4th Essential Step In All-Grain – All-Grain Brewing Series

The biggest thing that separates extract with specialty grain brewers to all-grain brewers is that with all-grain brewers you need a vessel called a, “Mash-Tun”.  You can buy these online but honestly I don’t see the point.  You can make them for a fraction of the cost and you don’t need any special tools.

But before I dive into how to build, I need to point out a few key points. When you are buying a cooler, I would get 2 of them.  One is going to turn into your mash tun and the other is going to be where you hold hot water.  So if you are going to go cheap, don’t go cheap on the mash tun but the one to hold the hot water.  You want something that also can hold about 10 gallons of water.

When you build your own mash tun there are two different approaches that are pretty popular.  One you put a stainless tube in a cooler and that is the easiest way.  I really don’t prefer this one based off my own experience.  What would happen  is that the tube would collapse on itself and end up making a stuck sparge.  So even though it was easy to put together, it turned into a big pain every time.

The other way to do it is a bit more time consuming but well worth it.  By the way I’ll put up pictures of one I just built with a friend of mine, but it took us 30 minutes.  The other way is that you make a manifold with CPVC piping on the bottom of the cooler.  So below are the directions on how to do the different steps.

I could not do a better job then some other blogs out on the internet so I copied what they had and the link is found by them as well.

How to make a Coffin Mash Tun

A local homebrewer has long had a large cooler he mashes in that has been dubbed the coffin. For NHD 2006 we decided to make a coffin for club use (CARBOY) and to do a 20+ gallon batch of 1.090 beer. The large cooler was a donation to the club by a member so all that was needed was the parts to assemble the system and the time to drill the tubing. The cooler that was donated was about 140 qt. Having made a 100qt cooler conversion for another brewer out of CPVC, I knew that it could easily be accomplished out of a few parts from the local home improvement store and local homebrewing shop. It uses a bottling spigot much like my other two rectangular mash tuns but then instead of a coil and copper, it is laterals of CPVC. If we were batch sparging we could have used a single outlet point and a braid or a SS scrubbie on the back of the bottling spigot, but due to the need to maximize grain in the batch, not enough room remained for the sparge water additions, so we elected to make a fly sparge system. The key is to keep the laterals off the walls to avoid channeling through the grain. Here is the parts list and the prices paid (including tax):

Price each
Bottling Spigot
Extra Gaskets for Spigot
90º Elbows – 1/2″ CPVC
45º Elbows – 1/2″ CPVC
Tees – 1/2″ CPVC
3/4″ x 1/2″ Reducer Busing CPVC
3/4″ Threaded Female to Glue Female CPVC
Grand Total

Parts for the manifold (note that three Tees are not pictured)

The layout is pretty simple. The bottling spigot will be put into the cooler through an enlarged drain hole after the old drain is removed. The 3/4″ Threaded Female connector will then be used on the backside of the bottling spigot and additional gaskets as needed. The bushing will reduce the size from 3/4″ to the 1/2″ CPVC.

From there the 45º Elbows can be used to get the pipe system to lay flat on the bottom of the cooler. The 90º Elbows are for the corners and the Tees are for the middle laterals and connecting to the 45º Elbow section. Of course your cooler configuration may differ, some coolers have the drain lower and some higher, your parts list would need to be adjusted for your configuration and cooler. In looking at the bottom inside of the tun (be sure to measure the bottom, not the top, most coolers taper), it became apparent that there was only enough room for 3 laterals if space was to be left at the sides to avoid channeling. I like to drill everything in the field, lats and connecting pieces, but I don’t drill any fittings. Let’s run through the tun fabrication from start to finish. First up, remove the existing cooler drain.

The cooler drain is generally threaded with a coupler tightened on the inside and a few gaskets. Once this is removed the hole may need to be enlarged. If so mark the cooler using a gasket from the bottling spigot as the guide and then remove the marked area.

For enlarging the drain hole I use a spiral saw, and mine just happens to be coordless. I have used other methods in the past from utility knives to saws and most are too violent for the operation and can end up damaging the cooler.

Once the hole is enlarged, insert the Bottling spigot with a gasket on the outside and at least one on the inside. Then tighten down the 3/4″ Threaded female. On this cooler it took two inside gaskets to make that connection.

After the spigot is installed the next piece is the bushing and then later you must figure a method to either move upward to the manifold or downward. If upward you may be able to use a single 45º Elbow, on ours to move downward it took two 45º Elbows and some transition pipe. This is probably the most difficult part to create so save it for last. Move on to the manifold. Try to stay 2″ off the walls at all times. That should allow you to cut the laterals, three in this cooler. Measure the inside length and cut the lats 5-6″ shorter. 2″ for each end and ~1″ for the elbow. You can always recut them even shorter, but to add back will take a coupler. The nice thing is that the pipe is extremely inexpensive if more is required. Once those are cut, trial fit them with the elbows in the bottom to see how you did. In my case the middle lateral had to be moved down in order to accomodate the transition piece for the manifold to lay flat. If this is the same in your case, just cut a short 1-2″ piece of pipe for the bushing, put on the 45º Elbow and then take the other elbow and a short straight edge and find the point where you can get them lined up and one is on the bottom of the cooler at a 90º angle to any lateral. In this cooler it took a cross piece and a few extra Tees to make the connection work out.

Once the lats and the connection to the back of the valve is decided, drill the bottom side of every pipe piece that lays flat to the bottom and that is 2″ away from the walls with a 5/64″ bit. I used a two speed cordless drill and found that the low speed setting was best. Put the holes fairly close together, no more than 1/2″ apart.

After drilling, reinstall the mainfold and see if any joints need gluing. Most of the time, none will. In this cooler only one required glue. Use cleaner and glue designed for CPVC.

Now you’ll have a coffin mash tun all ready for those team brews!

This tun was used for our2006 NHD brew and achieved 78% efficiency on a 70 lb grist and a 23 gallon finished batch size.

NOTE: Use CPVC for the mash tun manifold, not PVC. CPVC is made for the temperature ranges of mashing, PVC is not.


The Other Method

Cheap and Easy Mash Tun Rubbermaid cooler 48 quart from Menards.  Cost was $13.99.  (now it is on sale for $10.67!)  I knew this would work because a guy named Kevin used this same one (except mine has much fancier and deluxe tropical designs…) and so did Denny.  Both of their web pages helped me get ideas.

Braided Stainless Steel toilet supply line tube (Menards):  $3.19

4 clamps at $.58 each:   $2.32

Plastic valve 3/8″:  $1.50

5 feet hi-temp 3/8″ tubing 1.60/foot: $8.00

48 quart cooler:   $13.99

Total cost =    $29.00

Considering a cooler conversion kit can cost $30 itself, this appears to be a cheap and easy way to get into all-grain brewing.  I thought I would start cheap and easy, and if I ever want to upgrade, I can.  

OK here comes my tubing sob story.  I figured I needed hi-temp tubing so I bought the 3/8″ stuff (the wider of the two  typical sizes, the other being 1/4″).  Now I know I don’t.  I could have saved a few $ and made it even cheaper if I had not bought it, but I’m sure it’ll work fine.  Where I ran into trouble was in trying to get the hi-temp tubing through the spigot.  I WAS able to get the non hi-temp 3/8″ tubing through because its walls are a little thinner.  But the walls of the hi-temp tubing make it just too big to pull through no matter how tapered I made the tubing (see above).  That is when I found out that I can get away with using the non-hi-temp (and slightly smaller) 3/8″ tubing for the inner part of the mash tun.  I did use the hi-temp stuff I bought on the other side of the valve.  Bored yet?!

This was the open end of the braided tube.  I sawed off the ends seconds with a hack saw.  Then I pulled the rubber tube out with a pliers.  I decided to fold over the end, bend it onto itself with a pliers, and tighten a clamp as far as it can go.  All I really have to do is keep grain material from getting into the end and that should work.  

Here is the braided tube before I put it over the plastic tubing.  You can see how tight the tubing is in the spigot as it is slightly collapsed where it goes through.  After it was done I filled it with some water and it did not leak.  The water ran pretty quickly out of it through the tubing too, so I think I will get a good rate of collecting wort.

At left is the non hi-temp tubing.  At right is the hi-temp.  The inner diameter is the same (3/8″) but the outer diameter varies, with the hi temp being thicker.


Here’s the Midway Mash Tun ready for action.  It’s no different than a lot of guys have made but I thought I’d post how I did it.


Now What?!

Now all you need is a few more things and you can start your brewing.

  1. A burner – check out amazon or you local homebrew shop.  You want a turkey burner essentially.
  2. Large pot – Get a large stainless steel pot 7.5 gallons at the minimum.  You’re going to be boiling 6.5 gallons of water so keep that in mind.
  3. A pump up song – choose a song that you will play when you are going to put in the mash.  It’s a big moment – the song will add to the drama that will unfold.

That’s it!  The next post for this series we’re making the brew so get pumped! I still remember my first all-grain batch like it was yesterday, I was blasted, “Framed” by Chris Knight.  

Do you remember your first batch of brew or all-grain batch? Leave it in the comments below if you got a story .



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