Building a Mash Tun with Style
Your mash tun may be one of the most important vessels in your brewery. This is where the sugar is made, where the magic happens, as they say. There are literally thousands of different ways to make a mash tun, and hundreds of different vessels that you can use. This week, I wanted to talk a bit about the two vessels that we have some pretty extensive experience with, and show you (with the help of our video, How to Convert Your Cooler to a Mash Tun, embedded at the end of this article) our favorite ways to make a very clean, easy to use, and effective mash tun.
The First Vessel: 10 Gallon Cooler for Water
These 10 gallon coolers are great! They’re cheap, easy to work with, and hold temperature insanely well. They can also hold up to 22 lbs of grain, which makes for just the right amount of sugar in a 5 gallon batch! Because we cover the actual process of drilling and converting in the video, I wanted to talk a little bit more about the why.
First and foremost, an anecdote. My very first mash tun was this beastly green 10 gallon construction water cooler, which I ‘upgraded’ with a standard domed false bottom, connected to the ball valve with a piece of rigid tubing that turned super soft and pliable when it got warm. Haha, much to my chagrin, this damn thing stuck EVERY SINGLE TIME I tried to use it! Eventually, about 60 pounds of grain later, I realized what was happening, and changed the hose to some CPVC (back when that was a thing), and that helped quite a bit.
Now that I had the dip tube worked out as a single hard pipe, it was WAY too big at 1/2 inch, and pulled hard enough to compact the grain bed, so I was back in the same boat! So, the fix: this delightfully brilliant, stupid simple stepped or curved false bottom. Such a simple thing, but this made all the difference. The included 3/8 inch stainless steel dip tube that fits right into the smaller hole drilled in the false bottom is the perfect size, allowing for vorlauf with either a pump or gravity without getting crazy and compacting the grain bed.
So, now that you’ve heard (read, I guess) my story, let me tell you why we used what we used in the video, and how many different issues that are fixed before you even start the mash! The hard piped dip tube is HUGE, even if you don’t realize it, and an even bigger deal when you’re using a keggle (more on this in a minute!). This means grain weight is never going to squeeze the tube shut, and the way that fluid dynamics work, you are getting very even drainage over the course of the entire false bottom as opposed to all of the wort moving towards a single point in the center like if you were using Kettle Screen, which means less potential for channeling during your fly sparge, meaning more fermentable sugar into your brew kettle, fermenting vessel, and finished beer.
If you are batch sparging, you’ll worry less about this, but it’s still nice to know that you have even sparge water flow through the grain bed.
The other thing we did in that video to really pimp that cooler out was to add a thermometer. We used a Weldless Fitting with FPT x FPT, the opposite of the Weldless Fitting with MPT x FPT we used for the ball valve on the bottom port. These particular weldless fittings are very well made, and made for us homebrewers! They are clean, short, and easy to use, and at the end of the day, it should all be SUPER easy! More parts, more pieces mean more problems, which leads to inconsistent brewing process no matter how you brew!
The trick to adding this in, and making it super clean, is HOW you drill into all of that insulation. If you use a hole saw bit that’s 1-¾” , you can drill through all of the insulation to the inside wall of the cooler and leave yourself a pilot hole without actually going through that inner wall. From there, it’s the easiest thing in the world to pull the insulation, put your step bit back on, and drill your 1” hole for the weldless fitting and screw in the thermometer! This makes the install super clean and hides that you drilled anything at all! You also get the benefit of having a thermometer mid-wort for accurate temperature readings.
Vessel 2: A Whole Different Animal
Converted Kegs are, without a doubt, amazing! They are thick, well made, easy to work on, and most importantly, hold a lot of grain! We average at 39 lbs as our standard grain amount when we mash in the keggle, but you can do as little as 12 lbs safely.
We need to have a disclaimer on these, though. Maybe a disclaimer that’s a few parts long! First, as homebrewers, we are connected to a wide and awesome beer community that includes us and craft breweries, which we support 1000%, right? This is important, because if you are using kegs from craft breweries, you are hurting the community. Craft brewers pay big money to acquire and maintain kegs, and the keg deposit doesn’t even begin to cover it! We need to show our support for the craft brewing community by only using craft kegs when they are defunct and given/sold to us by that brewery. It’s the right thing, my friends. Always remember Rule #1 (Don’t be a dick)!
The next part is that kegs get old, and most breweries, big 3 and craft, generally have plenty of defunct kegs, so they are fairly easy to acquire legally. Just keep it in mind! There, stepping down off of the soapbox now!
So if you’re using a keg with the top cut open, this false bottom actually fits perfectly. It’s literally made for this use, and is even slightly curved up on the sides to account for the bottom of the keg! Grain bed compaction, especially if you are using a pump, is more of an issue here, so make sure you ramp your pump down on the OUT side when doing your vorlauf or recirculation.
WIth a keg, you have a couple of different options on the conversion part: either have someone weld in 1/2 inch couplers, or use the same Mash Tun Conversion Kit that we used on the cooler, and create a weldless version. They both have their benefits. I love how easy and fixed the welded couplers are, and also that on the weldless version, I can completely remove everything and clean it, soak it in vinegar to get rid of beer stone, and scrub all of the threads with a brush.
The real hard part here is getting all of the holes drilled and installed at the proper heights so that you eliminate as much cutting of the dip tube as possible. In the cooler, it’s absolutely unavoidable, but in the keg, you should really only have to take a little off of the back where it goes into the compression fitting.
Compression Fittings and You
These SS Compression Fittings are something that I’d never really worked with until we found them and decided to use them as a super clean way to do this install. Luckily, my partner in crime has a broader perspective of all things mechanical and how things fit together, so it was a no brainer for him!
The reason these are brilliant, and along the same lines as many mash tuns that you see with quick disconnects to disconnect the dip tube, like the BrewBuilt False Bottom Kits, is they have the ability to easily remove the dip tube and false bottom, you can easily clean and reset the false bottom every brew day. With the compression fitting, all you have to do is unscrew it once the ferrule is clamped, and it makes a super tight seal so the dip tube doesn’t move around if you accidentally hit it with your mash paddle.
When you install your ferrule, remember to do it just like the picture above: narrow side of the ferrule facing the actual fitting, and the small beveled piece pointed towards the fitting as well so that it lays flush on the ferrule. This pic also helps when, if you’re anything like me, you accidentally drop the whole thing and can’t remember how it goes together!
That’s it, friends! Between this post and our video below, you are ready to make the best mash tun to fit your brewing process, and do it yourself to boot! Don’t forget to connect with us on Facebook, Instagram and Twitter, and check out our other fun and super helpful videos on BrewChatter TV! Please leave your comments below and let us know how you built your mash tun, and how it works for you! Brew On!