Another batch size question

Brad,

I calculated my grain bill by hand the other day, and then plugged my recipe into BeerSmith.  

I was calculating based on 20L of wort going into the primary, with 3L left in the kettle with the hops and trub.  I was therefore calculating the grain bill needed to make 23L of wort.

I plugged all this into BeerSmith (3L lost to trub/chiller, 20L overall batch size) and the OG was higher than the OG from my by-hand calculations.  I then changed to a "23L" batch in BeerSmith and the OG estimate then exactly matched my by-hand estimate.

I thought you'd said that the batch size reflected the amount going into the fermentor, not the amount in the kettle at the end of boiling and chilling.

Seems that when estimating OG, the program is not accounting for the amount of wort that gets left in the kettle.

Put another way: Beersmith appears to be taking the weight of the total extract and dividing by the volume of wort going into the fermentor to determine OG, rather than dividing by the volume of wort in the kettle at the end of boiling and chilling, like I'd expect.

What am I missing?

I can send you the recipe if you want.

Thanks,
David

David,
 You are spot on - however at the core of the issue is how one defines "brewhouse efficiency".

 Other sources (including all other programs that I know of) define brewhouse efficiency as the gross percent lost during the brewing process to include things like trub loss and so on...therefore your brewhouse efficiency may be a little higher or lower depending on your losses.

 Could I calculate the OG into the boiler and then from the losses and boil off determine the OG for the brew into the fermenter?  Absolutely this could be done, but then one would not be using "brewhouse efficiency" to determine the OG, but rather "mash efficiency".

 To keep BeerSmith compatible with commonly used definitions and also the large group of people that have some idea of their gross brewhouse efficiency, I chose to stick with the standard definition.

 If you use the efficiency calculator for BeerSmith, you can easily determine your OG into the boiler and other efficiency numbers.

Cheers!
Brad

Brad,

That makes sense.  I wonder if, in the next version, it would be smart to have separate values for "mash efficiency" and "brewhouse efficiency" so that differences in the amount of wort lost to trub won't affect the predicted OG?

David

David,
 I'm thinking of (perhaps) adding additional outputs from the efficiency calculator that might allow one to calculate OG using an alternative formula based on mash efficiency and known losses.  

 I think this would meet your needs.

Cheers!
Brad

I must be a bit thick and or slow on the uptake. (Mind you, everything I do and read is new to me  - only two AG brews to date.)

Could you confirm what figure I should enter in my standard Batch size if I want to end up with 23L in my Primary.  (My kettle is keeping 2.5L for its own use.)

I understand that this figure of 2.5L should be entered in the equipment list under boiler - Top up water, which appears to than calculate the final amount to the fermenter.  But, should I leave my batch size in the recipe view at 23L or change it to 26L.? :-[

Pardon me if I answer my own question but I think it is necessary to do so.

Initially I got confused with Batch sizes by some of the assumptions and findings by other users of this forum in this and other topics.

After I read this latest thread and my question (as a guest) I read the Help file again.  You did know about the Help files, did you not?  It is the place to look when all else fails.

The help file regarding Batch Size states: Quote: "The finished batch volume, - i.e. the amount of beer you hope to brew" Unquote.

I do not think it could be written any plainer.  Therefore it stands to reason that everything (most everything) is worked out for you according to what volume (batch size) you wish to put into your fermenter.

I also read up about "Top up water" in the boiler and now understand what it is used for.  Initial look at time of completing the equipment setup could have been misleading.

We are lucky indeed that such a helpful tool as BeerSmith is provided for us and its author is available for support.

Thank you Brad for your continued interest in our wants and needs and your support.   Whilst you might not be able to satisfy everybodies needs, you are doing a wonderful job, you have a terrific program and I thank you for it...

Peter,
 The "Amount into fermentor" is exactly that - the amount you want to go into your fermenter.

 You should account for other losses by adjusting the brewhouse efficiency and various equipment water parameters.

Cheers!
Brad