how much space to leave in the boiler

[colin79]

Folks,

is there any advice on how much space should be left in the boiler? I tried searching this forum, but came up with nothin.
I have a Vevor 19-litre bucket with a flat lid. Filling to the top will mean any vapor will get pushed to the hose. All commercial stills have a nice rounded cap that will allow for some condensation inside the boiler, looks like 1/3 of the volume is not filled with ferment.
So, should I just fill 12 litres in my case?
Cheers
C.
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this is what I found outside of this forum and it says the headroom depends on the design. So, if anybody knows what is the adjustment for a flat lid, let me know.

Recommended Boiler Headroom for Distillation

When distilling, it's essential to leave adequate space in the boiler to prevent issues like overflow or "puking." The amount of headroom required can vary based on several factors, including the type of wash and fermentation level.
General Guidelines

Minimum Headroom: A common recommendation is to leave at least 20% of the boiler's total volume as headroom.

[MooseMan]

Yes you want to leave a little head space in the boiler, probably 12-14L would be ok in your still.
For stripping at a hard boil, you need the headspace to reduce the risk of liquid bubbling up into the riser, for spirit runs you want a little headspace to help separate fractions before they go up into the condenser. (If you could see inside as you come up to temp, you'd see the first vapours hitting the lid and dripping back down, all the while concentrating the foreshots, for example)

[PalCabral]

I had similar questions when I got started - here's a link. I got a lot of great valuable input in this thread, for which I am very grateful: viewtopic.php?p=7799506&hilit=headspace#p7799506

When I run stripping runs I never fill more than 80%, more often below 75%. However, I have had foam ups and pukes even when I only filled the boiler to 50%, and I used butter, so I took the advise I got in the beforementioned thread and got me a sight glass. Invaluable advise and invaluable piece of equipment. [utube][/utube]

I know a sight glass is not in the cards unless you want to rebuild your Vevor. All you can do is to run slow.

[Secale]

Filling 1/2 way is normal. I would never fill more than 5/8 of any still.
Headspace is needed to allow the liquid to gas phase so the process
of distillation runs smoothly.