The Speidel Braumeister comes in 10, 20 and 50L (it actually also exists in 200, 500 and 1000L, but that’s a different story, not covered on this website)
Doubtlessly, the most versatile model is the 20 liters version
It allows to brew the volumes of all 3 models very easily:
- 10L by using the short malt pipe
- 20L, obviously
- 50L if you brew to the max capacity (25L) twice in a day
That’s definitely the best option, it allows to make small-scale tests of 10L and then produce relatively large batches (50L/150 bottles) when you are happy with a recipe
50L is the best because it allows with the std malt pipe 50L batches with sparking properly easily up to 1.065 O.G. @~60L finished wort (1/2 US Barrel)
The 50L actually has a short malt pipe option, which allows it to scale and be used just like a 20L BM; you will NEVER boil over a 50L with a 20L Short pipe.
The 50L has more power to heat so again short malt pipe, fast rise times; it has two pumps vs. 1 on the 20L and smaller.
The 50L is larger so minor in accuracies in your ingredient list are a little influential in the finished beer vs. the same measurement error on a smaller batch.
Disadvantage of 50L is lifting the malt pipe with 13kg (26lbs) of saturated malt; A. Hard to pull manually and the vacuum break is really strong so tilt the pipe when lifting; B. Use a winch pulley system, some levered pull system to avoid spilling 170F hot wort on yourself and everywhere.
It takes a little longer to clean and fill a 50L volume.
Definitely use the Speidel insulation jacket to heat, mash and boil. Take off for cooling, and if you buy a BM+ with the cooling jacket, supplement that with an immersion or plate chiller