Thermo Pot Mash Tun Conversion

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Thermo Pot Mash Tun Conversion

Postby eclipse9101 » Thu Jan 21, 2016 13:02

Thought I would put up a few pictures of my recent mash tun build to help any fellow brewers out incase anyone has a build planned for the future.

Parts Used:

50 litre thermo pot from bergland
thermo pot bottom drain kit from brewbuilder
ptfe tape
51mm starrett tct holesaw
angle grinder with SS cutting disc
dremmell
3, 6 and 11mm cobalt drill bits
21mm qmax cutter


I started out by marking the centre point from inside the pot. I then drilled a 3mm pilot hole from the inside of the pot through both skins. After checking both holes lined up vertically I cut a 51mm hole in the outer skin from underneath the pot. The starrett cutter made easy work of this. I would recommend these to anyone thinking of doing a conversion like this!

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Note - I didn't use any cutting oil or water, just metal on metal. A few short bursts and careful pressure and the drill was through in seconds.

after carefully removing the insulation i drilled a 6, followed by an 11mm hole back through the inside skin.

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Next, after carefully measuring up where I wanted the ball valve on the front of the tun I drilled another 51mm hole with the starrett cutter. This time it was as close to the bottom lip as i could get. Directly inline with where the tap was going to be fitted.

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I had to actually cut down the pilot drill bit which is part of the starrett tct cutter. This was so I could drill the 51mm hole in the outer skin without the pilot drill doing through the inner skin!

I then layed out my length of stainless threaded pipe which would connect the ball valve to the elbow fitting on the underside of the pot. I lined this up exactly where It needed to be and proceeded to mark it either side and cut with the angle grinder.

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Then I used the dremmel with a standard cutting disc to carefully cut out a section of the lip from the inner edge. I then measured up where the ball valve would need to be mounted in order for it to be in line with the 90 degree elbow on the underside. I then used the qmax cutter to punch out the 21mm hole in the outer bottom rim.

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I then punched out the inner centre hole with the qmax and checked the fittings. The elbow would not quite fit in as the outer hole was slightly too small. So I used the dremmel to carefully cut 2 small sections away between the circle edge and the channel where the tube would be.

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I now proceeded to dry fit everything together to check it fitted properly. Unfortunately the deck drain fitting was a few threads too long to screw all the way into the elbow under the tun. I screwed 2 hex nuts onto it leaving about 3 threads exposed, camped it in a vice and used the angle grinder to cut off the excess threads. When I removed the 2 hex nuts this cleaned up the end of the threads nicely:thumb:

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And finally all fitted!

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I've not fitted the 3 piece ball valve yet as I had to order a 8mm thick stainless spacer washer to use on the outer of the pot behind the tap. This is because the tap will only screw onto the end of the protruding pipe by about 2-3 threads max! So the thick spacer washer will take up the gap and make for a neat finish. I will update with the final pics once its finished.

Hopefully this helps a few people out!

I would also like to say a big thank you to everyone who helped me and gave me some sound advice along the way.

Last edited by eclipse9101 on Thu Jan 21, 2016 15:23, edited 7 times in total.
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Re: Thermo Pot Mash Tun Conversion

Postby Kev888 » Thu Jan 21, 2016 13:55

Hi, your images aren't working for me. Sometimes thats because people link to a page rather than an actual image file, but in this case when I try to follow the links manually it seems they're located somewhere that isn't open to public access?

Cheers
Kev

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Re: Thermo Pot Mash Tun Conversion

Postby mark1964 » Thu Jan 21, 2016 13:56

Not working here either

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Re: Thermo Pot Mash Tun Conversion

Postby eclipse9101 » Thu Jan 21, 2016 15:06

pics fixed! thanks for the heads up.
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Re: Thermo Pot Mash Tun Conversion

Postby mark1964 » Thu Jan 21, 2016 15:23

did you fill the cut with expanding foam or similar?

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Re: Thermo Pot Mash Tun Conversion

Postby Kev888 » Thu Jan 21, 2016 15:26

eclipse9101 wrote:pics fixed! thanks for the heads up.

Yep, pics working now for me too. Looks like a neat job with the conversion!

Cheers
Kev

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Re: Thermo Pot Mash Tun Conversion

Postby eclipse9101 » Thu Jan 21, 2016 15:30

mark1964 wrote:did you fill the cut with expanding foam or similar?



Not yet. I have done 3 leak tests hot/cold and hot with oxy clean. No leaks! :thumb:

i'm not sure what the best approach would be to insulate the underside again. I was thinking maybe some tin foil to line the cavity and then using silicon sealant to pack out the voids.
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Re: Thermo Pot Mash Tun Conversion

Postby Kev888 » Thu Jan 21, 2016 15:51

FWIW I've seen pots where people have tunnelled through from the outside hole to the inner hole using a sharpened pipe, rather than taking the trench approach. Obviously thats too late in this case and not perhaps the easiest anyway, so I'm not suggesting its necessarily better, just mention it for comparison by other people reading.

Personally I wouldn't worry 'too' much about the insulation as you've removed it so neatly there aren't any huge voids. Expanding foam (as mark suggests) would be ideal to fill them, but I agree any not-very-conductive sealant that can be squeezed into the gaps would also work, preventing air circulating around there.

EDIT: Theres also the school of thought about just capping the trench/slot, in case you may ever want to get in and repair leaks etc.

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Kev

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Re: Thermo Pot Mash Tun Conversion

Postby eclipse9101 » Thu Jan 21, 2016 16:31

Some good points there mate. I thought about the stealthy approach to bury the piping under the insulation but I would have meant that the tap would be mounted too high up the side if I had done that. Might have just been my particular pot tho. I understand they are not all identical
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Re: Thermo Pot Mash Tun Conversion

Postby jonnymorris » Fri Apr 08, 2016 10:52

Looks like a really good job. Have you fitted a false bottom?
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