My Attempt At Building A Mash Tun

Ok, So I decided to get industrious and make my very own mash tun. For those not familiar, a mash tun is a pice of brewing equipment used with All Grain brewing. A mash tun is used to steep the grain and pull the fermentable sugars from it to create sweet wort, the beginnings of your beer. I got the basic directions from Homebrew Talk article: Converting a cooler to a mash tun. Please join me while I attempt to explain how I got all this together!

After what what probably far too much research for what turned out to be a simple device to build, I was set to begin. First up was getting a cooler. Either a rectangular or curricular beverage cooler will do. I picked up a 52qt Igloo rectangular cooler at Target, $20. You can also use a round beverage cooler for this, a common one being a 10 gallon model from Rubbermaid. Either way, you’re good.

The next question is what you are going to use in your mash tun to filter what will become the sweet wort from the grain. 3 options usually used: a copper manifold, a braided hose, or a false bottom. All have there advantages, an while the manifold seems to be the most efficient, I opted for the braided hose, as it was easier to put together and less expensive.  I had opted for the manifold, but Home Depot sold the copper tubing only in 10ft sections and I really didn’t feel like cutting all that up! So I went with the braided hose option.

Now that was the easy part. Several hardware pieces were now needed.   According to the directions, here’s what I was required:

Here are the parts you will need for the conversion (see picture, left to right):

• Rubbermaid 10 gallon round beverage cooler or any rectangular cooler
• all stainless steel ¼” hose clamps x 2
• brass square head plug (Watts A-737)
• ½” x 12” (or larger) braided stainless steel supply hose
• 3/8” female barb adapter (Watts A-298)
• 5/8” stainless steel fender washer (Note:You can convert a 1/2″ SS fender wash by widening the hole to 5/8″ if you cannot find one)
• 3/8” MIP x 1-1/2” brass nipple (Watts A-786)
• seal from plastic spigot of cooler (shown below)
• Teflon tape (note: everything to the left of the tape in the picture above goes inside the cooler, and everything to the right goes outside)
• 5/8” Inner Diameter O-ring (preferably heat resistant, if you can find one)
• 3 x 5/8” fender washers
• 3/8” threaded ball valve
• 3/8” male barb adapter (Watts A-294)

After heading back to Home Depot for these parts, I was home and all set. First step was to remove the plastic spigot that comes with the cooler. A quick turn of the washer on the inside and it was off. Now the key is to retain the rubber O ring and the washer. We’ll use these in a minute. Time to start on the inside.

Plastic spigot removed

Next step was setting up the stainless steel braided hose that would be used for keeping all that grain in and letting all that sweet wort out. I grabbed my Dremel tool and cut off both ends of the hose. Next, I took a pair of pliers and puled out the the plastic tube inside. What you have left is the steel housing that will allow the wort through. I placed the brass square plug into one end and placed a clamp over it to secure. Next, I placed some teflon tape on the brass nipple into the  other end. Grabbed a few Fender washers and placed them around the the brass nipple along with the plastic washer, then placed the female barb adapter on the brass nipple. I placed the seal from the plastic spigot on the inside and inserted the brass nipple.

Ok. Inside done. Now it was time to take the female adapter and pull it through. Done. I placed the rubber O-ring around the female adapter and placed 3 fender washers next to it. Next, I attached the threaded ball valve to the female adapter (after placing some teflon tape on it). Lastly was to attach the male barb connecter. Done. Ok, let’s test it out.

I took my completed mash tun outside and filled it with water. A turn of the handle and it was pouring water out great. Or so I thought. It was dripping from the fender washers ..dang. Ok, to compensate I added 2 more fender washers on the outside. Filled with water and again a drip. Ok, now what to do. After  several minutes of deep contemplation, I decided to switch the rubber O-ring to the inside and the plastic washer to the outside. Once complete, I filled with water again. A quick prayer and I turned the handled….no leak! Imagine my relief. I had successfully built my very own mash tun.

Eureka!

Now it was time for the first all-grain batch the next weekend, which went very well. One issue I ran into was the brass plug attached to the braided hose. The clamp wasn’t on tight enough, which allowed grain to sneak in and clog the hose. This slowed down the pour into the kettle and also lost me a little sweet wort. This was corrected and the next batch should be fine.