When I first joined the Brew Crew, I had to figure out how to contribute to the group... because they had already spent quite a bit of money on equipment. They were just starting to do 10 gallon batches of All Grain brewing, but the Mash Tun was almost completely worthless. So, I bought two 10 gallon cylindrical coolers for use as a Mash Tun and a Hot Liquor Tank.
I say the equipment worthless because they almost killed themselves with steaming hot water. The new setup (pictured on the right) is quite nice. The water stored in the HLT flows down the tube into the sparge arm for the Mash Tun.
The 2 coolers were modified to not fail when they were filled with really hot water. The first thing to go was the stock valve. These were normal dump-water-on-coach coolers, so the original valves were setup for cold water... and wouldn't take the extreme temperatures we were going to put them through. So, we got some nice ball valves to replace those with. In the Mash Tun, Tam (on the left side of the picture) and Brenden (right side) built a false bottom so the new valve wouldn't get plugged with grain. Then to accomodate the sparge-arm, the lid to the Mash-Tun is raised off the rim of the cooler with some rubber stoppers.
We've brewed 30 gallons with the new equipment, and it seems to work pretty dang good. Questions?