Hitting predicted OG beersmith

[Ben034]

Hi, I just want to check if anyone had an idea of how my OG was missed since changing my set up recently. I use Beersmith to predict OG. This was predicted as 1042 for a Kolsch I made yesterday.

The predicted pre boil gravity was 1032. I hit 1030 which was ok. I would just lower the efficiency next time on the equipment profile to use a little more grain.

However, I then missed the OG by 5 points (actual OG of 1037 when should have been 1042). I thought it must be the post boil volume is higher than expected but it was only 0.3L over so would not account for much of the variation. I checked all gravity measurents with a hydrometer and refractometer so I don't think the readings are off. I used malt extract to alter the efficiency to a more respectable 1040 before transferring to fermenter.

Any ideas? TIA

 

[Dutto]

Check the predicted "Efficiency". This is usually why the OG is missed.

 

[Ben034]

I may have answered my own question by thinking it through again. I think the volume was 0.8l over. The volume would have been correct pre cooling shrinkage.

 

[Ben034]

Thanks. Yes the efficiency was a little off but biggest issue was induction hob seemed to boil off at a lower rate for some reason. This meant pre boil gravity was nearly correct but OG was way off.

Check the predicted "Efficiency". This is usually why the OG is missed.