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Mash Tun Design

I recently told you about my desire to rebuild my brewery and my need to retool a couple pieces of equipment.

This post will address some thoughts on my mash tun.  I currently use a 50qt “ice-cube” cooler.  I like coolers because they are already insulated and come in a variety of shapes.  They are relatively cheap and easy to drill hole or what have you.  The biggest draw back is the flat bottoms.

I think the ultimate mashing device would truly drain from the bottom, beneath the grain bed.  Furthermore, there would be no pick up tube pulling wort off the bottom UP and OUT the side of the tun.  In my mind I have been pondering using a 15.5 gallon keg upside down.  My thought was to remove the sanke keg spear and valve assembly just leave the inch and a half throat open.  Then turn the keg upside down and cut out the bottom of the keg.  Using a false bottom and a couple tri-clover type fitting I could get a keg mash-tun that truly drained from the bottom without the need of a pick up tube.

I think its an interesting idea.  And I like the idea of building something sort of unique (although, I have heard of people doing this, I haven’t seen to many of them in pictures on posts).  The only draw back I have to the idea is that it would certain ruin the keg of any other application should I decide I want to build a direct fired tun or use it as a HLT or kettle in the future.  Kegs are expensive and sort of hard to get these days.

So I worry about not being happy with that type of design, or it not working out right.  If I build a normal keg mash tun with a false bottom and pick up tube assembly (which works for plenty of people), then I could heat mash water in the mash tun directly and not have to transfer water from a heated source into an upside down non-fired mash vessel….
Decisions decisions…
What are your thoughts?  Maybe you just want to see me ruin a keg for giggles????



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  1. As I read your post I came to the same conclusion. Kind of an expensive experiement, but, I’m pretty conservative about these things. At least that’s what my friends tell me.

    So is the flat bottom causing you to leave some of the runnings behind? Is that what you don’t like? Also, even the more professional systems use pickup tubes. Not that you couldn’t innovate here and introduce a new idea.

    Also, how would you maintain your mash temp if its not direct fired from the bottom?

  2. Adam:
    I am generally fairly conservative with these things too. Plumbing is not really my expertise. I am willing to try most things, I just don’t necessarily have the right tools to do the best job possible.

    To that end, yes my pick up tubes tend to break suction to early and I leave more wort behind than I should. This in part is because I am using copper tubing with non soldered fittings, so they start to suck air and lose suction. I need to borrow someones torch and teach myself to solder the joints. I know its easy I just haven’t tried it yet.

    As for the mash tun. I know a couple guys that use kegs as mash tuns and they have them wrapped in insulation like a water heater. They don’t lose much temp, and they aren’t directly fired. Regardless, of that I also forsee maybe trying a HERMS time set up eventually too if I went that far with the equipment….but more plumbing issues.

    Anyhow, I am still leaning towards giving it a shot, just to try something new and maybe have a novel way of latuering.


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