Mash Tun Design

I want to build a Mash Tun out of a Keg. What is the best design or any advise before I start. Thanks for the help

Cut off top, install false bottom and valve, install a thermometer, and wrap with foil insulation.

If it's going to be mounted in a stand of some type, flip it over and cut the BOTTOM out and install the drain on the 2" flange which is now at the bottom.

Bobby do you have any pics of the Mash Tun?? The Tun is going on a Brutus 10 clone so the fittings would be in direct contact with the burner. Wouldn't that be a problem??

Bobby's recommendation will only work for an electric set up. I have some pics in my signature line.

pickles said:

Bobby's recommendation will only work for an electric set up. I have some pics in my signature line.

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I think you mean you cant direct fire with that setup, which is true but i dont see to many people direct firing their mash tun anyways.

My advice, having a bottom drain is absolutely the best way to go. You dont necessarily need to turn the keg upside down to achieve that. I did it for my mashtun, but i made my boil kettle bottom drained by simply welding a fitting into the bottom. Either way works, id probably recommend just cutting the top out and welding a fitting into the bottom, im sure you could do it weldless as well.

+1 for bottom draining if possible. I direct fire my bottom drain HLT without any problems. I flipped the kegs like Bobby suggested above so that I could route the plumbing through the keg handle holes and not have to modify my stand. Plumbing it this way creates a small air bubble in the drain line, and in restrospect I wish I would have left the kegs upright and just modified the stand for bottom drains. I have to drain a few ounces as the tun is heating up to purge the air, which isn't a big issue, but it's still not ideal. I may re-route the plumbing and modify the stand someday, but it works well enough for now.

I believe you could direct fire a bottom drain just fine. You'd never burn without the wort moving anyway. If you were really worried about it, you could just add a heat shield or block off burner tips that are directly hitting the tubing. No matter what the heat source, I'd never build a tun with a side drain again.

I often read that you can't direct fire such a setup but it's never been tested and verified to be a problem.

I also reccomend buying the lid before cutting the top so that you can cut it to the exact size you need.

Bobby_M said:

I often read that you can't direct fire such a setup but it's never been tested and verified to be a problem.

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My testing has verified that it's not a problem, for me at least. I direct fire my bottom drain HLT every batch, and even though I use a HERMS I direct fired my bottom drain MLT once when I was having mechanical difficulties, and had no issues at all.

Edit: Disclaimer- I have only brewed once direct firing the MLT, and I'm unsure if repeated use would cause any issues, like caramelized wort build-up inside the plumbing. I do know that it worked well the one time, and that the direct fired HLT works well every time, but I can not verify that a direct fired MLT works well long term.

Don't forget the tippy dump.

Direct firing doesn't burn the gasket on the tri-clamp fitting? That surprises me, but I have no actual evidence to refute it.

Silicone is good for up to 600F and with wort running through it, it shouldn't get much over wort temp.

pickles said:

Direct firing doesn't burn the gasket on the tri-clamp fitting? That surprises me, but I have no actual evidence to refute it.

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My rig is way too ghetto for tri-clamps, just brass and copper plumbing parts with two silicone o-rings. Never had any issues. As Bobby pointed out, the liquid inside keeps the fittings relatively cool, and silicone has pretty high temp ratings (I've read conflicting numbers from 450F-750F). I was more worried about the seats inside the ball valves than anything else since I wasn't sure what type of plastic they're made of. I hoped they were PTFE since it's rated for similar temps as silicone, but whatever they're made of appears to be good enough.