Appendix C - Chillers
Wort chillers are copper heat exchangers that help cool the wort quickly after the boil. There are two basic types, Immersion and Counterflow. The first works by circulating cold water through the tubing and submersing the cooling coil in the hot wort. The counterflow version works by running the hot wort through the tubing while cold water runs outside in the opposite direction. The basic material for both types is 3/8 inch diameter soft copper tubing. Half inch dia. tubing also works well, especially for large scale immersion chilling, but 3/8" is the most common. Do not use less than 3/8" because the restricted water flow impairs cooling efficiency.
Immersion chillers are the simplest to build and work very well for small boils done on the stove in the kitchen. An immersion chiller is easy to construct. Simply coil about 30 feet of soft copper tubing around a pot or other cylindrical form. Spring-like tube benders can be used to prevent kinks from bending during forming. Be sure to bring both ends of the tube up high enough to clear the top of your boiling pot. Attach compression-to-pipe thread fittings to the tubing ends. Then attach a pipe thread-to- standard garden hose fitting. This is the easiest way to run water through the chiller without leaking. The cold water IN fitting should connect to the top coil and the hot water OUT should be coming from the bottom coil for best chilling performance. An illustration of a immersion chiller is shown below.
Figure 157 - Immersion Wort Chiller
The advantages of an immersion chiller are that it is easily sanitized by placing it in the boil and will cool the wort before it is poured into the fermenter. Make sure the chiller is clean before you put it into the wort. Place it in the boiling wort the last few minutes before the heat is turned off and it will be thoroughly sanitized. Working with cool wort is much safer than hot wort. The cool wort can be poured into the fermenter with vigorous splashing for aeration without having to worry about oxidation damage. The wort can also be poured through a strainer to keep the spent hops and much of the break material out of the fermenter.
Figure 158 - Chilling in Place.
Counterflow Chillers are a bit more difficult to build but cool the wort a bit better. Counterflow chillers use more water to cool a smaller volume of wort faster than an immersion chiller so you get a better cold break and clearer beer. The drawbacks are keeping the inside of the chiller clean between batches and preventing hops and break material in the kettle from clogging the intake. A copper pot scrubby can be attached to the end of the racking cane to help filter out hop particles.
The increased efficiency of a counterflow chiller lets you use a shorter length of tubing to achieve the same amount of wort cooling. The tube-within-a-tube chiller can be coiled into a convenient roll. The hot side of the chiller, the racking tube intake, needs to be copper or another heat resistant material. Plastic racking canes tend to melt from the heat of the pot when the hot wort is siphoned into the chiller. Counterflow chillers are best used when there is a spigot mounted on the side of the pot negating the need to siphon the wort.
Figure 159 - Suggested Counterflow Wort Chiller Design
Figure 159 shows one example for building the counterflow fittings and assembling the copper tubing inside the garden hose. The parts are common 1/2 inch ID rigid copper tube, an end cap and T sweat-type fittings. The parts are soldered together using lead-free silver solder and a propane torch. The ends of the garden hose are cut off and reattached via the tube clamps to the T's. The 3/8 inch diameter soft copper tubing that the wort travels thru exits the end cap thru a 3/8 inch diameter hole. The opening for the tubing is sealed with a fillet joint soldered around the hole.
There is a company that manufactures fittings exclusively for building counterflow chillers. These fittings are known as Phil's Phittings from the Listermann Mfg Co. The fittings make building a counterflow chiller very easy.
There is a third type of chiller that can be considered a hybrid of the previous two types. This chiller has the hot wort flow through the copper tubing like a counterflow, but the cooling water bathes the coil similar to an immersion chiller. This type of chiller is very popular and can be built for about the same cost as a counterflow. The basic material is 2 feet of 6 inch diameter PVC pipe. Brass or plastic hose barbs can be used for the water fittings but brass compression fittings should be used to attach the copper tubing to the hot side of the chiller. To obtain a good seal, a rubber washer and the "flat" of the compression/NPT fitting should be on the inside of the PVC pipe. With this type of chiller, it is important to have good water throughput to get a good chill. Another option is to place a smaller diameter closed PVC pipe inside the copper coil to increase the flow of cooling water along the coils, rather than thru the middle of the chiller body.
Figure 160 - Hybrid chiller inside a PVC pipe.