My Homemade Mash Tun
My home-made mash tun
Here are some pictures of my home made mash tun.
It's a Thermos brand 'Weekend' insulated coolbox with a capacity of 28 litres and currently (2008) cost about £14. Near the bottom I've cut a hole in the side and installed a plastic 'drum tap'. These are available in just about all homebrew stores - they're the same as are used on pressure barrels. It is important to note that the tap is fixed to the inner shell of the box - the polystyrene insulation and the outer casing have a slightly larger hole than the inner, so that the flange of the tap will fit through and allow the tap to mate against the inner shell. The only thing wrong with this box is that the insulation of the lid is not very good. I just fold up an old woollen blanket and put it on top of the lid to hold in the heat. I've used a thermocouple to measured the internal temperature during a mash and it drops just a couple of degrees C during a 75 minute mash.
The copper manifold
This is the copper manifold. It's made from 8 short pieces of standard 22mm copper pipe as used in domestic plumbing, 4 '90° elbows' (22mm), 2 'equal tees' (22mm) and one 'reduced branch tee' (22mm x 22mm x 15mm). The diameter of the 'reduced branch tee' is just right to fit inside the stub of clear plastic tube sticking out from the tap. If you're lucky you'll be able to get short offcuts of copper like these for nothing from a plumber.
The straight pieces of copper have slots cut in them about 5mm deep and at about 1cm intervals. Originally I used a simple hacksaw to cut the slots but they weren't really wide enough and I increased the width to about 1.3mm using a thin file. You could most probably use a 'Dremmel' drill or something similar to widen the slots if you didn't have a thin file.
The whole manifold is soldered together, although I have since read that it's a good idea to keep it so that it can be taken apart for cleaning and if I ever made one again I'd probably do that, although it's not been a problem so far. I just sterilise it after use and just once in the last 10 years I've warmed it up with a blowlamp and given it a few good taps on a piece of wood to loosen any bits of rubbish that might be inside, so it's up to you if you decide to make one yourself. The manifold just sits in the bottom of the cooler with the slots facing downwards and you should be able to see from the picture that the 'reduced branch tee' is at a slight upward angle so that it joins neatly with the clear plastic tube.
Inside the mash tun
This is a view inside the coolbox, without the manifold in place. There is a short length of clear plastic tube, about 20mm outside diameter and 15mm inside diameter, which is pushed into the inside of the tap. This connects to the copper manifold. The tube is about 45mm long and protrudes about 25mm from the end of the tap. If it is a tight fit inside the tap the tube can be softened in hot water before being pushed in. It doesn't have to be a tight fit either in the tap or on the manifold.
This is my second mash tun - the first one was thrown out in 2005 after I dropped the manifold in it and cracked the bottom - but it's the original manifold that I made early in 1998.