Mashing times and boiling times for 20 gallon batches

[ruppaloop]

I'm currently moving to a 30/30/30 gallon all grain set up so that I can do 20 gallon batches. My questions are:

1) What kind of mash times would I need with that much grain?
2) What kind of boil times would I need with that much wort?
3) As a bonus question: is it feasible to take 5 gallon recipes and multiply by 4 to get a 20 gallon recipe?

Cheers

 

[BlackGoat]

mash and boil times should be exactly the same for a 2, 5, or 20 gallon batch. As for your third question, yes scaling up is that easy. The Brewer's friend calculator has a scaling tool under the tools tab where you can input in a recipe and scale it up... http://www.brewersfriend.com/homebrew/recipe/calculator/

 

[johngaltsmotor]

The one thing to watch for with scaling up that much might be the hop additions, I've heard people say that you can't simply multiply the hops. Double check that with one of the software calculators to ensure the same IBUs.

Brewersfriend says "Rounding differences will cause minor variations in the stats after scaling. IBUs will differ the most because the relationship between boil volume and bittering units is not linear."