There's only two things about my setup that aren't in the title:
- I have the wetsuit for the boiler - it saves on power to boil but will also affect observations regarding power input vs boil temps, etc.
- I bought the 4mm probe kit for the temperature monitor so I can sit and watch TV while keeping an eye on the temps at the top of the still. I love this thing, it's worth the bucks and time spent pulling apart your thermostat to get the convenience. I can see the temps from my PC, and when I go and sit in my comfy chair to watch TV I can turn the display around and watch it from there.
Using the setup is pretty simple if you are doing a spirit run:
- make sure to install the 0.6mm fitting they supply
- fill the vessel with the wash
- turn on both elements, give it all 2400 watts
- bring the wash up to roughly 60 degrees celsius
- make sure to turn on the water supply to the condenser now - not doing it till now saves on water if that's a factor for you
- use the probe they supply. Place it in the condenser head. When it hits roughly 78c you should see alcohol coming out of the take-off arm.
- at this point you can switch to just using the 500 watt element, turn off the 1900 watt element, it's too powerful and will cause over-boils
- discard the foreshots, see other posts for information about this
- follow guides on taking heads, hearts and tails
- at some point deep into the tails you will want to either switch off the run or switch to a "stripping run". I have been doing this when the ABV drops below 35% (roughly). This is simply because it takes perhaps 12 hours of reflux runs to get to this point and I am dying to finish the run. A stripping run at this point allows me to get the last of the tails faster.
My first attempt was cautious, using the 1.0mm fitting, but keeping the power use down to 500 watts for most of the time. It was stripping, but slowly. Sure, it was several times faster than a reflux / spirit run, but is was still really slow. Liquor was dripping out instead of pouring out.
I started that run at 3:00pm and finished it at 11:00pm, a total of 8 hours. Now, I did mix in some extra feints during this time, but I also poured off some liquor from the tank due to over-boiling issues. Clearly this needs to be faster, and it can be - we will cover that soon.
Firstly, some parameters. Liquor starts to come out of the spout around 90% ABV, and perhaps 79 Celsius (measured at the condenser). I'm running the stripping run until the out-take is roughly 20% ABV and the temperatures are right up near 98% or higher. There's no point going further, in fact, some might say there's no point even going that far.
Things I did wrong:
- overfilling the boiler. I filled it to 30L first time around and that's simply too much. It vomited several times, even when I had the recirculation arm fixed in place. I tried the "distilling stabiliser" the LHBS sold me, and a tablespoon of butter. It still spewed onto the floor. That would happen when I ran with the 1900 watt element switched on, but was not an issue with the 500 watt element. I suggest instead you fill to 23 litres as this will provide a lot of headspace for boiling.
- Running with the wrong element switched on. Use 500 watts for reflux runs, 1900 watts for stripping runs.
- Most important - I didn't unpack the reflux column for the stripping runs.
With that fitting, and running with 1900 watts of power, I was having to get up every 15 mins or so to attend to the still - turning off the power for a few mins to stop it spewing over the floor. If left unattended it would eventually boil over, frothing up into the column (I could hear this happening) and spray it's load all over my nice clean floor.
I would flip it over to 500 watts, leave it for a bit to cool, then flip it back, and so on. It's a nightmare.
So, the big lesson is, to run in stripping mode you must remove the steel wool packing in the column to stop the still from boiling over. Just this simple change has allowed my second run to complete in about 4 hours instead of 8 hours. By doing this I was able to run at 1900 watts the entire time, vastly increasing the speed at which I could take off the alcohol.
I didn't remove it all. It's kinda hard to reach up in there, but using a fork I was able to remove 5 - 6 of the scrubbers. That's the majority of them removed.
I have a large supply of cold water, very large (21,000 litres), which I can re-circulate. It's in a concrete tank so it comes into the still at perhaps 16 Celsius.
During these stripping runs, the cold water, which usually exits from the condenser quite cold (for reflux runs) is coming out around body temperature, and sometimes a bit hotter. That condenser is having to work a fair bit harder, but that's for the best. With my lovely cold water supply pushing as hard and fast as it can through the condenser it is able to reasonably cool the head down when running at full speed.
Summary
I was seriously getting frustrated with this still's lack of power control. While it provided a nice level of power for refluxing, it was too high for stripping. De-tuning the reflux still has allowed me to make full use of the power and cooling available to make the stripping runs happen at a more reasonable speed.
I think if I was going to build a still I would ensure I could have control of the power input, either via a gas burner, or more likely a PWM element (or maybe an induction stove).
That said, it is possible to get the Brewzilla Robobrew to play nice, you just have to remove a little bit of steel wool.
TLDR: Detune the still for best results when stripping. Remove most of the steel wool column packing.
Notes:
- touching the water take-off from the condenser will give you a good idea of how much energy is being added in the condenser. In reflux runs it's typically quite cold. When stripping, it's typically warm. If it's coming out hot, you don't have enough cooling. I have a pretty oversized pump pushing cold water through mine, so it can cope with some pretty hot conditions. If the water is coming out hot, you either need to put less energy in (switch to 500 watts for a while, not ideal) or lower your input water temps or the speed at which they pass through the condenser.