tall-skinny or short-fat mash-tun

[herman2011]

Does the aspect-ratio of a mash-tun's dimensions matter like it does for brew-kettles? i.e. would a keggle mash-tun be better or worse than short-fat mash-tun like the 15gal polarware pots? e.g. I could imagine a taller grain bed might be slower to distribute the heat in a recirculation... or maybe not? Stout Tanks, for example, just scales up by making vessels taller, including their mash-tuns, rather than wider. But commercially mash-tuns are usually shorter and fatter... roughly equal height and diameter. Maybe this doesn't really matter. Just wondering what y'all think.

 

[freshhoarse]

Ideally you want depth to equal width. Puts less pressure on the grain bed for less chance of stuck sparges and better heat distribution.

 

[LuiInIdaho]

I think that a tall skinny mash tun will give you a better, more uniform grain bed. A shorter fatter mash tun will give a more shallow grain bed. I think that all of this only important if you fly sparge. The differences in mash tuns becomes less relevant if you batch sparge. That sums up my thoughts on this subject.

Mark

 

[herman2011]

Thought I'd resurrect this to see if there are any further thoughts on this...

 

[headwall]

Ideally you want depth to equal width. Puts less pressure on the grain bed for less chance of stuck sparges and better heat distribution.

I think this is key. In my mind, an ideal grain bed is as tall as it is wide. Too tall and you may have issues with a stuck mash. Too shallow and you may have trouble getting uniform rinsing and drainage of the grain bed and your efficiency may suffer, plus you'll have a greater surface area facilitating heat loss. If I had to swing one way or another, I go with slightly taller vs wider. I would pick something with the dimensions of a keg over a wide, shallow pot any day.

 

[orangehero]

At the homebrew scale it usually doesn't matter. Commercial mashes can be over 18" deep. You should size it so that your smallest batch size still has a reasonable depth and covers your thermometer probe if you have one.

 

[orangehero]

It is recommend that the loading on false bottom be:
Dry milled grist: 160-175 kg/m2 (32.8-35.8 lb/ft2)
Conditioned and milled grist: 170-210 kg/m2 (34.8-43.0 lb/ft2)
Steep-conditioned and milled grist: 200-310 kg/m2 (41.0-63.5 lb/ft2)