15G Batches - is 20G Mash Tun big enough?

[dudes]

Planning a set-up with a 20G BK to be able to get 15G in the fermenter.

With AG am I going to run into any issues with a 20G capacity MT (and false bottom taking up space) and fly sparging? Should I go bigger?

 

[EuBrew]

I think it would be fine, Bobby_M has a table in this link https://www.homebrewtalk.com/f11/how-big-your-mash-tun-needs-123585/ that goes up to 15.5 gallon, so you should be fine with what you've got.

 

[dudes]

The calculators show that I can probably do about 45lbs of grain and still have a LITTLE space for fly sparging. 45 lbs of grain might limit me on how many 15G batches I can do.

That's my read, so I was looking for any definitive answers, either
a) no sweat, have a homebrew
b) spring for a larger MT, and have a homebrew

 

[Bobby_M]

5 gallon tun would be good for about 300 gravity points so 4x that is 1200 gravity points. 1200/15 gallon batches has a OG limit of 1.080. If you wanted to do a specialty imperial beer in that tun, you might want to reduce down to a 10 gallon batch which could give you 1.120.