DIY: Mash/Lauter Tun

Making your own Mash/Lauter Tun

In college, we discovered a loop-hole in our club funding policy. While it was against the rules to use student club funds to purchase alcohol, it turns out buying equipment and ingredients that could be used to make alcohol was perfectly fine. So I helped found The Brew Society, and last I heard, the club is still going strong many years after my graduation. Back then, we did strictly all-grains, and we brewed them pretty seriously (using the bio department's incubation rooms to regulate fermentation temperatures and the autoclave to sanitize all of our bottles and equipment).

Once in grad school, home brewing sadly got pushed to the side, and for years I didn't even own any brewing equipment. Just last year, however, I came into possession of a friend's brew kit - and since then I've been dabbling with partial grains. Getting ahead of myself, I recently went ahead and purchased ingredients for an all grain; unfortunately, I have no all grain equipment. So, rather than buy a mash tun and lauter tun, I've decided to build it all myself. Now you can spend A LOT when it comes to this type of equipment, so if I can save money without sacrificing functionality, then I'll do it. Hopefully others who are in the same boat may find this helpful.

I don't plan on brewing anything larger than 5 gallon batches, so when I first started shopping around for Rubbermaid coolers, the 10 gallon seemed a bit large for my desired scale. A nice compromise was the 7 gallon Rubbermaid cooler, which can be found at Walmart.

Once I had this in my possession, the question became either to use false bottom or manifold - I chose a false bottom. So now that I knew what I wanted, I purchased the rest of my supplies:

Supplies:
Rubbermaid 7 gallon cooler ($40.00)
Stainless steel false bottom ($30.00)
5 ft Tygon Norprene tubing ($6.00)
3/8" ID copper pipe ($0.25)
3/8" in-line valve ($2.50)
2 stainless steel hose clamps ($0.75)
Permatex clear RTV silicone sealant ($5.00)
Adjustable wrench (borrowed)
Pipe cutter (borrowed)
Half-round file (borrowed)
Hack saw (borrowed)

Total: $84.50

The end price turned out to be a little more expensive than I had originally hoped, but compared to most MLT that you can buy online, it's still over a $100 savings. The cooler is definitely the most expensive part of this assembly - there's no getting around that. To save a little more money, the false bottom could have been replaced with a manifold; however, the false bottom seems to get better efficiencies and is less prone to stuck mash.

Assembly of the mash/lauter tun was quite simple and fast. Using an adjustable wrench, the plastic nut on the inside of the cooler was removed (the nut is an odd size, so an adjustable wrench works best). Rather than spend +$50 bucks on a ball valve/bulk head package, I followed a similar prep posted on RonBlog. The faucet was taken out of the cooler, and using a hack saw, the faucet end was removed from the bulk head.

A small length of 3/8" copper pipe was inserted through the faucet bulkhead. It was a snug fit, but I used food grade silicone sealant to ensure a watertight fit.

Now it's important when using a sealant that comes in contact with any type of beverage that you make sure it is food-grade sealant. A way to check is to look for the NSF seal of approval. If it doesn't say so, then it's probably not good for you. Don't go cheap on this either - you may not care, but your friends that you share your beer with probably will. A good sealant to use is Permatex's (#66B) RTV silicone sealant. It passes the NSF 51 Standard (food safe), and it's waterproof and flexible with a temperature range up to 450 °F!

Once the bulkhead is placed through the cooler wall and tighted down with the nut you previously removed, you can now connect the false bottom to the copper pipe. I used Tygon's Norprene tubing, which is designed for hot beverages so you know it's food safe. This tubing is thick-walled so it won't collapse under weight of the grain bed, and it's good up to 275 °F. On the outside of the cooler, I affixed more tubing and an inline valve (food grade). These were tightened down with hose clamps, and the job was finished. Very simple.

UPDATE: After its inaugural run, this MLT held its watertight seal, and was able to maintain its temp for an hour (only losing 1 °F in that time). I also got an efficiency of around 90% using a batch sparge. It was very easy to clean up - definitely worth building one of these.