My Electric Brewery - Part 5a, Mash Tun Phase 1

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chastuck

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Now the Christmas break is over I have started work on the mash tun. I’m using the usual Bergland thermopot and the size is 80L, which is bigger than I have used before, but more in keeping with my completed 100L HLT and proposed 100L boil kettle. All the thermopots I have converted in the past have been built using a fabricated SS 304 skirt or ring within the bottom rim of the pot and I’ve done the same this time. The SS skirt dimensions are 2mm thick with od of 484mm and 75mm high.
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I prefer to use a skirt for the drain and ball valve pipe work as I think hacking slices out of the bottom of the thermopots to accommodate the drain fittings is a less desirable approach. The od of the skirt was deliberately chosen to be 1mm less than the exact id of the bottom rim of the thermopot. This means that, due to the manufacturing tolerances of the pot, the skirt initially doesn’t fit! There is an element of flexibility in the stainless steel ring, so the thing to do is to fit as much in as you can – this is about two-thirds of the circumference – and then use a sash clamp to push the ring together and knock it into place with a rubber mallet. Once all the circumference of the ring is partially in, I went round the top of the ring with a club hammer and block of wood and knocked it firmly into position, making sure that the height was the same all the way around the pot and that the pot was level when on a flat surface. (When you invert the pot to do this banging make sure it is resting on a thick blanket and a sturdy work platform.) This way of fitting the skirt means that it is such a tight fit that no bolts or welding are needed to keep it in position. It’s never going to move! Here’s a picture of the skirt fitted and the drain hole drilled ready for the skin fitting drain:
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As I mentioned in earlier posts of My Electric Brewery construction, I am trying to emulate the design and set up of The Electric Brewery website, without the expense of buying the Blichmann Boilermaker kettles. The Boilermaker pot used as a mash tun in The Electric Brewery has a circulating ball valve, a dial thermometer, and a sight glass. But the Boilermaker is a single skinned vessel and these three items are difficult to fit through the double skin of the thermopot. However, it can be done and I will explain the way I have done it. The gap between the two walls of the thermopot is about 20mm. Two ½” BSP ‘O’ ring nuts from ebay (http://www.ebay.co.uk/itm/LOCKNUT-1-2-B ... 4ab69c74b7) have a combined back to back width of 19mm. A hole wide enough in the outer skin has to be drilled to take the 40mm shim that contains the expansion of the red silicone washer to make the weldless seal. To cover up this hole, a washer wider than the hole is needed. In this respect I had some washers custom made in 1.5mm thick 316 stainless which are 50mm od and 22mm id (http://www.lasermaster.co.uk/easy-order). When the assembled fitting is tightened up on the inside of the pot this large washer is pulled against the outside skin to form a neat finish and covers the hole. A homemade silicon washer behind the back of the large washer ensures a good seal. The large washer that covers the hole has to be bent into a very shallow ‘V’ to take account of the curvature of the pot. I did this by placing it into a vice at exactly the halfway point and giving it a few gentle taps with a hammer. The circulating ball valve and the dial thermometer were both fixed in this fashion. See pictures below:

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A 5ft sparge hose will be fitted to the circulating ball valve via an elbow and a hose tail.

The lower end of the sight glass was fitted in the same weldless manner as the thermometer and recirculating ball valve. The sight glass will have a 3/8” BSP thread cut on it, and this mounts into a ½ x 3/8 x ½ Tee. A temperature probe will be fitted horizontally into the T piece to give an additional measuring point.

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The top support for the sight glass is a M6 stainless steel eyebolt. The skin of the thermopot is less than 1mm thick and there is a danger that the bolt could easily pull through the thin skin. What I have done is to fit the bolt to a small plate of stainless steel, and then rivet the plate to the outer wall using stainless steel blind rivets. The plate was bent into a shallow curve to match the pot profile. The fixing doesn’t penetrate the inner wall at all. Some JB Weld around the eyebolt fixing nuts, and along the edges of the plate before riveting, ensures a water tight seal and aids bonding.

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As on my other pot sight glasses, I have cut a 3/8” thread on top of the sight glass and fitted a round blanking cap loosely to stop any ingress of unwanted matter.

Some views of the inside of the pot:

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The next phase of this stage will be to fit the output ball valve and test for leaks. More posts on this to follow.
 
That is excellent work , looking good . I have a thermo pot and have fitted a thermometer similar to yours , makes brewing so much easier no messing about checking temp . Great photos too , very useful to those wanting to have a go . :clap:
 
Did you choose a Thermopot because you brew outside? Were you tempted to just use 3 identical pots for your system?

Just trying to weigh up the pros/cons for thermopots as an MLT.
 
Nice work C :thumb:
Did you choose a Thermopot because you brew outside? Were you tempted to just use 3 identical pots for your system?
Unless you brew in an environment where it's the same temp as your mash you'll always need to be insulated, or, replacing the heat loss with a HERMS/RIMS system :thumb:...and even if you have a HERMS/RIMS insulation helps reduce energy consumption which can only be a good thing considering prices :roll:
 
AllTheHops said:
Did you choose a Thermopot because you brew outside? Were you tempted to just use 3 identical pots for your system?

Just trying to weigh up the pros/cons for thermopots as an MLT.
Vossy1's comments above sum it up really. I have to brew on my garden patio so need to take account of heat loss and electrical efficiency. When I use the HLT and boiler I will insulate these with foil backed camping bed foam. Additionally, by using a thermopot it gives me the option of using the mash tun independently of the electric brewery setup.
 
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