beersmith pre boil problem

[matc]

Very often, I get a lower measured pre boil volume than expected. Sometimes I'm spot on and sometimes not. What could affect this thing.

Today, I was planning for a 28L pre boi volume but I got 25 L. I've checked my mash tun deadspace twice and everything's ok. The only thing new I added today was brew pump but I can't lose 3L because of that. I've also measured carefully my grains and water volume.

Is it possible that my grain absortion was higher than usual ?

I'm getting pissed because of that

oh btw, forgot to add that despite having 3 liters less than expected, I still achieved a perfect gravity. That's weird no ?

 

[Oginme]

If you have good accurate measurements of water in, grain weight, volume out and dead space, you should be able to plug these values into your equipment and mash profiles in beersmith to make the volumes come out more accurate.

If you achieved your target gravity with 3 l less wort, you also probably also need to adjust your efficiency, though I would make the volume adjustments first and see how that effects your efficiency.

 

[raysmithtx]

Since it's the pre boil volume you are having a problem with I will venture a guess that your grain absorption rate is incorrect. If larger grain bills are off more than smaller ones then look there.