Missed OG - Hit preboil

[Vermelho]

So I was brewing a clone of Two Hearted Ale over the weekend and hit my preboil gravity of 1.052. I was supposed to end up with a post boil gravity of 1.064 but ended up with 1.058? I had the lid off the whole time and ended up with 22litres as expected. Any ideas how this was missed in between? I also boiled for 60 mins.

[nigel_c]

What software are you using?
You may have to adjust your effiency.
Sometime a recipe will be set to 70% effiency and your system will average about 65-68% . It's a matter of adjusting the recipe to hit the numbers your software produces or the recipe is based on.
Another option is to have some DME on hand and adjust your FG in the last few mins by adding 50g or so just to hit the numbers.

[Vermelho]

The problem is I hit my pre-boil gravity, I would've expected everything to line up after that. Does hitting my pre-boil gravity not indicate a good extraction rate already? My efficiency did come out 68% so I'll up it next time and see if this helps.

[Pheeel]

What was your pre boil volume?

[Sorcerers Apprentice]

Just looking at the maths
Expected result:
64 - 52 =12 gravity points
(12 ÷ 52 ) × 100 = percentage boil off = 23%
Preboil volume - 23% = 22 litres ( your post boil volume)
100 -23:=77
77% of preboil volume = 22
(22 ÷ 77) × 100 = 28.5 litres = preboil volume
Second scenario: ( what you ended up with )
58 - 52 = 6 gravity points
( 6 ÷ 52) × 100 = 11.5% boil off
Volume
Preboil volume - 11.5% = 22 litres
88.5% of preboil volume = 22 litres
Therefore preboil volume = 24.85 litres
So in short if your preboil volume was around 28.5 litres then there is possibly a problem with your saccharometer/ hydrometer/refractometer
If your preboil volume was approximately 24.85 then there is a problem with your software calculator, predicting 1064
The predicted boil off is at best an estimate as it depends upon the shape of the Boil Kettle, the larger the surface area then the larger the Boil off. It also depends upon the amount of heat applied ie how many kettle elements or size of gas ring. Believe it or not barometric pressure impacts on the Boil off rate as it changes the boiling point of water, so it's also weather dependent.

[Vermelho]

Just looking at the maths
Expected result:
64 - 52 =12 gravity points
(12 ÷ 52 ) × 100 = percentage boil off = 23%
Preboil volume - 23% = 22 litres ( your post boil volume)
100 -23:=77
77% of preboil volume = 22
(22 ÷ 77) × 100 = 28.5 litres = preboil volume
Second scenario: ( what you ended up with )
58 - 52 = 6 gravity points
( 6 ÷ 52) × 100 = 11.5% boil off
Volume
Preboil volume - 11.5% = 22 litres
88.5% of preboil volume = 22 litres
Therefore preboil volume = 24.85 litres
So in short if your preboil volume was around 28.5 litres then there is possibly a problem with your saccharometer/ hydrometer/refractometer
If your preboil volume was approximately 24.85 then there is a problem with your software calculator, predicting 1064
The predicted boil off is at best an estimate as it depends upon the shape of the Boil Kettle, the larger the surface area then the larger the Boil off. It also depends upon the amount of heat applied ie how many kettle elements or size of gas ring. Believe it or not barometric pressure impacts on the Boil off rate as it changes the boiling point of water, so it's also weather dependent.

My preboil was just shy of 28l and I ended up with 22l into the fermenter as expected.I need to do a couple more brews to figure this out I think. On the plus side the beer is down to 1.011 and tasting delicious.

[Sorcerers Apprentice]

I'd also double check your hydrometer. You can check them by using distilled / RO water for 1000 then by dissolving measured volumes of sugar into the water, or compare with someone else's one might be easier.
If you've boiled off 6 litres then the gravity reading should have been higher