Hi, thanks for the response and explanation Yooper, and sorry for my late reply.
I have to say that personally I was unaware of the distinction between the parameters used in the recipe builder and the brew session, and to me it still doesn't seem obvious from looking at the software although there are a few hints if you go looking for them. To my mind there doesn't seem to be any gain to this since there's nowhere in the brew session to actually adjust the recipe based on equipment parameters from what I can see? For instance, I designed a recipe at 74% brewhouse efficiency. In actual fact, by back-calculating through my equipment profile after the brew, the best I can achieve with that grain bill is 70% (at 100% conversion efficiency) due to high loss volumes. This isn't highlighted at any point of the process, and even if I had realised this prior to brewing there is nowhere in the brew session to work out the actual grain bill required to hit the recipe OG.
There also certainly appears to be a fault in relation to the calculated efficiencies in the brew session based on volumes. I've dummied up a few variations of recorded volumes and gravities in a session to try to identify where the fault is (please ignore the comments fields).
The first dummy session here (Figure 1) was made to try to maintain the same efficiency and gravity through the pre-boil, ending kettle, and brewhouse steps. As can be seen, to achieve the same pre- and post-boil efficiency, I had to
increase the water volume (by the same volume as the kettle deadspace in the equipment profile) at the same gravity to maintain the efficiency. Clearly this is a fault, as per the BF FAQ definition of ending kettle efficiency:
Ending Kettle Efficiency: The percentage of total sugars in the kettle after the boil. Theoretically the same as Pre-Boil Efficiency, provided accurate measurements at both points (minus rounding error).
Since the quantity of sugars is not changing through the boil in this ideal/theoretical scenario the SG is unchanged then the same volume of wort (sugars) should be required to deliver the same efficiency.
Figure 1. Ideal scenario of maintained efficiency and SG with required volumes.
This is perhaps highlighted even more clearly in Figure 2 where I used the BF boil-off and dilution calculator to calculate what the actual ending kettle SG should be for the boil-off rate used in the applicable equipment profile. In this case, despite having the same quantity of sugars pre-boil and ending kettle, the efficiency has dropped by 10% when it should be identical.
Figure 2. Boil complete volume from equipment settings, boil complete SG from BF boil-off and dilution calculator using pre-boil inputs
The problem here is that I cannot even use a dummy brew session in BF to work out what grain quantity will be necessary to hit the required OG and fermenter volumes of the recipe, nor can I use it to work out the correct efficiency to plug back into the recipe builder in the first place. Obviously I can do that through a spreadsheet tool or some other software, but that really shouldn't be necessary when all the tools appear to be in place in BF - just working incorrectly from what I can tell.
Certainly it appears that in this scenario the fault is due to mis-treatment of the kettle deadspace when calculating volumes, efficiencies and gravities.
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As an aside, my preference for the brew session and recipe builder would be to expose the conversion efficiency as a parameter that can be defined/adjusted. Based on the recipe quantities and the existing equipment profile parameters all the subsequent efficiencies can be derived from the conversion efficiency (if the calculations did not have errors) - in this manner there will be no chance of specifying an ending kettle or brewhouse efficiency that is higher than what can actually be achieved for that recipe on that equipment, assuming the conversion efficiency entered is sensible.
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Apologies for the essay here and any frustration in my earlier posts. It's just disappointing to invest time and money (consumables) brewing a beer that was never going to be able to meet the recipe specifications due to software problems. A more experienced brewer may have been able to pick up on that prior to brewing, however I have been relying on the calculations on BF and assuming them to be reliable.