The Mash Tun

Many of the systems that I looked at on-line used a converted keg as the mash tun. I had it in mind that I would do this also, but I had a hard time justifying the cost. The mash tun was never going to be direct fired, it had to be insulated, and it had to be big enough to do 10 gallon batches. The picnic cooler is about $15, the converted keg is over $100 plus it's uninsulated. No brainer, use the cooler.

The other issue is the false bottom. You must have some way to draw out liquid and leave the grains behind. The two most popular approaches to this are:

1. A screen or perforated metal sheet (false bottom)

2. A pipe or series of pipes with narrow slits cut into them

(slotted manifold).

For the picnic cooler type mash tun, I think the slotted manifold approach is much better suited than the false bottom.

I read numerous articles about the perforated metal false bottoms and fully intended to use one, until I saw one in action. The little round holes constantly plugged up with individual grain kernels and was a pain to clean out. On the other hand, the slotted manifolds are much cheaper to make, and in my opinion work superior (at least on my system) to the perforated metal false bottoms. With the proper design, a slotted manifold will provide superior resistance to grain intrusion and also allow wide open recirculation flow rates which are beneficial in a recirculation type mash system. I do not buy into the logic touted elsewhere regarding the "% open area". My slotted manifold has only a fraction of the % open area of the screen or perforated metal and has worked flawlessly. I can recirculate wide open and I haven't had a stuck recirculation yet.

My manifold was made from 1/2" copper pipe (for sweat type plumbing applications) slotted with a narrow band saw blade about every 1/2" or so. The long lengths of pipe were fitted into a drilled 3/4" copper pipe at either end with one end fitted with the pipe that goes to the mash tun outlet. I hold the manifold in place with a stainless steel screw used as a hitch pin through a copper fitting screwed into the bulkhead fitting through the wall of the Mash Tun.

Using a picnic cooler has the advantage that it is easy to modify with holes and ports. I had to modify the drain port on the cooler to accept the bulkhead fitting for the outlet. I did this with an exacto-knife, try that on a stainless steel keg. There are two valves on the outlet of the Mash Tun (not three like the photo shows). The valve closest to the Mash Tun is the recirculation valve to the pump. The other valve is used for strike water into the mash tun, and sparging to the kettle. The third valve was for sampling the runnings, but I hardly ever used it and it just made the whole assembly heavier, so I eliminated hit. Since the mass of these valves is significant (even with only 2 valves), I used a rather heavy duty brass bulkhead fitting. Remember, ball valves are heavy, and you do not want this fitting to leak or break off. Pick up a good, heavy duty bulkhead fitting for this connection. Go to the links page and look under The Parker Store for a place to get brass bulkhead fittings.

Lastly is the return manifold. This provides the means to allow the wort heated by the Heat Exchanger to gently return to the top of the mash. It is also the means to distribute sparge water during the sparge. I constructed the manifold from 1/2" copper pipe friction fitted together so that it would come apart for cleaning. A series of 1/4" holes allows the recirculated liquid to gently flow out onto the top of the mash. The "H" support bracket provides a place from which to hang the manifold. The manifold is connected to a quick disconnect fitting, through the wall of the Mash Tun, which is then connected to the Heat Exchanger.

Click here for details on the Mash Tun Stand.