How Do I Predict First Runnings Gravity

[smyrnaquince]

I recorded my first runnings gravity and volume from a beer I brewed this weekend. Is there a way to predict what the first runnings gravity should have been?

The reason that I ask is that I think this will tell me how well my mash converted the starches.

I do take the before-boil gravity and the total wort volume (mash + sparge) so I can calculate my efficiency, but this number is also influenced by how well I sparge.

On a related note, my final runnings were at 1.013. For a batch sparge, is this reasonable?

 

[Croyzen]

How to Brew 3rd edition chapter 18 table 27 shows typical malt yields in points/pound/gallon. Find your grain bill and use the equations from the chapter to see where you stand. Don't have the book? That would be crazy!

 

[skydvr74]

See this page
http://www.braukaiser.com/wiki/index.php?title=Understanding_Efficiency

 

[smyrnaquince]

I do have How to Brew. Thanks for the pointer.

Looks like I do the calculations for the expected yield, then use the proportion of first runnings out to total mash water in to figure out how much of those sugars should have ended up in the first runnings.

Thanks.

 

[Croyzen]

Awesome! That's it.