The Compleat Distiller

THE COMPLEAT DISTILLER 51
The Reflux Coil
Many people prefer to make this type of coil condenser to
condense vapor at the top of a column because it is simple to
make, despite its complicated appearance. Since it is most often
used to condense reflux, it is simply called a Reflux Coil.
Soft copper tubing 5mm ( 3 / 16 inch) to 6.5mm (¼ inch) in diameter
is the best material to use. This size tubing is widely sold in coils
for use in hydraulic lines, refrigeration and some plumbing
applications. The smaller diameter tubing is better, because it is
easier to bend and less likely to flatten, but the larger size can be
used if you're careful.
Fig. 4-7
You need a hollow former to make a reflux condenser. This could be a short length of pipe with an
outside diameter matching the inside diameter of the coil you want to wind. Even with 5mm ( 3 / 16 inch)
tubing, don't attempt to wind a coil smaller than 36mm (1½ inches) inside diameter, because the tubing
will start to flatten out. You can calculate how much copper tubing you need, but as an example, 4¼
meters (14 feet) of 5mm ( 3 / 16 inch) tubing on a 36 mm (1 ½ inch) former will make 27 turns, leaving
150 mm (6 inches) free at each end for the connections at the top. The length of the coiled part is just
over 250 mm (10 inches), and it will fit neatly into a 50 mm (2 inch) diameter column.
Start by threading the tubing through the middle of the former, leaving about 150 mm (6 inches)
sticking out. This will be where the water hose is attached. Then, carefully form a looping bend and
start winding the rest of the tubing around the former, back toward the end left sticking out. If you
manage to keep all the coils close together, you should end up with about the same amount left over.
After removing the former, carefully stretch the coil out a little bit. You'll find that the coils will then
be spaced apart by up to the diameter of the coil tubing. Finally, bend the two feed pipes at right angles
to the coil (being careful not to kink the tubing) and you'll have a convenient "hanger" to hold the coil
in place when you insert it into the top of the column. With a close fitting shroud, this condenser can
easily handle up to 2 kW. The closeness of the shroud encourages vapor to flow between the coils
rather than past them. Loosely packing metal scrubber material around the top of the reflux coil will
encourage intimate contact between the vapor and the condenser coils (this trick also works with a Cold
finger).
Condensers - Summary
We have discussed the designs that we’ve found most useful for small scale distilling. You may think
of others, and we encourage you to do so, because innovation and experimentation are the most
enjoyable parts of this hobby. Throughout history, thousands of people have worked to design a better
mousetrap. You can join this happy band of inventors and design a better condenser!
As you design your equipment, you may even start with the old moonshiner's coiled tube (or “worm”)
in a barrel of water - essentially, a Graham condenser with a very large shroud. It is efficient, and is
used to this day in many commercial whiskey distilleries.