Mash/lauter tun question

[CDangerBrew]

I am curious if anyone in forum land is using an over-sized mash tun with your brewing systems. The mash-tuns I have been looking at upgrading to have screens rated to 12* P. Our lowest in gravity beers are around 13.5* P, with an average around 16-17* P. Does it make sense to get a bigger tun to accommodate these beers, and would it be a problem to brew a session beer in an over-sized tun. Trying to make the right choices for our new brew house, any thoughts?

[CDangerBrew]

No one has an opinion on this? We are currently in expansion plans and are building out a new brewery. Just curious if anyone has put an over-sized mash/lauter tun into service to accommodate higher than average grain bills, pro's vs con's, or am I over thinking this?

[Bham Brewer]

I'm curious where you are getting quotes from? I have brought in a bunch of quotes lately and generally they say they can handle 16P for a full knock out volume.

[CDangerBrew]

The manufacturer we are pretty much set with going is DME, their screens are rated to 12*P.

[Bham Brewer]

That just doesn't add up, I have never heard of a mash tun only able to handle a 12P mash, especially from one of the major players... Have you discussed this with them directly and said, "Look, our beers will be between X and Y, will this mash tun handle it?"

[CDangerBrew]

We are still a year out from breaking ground, but have not spoken with them at length about this. There is another brewery in our area that has one of DME's systems. When I toured their brewery, the brewer told me of the 12*P rating. I was surprised, the brewer at this facility said they will use the tun as needed and worry about it later. Knowing this going in, I asked about it in my quote request. I requested what I would like the tun to handle (x*P) and they quoted me a bigger tun.

[Bham Brewer]

So you're saying that (just throwing out numbers here, I don't know what your projected capacity is) DME told you you needed a mash tun scaled for a 20 bbl brewhouse to do your 10bbl brew length?

[CDangerBrew]

Correct, although I did ask for a tun to be able to handle up to 25*P. Maybe therein lies the bigger tun quote, but it does not change the fact that their screens are only rated to 12*P.

So maybe I'll rephrase in asking, if you could order an over-sized tun to accommodate your bigger beers would you do so? Take Bham Brewer's scenario of 20 bbl tun and overall 10bbl system, would this make any sense? I suppose it will depend on where your over-all average gravity sits.

[Bham Brewer]

I would expect a need for a double sized tun in order to do a full kettle of a 25P wort, however, I would NOT buy a tun that allowed for only a 12P wort at full knock-out volume. Seriously, I have never heard of such a thing. Either there is something not being communicated sufficiently on their part or there is something seriously wrong with their tanks... I am thinking the former. Consider this; you keep referring to the screen itself, now, do you think they use a screen that is literally twice as strong on a vessel twice as large? I am no tank designer, but I seriously doubt it. Unless they DO, then there is no reason to think that the screen would hold the increased weight of the mash in the larger vessel. True, you aren't going to have a mash twice as deep in the larger vessel, but it will still be substantially deeper and have a greater weight in pounds /sq foot as a result. Not sure where the differences are, but as a way of comparison, I used to brew on a JVNW brewhouse that had been expanded upwards from 15 to 30 bbl. The screens were fine with a 16P 30bbl knockout and 25P 15 bbl knockout.

This bizarre issue aside, if a SUBSTANTIAL percentage of your beers are over 16P you may want to go with the larger tun, otherwise you are going to be doing multiple brews to fill a tank. IME, the vast majority of mash tuns easily accommodate a 15-16P mash, getting past that point you will have to reduce your knockout volume to have a mash/wort ratio high enough to get the higher gravity.

[Bham Brewer]

If you haven't already, I would be getting quotes from EVERYONE... also, before I went further with what you have, I would ask a consultant to look at the quote and get definitive answers from the manufacturer

[yap]

so being a bit new and having never dealt with bigger systems I didn't want to be the first to speak, but I agree I am confused....

Yes you may need a bigger volume tun to do bigger gravity batches, but why would the SCREENS be rated at 12°? If it is due to the bracing underneath handling the weight, then have them brace it better. If it is due to the wedge wire blinding under the weight of extra grain then spec different screen material.

To reiterate, I am no expert (my mash tun is a converted dairy tank) but I am curious why there would be a plato rating on the screens themselves...

[CDangerBrew]

Thank you for input guys, again, I have not sat down with the manufacturer about these issues. I did go through the quote again. Under design parameters for the mash/lauter tun, sure enough, said density rating up to 12*P. I may have to think about another manufacturer. We did get six different quotes to begin with. I was leaning towards DME because I have seen the equipment and there are numerous brewers around here using them (some are award winners). I probably would have never asked these questions in the first place, the whole 12* Plato thing got me thinking.

[dick murton]

I am equally puzzled by the way this has been described. My personal feeling is that DME are saying that the design of the tun will allow you to produce a given volume of wort at 12 P at an extract efficiency of say 90 %, assuming an all malt grist.

If you want to produce the same volume of all malt grist with a high gravity, say 16 P, then you will need to add more malt because you have to stop sparging earlier and lose more extract, say only 80 % extract. Therefore you need a bigger mash tun. If you want, you could then produce a larger volume of low gravity beer from this increase malt charge, at a high efficiency, or reduce the malt charge to get the same volume at a lower gravity.

So I believe they are saying you will get say 90% efficiency if you aim for 12 P, and only perhaps 80 % efficiency if you aim for 16 P, and even lower, say 75% if aiming for 20 P.

Does this make sense ?

[YSBrewer]

Interesting topic. Subscribed...

[Natrat]

This makes no sense...

I have brewed on various DME systems, and have done very high grav brews in them without coming close to their top capacity. Also, when buying a DME system, I never got a metric like that.

Maybe it's because I always specified how much grain I want to be able to fit into the tun.

I like the DME mash tuns, as they are quite shallow and wide, and I find I get lower extract with narrow and tall mash tuns. I'm not a fan of the "valentine arm" for vacuum break, but they work.

Rather than asking the manufacturer what they think, I'd just tell them what you want. Sit down with your recipe, figure out exactly how much malt you want to use, and tell them you want a mash tun that can handle 1250# or whatever of malt. Then ask them what dimensions they recommend. Again, flat and short seems better than tall and narrow (to me.)

Good luck!
Nat