Brewfather - Pre-boil Gravity

[dwalsh27]

Just did an Irish Red Ale and my corrected Pre-boil gravity was 1.052. This puts my efficiency at 99%! See attached batch sheet. Is this measurement supposed to be the "Hot" value (not-corrected) as this would make more sense putting my efficiency at 78%. My OG came right on at 1.046! Can't figure this out. New to Brewfather.

Thanks in advance.

 

[dwalsh27]

Just to clarify, the reading was 1.041 at mash temp which corrected to 1.052.

 

[McKnuckle]

Gravity increases after the boil, which is the opposite of what you recorded. So your pre-boil reading was not accurate.

Hydrometer correction is way off with large discrepancies from the calibration temperature. Most hydros are calibrated at either 60ºF or 68º. To be even close, you need to measure gravity at no more than 20º higher.

If your volumes are accurate (29 litres to 27 litres, 2 litres boil-off), and OG is accurate at 1.046, then your pre-boil gravity was 1.0428.

P.S. Set the Brewfather "Cooling shrinkage/Boil expansion" setting in the equipment profile to 0 for best results. The conversion causes some havoc with efficiency calculations.

 

[dwalsh27]

Thanks. So better to cool it to 20c then take reading. My mistake. How did you calc the pre-boil from the vol and OG? Should I adjust my boil off vol to 2 litres?

 

[McKnuckle]

Here is the calculator for determining gravity based on boil-off. And I assumed you actually measured 2 litres of boil-off from what you posted. If that's accurate, then of course you should modify your equipment profile to match.

 

[dwalsh27]

Here is the calculator for determining gravity based on boil-off. And I assumed you actually measured 2 litres of boil-off from what you posted. If that's accurate, then of course you should modify your equipment profile to match.

Thanks for your help!

So does Fermenter Volume include yeast starter or is it pre pitch?

 

[McKnuckle]

Fermenter volume does not include yeast starters, or any other volume added that wasn't produced by the brewing process itself.