Dead space in mash tun

[The-Engineer-That-Brews]

I mash using two 30L bins one inside the other, with the base of the inner one replaced by a fine stainless steel mesh:

While mashing I recirculate with a pump, heating the wort along the way using a heat exchanger.

I'm still really quite inexperienced with all-grain, so I tend to follow the recipes to the letter - but last time I brewed I noticed that with the recommended volume of mash liquor the water didn't completely cover the grain.

So today I decided to measure the 'dead space' under the mesh. It's only an inch high but I was astonished to find that I had to add 3L of water before the mesh was covered (!)
I guess that explains why the top of the grain bed was dry then...

SO - decisions... should I:

(1) stop stressing: I'm recirculating, so all the grain is all 'wetted' during the mash, and this 'dead' volume is all recovered when I collect the wort;
and/or (2) increase the volume of mash liquor by 3L (and reduce the sparge volume by the same amount?)
and/or (3) eliminate this dead space by filling it with (e.g.) a coiled up, plugged, length of silicone hose

Answers on a postcard please...

 

[Buffers brewery]

Marbles! That what I use as a false bottom. Glass balls by another name!

 

[The-Engineer-That-Brews]

Marbles! That what I use as a false bottom. Glass balls by another name!

Ah yes! I've seen them in the bed of your super sparge-o-matic on your video :-) :-)
Very nice - but I reckon a length of silicone hose might be quicker to heat up...

 

[Buffers brewery]

I just pre-heat my balls (excuse the language ) with water from a kettle before I start my mash. But if you've got plenty of tube handy......

 

[The-Engineer-That-Brews]

I just pre-heat my balls (excuse the language ) with water from a kettle before I start my mash. But if you've got plenty of tube handy......

Hmmm... the balls would certainly allow liquid to flow past more easily so maybe you've got a point there.
I'm still not sure I shouldn't just knock the mash liquor up by 3L and take it off the sparge volume tho!

 

[The-Engineer-That-Brews]

.

 

[chthon]

That is what I do. I have the same kind of setup, although I use it only for sparging and filtering. I have a headspace of 2 l, which I fill with water at 72° C, which I have taken from my sparge water. Then I transfer my mash to it. But I start with circulating (vorlaüf) 4 liter of fluid before I really start sparging.

 

[The-Engineer-That-Brews]

That is what I do. I have the same kind of setup, although I use it only for sparging and filtering. I have a headspace of 2 l, which I fill with water at 72° C, which I have taken from my sparge water. Then I transfer my mash to it. But I start with circulating (vorlaüf) 4 liter of fluid before I really start sparging.

Wow - transferring the mash to it must be quite difficult!

 

[Buffers brewery]

just knock the mash liquor up by 3L and take it off the sparge volume

I guess providing you can drain your dead space at the end of the mash/sparge, that's the pragmatic route.

 

[chthon]

Wow - transferring the mash to it must be quite difficult!

My setup is only 10l, and transfer is done with a small saucepan.

 

[Hop_it]

I had the same problem with my homemade mash tun. I used something similar to the marbles idea - in my case the decorative glass beads/pebbles that people put in plant pots etc. They have the small advantage of being flying saucer shaped, so they don't roll away. However, they are quite expensive, so I also bought a couple of cheap white HDPE chopping boards from Lidl or Aldi, and I cut them (with a jigsaw) to fit in the base of the lower bucket. They take up some of the dead space, are food safe and are also easy to clean.
I don't use sophisticated brewing software myself, but I believe that many of them do have the possibility to enter a figure for dead space, and thereafter calculate the appropriate mash and sparge volumes. Failing that I would just add it to the mash volume, and sparge with whatever is left.

 

[GeorgieV]

(1) stop stressing: I'm recirculating, so all the grain is all 'wetted' during the mash, and this 'dead' volume is all recovered when I collect the wort;
and/or (2) increase the volume of mash liquor by 3L (and reduce the sparge volume by the same amount?)
and/or (3) eliminate this dead space by filling it with (e.g.) a coiled up, plugged, length of silicone hose

For me option 2 works fine. I haven't noticed any significant reduction in the efficiency even though my mash tun dead space is just over 4 L.

 

[The-Engineer-That-Brews]

I had the same problem with my homemade mash tun. I used something similar to the marbles idea - in my case the decorative glass beads/pebbles that people put in plant pots etc. They have the small advantage of being flying saucer shaped, so they don't roll away. However, they are quite expensive, so I also bought a couple of cheap white HDPE chopping boards from Lidl or Aldi, and I cut them (with a jigsaw) to fit in the base of the lower bucket. They take up some of the dead space, are food safe and are also easy to clean.
I don't use sophisticated brewing software myself, but I believe that many of them do have the possibility to enter a figure for dead space, and thereafter calculate the appropriate mash and sparge volumes. Failing that I would just add it to the mash volume, and sparge with whatever is left.

You, sir, are a ruddy genius. I was looking at the glass pebbles (or indeed, just pebbles!) but HDPE chopping boards are a much better idea. Aldi here I come! :hat:

 

[Hop_it]

You, sir, are a ruddy genius. I was looking at the glass pebbles (or indeed, just pebbles!) but HDPE chopping boards are a much better idea. Aldi here I come! :hat:

Thank you . . . . . Not exactly a genius, but I do occasionally have a bright idea that actually works