Final Volume, Boil Trub and Chiller Losses Effect on OG

When I brew I like to finish the boil with 6 gallons in the kettle then siphon 5.5 gallons to the fermenter, leaving 0.5 gallons of boil trub behind. 

Which way is the correct way to enter this information into the Equipment setup? Doing it different (but seemingly equivalent) ways gives me different estimated OG's.

Method 1: Enter 5.5 gallons as the Final Volume and 0.5 gallons as the Loss to Boil Trub and Chiller. Example OG = 1.058

Method 2: Enter 6 gallons as the Final Volume and 0 gallons as the Loss to Boil Trub and Chiller. Example OG = 1.053

Shouldn't these two methods produce the same OG, since they start with the same pre-boil volume and end up with the same post-boil volume in the kettle?

Method 2 replicates the OG of recipes in Jamil Zainasheff's and John Palmer's book "Brewing Classic Styles" simply by entering the ingredients and a 70% efficiency. Using Method 1 always overshoot the OGs given in the recipes.

Hi Beerthoven,


I use method 2, the main reason for that is I prefer to calculate my recipes based on extract efficiency rather than equipement efficiency. What I mean by this is I prefer to know my eff numbers pre and post boil (prior to transfer) which gives a true reading of how well you are extracting the goodness from your grain.

I know how much wort I lose in the transfer to my fermenter and this doesn't effect my O.G in any way 23 lt of O.G 1.050 with no losses is the same as 21 lt of O.G 1.050 if I spill 2 litres during the transfer. Efficiency into fermenter is meaningless to me. However that is just my way of doing things and is not the only way.

Cheers
Andrew

The method is up to you - BeerSmith considers the overall batch efficiency as a gross figure for efficiency into the fermenter.  If you prefer to have it as efficiency out of the boiler, then use method 2.

Cheers!
Brad

Thank you for the quick responses.

Like Andrewqld, I prefer to base my recipes around the extract efficiency of my mash/lauter process rather than equipment efficiency, so I'll continue to use Method 2.

I do not entirely understand why the two methods result in different estimated batch OG's, though. I guess I need to reread the chapter in Daniels' book on hitting target OG and work out some examples by hand.

I've looked through much of the BeerSmith help, but is there a section where these calculations are explained that I may have overlooked?

No,
  I don't have a detailed article specifically on the efficiency parameter.  I am looking at adding additional options for future versions to allow one to specify mash efficiency rather than overall batch efficiency, and then count losses from the mash forward.

Cheers!
Brad