I’ve read many web-pages on the subject of converting a 10-gallon Gott cooler (now Rubbermaid) into a mash-tun. I came up with my own approach, which I think is much easier and cheaper too. To begin with, get a 12″ Phil’s Phalse Bottom. It fits a 10 gallon Gott perfectly. The tricky part is always the “bulkhead” fitting, where the wort line passes through the wall of the cooler. Phil suggests using a drilled rubber stopper with a 3/8″ OD copper tube. I think that will leak, especially if you accidentally bash it with the paddle while stirring your mash.
Here’s how I did it:
Start with your basic 10-gallon Rubbermaid or Gott cooler (mine is a Rubbermaid, purchased rather expensively at a restaurant supply.)
I ran the wort line out the spigot hole at the bottom, like everyone else. You have to remove the spigot. The spigot is held on with a large plastic nut on the inside, and a rubber gasket.
Here’s where my method departs from others I’ve seen. Gott has conveniently already solved the bulkhead problem with this spigot. Perhaps we can find a way to leverage their work. Since we were originally just going to throw this part away, we may as well take it apart first (in the interest of science). If you push the spigot button, you can use a sharp knife to cut off the plastic valve that will protrude from the inside of the spigot: The valve core will then fall out the other side.
To make this into a bulkhead fitting, we need to run a piece of tubing through the spigot body in a water-tight way. For good flow-rate and resistance to clogging, I used the ubiquitous 3/8″OD copper tubing from Home Depot. The spigot body has a hole straight through it that the core used to be in. The hole is too small for the 3/8″ tubing, but the spigot body has enough material that we can enlarge the hole just enough to get a tight fit. I just used a 3/8″ bit in the drill press:
Then you can push the copper tubing through the hole to complete the bulkhead fitting:
At this point, I replaced the spigot on the cooler, with the original rubber gasket and plastic nut. Filled with 10 gallons of water, it was water-tight. Nevertheless, to be extra sure, I applied some food-grade sealant around the joint on the inside.
And that is basically it. No futzing about with poorly-fitting rubber stoppers, no search for some elusive combination of Home Depot pipe-fittings (I wish I could get all that time and effort back now.)
Install the Phil’s Phalse Bottom inside of the mash tun. A short piece of 3/8″ID plastic tubing will form an adequate seal with the copper tubing on the inside. Don’t bother with hose-clamps or anything, this connection doesn’t have to be water-tight. But it should be firm enough to withstand a bump from the stirring paddle without coming off. On the outside, you can install a valve on the copper tubing to control the flow-rate during sparging and run-off. I used a compression-fit quarter-turn ball-valve. The large port of a ball-value is desirable to avoid getting clogged by bits of grain husk that may get through the false-bottom before the filter bed is set. If a bit of grain gets in there, just open the valve all the way for a second to push it through.