[RPIScotty]

I typically reference maximum extract potential and then apply an efficiency factor to it for determining pre-boil gravity.

I was recently reviewing Denny's NOTI Brown recipe to use as a springboard for an upcoming Brown Ale brewday and noticed that his ProMash report had lower than expected extract potentials.

Is there an additional factor applied to the maximum extract potentials values to arrive at the "brewer's" extract potential that gets referenced in "How to Brew"?

[kramerog]

I looked at the extract potentials at http://www.tastybrew.com/forum/thread/113723 and they seem normal. 

There is a separate brewhouse efficiency of 77% in the recipe.   There are three parts to brewhouse efficiency: (mash) conversion efficiency which can approach 100% for homebrewers, lauter efficiency which is generally hard to get over 90% for homebrewers because the grain bed retains a lot of wort, and kettle (?) efficiency which is dependent on how much wort you leave in the kettle for hot break and hops.

To quote Palmer "The [brewer's] extract efficiency is dependent on the mash conditions and the lautering system."   Extract efficiency is equal to the first two parts of brew house efficiency.