Spike Brewing Giveaway - New v3 Kettle

Home Brew Forums > Home Brewing Beer > Brewing Software > Beersmith Boil-Off/Pre-Boil Gravity
Thread Tools
Old 09-17-2012, 01:32 PM   #1
Feedback Score: 0 reviews
Join Date: Aug 2009
Location: Germany
Posts: 1
Default Beersmith Boil-Off/Pre-Boil Gravity

Hello Everyone,

I have a problem understanding the numbers in the "Boil Off Tool" of BeerSmith.

The attached image shows the following data:
- Starting Volume: 25.20 liters
- Starting Gravity: 1.053 (53 gravity points)
- Post Boil Volume: 21.98 liters

So far so good. With these information I am able to calculate the "Post Boil Gravity" on my own using the following formula:
V1 * GP1 = V2 * GP2 (1)

This gives me a post boil gravity of 25.20*53/21.98 = 60,7 => 1.061 as shown in the tool.

But the actual starting volume after subtracting the shrinkage due to the temperature difference is only 24.28 liters. Formula (1) needs volume data to be at the same temperature I assume. Therefore, I get the following result:
24.28*53/21.98 = 58,5 => 1.059

Why does Beersmith not take the shrinkage into account to calculate the post boil gravity?

Click image for larger version

Name:	boiloff.jpg
Views:	170
Size:	15.6 KB
ID:	75997  
DerLars is offline
Reply With Quote
Old 09-18-2012, 06:15 PM   #2
Feedback Score: 1 reviews
Join Date: Sep 2011
Location: Macomb, MI
Posts: 274
Liked 26 Times on 18 Posts
Likes Given: 12


I'm on my phone @ work, so I can't type too detailed of a response. I think what BS is doing is assuming that the starting volume hasn't expanded because of heat, so you don't need to "shrink" it. I'm not sure how true that is in the real world, but I would bet that at 165ish *F you haven't had nearly the full expansion in volume that you get at boil temps.
thisoneguy is offline
Reply With Quote

Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
Pre-Boil Gravity & Mash Efficiency in Beersmith 2 HopHead73 Brewing Software 5 05-22-2012 10:59 PM
BeerSmith Est. Pre-Boil Gravity Beerfly Brewing Software 1 04-03-2012 02:21 AM
When using the Beersmith or Promash refractometer tool is OG after boil or pre-boil jetmac Brewing Software 7 05-02-2011 03:45 PM
Beersmith boil off question skibb Brewing Software 1 11-11-2010 01:29 PM
Beersmith Boil Off thdewitt Brewing Software 28 12-09-2009 02:04 AM

Forum Jump