Slow Draining Mash Tun Advice Needed

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Slow Draining Mash Tun Advice Needed

Post by CharlieM » Sat Aug 06, 2011 12:29 pm

Hi All,

I have bitten the bullet and decided to step up from brewing extract kits to full mash brewing. I have taken the budget root of using plastic kit and DIYing what I can. I did my first brew last weekend using it. I decided to start off simple by using an "All Grain Kit" to make a Spit Fire clone from Incidentally I bought the 3 60l containers I used to make the HLT, MT & Kettle and can recommend them. They even got in touch to confirm all the hole sizes I had asked for which the cut at no extra cost!

Back to the reason for my post. During the first run the Mash Tun took over an hour to drain & that took a lot of blowing on the tube before I could get any real amount of wort to flow. Once it started flowing at a consistent rate I could leave it and it to continue to drain. Draining after the sparging took exactly the same length of time. Both the MT & Kettle have a manifold made of 22mm copper pipe in them. It has holes drilled in the under side of the 3 straight peices of pipe. This allows it to drain to a very shallow depth via the siphon effect. However clearly in the MT it must be getting clogged and stopping it draining. In the kettle it worked pretty well leaving lots of material in the kettle. Ultimately I am thinking of moving to a RIMS setup so I will defiantly need a much larger & more reliable flow rate out of the MT for that. I think I will stick to my current process for a while first, but I would still like a better flow rate.

[img] ... G_5851.jpg[/img]

If the above image doesn't work I have an album on Google+ with more photos. ... 2210554609

So my question is what does you recommend I do. Drill more hole in the top side in manifold in the MT, fist how bigger drill bit does everyone use the holes. Any other suggestions may be wrap some wire mesh around it?

Incidentally that small closed copper pipe is what houses my One Wire digital temperature probes. I have put one in each vessel including my old FV that came with my first beer kit. I have got a NetDuino Plus micro controller currently just logging and displaying temperature values. So it let me monitor temperatures on my Tablet any where I had WIFI around the house (it was an F1 weekend). Ultimately I am going to use it to control the various heating elements. I might make a post on that when I have it more complete.

Charlie M

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Re: Slow Draining Mash Tun Advice Needed

Post by gregorach » Sat Aug 06, 2011 12:37 pm

Most people seem to cut slots in their MT manifolds, and plenty of 'em...



Re: Slow Draining Mash Tun Advice Needed

Post by Wolfy » Sat Aug 06, 2011 12:49 pm

False bottom mash filters work well in circular mashtuns, you can get them in stainless steel or make your own with various materials including by simply drilling many holes in another similar sized plastic bucket and then sitting it inside the first one (you could even do that and sit it over the top of your existing manifold).

None of your pictures show the bottom of the manifold but to me it sounds like you need many more openings, holes or cuts in it before it will work well.
This is what mine looks like - you should be able to see the cuts all the way along it so it would not hurt to either drill more holes in yours or take a hack-saw to it:

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Re: Slow Draining Mash Tun Advice Needed

Post by Kev888 » Sat Aug 06, 2011 1:52 pm

Yep,thats quite a small manifold you have there, and also holes get more easily blocked by grain than slots - I'd imagine it'd work very well as a hop stopper but I can see it wouldn't allow a vary fast run-off from the mash.

Now that you know the speed it works at, you may be able to help things a bit by working slowly from the very start; if you run off too quickly to begin with it can sort of compact the grain bed and smaller particles around the filter and make it worse than it needs to be.

But really to get any sort of speed you would have more holes or ideally more slots. Preferably it would be a bigger manifold too; thats particularly so if you fly sparge - with that method it is preferable to drain the wort quite evenly from across most of the bottom of the grain bed; if you only drain from a fairly localised point then the wort can form channels heading for it, which can help the sparge liquor bypass some areas of the grain.

EDIT: thinking about it, your bucket would also suit a round plate type of 'false bottom' design too - Jim has illustrated this here, and though he used a hob cover people have used all sorts of stainless trays/platters or platic plates and so on, some even use a dremmel cutting disk to make slots rather than drill holes - there are quite a few threads on here detailing their builds.



Re: Slow Draining Mash Tun Advice Needed

Post by CharlieM » Tue Aug 09, 2011 1:23 pm

Thanks all for the suggestions. I think I will start drilling loads more holes in to the top side of the manifold. I suppose in the Mash Tun the siphon effect is less important as there will always be the grain bed to reduce the volume below the tap. The same manifold design worked great in the boiler.

What's the best size of holes to make? The current ones were made with a 1.5mm dill bit. The bigger the hole the better it drains but the more material ends up in the boiler.



Re: Slow Draining Mash Tun Advice Needed

Post by LansonBrewer » Tue Aug 09, 2011 1:55 pm

1.5mm-2mm is about right for the holes.
Slits (with a hacksaw or dremel) are better.
As Kev mentioned, it might be worth getting a bigger manifold that covers more of the base of the vessel.


Re: Slow Draining Mash Tun Advice Needed

Post by boingy » Tue Aug 09, 2011 2:00 pm

Yep, hacksaw slits are the best way forward. Cut them on the underside, just shy of halfway through.


Re: Slow Draining Mash Tun Advice Needed

Post by CharlieM » Tue Aug 09, 2011 8:32 pm

Ok slits with a hack saw does sound like the best option. However I don't want to weaken the pipe too much. That said its 22mm so the size of slit doesn't have to be that large a ratio of the pipe to slit.

The bottom of the container has a raised donut shapped raised area so if manifold was any bigger it wouldn't clear the raised part of the bottom.

Thanks for the suggestions.


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Re: Slow Draining Mash Tun Advice Needed

Post by davew » Tue Aug 09, 2011 10:16 pm

How about a large sheet of voile material to line the mash tun and hold the grain?
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Re: Slow Draining Mash Tun Advice Needed

Post by dynamic dave » Tue Aug 09, 2011 10:46 pm

I bought a mash bag which i just place at the on top of the copper strainer works fine.


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Re: Slow Draining Mash Tun Advice Needed

Post by flytact » Wed Aug 10, 2011 12:10 pm

My holes are drilled into the bottom of the manifold not the top. When I did that my efficiencies jumped.
Perhaps some rice hulls to add more filtration?
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Re: Slow Draining Mash Tun Advice Needed

Post by CharlieM » Tue Nov 01, 2011 3:25 pm

I took a hacksaw to my Mash Tun manifold. Had to wait for my next brew to see if it worked.

Its made a massive difference! It's completely free draining now. Not only that but virtually nothing solid is getting through once its run a few seconds. Also I have hooked up my pump to run it as a HERMS set up. This also worked great, its still free flowing with the pump on.

Thanks all for the great advice.



Re: Slow Draining Mash Tun Advice Needed

Post by Deller12 » Tue Nov 01, 2011 4:30 pm

I made the jump to a full stainless false bottom and got to say works extremely well. But before used a piece of 22mm copper pipe about 200mm long witch I peppered with 6mm holes and blocked one end with a copper end cap. I then slipped over the top some stainless steel braid and added a 22m-15mm reducer the other end. I used a couple of stainless steel jubilee clips each end toy stop the braid moving and it work a treat the wort flowed poured out :D

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