Beer stripping is simply a fast, crude distillation of the beer in a pot still in order to obtain most of the alcohol in a smaller volume of water. This smaller volume of distillate, about a quarter of the original volume of beer, is easier and cleaner to handle in the small precision equipment used for the final stage of fractional distillation.
An effective and fairly inexpensive beer-stripper can be fabricated from a 30 US gallon (113 litre) domestic hot water heater. A sketch of the water heater and the modifications required are shown in Figure 2. A 3/4 inch inlet for cold water is provided by the manufacturer on the side at the bottom and another 3/4 inch hot water outlet near the top. A third 3/4 inch pipe connection will be found by removing the sheet metal cover and fibreglass insulation from the top of the tank. This is where the magnesium rod used as an anti-corrosion device is installed. Remove it since it is not needed in our application and we may need the 3/4 inch connection for the installation of the steam-condensing system.
The steam-condensing system, as shown in the diagram, is made from 1/ inch copper pipe. An adapter, or series of adapters, will be needed to go from the 3/4 inch female pipe thread in the top of the boiler to the 1/ inch copper pipe used for the rest of the system. We suggest that a union be provided to permit easy disassembly if required.
A 1/ inch copper tee as shown permits the fitting of a cork and thermometer to read the temperature of the vapours distilling over. These vapours are condensed by means of cold water running through a coil of copper tubing inserted in the down-stream vertical section of the 1/ inch pipe. To make this coil use 12 feet or so of 3/16 inch flexible copper tubing (obtainable from automotive supply stores), push one end into a short length of 3/4 inch pipe and wind the remainder tightly around the outside. The two ends of the coil are either brought out through the top elbow where they are soldered into place or, more simply, brought out through a large cork inserted in a copper tee. The second version is shown in Figure 2a. Be careful to ensure that the direction of cold water flow is counter-current to vapour flow as it is more effective this way.
The lower side connection to the boiler, normally the cold water inlet when the apparatus is used for domestic hot water production, will become the inlet for beer from the fermenter and also the drain for the exhausted beer after stripping. Fit this connection with a 3/4 inch ball valve and screw into it an adapter for connecting a rubber hose. Do use a ball valve at this location, and not an ordinary faucet, because the yeast in beer forms sticky clumps when boiled and there should be a wide opening for the yeast clumps to exit to drain.
The upper side connection (the hot water outlet) is seldom used and could be plugged, but it is just as easy to close it with a faucet. It could then be opened if required and used, for example, as an overflow indicator when washing up.
The thermostat which controls the temperature of the water must be removed or by-passed. Since we wish to boil the beer and collect the vapours, a thermostat which switches off the current at a temperature well below the boiling point of water would obviously defeat our purpose. Disconnecting the thermostat may seem dangerous, and it would be if we had a closed system, but as will be seen from the diagram the top of the boiler is constantly open to the atmosphere via the 1/ inch inverted-U vapour line and condenser so there can be no pressure build-up. It is no more dangerous therefore than a boiling kettle of water.
Small domestic hot water immersion heaters of this size will probably have a single 3000 watt, 240 volt heating element at the bottom. If there is a top element (as there is in larger water heaters) it must be disconnected permanently because the boiler as used in the present application is never full and a top element would burn out. A 3000 watt element should provide about 6 litres of distillate per hour.
After beer stripping, allow a little time for the exhausted beer to cool down and then dispose of it through the ball valve to drain. Back wash with fresh water and drain a couple of times after each run to reduce the possibility of yeast build-up.
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