BeerSmith said:
Hi,
The problem is related to the use of brewhouse efficiency for all grain recipes - the program uses the "into fermenter" volume for OG calculations including for extracts. For all grain recipes this is fine since the total brewhouse efficiency includes all losses by default.
The root of the problem seems to lie in how mash efficiency is determined based off brewhouse efficiency, which includes transfer losses to the fermenter.
For all grain, it seems like BeerSmith factors in trub loss twice. Once for their actual losses, and a second time, to a much smaller degree, due to its inclusion in 'brewhouse efficiency'. At least that is what my reverse engineering seemed to show. The effect is small, but seems to be there.
BeerSmith said:
For extracts, I agree that I should change the code to include the trub loss in the calculation as it does carry away some points of extract, and should reduce the OG proportionally.
For all brew styles, I think a better solution is to define brewhouse efficiency as 'to the kettle', and have trub loss and kettle efficiency be the numbers user adjust iteratively, since they are easily estimated beforehand, and actually determined on brew day. It would be the great unified theory of brewing- one set of rules for everyone.
If there is no 'brewhouse efficiency' input for extract recipes, yet trub losses are considered part of 'brewhouse efficiency' for all grain, this creates an inconsistency. It makes no difference whether extract or all grain was used to get to the post boil stage when trub losses occur. It also makes no difference whether extract or grain was used on whether sugars are lost in the trub. I don't see why there would need to be any difference in the equations/algorithm post mash to account for trub losses. It seems like an unnecessary branching that will cause code maintenance issues down the road, and possibly immediately depending on how your recipe converter is coded. The more important side effect is the impact on the user experience for guys switching from extract to all grain. If current all grain guys are already confused by how BeerSmith handles trub loss and brewhouse efficiency, those switching from extract to all grain will be doubly so, since they will be accustomed to trub loss being handled as one would expect by decreasing OG or scaling the recipe appropriately.
Using only a 'to the fermenter' input for tuning results in a loss of information since the source of the losses isn't identified when the software is tuned by only adjusting 'to the fermenter efficiency' over multiple batches. While it does get things 'close enough' eventually, I don't see any reason to not do it correctly, and possibly save an iteration or two.
Accounting for 'to the fermenter' volume issues would be much easier with an actual volume field, directly related to losses between the kettle and fermenter, that could be adjusted with some hard numbers. Just what could it possibly be called so everyone would immediately understand what the field meant? I know I have seen it somewhere.
The 'to the fermenter' definition further complicates things when an equipment or ingredient change (like whole hops vs. pellet) results in a trub loss change. Without some fairly complicated hand calcs, which most people buy BeerSmith to do for them, picking a new efficiency number is a bit of a crap shoot for the first brew post-change. The BeerSmith definition of brewhouse efficiency also confuses many first time users, and increases the learning curve. There are many threads on other forums where this issue has been brought up, usually ending with some harsh words when the root of the problem is explained.
There could always be another efficiency calc for 'to the fermenter', or 'to the bottle', for the guys who want to know for pricing, final product volume, OCD, anal retention disorder, etc. For most of the rest of us, we are concerned more with getting the OG, IBU, SRM, etc. in the kettle correct. I think it would even be useful to allow for user input of predicted mash efficiency as an advanced option.
BeerSmith said:
I apologize - this has been the same for the last 8 years and this is the first time it was raised as an issue. I'll make sure the fix gets into the next release.
Brad
While this may be the first time the extract bug has been identified (and one I found only while trying to more clearly define the effect of trub loss for all grain brews), the issue of brewhouse efficiency and trub losses causing confusion and making recipe sharing difficult has been raised many times. The only indication that anything is amiss after a trub increase (without a corresponding guess at the new 'to the fermenter' efficiency), is in the fine print in the form of a magical jump in mash efficiency (even over 100%).
Kai, of www.braukaiser.com fame, has commented similarly about the design choice of 'to the fermenter' for brewhouse efficiency; but only in regards to recipe sharing, and not about the correctness of the implementation. I think this is only because he has not heard of the issues with it. I think he would come to the same conclusion as I have regarding the implementation, if he looked at it closely.