Building a keg bottom draining mashtun

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dmcman73

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I just got a 15 gallon keg for free, the spear in it was damaged so it was already removed and the keg is in excellent condition.

My plan is to cut out the bottom of the keg and use a triclover kit on the "top" to convert it to bottom drain.

To insulate, I am gluing aluminum foil to one side of 3/4 inch foam insulation (pink stuff from the box stores), cutting the 3/4 foam into 1" strips. I am then going to place them all around the keg (aluminum foil side towards the keg) and then use expanding foam in the seams if the foam strips. Once the foam is dry, trim it down and then build a wood covering around it with 1" wood strips. Between the aluminum reflecting the heat back, 3/4" foam and the wood acting as an insulator, I should keep some good temps.

Tbe bottom and the top of the keg will also be installed as well.

I will post pics here as I progress.
 
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dmcman73

dmcman73

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So here's my progress so far. I drilled a hole into the bottom of the keg and made a really crude jig with a carriage bolt in it to hold the angle grinder. After I cut the hole, I cleaned up the edges and then I used some 3/8 inch silicone hose I had laying around, sliced it down the middle and then ran it around the edge. This way, no cuts or scrapes and it provides a really nice seal for the lid I am going to make.

The lid is a 13" round stainless steel pizza pan. The pan area (where the pizza would be) will be filled with thick foam. The bottom of the pan will sit in the hole of the keg while the edge of the pan will sit on the silicone.

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dmcman73

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So I was able to get the insulation done today. I used one sheet of 3/4 inch thick foam insulation. I cut them 21.25" long and slit them 2 inches apart where I then bent them. I used blue painter tape on the back of the foam (side going against the keg) going width wise to keep it all together. And then wrapped it around the keg and used some left over aluminum duct tape I had to keep it tight. There is a 1" space from the edge of the keg to the edge of the foam (top and bottom), this is where I am going to cut out a circular wood ring to go around the keg and that's where I will be tacking the wood planks too. After I wrapped the outside of the keg, I used an old happy meal "monster high bucket" (don't judge) to go around the bottom drain port and taped it in place all around to make it tight (so the foam wouldn't expand into that area) . I filled the cavity with expanding foam and then used a round piece of foam I cut out with a hole in the middle as the "top" to finish it off. I used tape going across the top of the round foam to keep everything in place so the expanding foam wouldn't push it off.

The lid, which I used a 13" pizza pan) has a round piece of foam taped to it as well (using aluminum tape) and then I punctured two hole into it and filled the void between the pan and the pink foam with expanding foam.

The expanding foam I used was the one made for windows and doors so it wouldn't destroy everything when expanding.

It looks a mess right now, but once it's dried, I am trimming it all down smoothly.

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30Bones

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Oh my that is quite the project. Nice work. So no plans to heat this in any way? I used to recirc my mash to maintain temps and never wrapped my keggle. Sloooooowwwly building a bottom drain electric setup and am on the fence about keeping my cooler mash tun or going to a HERMS
 
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dmcman73

dmcman73

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Oh my that is quite the project. Nice work. So no plans to heat this in any way? I used to recirc my mash to maintain temps and never wrapped my keggle. Sloooooowwwly building a bottom drain electric setup and am on the fence about keeping my cooler mash tun or going to a HERMS
No, no plans on heating it which is the reason why I am insulating it the way I am. My cooler that I have (round orange one from Home depot) was able to maintain temps over the course of 60 minutes with no issues and the insulation that's in those coolers is the same type of expanding foam. I figured with the solid core foam wrapped around it, it should give me (at least I hope) the same performance as my plastic one.

I was able to trim all of the excess foam off of the keg last night and also paint it black. I figured the paint will help with any moisture that may get on the foam and since it's black, help retain some heat.

The next step in this project is to get the wood and build all the slats to go around the keg which will protect the foam, add to the insulation to retain heat and will make it look nice. Once I start cutting the wood, I'll post pictures as I assemble it.

I have all my ingredients to make an Irish Red so hopefully, I can test drive this soon.
 
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dmcman73

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nettekdl

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You can prevent air gaps in the insulation by cutting into what are called lags, take the circumference of the bare keg and divide by number of pieces, add for insulation thickness and do the same then bevel the pieces accordingly to get a smoother finish and no spray foam mess. Probably totally unnecessary but I guess I'm an aesthetic nut as I insulate mechanical systems for a living. Nice job on the build, I may have to build something similar with the keg I have waiting for a purpose
 
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dmcman73

dmcman73

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You can prevent air gaps in the insulation by cutting into what are called lags, take the circumference of the bare keg and divide by number of pieces, add for insulation thickness and do the same then bevel the pieces accordingly to get a smoother finish and no spray foam mess. Probably totally unnecessary but I guess I'm an aesthetic nut as I insulate mechanical systems for a living. Nice job on the build, I may have to build something similar with the keg I have waiting for a purpose
Thanks! That's what I am doing for the wood outer layer, since the foam will never be seen once the wood is on, I wasn't going to spend all that time cutting the foam.
 
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Well, minor set back. This is what happens when you thought you planned everything out but in reality you'll always miss one thing. Apparently the window and door version of great stuff isn't very good to fill large voids. even though it expands and filled it all it doesn't dry. looks like I have to cut the bottom foam and scoop that mess out. the next thing I'll try is great stuff for large gaps and cracks, I think this version should do the trick. I've seen other people filling buckets with this expanding foam and not having a problem.
 

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Interesting project! I'm sure that you are much bigger and stronger than I am, but my first thought was, "Wow- that sucker is going to be HEAVY!" :D

I have a bottom draining keg for my MLT also, and even empty it weighs like 30 pounds. There is no way I could lift it with no handles and with the heavy wood liner, especially when it's full of wet spent grain.

I have a HERMS though, so I don't worry about insulating it. I will point out that stainless kegs do hold heat better than I anticipated, even when not using the HERMS if they are preheated. They aren't as good that way as coolers, of course, but they aren't that bad. A lid really helps hold in more heat that I thought it would.
 
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dmcman73

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Interesting project! I'm sure that you are much bigger and stronger than I am, but my first thought was, "Wow- that sucker is going to be HEAVY!" :D

I have a bottom draining keg for my MLT also, and even empty it weighs like 30 pounds. There is no way I could lift it with no handles and with the heavy wood liner, especially when it's full of wet spent grain.

I have a HERMS though, so I don't worry about insulating it. I will point out that stainless kegs do hold heat better than I anticipated, even when not using the HERMS if they are preheated. They aren't as good that way as coolers, of course, but they aren't that bad. A lid really helps hold in more heat that I thought it would.
To me, it's not that heavy but I do plan on building a dump tray to secure it too so all I need to do is tip it and shovel out the spent grains. I clean everything on the stand so I don't need to move it to anywhere.
 
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It seems like a lot of extra work using the rigid foam when fiberglass or mineral wool would have just wrapped around.
Took me 20 min to cut the foam and tape it to the keg tight, not cutting marble here. Mineral wool or fiberglass is another option but, those don't dry out as fast, or at all, if moisture gets in there. The foam I used is made for subfloor so it's built to handle moist/wet areas.
 

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Excellent project! For cutting your wood evenly and cleanly, I found a website that had a really nice calculator on it to figure your angles so they fit together cleanly. This guy used it to make a drum. Anyway, Here is the website
 

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To me, it's not that heavy but I do plan on building a dump tray to secure it too so all I need to do is tip it and shovel out the spent grains. I clean everything on the stand so I don't need to move it to anywhere.
I have a tippy dump too, and it definitely helps with labor! I do still need to move it occasionally, though. If you can hang it upside down after you dump it, by flipping it all the way over, the helps drain it plus it allows access to the fitting on the bottom. I don't take mine apart completely very often, but sometimes the gasket needs adjusting or changing, or sometimes the bottom drain can get some debris in there, so that is very helpful.
 
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dmcman73

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I have a tippy dump too, and it definitely helps with labor! I do still need to move it occasionally, though. If you can hang it upside down after you dump it, by flipping it all the way over, the helps drain it plus it allows access to the fitting on the bottom. I don't take mine apart completely very often, but sometimes the gasket needs adjusting or changing, or sometimes the bottom drain can get some debris in there, so that is very helpful.
Thanks for the suggestion! I was planning on building the tip tray with removable pins so that I can pull the whole unit off the stand when needed.
 

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I f%%ked myself once with that Great Stuff, trying to fill a void, more like a cavity.........They don't tell you on the directions that it needs ambient moisture to cure.
I was filling a cafeteria milk cooler cabinet, 1 1/2 wide, 24" tall, and 24" deep.
Made one HELL of a mess in my shop!

DOW Chemical reimbursed me for six cans of the stuff, after I called them and asked why their product wouldn't "set up" !

Just for future reference to all, if filling a big void, get 2 part foam!


Edit: you won't have to "scoop" it out, just remove the tape or whatever is holding it within, and it will run out, then set up.

Have some old cardboard under it when you do, to catch that crap!
 
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I actually punched a series of holes into the Styrofoam to allow air in and also sprayed a mist of water over and into the holes. Hopefully that will help it setup.
 
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Excellent project! For cutting your wood evenly and cleanly, I found a website that had a really nice calculator on it to figure your angles so they fit together cleanly. This guy used it to make a drum. Anyway, Here is the website
Thanks Takuie!
 
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Decided to do a dry fit of the slats I made so far, pretty good. I need to make about 15 more, sand down the wood rings around the keg and then, attach the slats permanently. Once that's done, I just need to make the wood covering for the lid and make the "feet" so there's clearance for the bottom drain plumbing.

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Sorry for the lack of updates, I was really busy at work but today I finally managed to build the outer wood "skin". I made a change to the wood, I cut all the pieces in half to make them thinner (make it half the weight) and I planed all of the pieces so they were the exact thickness.

Right now it's been rough sanded, I'm deciding if I want to leave it that way to give it an old sawn look or to sand it down before staining/sealing it.

Here it is as it is now. I gave to fill in all the nail holes and sand it but the band I will put on the top and bottom will cover those.

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Now that is impressive! Love how it's in the spirit of a wooden mash tun, but uses stainless and insulation, still used in the same manner without direct heat. For ease of cleaning and longevity.
 
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dmcman73

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Thanks BigRob, I'm hoping to break this in this weekend to brew an Irish Red. Hopefully it performs as well as my old plastic cooler mash tun.
 
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The copper bands are made from copper flashing, the type you use on the foundation prior to laying wood. I found copper bands online but they were expensive. Since it was only decorative, I used what I had.
 
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OK, nearly done!! Unfortunately my time to spend on this has been an hour here and 10 min there so progress has been slow. I just finished making the legs for the tun from some left over pine 4x4's I had when I built my daughter a bed.

Bottom drain plumbing is installed and all I have left to do is finish the lid, stain/seal the new legs and clean it!

What does everyone think?

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helterscelter

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Damn nice. That's what I think. Any thoughts on a different support for the drain? Having to remove two screws has got to be a little awkward, and I suspect the wood they are in will wear out eventually.
 
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dmcman73

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Damn nice. That's what I think. Any thoughts on a different support for the drain? Having to remove two screws has got to be a little awkward, and I suspect the wood they are in will wear out eventually.
Thanks!

As for the drain, I really don't ever plan on removing it at all unless it's to replace the gasket. If I find that I have to remove it regularly than what I plan on doing is replacing the screws with studs where one end is a wood screw and the other end is a machine thread. I can then use wing nuts to hold the strap on and keep the wood blocked fixed on.
 
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Another small update, I've been toying with the idea of adding a logo to the barrel. I printed this out as a roof of concept to see if it would look good. I may have it printed out on vinyl and stick it on.

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Put it on there with a wood burning setup.

I think it would be more fitting, versus a big vinyl placard.

Just think, you could use a magnifying glass, and sit out in the Sun and burn it on there...........:D
 
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dmcman73

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Put it on there with a wood burning setup.

I think it would be more fitting, versus a big vinyl placard.

Just think, you could use a magnifying glass, and sit out in the Sun and burn it on there...........:D
I was actually thinking of doing that, using the picture I had on there as a stencil. The other option I was thinking of was to paint it on and then sand it a bit to give it that worn look.
 
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dmcman73

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Well, I just made my first brew yesterday in the new mash/tun, it's officially broken in. It performed perfect. Held Temps in a 60 min mash and only dropped less than 2 degrees in that time, and that was without preheating it (I forgot).

Cleaning it was a breeze, as easy, if not easier (since the grains were almost dry due to the bottom drain) as it was to clean my old cooler one.

I am extremely happy with it.
 
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