Did that Foxy 20ltrs in a 20 ltr brew so only 5 litres left to sparge and stirred loads of times but it still kept building up and the bottom emptying. All fully insulated with the Brewzilla jacket and pipe cover.
https://crispmalt.com/en-us/news/how-to-use-oats-in-brewing/
Just trying to get my head around it so seeing how much flow I can get with less flour in it.
I could add Oat husks but the grainbill is simple just 3100g od Pilsner and 250 of Torrified Wheat and as I added 200g of them to the last brew it did not do the trick still had to keep stirring to release the water back to the bottom reservoir several times
Ps the last brew was not a over large grainbill but it was a porter with plenty of adjuncts, crystal etc with a low DP of 34 so that may not have helped
Increasing the reservoir (lifting the malt pipe) won't solve the problem, just delay its appearance. This can make matters worse.
A difference in liquid levels, between that inside the malt pipe and that outside, gives a differential pressure.
Where the levels are the same, it is a floating mash (no pressure on the grain bed).
But as difference between levels increases, more weight is taken by the grain bed, the differential pressure compresses the grain bed, restricting the flow, increasing the level difference......! Ultimately when there's no liquid left under the malt pipe, the base of the grain bed is supporting total weight of grain and water above. This leads to a compacted bed, which doesn't drain.
Oats in brewing this article from Crispmalt, discusses bed compression and differential pressure.
I started with BZ4, doing a vigorous stir at dough in, using a spiral drill mixer. But often got slow draining, or stuck, mash, needing lots of subsequent stirring.
Worst brew was a Weisenbock, 6.5kg grain 50% being wheat, that needed stirring multiple times. This stopped the grain bed being a filter, so lots of flour fell through and settled on base, this then burnt during boil. I had an overheat shutdown for a while (around 120°C), and ended up with 6mm of burnt black crust.
Beer tasted extremely smokey.
But all going much better, since finding Graham Wheeler's suggested method (British Real Ale 3rd ed), of minimal stirring at dough in, just enough to break up lumps.
The idea is to avoid knocking off, any air attached to the grain, as attached air increases buoyancy and forms a more open bed.
Never stir the mash after this, and don't put on the top plate (until squeezing dry, after sparge).
After dough in, leave a 15 - 20 minute grain bed rest period, for the grain and flour to hydrate, before starting slow recirculation through the grain.
I imagine that once hydrated, each grain will have expanded, so making a firmer filter matrix.
After 10 min, throttle for max flow, without level rising any more than 10mm.
Doing recipes with 50% wheat, or 25% rye, I still never achieve 100% recirculation. A 25 or 30% flow might work slower, but it's easier than having to sort a stuck mash.
For step mashes, I try to get most of each step, from gradual additions of boiling water (without stirring).
I'm just wondering, if slow water additions could be better done from a boiler, via my hose on the drain tap?
