Trying to understand Brewfather Water Calculations

[uweschmitt]

Hi all,

my Brewfather predictions between mash and brewhouse efficiency are off and in order to understand how I have to change my equipment profile I try to reverse engineer how brewfather calculates numbers.

My first attempt is this recipe where I set all mash / sparge losses to 0, grain absorption rate is 0 also.

I get this weird result:

- total water 12.4 l
- pre boil volume 12.92 l

I tried different boil times, but the pre-boil volume is always off (but slightly changing in the range 0.4 - 0,5 l).


Any idea where this extra water is coming from?

 

[DBhomebrew]

mash / sparge losses to 0, grain absorption rate is 0 also.

I can't imagine this is anywhere near your actuals.

The dissolved solids add some volume. A half liter? I don't know.

 

[uweschmitt]

I can't imagine this is anywhere near your actuals.

I choose this to play with the numbers.

Meanwhile I increased grain loss and mash tun loss, and when I do the math manually, brewfather is still off by the same amount, or my my math is wrong.

 

[uweschmitt]

The dissolved solids add some volume. A half liter? I don't know.

Good idea. Tried this out and I increased malt but the offset is still the same.

I posted meanwhile at the brewfather issue tracker, I hope I get some response.

 

[kurds_2408]

Is that the default 4% for heat expansion on preboil?

 

[uweschmitt]

Is that the default 4% for heat expansion on preboil?

Good point, checked it. The increase from 12.4 to 12.92 is 4.2% so pretty close.
I assume the deviation comes from rounding (12.42 would be the right number for mashing, but brewfather does not show the 2nd digit).

Thanks.