The Compleat Distiller

THE COMPLEAT DISTILLER 46
Immersion element boilers
An immersion-type element is usually mounted through the side of a boiler and is in direct contact with
the liquid. Immersion elements are available in a wide variety of shapes, sizes and power capabilities.
Usually, these elements are designed to bolt to a flange or screw into a special fitting. You can
purchase the appropriate fitting and have it welded or brazed onto almost any style of pot. Another
type of fitting (the bulkhead fitting) is designed for mounting devices through sheets of metal, and if
you have (or can create) a flat surface on your vessel, you can easily mount one of these.
Another route to an immersion boiler is to modify a small electric water heater. These “point of use”
water heaters are readily available in sizes ranging from 20 to 60 liters (5 to 15 US gallons), with
heating elements usually in the 1000 – 2000 watt range. They are well insulated, and have convenient
and well-labeled inlet and outlet connections. The outlet will be on the top, and will become the exit
path for vapor. The "inlet" may be on the top or the side of the cylinder. It is very important to
differentiate between the "inlet" and "outlet" fittings, because the inlet is often connected to a tube
inside the unit that delivers cold water to the bottom of the tank. It is therefore always immersed in
liquid, and cannot deliver any vapor! The inlet needs to have a valve or cap attached that remains
closed except when filling or draining the unit.
Water heaters have built-in thermostats that prevent them from boiling. Since you want the contents to
boil, you must remove this thermostat from the circuit. Some water heaters have a sacrificial anode of
magnesium or magnesium alloy, which should be removed if possible. If you are not completely sure
of your skills as a plumber or an electrician, get someone to do the work for you! Many home brewers
have found that a few bottles of their product can be traded for a lot of work on equipment.
Indirectly heated boilers
There are many advantages to an indirectly heated boiler, but other than the “pot in a pot” technique,
they are difficult and expensive to build. You might be able to find a jacketed cooking vessel at a used
restaurant supply store, and that would be the best way to create a true indirect heating system. Vessels
with heating coils are generally too large to consider for a small-scale boiler.
This method is used extensively in industry, because a single boiler can heat many pieces of equipment.
Industrial applications usually use steam as the heat transfer medium, because it is very efficient.
Steam can be heated to very high temperatures and its own pressure will move it around the system,
while hot water systems require a separate pump.
Whatever the advantages, steam heating should NEVER be attempted by the amateur! STEAM IS
DANGEROUS. Because of the dangers of steam, pressurized boilers require licensing and regular
inspections, and still manage to explode and kill people on a regular basis.
If you want to try this technique - and it can offer significant safety advantages if you are heating with a
flame - then use hot water for the heat transfer medium. NEVER operate a pressurized system.
Boilers - Summary
All of these methods of heating are suitable, and each has advantages and disadvantages, so none of
them can be declared the winner. Choose your design based upon your own unique situation.
You can make a boiler yourself (paying due attention to grounding and electrical safety, or to fire and
ventilation if using open flame heating) or you may choose to buy a boiler ready-made. Small
electrical water heaters are a good option because they're compact, sturdily made, and are usually well
heat insulated (which saves on your electricity bill). Using a water heater for a boiler is described in
more detail later, in the section on Pot Stills.