Lost Efficiency After Boil?

[violinguy]

I lost ten points after the boil. My pre-boil eff. was 74% and my brew-house was 64%? How is that possible.

And don't be afraid to explain it like you would to a 5th grader.

 

[Gnomebrewer]

BH efficiency incorporates trub losses. How much trub do you dump?



And put your hand up before asking questions or you'll get a detention! (is that OK for a 5th grader?)

 

[imasickboy]

Your preboil efficiency is only looking at how many of the potential points per gallon you were able to extract from the mash. Brewhouse efficiency calculates how you utilize those points in creating a certain volume of wort.

 

[doug293cz]

Pre-Boil Efficiency = Post-Boil Efficiency, unless you add sugar or spill a lot of wort (including by boil over.)

Brewhouse Efficiency = Post-Boil Efficiency * Fermenter Volume / Post-Boil Volume [in BK]

Thus Fermenter Volume / Post-Boil Volume = 64% / 74% = 86.5%. So, unless your measurements are off, you left 13.5% of you volume in the BK when transferring to the fermenter.

Brew on

 

[violinguy]

Something's not right then because I put just a tiny bit under 3 gallons into fermenter (3 gallon batch) and left nothing but a few drops. Hops in bags so no sludge there. Either I don't understand how to calculate this stuff (brewer's friend is a big help), or the sugar fairy gets in there and takes away some of my valuable gravity points. You know, just when you think you're beginning to understand this stuff...

 

[doug293cz]

Once you get to the boil, the only way to lose sugar is to lose wort.

It is pretty easy to get erroneous pre-boil SG measurements if there is any sparging or top up water involved. It is much more difficult than you think to homogenize concentrated wort and dilute wort/water. It requires very vigorous stirring. If you don't get it homogenized, it's possible to sample from either a high SG region or a low SG region. Either one of these will play havoc with the agreement between your pre-boil and post-boil efficiency calcs.

Brew on

 

[Gnomebrewer]

Yep. What Doug said. I wait until my wort has been vigorously boiling for a few minutes before taking my pre-boil gravity measurement. A rolling boil does a pretty good job of mixing.

 

[violinguy]

It is pretty easy to get erroneous pre-boil SG measurements if there is any sparging or top up water involved. It is much more difficult than you think to homogenize concentrated wort and dilute wort/water. It requires very vigorous stirring. If you don't get it homogenized, it's possible to sample from either a high SG region or a low SG region. Either one of these will play havoc with the agreement between your pre-boil and post-boil efficiency calcs.

Brew on

This is most likely what happened. I did a pour-over sparge and I thought I gave it a good stir, but it seems it wasn't good enough. Along with the grains that were NOT double crushed like I normally get, it makes sense that my efficiency suffered. More things to do better next time. Mmmmmm, next time.....

 

[jcaggiano]

Let us know how the beer turns out. Sometimes the numbers don't add up to the finished product!

I had a coffee brown ale that never should have fermented that was a likely the best beer I have done!