Its just about making it easy to get the spent grist out without having to lift anything. Same thing as the other MLT's that have hinges welded to them so they can rotate to empty the grist - same here but sideways. A full length slot would provide easy removal of the spent grist. No advantage of this over the upright version, and as MHB says, the false bottom wouldnt be full width (unless the false was curved itsself), so that may be a disadvantage but at HB scale may not matter enough to worry about it. At first I thought the sides would be sparged less, but now I think of it if they get the same amount of sparge water as the middle, as would be the case if there was a layer of sparge water on top as is the norm, it may actually turn out to be perfect.
It could have bearings fixed to the center of the sides mounted inside short pieces of steel pipe like in the sketch above, or mounted on rollers at the bottom to allow it to turn or both.
Anyway, lets not turn this into which method, I just suggested another way. I'm sure we all agree that being able to rotate the mash tun so the bulk of the spent grist can be dumped into a wheelbarrow so we dont have to lift 20+Kg of spent grist may be the most important aspect of the ultimate brewery. :icon_cheers:
In terms of having the whole thing encased in walls leading to a drain so it can be hosed down - yes the electrics are the tricky part, an element with sealed wires would be a must, and yes it would be hard to seal every other electrical thing so they are waterproof, but that would be the 'Ultimate' and that is the topic
Encasing everything would also keep the heat in but not the reason for doing so - more to avoid having to build a graded floor with a drain into the brewery shed.
Do you flush all 4 to 10Kg of your grist down that valve yardy? Always wondered but never seen a definitive answer.