Thumper Sizing and Use
Posted: Sun Oct 27, 2019 6:07 am
Size is arbitrary to how you want to use it. The bigger the thumper the more energy applied to the pot, because the thumper will bleed off some of this energy.
Here's a few different ways people use thumpers.
As a steamer setup. Put another way the boiler is filled with water or clear liquid from fermentation but the "thumper" is loaded with the grains, sludge and clear liquid. Nothing in the thumper will burn or scorch as no direct heat is applied and the highest temp ever introduced will be water vapor and at 212 F/100 C temp. This type of setup is great if you ferment on the grain and just want to load it all right into the still. A near 1 to 1 boiler to thumper setup is great for this.
The traditional method of using a thumper that is roughly 1/3 the size of the boiler. Ideally you load the thumper with low wines of around 40% or so and the boiler with your 8% or so ferment. This is similar to a double distillation as the average of what leaves the boiler is 40% or so which is feeding the thumper which then leaves as "high wines" or roughly 70% or so.
A thumper can be filled with nothing but water and used as a filter to get a bit more pure product but not any higher ABV.
A thumper (even small) can be used to make Gin/Jenever. You can load all the macerated vodka/spirit and botanicals directly into the thumper without worry of scorching of the botanicals regardless of how the boiler is fired. Doesn't matter is a heating element or direct fired as no botanicals are present in the boiler. The thumper only gets heated by the water vapor.
You can also use a double thumper setup. Many Rums use a system like this but they typically call the thumpers retorts. The typical load/setup in this setup is the 8% or so in the boiler, 40%ish low wines in the first retort and high wines or 70%ish in the second retort. This would allow a triple distillation in one pass. While Irish whiskey isn't traditionaly made this way, it could be done like this with great success for triple distillation with increasing "boiler" charges AND nothing higher than 8% to typical low wines in the boiler.
Even if you don't specifically load the thumpers/retorts with said % it will work out that way itself due to the ABV output from each section. This would allow you to load both retorts with only low wines for safety reasons while still getting the advantage of the 2nd thumper. Some rum producers do exactly this.
When ever you add a thumper you need to understand what happens with the pressure in each "boiler". You no longer have an open system but a closed system which requires a whole other level of safety especially when you reduce power or kill the heat to the boiler. The "suck back" that happens when power is reduced is enough to collapse the boiler if not robust enough. This is especially common in thin copper "moonshine" stills.
For that reason you really want a way to manually vent the piping between the boiler and the thumper. This way when you turn off the power you can open the vent between the "pots" and make the system open again. This can be as simple as a T fitting in the piping between the boiler and the thumper with a ball valve on the 3rd side of the T. This way you can easily open the ball valve which reduces any pressures.
This is the one reason I do like to have a thermometer on the pot itself. You can keep an eye on the temp to make sure they don't drop when you don't expect it (ie ran out of propane and lost heat). Many digital thermometers allow you to set a temp that fires off an alarm. This is an excellent use for that feature. An alarm at 190 to 200 F or so depending on still would give you a warning the pot is starting to cool off and needs venting.
Depending on the amounts you fill the boiler and thumpers you can get some minimal reflux as well using the head space of the pot. This reflux action is minimal compared to a reflux still but can get you a bit which helps with cuts.
Watch this video from George at Barley and Hops Brewing which is valuable info on thumper safety.
Here is another article full of good info on thumpers and retorts which is short but a good read. http://cocktailchem.blogspot.com/2018/0 ... tills.html
Thumpers are great and can be used quite safely when you stay with your still 100% of the time while it's running (should always do this). But it would be wise to learn to run a pot still without the thumper first to get at least a few runs under your belt. Learn to craw before you walk type thing.
Hope this info helps,
Carlo
Here's a few different ways people use thumpers.
As a steamer setup. Put another way the boiler is filled with water or clear liquid from fermentation but the "thumper" is loaded with the grains, sludge and clear liquid. Nothing in the thumper will burn or scorch as no direct heat is applied and the highest temp ever introduced will be water vapor and at 212 F/100 C temp. This type of setup is great if you ferment on the grain and just want to load it all right into the still. A near 1 to 1 boiler to thumper setup is great for this.
The traditional method of using a thumper that is roughly 1/3 the size of the boiler. Ideally you load the thumper with low wines of around 40% or so and the boiler with your 8% or so ferment. This is similar to a double distillation as the average of what leaves the boiler is 40% or so which is feeding the thumper which then leaves as "high wines" or roughly 70% or so.
A thumper can be filled with nothing but water and used as a filter to get a bit more pure product but not any higher ABV.
A thumper (even small) can be used to make Gin/Jenever. You can load all the macerated vodka/spirit and botanicals directly into the thumper without worry of scorching of the botanicals regardless of how the boiler is fired. Doesn't matter is a heating element or direct fired as no botanicals are present in the boiler. The thumper only gets heated by the water vapor.
You can also use a double thumper setup. Many Rums use a system like this but they typically call the thumpers retorts. The typical load/setup in this setup is the 8% or so in the boiler, 40%ish low wines in the first retort and high wines or 70%ish in the second retort. This would allow a triple distillation in one pass. While Irish whiskey isn't traditionaly made this way, it could be done like this with great success for triple distillation with increasing "boiler" charges AND nothing higher than 8% to typical low wines in the boiler.
Even if you don't specifically load the thumpers/retorts with said % it will work out that way itself due to the ABV output from each section. This would allow you to load both retorts with only low wines for safety reasons while still getting the advantage of the 2nd thumper. Some rum producers do exactly this.
When ever you add a thumper you need to understand what happens with the pressure in each "boiler". You no longer have an open system but a closed system which requires a whole other level of safety especially when you reduce power or kill the heat to the boiler. The "suck back" that happens when power is reduced is enough to collapse the boiler if not robust enough. This is especially common in thin copper "moonshine" stills.
For that reason you really want a way to manually vent the piping between the boiler and the thumper. This way when you turn off the power you can open the vent between the "pots" and make the system open again. This can be as simple as a T fitting in the piping between the boiler and the thumper with a ball valve on the 3rd side of the T. This way you can easily open the ball valve which reduces any pressures.
This is the one reason I do like to have a thermometer on the pot itself. You can keep an eye on the temp to make sure they don't drop when you don't expect it (ie ran out of propane and lost heat). Many digital thermometers allow you to set a temp that fires off an alarm. This is an excellent use for that feature. An alarm at 190 to 200 F or so depending on still would give you a warning the pot is starting to cool off and needs venting.
Depending on the amounts you fill the boiler and thumpers you can get some minimal reflux as well using the head space of the pot. This reflux action is minimal compared to a reflux still but can get you a bit which helps with cuts.
Watch this video from George at Barley and Hops Brewing which is valuable info on thumper safety.
Here is another article full of good info on thumpers and retorts which is short but a good read. http://cocktailchem.blogspot.com/2018/0 ... tills.html
Thumpers are great and can be used quite safely when you stay with your still 100% of the time while it's running (should always do this). But it would be wise to learn to run a pot still without the thumper first to get at least a few runs under your belt. Learn to craw before you walk type thing.
Hope this info helps,
Carlo
