On of the most popular high efficiency mash tun design is the 5 gallon Igloo cooler.
This cooler can be picked up at almost any hardware store for around $25, and a 10
gallon for around $40. A 10 gallon mash tun should be used for 10 gallon batches or
high gravity 5 gallon batches.
The design of these coolers holds heat extremely well, and adapting a manifold is quite easy. The 5 gallon design can hold up to 12 pounds of grain, which can get you a wort around 1.065.
Your manifold can simply be 1/2 copper tubing with slots cut into the tubing. A hack
saw works for this, but a dremel or some sort of power tool makes easy work of this.
Drilling holes is another option, but keep in mind the diameter should be smaller than
the size of the grain… and you’ll need alot of them! Slots cut about 1/8″ apart will
work just fine and is a lot easier.
Remember to remove any burs created from cutting the slots and remove any grease
or grime before use. A simple solution of star san and warm water cleans copper to a
bright shine. If you solder any connections, be sure to remove any remaining flux and
leave some connections open for easier cleaning. The connections at the valve can be
soldered, while the remaining connections are left open.
Sanitation is not required, as the wort will be boiled after this process anyway. You will
find that the acids from the wort will clean your manifold to a bright shine… so if the
manifold is dirty, that dirt ends up in your wort.