Can I ask about mash tuns?

[aamcle]

I've only used BIAB so I know dip all about tuns but there seem to be two basic layouts.

A false bottom with a space under it.
Does the space fill with wort or is it mainly empty as the wort runs/pumped out?
Can a heater be fitted under the FB is it worth it?

A braided or perforated tube to let the wort run out.

What are the advantages and disadvantages of each type?

Many Thanks. Aamcle

 

[Fil]

And the ever popular copper manifold too
Or a grain bag similar to your biab bag...
its a matter of choice, FB's are i think the best option as i believe they generally stick less frequently, but can be more expensive and trickier to construct.

however each option will have its champion, i got a stuck mash using a braid once and never with the fb, ..fingers crossed so far.. gone n jinxed it now

nothing stopping you experimenting with a few options tho.

u can stick a heater under a fb, but imho your better off relying on insulation to maintain a temp as any heating cant be applied evenly without some sort of recirculation or mixing.

 

[PD]

The problem with a bottom draining FB. well not a problem just something to be aware of.
My FB has an inch ss rim fitted, therefore there is a void below it. and the grains sit on top.My system requires 7 litres of water to fill that space up to the level of the FB.
If my recipe calls for the mash to be done in say 10 litres of water for 90mins. and I only add 10 litres of water, that means there is 7 litres in the void and the grains are having to mash in only 3 litres of strike water, a bit thick !
I have to add the 7 litres onto the strike water amount so the grains are sat in the prescribed 10 litres of strike water and there is the 7 litres underneath....17 litres in all to come off the final total of water.
After the mash I run off approx 8 litres of the mash water to ensure I get clean runnings and that all that water from the void is removed and returned to the top of the mash, and allowed to trickle through the grains.
I then continue with either fly sparge or batch sparge...remembering that I've already used 17 litres of water not just the 10 litres of the recommended strike water.
This caught me out a couple of times when I first started and I kept getting my final volumes wrong.
Becaue my tun is bottom draining it is not really " dead space " as its drawn off and returned.
Doing it this way ensures the sugars washed out of the grains are mixed thorough out the mash water.
You can fit a heater in this " void " although any grains getting through may get " burnt " and you would really need ( as mentioned ) some kind of re circulation, in effect some kind of basic hermes system.
Just try and remember you have a " dead space " under the fb,....but its not really..lol.

 

[oldjiver]

I use a commercial grain mashing/ sparging bag cost about £8. Drains very quickly and freely. I used to use a bit of curtain material many years ago but I was dreadfully slow. So you need to get the hole size just right. My bag is only just long enough for my 5gall (US) IGLOO mash tun, so anything bigger would be a make-your-own job.

 

[Aleman]

The problem with a bottom draining FB. well not a problem just something to be aware of.
My FB has an inch ss rim fitted, therefore there is a void below it.

In the ideal world you would want to minimise the dead space . . . On my 50L tun the FB sits on 4 legs which are made up of 2 8mm stainless nuts . . . I have around 2 or three litres of dead space . . . which is not enough to worry about, but does get added to the losses in beer smith

Could You add a heater in there? . . . . Why would you want to? I know that you can with BIAB, but that is because you have a much thinner mash than you do in a 3V system. Heat is not transferred evenly, which will lead to hot spots and denaturing of the mash enzymes. You can always stir, but this has issues with releasing starch, shredding the husk (leading to tannin removal).

There are other ways to achieve multi temperature mash without heating the mash tun, and if you are loosing heat from the tun then you don't have adequate insulation.