Immersion Method
The immersion method chills the boiled wort by recirculating cold water through the following path:
Cold water in mash tun to pump 1 to copper plumbing to immersion chiller (shownabove) back to mash tun
The temperature of the wort in the kettle drops while the temperature of the water increases.
My brewery utilizes the immersion chiller system.  It will chill 6 gallons of 212-degree wort to 75 in 40 minutes.
 

Materials	Special Equipment
50 Feet of 3/8”OD Flexible Copper Tubing Several feet of 3/8”OD (1/4”ID) Solid Copper Tubing (OPTIONAL)  5 Copper Elbows for 3/8” Solid Copper Tubing (OPTIONAL)  Copper Wire for binding, 1/2" to 3/8"OD Reducer Clamps, Surgical Tubing, and Hose Connectors (To attach to Supply & Return)	Copper Tube Bender if not using solid tubing instep 2.

 
Procedures
Note:  The 50-foot coil of flexible tubing is necessary when 10-gallon brews will be chilled. Otherwise, a 25-foot coil, which will reach up to the middle of the kettle, is adequate to cool 5-gallon brews.
 
Step 1  -  Wrap the coil of flexible tubing around a 5 gallon soda keg or 9.0 ” cylindrical object.
Leave enough tube on the ends to extend to the supply and return connections.
Step 2  -  Bend the tube at the top out toward the cooling water supply connection.
Bend the tube at the bottom up to the top and then out to the cooling water return connection.
OR: Construct the same tubing for supply and return, except use solid tubing and elbows as shown above.
This size copper tubing is available only at plumbing supply stores for contractors, not hardware stores.
Note: Solid tubing will require that some soldered fittings come into contact with the brew.  Reportedly, when solder contacts hot brew, it may result in chill haze in the finished beer.  My system utilizes soldered fittings on the chiller with no perceptible result in chill haze.  Your choice.
Step 3  -  Support the sides of the chiller with straight lengths of flexible or solid tubing.
Leave at least a 1” gap between each loop of the chiller.
Bind the straight tubes to the chiller with pure copper wire (home electrical copper wire).
If solder in the kettle is acceptable, solder some or all of the twisted ends where copper wire has been used.  It will add strength to the chiller and reduce the chance of the wire becoming undone.
 
Assemble the connections to the water supply and return as shown above.
Use short pieces of braided rubber tubing at the end of the 3/8” copper tubing.
Braided tube adds flexibility and will allow easier connection.
The plastic or metal hose connectors screw together for quick removal.
 
Wait until Step 9, Plumbing, to construct the 1/2” chiller water supply and return tubing.