If you have just finished boiling a batch of unfermented beer, also known as wort, you have two immediate concerns. The first is getting it into a fermenter, which will protect it from air and microorganisms that can contribute off-flavours. The second is reducing its temperature so that yeast can be safely added. Counterflow wort chillers allow you to transfer beer directly to a fermenter while cooling it in seconds or minutes. Counterflow chillers have one tube inside another. The interior tube, made of copper, carries hot wort flowing to the fermenter. The exterior tube, usually a garden hose, contains water flowing in the opposite direction. The hot wort transfers heat through the copper tubing and into the water. This process quickly chills the wort.
Clean the fittings. When soldering, you need to remove oxidation from areas that will be joined to ensure a secure, watertight fit. Using sandpaper and wire brush, clean the interior surface of the caps, the exterior surface of the lengths of 1/2-inch copper pipe of and the interior surface of the T-fittings.
Apply flux. Use the acid-free brush to apply the flux to one of the cleaned surfaces. You will need to solder these fittings one at a time, so only apply flux to the parts you are about to solder to prevent dust from sticking to the flux. For example, each length of pipe will eventually get soldered into the T-fitting. Apply flux to one the end of one length of pipe, and insert it into one end of the T-fitting. It should fit snugly.
Solder the joint. Using the propane torch, heat the fitting so it is very hot. Turn the torch off and immediately touch the fitting with the solder. The solder should melt and get sucked into the joint. Drag the solder all the way around the cap while it is still hot to make sure there are no gaps in solder. Make sure that it is the heat on the pipe, and not the torch, that melts the solder. If the torch melts the solder, it will not get sucked into the joint and will not form a watertight seal.
Assemble all the fittings. Repeat Steps 2 and 3 until all lengths of pipe are soldered onto all three ends of the T-fitting, then solder one cap onto the end of a length of pipe that passes straight to the other end. Make sure you do not weld the cap to the length that leads to the 90-degree turn. Solder a cap to the other t-fitting so there is one cap for each "t". If you make a mistake here, it is easy to fix. Just heat the solder and, using pliers, pull it from the fitting while the solder is still molten.
Drill the caps using the 1/8-inch drill bit. Drill a hole in the centre of one of the caps, then enlarge it with a 3/8-inch bit. The end of the 3/8-inch copper tubing should fit snugly through this hole.
Cut the ends off the hose using shears. Cut about 4 inches from the end. This will leave enough space so that the ends can be clamped later to the t-fitting.
Insert the 3/8-inch tubing into the garden hose. Pull the hose or push the tubing until the hose completely envelops the tubing with a couple of inches of tubing sticking out from either end.
Slide the hose back a few feet and place the tubing through the straight branch of the T-fitting so it travels past the 90-degree branch and out through the drilled cap. About 2 inches of tube should stick through the cap. Repeat the steps in the first section to solder the tube into the drilled cap.
Slide the hose back to the length of 1/2-inch tubing. Using a screwdriver and hose clamp, secure the hose to create a watertight seal. Attach one of the short ends of the hose, the part that attaches the spigot for example, to the remaining branch of the T-fitting. Be careful; if you clamp the hose to the flexible tubing, you might end up crimping it.
Attach the other end. Repeat the previous steps to sleeve and solder the 3/8 inch tubing through the T-fittings, then use hose clamps to secure the remaining pieces of hose.
Attach the hose-end to a spigot or water source to make sure the hose clamps are watertight. Use a screwdriver to tighten them if water leaks. Using your normal beer siphon, attach the 3/8-inch nipple to your brewpot and allow water to travel through the tube. This is the space the beer will travel. Make sure the soldered fittings are also watertight. If everything checks out, coil the finished chiller into tight curves and use zip ties to secure the coils to one another.
To use the wort chiller, attach one end of the hose to a sink or water source and the 3/8-inch nipple to your brewpot. Allowing the water and the brew to flow in opposite directions will result in faster cooling. Remember to clean the chiller before each use. Unfermented beer is an ideal environment for microorganisms that make beer taste bad. Clean your system by allowing your standard brewing cleaner to flow through the system. The space between the hose and the interior pipe does not need to be cleaned.
Soldering is not difficult to learn, but it involves high temperatures and can be dangerous. If you have never soldered before, consider asking a friend with experience for help.