Questions about fermentation vessels and sparging

[Tehpet]

Hello,

I'm going to start my brewing journey next month when I get my new flat. As a chemistry student everything in brewing sounds very interesting.

I think of getting 30 L (all-in-one) mash kettle as my space is very limited. First thing I'm wondering about is fermentation vessels. I would like to do 20-24 liter batches and divide the wort into two to three fermentation vessels and experiment with different yeasts and/or dry hops. I've read that there shouldn't be (taste) differences between glass/plastic/stainless so I'm probably going with plastic for now.
There seems to be 12 liter or 19 liter plastic containers available. Is 12 liter container too small for 6-8 liter wort? Is there any real difference between (12L) 25 euros Speidel or 8 euros bucket with wide lid (in terms of taste/quality of fermentation)? If I'm getting two to three of those the price difference is noticeable. I know I could get one 30 liters vessel for price of two/three of those but...

For second, I have already been playing with brewersfriend software, set 'Batch size' to 24 L and pressed 'Brew Day' button. I have set water/grain ratio to 3 L/kg and software tells me to use 18.83 liters of strike water and 14.6 liter of sparge water. Then I should have 27.8 L wort volume before boil. Probably a stupid question but can I fit 18.83 L + 14.6 L = 33.4 L to my kettle? It seems my grain absorbs 5.5 L and well, 33.4 - 5.5 = ~27.8 so it should be fine for 30 liter kettle or is it going to overflow?

Thank you for all answers!

 

[MrHadack]

Hello!

First, with regard to the fermentation vessels:
I've been brewing with both food-grade wide mouth buckets and glass carboys for a very long time. There is no difference in taste. I much prefer buckets as they are easier to clean and can also server other purposes in the brewing process if needed.
12 liter container would not be too small for 8 liters of wort. On higher gravity beers with particularly active yeast there's a small chance you could get some blow-off through the airlock, but I wouldn't worry too much about that.
I suspect that after no too long you will want to do single batches once you're done with the experimentation phase. So perhaps the best course is to purchase one 12 liter and one 19 liter. You can split the batches between the two, or use the 19 liter for single batches.

Now, with regard to batch sizes / kettle:
Why set the batch size to 24L in the first place? Most recipes I come across are set at 5 gallons (slightly less than 20L), though this may different for you. I think 20L would be fine with your equipment.
However, if you really do want 24L, I think you will get overflow with your kettle. You must remember that grain also takes up room in the kettle, so I am not sure how you'd manage the sparge process. When it comes time to boil, even with the loss due to grain absorption you'd be left with a scant 2L of headroom in the kettle. The wort will expand ~ 9% in volume by the time it reaches boiling which gives you: 27.8 * 1.09 = 30.302 L. Additionally, you really want a good strong boil which will add turbulence causing more overflow. Adding hops causes an initial foaming which would certainly add to the trouble if you have little to no head room.
Reducing to 20L is, I think, about a 12% reduction, which (if everything scales linearly) results in a full expanded boiling volume of ~25L, which is perfectly good for a 30L kettle. Just some thoughts. Perhaps double-check my math. But from experience it seems right to me.

-Mark