of the tube with a pair of pliers and fill it with water, then crimp the other end to seal the water in. Gently wrap the tubing around your cylinder into a coil, but leave the ends straight. Then cut the crimped sections off with a pipe cutter and drain the water out if you used any.

3. Solder tee fittings
Once your tubing is wrapped into a coil, set it aside while we put together the tee fittings that will fit on each end of the copper tubing. Take two of the copper tees and solder a 2-inch (5-cm) section of 1⁄2-inch copper pipe on each end. Test fit each fitting, then clean the surface of the copper, apply your flux, and solder the connections. Then solder a copper reducer on one of the straight ends (not the perpendicular end). Some reducers are made with an indent stop on the inside that will need to be removed with a round file or 3⁄8-inch drill bit so that we can later feed the 3⁄8-inch copper tubing through.

4. Install tee fittings
Slide the tee sections over the 3⁄8-inch tubing so the tubing feeds through the reducer. Make sure the tubing protrudes past the end of the reducer, and the rubber hose fits over the 1⁄2-inch pipe on the other end of the tee fitting. It’s a good idea to test fit everything and mark where the contact areas will be for soldering. Clean the copper tubing and inside of the reducer, then apply flux before feeding the tube through one last time. Next, solder the connection between the reducer and the inner copper tubing. Use stainless hose clamps to secure the rubber hose onto the copper pipe. Now take the ends of the hose with the garden hose fittings we cut off earlier and attach them to the perpendicular end of the tee fitting on the 1⁄2-inch copper pipe. Use the end with the female garden hose fitting on the wort output end of the coil, and the male garden hose fitting on the wort input end, and secure with stainless clamps.

5. Attach the thermometer
Next we’ll attach the thermometer section to the wort output end of the chiller. Take your remaining tee fitting and solder two-inch (5-cm) sections of 1⁄2-inch copper pipe to one of the straight ends and the perpendicular end. Leave the opposite straight end open; this is where the rubber stopper and thermometer probe will go. Solder on the remaining reducers to the 1⁄2-inch pipe on the tee. Now take the 1.5-inch (4-cm) section of 3⁄8-inch copper tubing from step one and solder it to the reducer on the straight end of the tee. This is where we’ll attach the vinyl or silicone tubing to fill the fermenter. Solder the reducer on the perpendicular end of the tee section onto the output tubing on the coil. Take your #00 rubber stopper and drill a hole slightly smaller than the diameter of your temperature probe through the middle so the probe slides into the hole snuggly. Push the stopper into the open end of the tee fitting.

6. Finishing touches
Tie the coil together with zip ties, clean up any residual flux, and cut or file any sharp edges. We want to make sure the inside tubing is very clean, since this is the material that will be in contact with our wort. To clean the inside of the tubing use several iterations of hot water, then alkaline cleaner, hot water again, then a vinegar solution, and repeat. When warm water flows through the chiller free of chemical aromas and debris you are done.

To use your new chiller, simply attach some 3⁄8-inch vinyl or silicone tubing to the copper tubing on each end of the chiller. The other end of your wort input tubing attaches to a 3⁄8-inch barb on your kettle valve (if equipped) and the wort output end goes into your fermenter. Then hook up your garden hose to the water input female fitting and attach a separate section of garden hose to the water output male fitting so that it drains into a sink, your yard, or any water safe area.