Mash Tun - Round Cooler

A mash tun is vessel in which fermentable sugar, color, and flavor elements are extracted from several pounds of malted grain (of various types). The resulting liquid is then boiled for about an hour, with the addition of hops at various points. Then the brew is cooled, transfered to a fermenting vessel, and yeast it added. In about 10 days or so (depending on many factors), you've got beer! Of course, then you have to let it age a bit and then bottle it or keg it.

Anyway, this is a relatively cheap (and very easy) way to make a high-quality mash tun.

Read on for the parts list (with photos) and step-by-step directions.

For information on the basic process of homebrewing, see John Palmer's very excellent How To Brew online book.

Now, on with the project.

Parts List
(1) 5-Gallon Igloo style round cooler ($20 at Target)
(1) Kewler Kitz "Basic Plus" conversion kit ($30 at Northern Brewer)
(1) 9" Stainless Steel False Bottom ($22 at Norther Brewer)
(1) 1/2" MPT to 3/8" Barb fitting, brass ($2 at Northern Brewer)
(1) 1 foot of 3/8" ID high-temp vinyl tubing ($1.60 at Northern Brewer)
(1) 2 feet of 1/2" ID vinyl tubing ($1 at Northern Brewer)
(1) Roll of teflon pipe tape ($1 at Home Depot)
Total Cost: about $78.
Construction Time: about an hour.

5-Gallon Cooler

Kewlwer Kits conversion kit

9" Stainless Steel False Bottom

1/2" MPT to 3/8" Barb fitting, brass

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STEP 1: PUT THE FALSE BOTTOM IN THE COOLER
First, remove the cooler's spigot by unscrewing it from the inside. Then drop the false bottom in:

STEP 2: INSTALL THE BULKHEAD
Put the Kewler Kit bulkhead fitting (the stainless steel silver part) through the spigot hole from the inside of the cooler. The small rubber seal goes on the inside of the cooler. At this point, it will look like this:

Put the large rubber seal on the outside of the cooler. At this point, it will look like this:

Now tighten the brass nut on the outside of the cooler, making sure that the grooved side of the nut faces toward the large rubber seal. The grooved side of the nut looks like this:

Tighten the nut just until you get some resistance. Hand-tighten the whole assembly from the inside of the cooler by turning the bulkhead. Once it's good and tight from the inside, you can use a wrench to tighten the nut on the outside. At this point, this is what you'll have:

STEP 3: INSTALL THE BARB
The 3/8" brass barb fitting screws into the bulkhead. It steps down the thread size from 1/2" to 3/8" so that the outlet barb on the false bottom (which is also 3/8") can connect to the bulkhead. First, you'll need to give the barb threads a few wraps of teflon pipe tape. Once threaded, the barb in the bulkhead looks like this:

STEP 4: CONNECT THE BALL VALVE
Now we can connect the ball valve to the outside of the cooler. This is fairly straightforward, as it just screws on the thread. The only tricky part is that it is hard to make the ball valve assembly line up with the valve handle facing up. If you screw it on and it doesn't line up right (ie - the handle is not above the rest of the valve), use your wrench to turn the brass nut until the handle lines up right. Here's what it looks like when the handle is on top:

STEP 5: CONNECT FALSE BOTTOM BARB TO BULKHEAD
We're almost done. All we need to do now is use a short piece of high-temp 3/8" ID tube to connect the barb on the false bottom to the barb on the bulkhead. Between 2 and 3 inches should do it. It's better to start off longer and cut it down to fit. Once connected, it looks like this:

STEP 6: TEST THE INTEGRITY OF THE CONNECTIONS
Okay, now we're done with the hard part. But we need to make sure that the all of the fittings and connections are watertight. Even a very slow leak is a bad thing during the course of a mashing and sparging. Put about three or four gallons of hot water (from your tap is hot enough) in the cooler and let it sit for at least half an hour. If there are no leaks whatsoever around the circumference of the ball valve (or anywhere else for that matter), then it's time to have a homebrew, congratulate yourself, and let the water out:

IT WORKS!!!