So the centre overflow is just there in case you get a stuck mash and you’re not keeping an eye on it?
It definitely looks like it might get in the way a bit.
Thanks for the replies by the way!
No. While it does act as a kind of emergency overflow that is not its primary purpose. Its primary purpose is as part of the mash temp management system. Because the heating elements and temp sensor are both on the bottom plate you have to ensure you have a consistent and continuous flow of wort over the bottom plate to ensure you get even heating of wort and avoid 'hot spots' in areas of wort stagnation, and to ensure as accurate as possible temperature reading that as accurately as possible represent the temp of the entire wort volume.
By having continuous overflow (which you should have) down the tube then you are ensuring you are mixing slightly cooler wort from he top of the malt pipe with wort at the bottom ensuring mixing and continuous flow and movement of the wort under the malt pipe to ensure no wort dwells for any length of time on and around the bottom plate.
It's clearly less of an issue if your grist is not a thick mash so you get unrestricted flow of wort down the 'grist column'? but if you have a thicker mash then the flow of wort through the grist column is restricted and you risk stagnation of wort over the bottom plate and inaccurate temp readings.
For evidence that this is an intentional and, I'd argue, necessary design feature of the system, just look at the latest variants of the Grainfather. Now they have removed the central overflow pipe but they've replaced it with a line of perforations up the side of the malt pipe so you can't avoid a circulation of wort.
Now I'd accept that the central overflow pipe on the BZ 3.1.1 is not a particularly good design because it lets grain that is floating on the top that hasn't been captured under the perforated top plate (which isn't in itself a particularly good design) down the overflow pipe onto the bottom plate hence the new and improved perforated malt pipe designs you see in the latest Grainfather units. that is why Grainfather released al small basket filter to keep grain away from the overflow tube opening. Personally I've attached a few inches of bazooka filter to the top fitting that sits on top of the overflow tube which is effective.
As for the bottom mash filter - works fine for me...I've noticed if I avoid any vigorous stirring during mash in...especially early on when there isn't much grain in there there I don't get any grain trapped between the two plates. Vigorous stirring pulls up the fine mesh and allows grain to get in-between and potentially cause stuck mashes. As to wether you actually need it or not depends on your grain crush. The bottom plate perforations are not particularly small so if you want a more fine grain crush then you will just get more grain in your wort.
The BZ 3.1.1 is a great bit of kit and is intended to make brewing 'easy and straight forward' but it isn't perfect and does require some level of technique and a more thoughtful approach when you use it to get the best out of it. My journey with my Brewzilla has had me finesse my approach and process and my beer and brew days have improved as a result.
