Esky Mash Tun - What Size for 20L No Sparge?

[cpsmusic]

Hi Folks,

Just a quick question. I currently use a 26L esky as my mash tun for 20L batches and this works out well when doing batch sparges. I'd like to try "no sparge" which means having everything in the mash tun at the same time - for most batches I do that would be about 5kg of grain plus 26L of water. Just wondering what size esky would be appropriate for batches of this size?

ATM, I'm thinking of getting one of the Coleman Xtremes. Out of interest, the Coleman Xtreme 95L jobs are currently $120 at Masters which is actually cheaper than any of the suitable smaller ones! I'm thinking that these would be too big for what I'm doing right? Especially as I'm also interested in getting an immersion heater. I've found a 58L for $129 - would that be a suitable size? Or would something a bit smaller be better - say the 38L (too small?) or the 47L?

 

[MHB]

You have to look at what you are going to put in there, it will be mostly water the amount you want into the fermenter plus all the losses along the way so we need to work backwards.
20L Lets say you mean 20L to packaging (keg/Bottle) allow 2L for loss in fermenter - 22L
Kettle dead space, include loss to trub and hung up in hoses... say another 2L - 24L
Vaporised during boil, well lets say 10% so star of boil volume L*0.9=24 Start of boil = 24/0.9 = 26.67L
Not quite exact but say you loose 1L/Kg of malt with expended grain, another 5L gives us 31.67L of water at the start (or added by the time you are ready to drain down to the kettle)
The volume occupied by hydrated milled malt is usually taken to be 0.7L/Kg (0.65-0.8 depending on the grind) but 5Kg of malt at 0.7L/Kg is 3.5L

All up you are looking at 31.67+3.5 = 35.17
A bit of room to stir and allowance for the odd high gravity batch is a good idea the books say 30-40% excess capacity, 45- 50L is the right answer.
I have rounded up rather than down You could probably get away with the 38L but if you want to branch out and try some more adventitious beers later it might limit you - I would go for the 47L
Mark

 

[cpsmusic]

Thanks for the detailed answer. If I'm doing mainly 20L batches, how big would be "too big"? The reason I ask is that Masters have 95L coolers that are cheaper than the 58L version but I was thinking that the mash will be shallow and that means that an immersion heater won't work properly. Is there a point where the cooler becomes too big?

 

[goid]

You have to take into account the air space left in the esky. With more air you need to account for a bigger loss in heat from the grain bed once you add the strike water and close the lid. Also every time you open and close the esky. You can put something on top of the mash like some foil or alike to cover the mash and lessen this effect.

 

[MHB]

Yes
There are two main ways
First if you are using the grain bed as a filter it needs to be a certain depth, depending on the fineness of the grind and the resulting degradation of the husks that form the filter 100-150mm of grain would be a minimum for a very slow runoff and/or sparge, 250-300+mm, is much better for most home brewers (take the volume of grain from above, play around with the volume of a cylinder equation V=Abase*height to work out height of grain bed for various tuns)
Second most of the heat loss in a reasonably insulated tun is through the surfaces, the bigger the diameter the greater the loss, if you double the diameter the aeroa from where the heat is lost goes up (well from A=Pi*r^2, if you double the diameter the area goes up really fast) (you other losses go up pretty dramatically to)

If its a decent esky it should last you for a decade or more, I wouldn't let a couple of bucks be the decider - go for the one that best fits the job
Mark

 

[Whiteferret]

Also remember that most Esky volumes are a total including the volume of the walls so use a tape measure and calculate from the internal size for yourself before you buy.

For example my 150 Liter mash tun is really a 120 Liter.


edit for example.

 

[cpsmusic]

Also remember that most Esky volumes are a total including the volume of the walls so use a tape measure and calculate from the internal size for yourself before you buy.

For example my 150 Liter mash tun is really a 120 Liter.


edit for example.

Thanks - that's a great tip! I was just at Bunnies looking at the coolers and opened up a few and thought the volume looked quite a bit less than what was on the label! Now I know why!

 

[Mardoo]

Yep, esky sizes are almost always packing volume (external volume), not internal.

 

[mudd]

My opinion is not to go too large. If you want to knock out a stronger beer there are options to actually sparge in that case.
Disclaimer I'm actually a fan of fly sparging so in my case I find I comfortably do a double batch in a 42L esky.

Calculations above looked spot on.

Worth thinking about what type of system you would like to finally have.
Cheers Mudd

 

[cpsmusic]

My opinion is not to go too large. If you want to knock out a stronger beer there are options to actually sparge in that case.
Disclaimer I'm actually a fan of fly sparging so in my case I find I comfortably do a double batch in a 42L esky.

Calculations above looked spot on.

Worth thinking about what type of system you would like to finally have.
Cheers Mudd

I'm actually pretty happy with my esky mash -> stovetop boil.