Very Odd Water Change when Selecting Fermentor

[AHarper]

This is a very odd one.

I had a perfectly saved recipe that had all the correct values that I wanted to investigate a small change from the original
Ending Kettle selection. On the change of the TARGET drop down to FERMENTOR the water requirements for BATCH size went up to 77.493 Litres from 21 Litres. Other values such as the OG etc. changed too.

Something very strange happening here - never seen it before.

The recipe is https://www.brewersfriend.com/homebrew/recipe/view/1230986/shut-your-trappist


Original recipe settings

Setting on the change of TARGET drop down

 

[Mark Farrall]

I'm seeing something very similar. Changing to fermenter as target, the batch size jumps from 12 litres to 44 litres. Looking at the quick water requirements I can see a large top off amount that explains the difference. I can't find anywhere in the recipe where a top off amount is added. Mash guidelines just has the one 16 litre strike water entry.

My recipe is at https://www.brewersfriend.com/homebrew/recipe/edit/841466

 

[Mark Farrall]

Playing around on another similar sized recipe. Grabbed a screenshot of the QWR before anything was changed (at least by me). Changed target to fermenter, got the overly large batch size 12 litres to 43.92494 litres, with a QWR identical to the screenshot above. Manually changed the batch size back to 12 litres and the QWR now matches the screenshot I had before the change.

I also rounded off the initial strike water addition, from 16.3 to 16 litres. The QWR continues to show the strike water at the original 16.3 litres. Even after a number of saves and a page reload. I can see this is from equipment estimates, so maybe it has no relation to the mash guidelines. Though if it's equipment based why does it have a 1.6 litre top off?

I'm just catching up on these changes, so I'm not sure what's the expected behaviour. I didn't have a chance to try this out when it was in beta.

 

[AHarper]

I'm not sure but - and this is a pure guess - the system is multiplying the Kettle volume ( in litres) by the conversion between Gal / Litres (3.7854) then subtracting the Kettle + Misc losses.... with some rounding errors involved as the multiplying factor is curiously similar.
As I said it is a wild guess but it is a curious problem and I don't know the full equation used.

UPDATE: If you change the Equipment profile setting to No Equipment Profile Selected then the problem remains so the above statement - about using system Losses - also fails so it is total rubbish - please ignore it.

 

[Yooper]

@Pricelessbrewing this seems to be related to what you're working on.

 

[Pricelessbrewing]

2 things here it looks like.

1) The "hidden" Batch size issue has been identified, @Yooper this is in #2290. We'll push a patch update out as soon as possible, thank you for the additional examples!

2) At this time, the QWR is based on the Recipe boil volumes, the mash guidelines Mash Thickness parameter (but not the steps themselves), and the equipment profile. When there's discrepencies, the "equipment estimates____" warning is shown for that particular step. The top off lines in the QWR should show up whenever the recipe postboil volume is less than the recipe batch size. Since the batch size is behaving strangely, this makes sense that the top off lines are showing up where they shouldn't be like in @Mark Farrall example above with a topoff of 33 liters. to hit the "hidden" batch size of 44L