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Mash Tuns for Home Brewers

Various set-ups are used by home brewers to mash their grains. The main criteria are:

  • Good insulation to maintain the temperature of the contents for up to 1 1/2 hours
  • A reliable filter to allow the sweet wort to be run off when the mash is complete

Picnic Cooler Mash Tun

A popular design is the picnic cooler mash tun which takes advantage of the thermal insulation around a cheap plastic picnic box. The box is fitted with a standard barrel tap and the filter is usually made from lengths of 22mm copper pipe with saw cuts placed at regular intervals to allow the wort to drain out.

Thermopot Mash Tun

Former forum regular Vossy published this design, using a commercially available insulated stainless steel pot as the basis for a very shiny mash tun! Use the navigation bar at the top and bottom of this pane to find his three-page build guide.

False Bottom Mash Tun

My favourite design  is the 'false bottom' mash tun using a standard plastic brewing bucket. The design below was inspired by a guy who went by the name of Daab on my forum; his design used a plastic plate for the filter, but I made mine from a stainless steel hob cover that I picked up in a market for a few quid. In my experience this kind of mash tun drains far more reliably than a picnic cooler type resulting in fewer stuck mashes.

Making a False Bottom Mash Tun

Insulation

The first task is to insulate your bucket (which must be fitted with a drum tap). I actually used an old home brew boiler. A good, cheap form of insulation is camping mats which can be bought from outdoor shops. If you keep your eyes open, you might even get one for next to nothing in a supermarket at certain times of the year. Just cut the mat to suit and wrap it round the plastic bucket, fixing it with duct tape or similar.

False Bottom

The heart of the mash tun is the false bottom which holds back the steeped grains and allows the sweet wort to run off into the boiler. The following pictorial guide shows one way of making your own false bottom - in this case from a cheap stainless steel hob cover.

Materials Needed

  • Stainless steel hob cover
  • Brass or stainless steel tank connecter
  • 15mm Yorkshire 90 degree elbow joint
  • Small length of 15mm copper pipe
  • Length of flexible plastic tubing to fit over 15mm pipe

Build Sequence

1. The raw materials:

mash tun false bottom stainless steel blank parts to make mash tun false bottom

2. Drill a central hole in the hob cover and fit the tank connector, then cut the top of the tank connector off to leave the fitting flush with the top of the nut.

tank connector fitted to mash tun false bottom mash tun false bottom with tank connector  cut flush

3. This is the real pain - you need to drill as many 2mm holes as you can, spread evenly over the stainless steel cover. My advice is to buy a pack of cheap 2mm drills - you will break a lot of them drilling stainless steel even if you're careful....

holed drilled in mash tun false bottom

4. Fit 2 short lengths of 15mm pipe into each end of a 90 degree elbow, then feed one end into the tank connector, and finally fit the whole assembly into your bucket, threading the flexible tubing into the tap barrel.

elbow joint fitted to mash tun false bottom final assembly of mash tun false bottom

I used an old boiler as my bucket, so there's an element stuck in there; it's handy for clamping the filter down, but isn't connected up to any supply.

The flow rate from this mash tun is excellent and I have yet to have a stuck mash with it.

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