Conversion Efficiency Question

[DoubleAbrew]

I have done about 5 brews now where the conversion efficiency comes out to around 110%. How is this possible? I have read, and re-read the directions more times than I care to count, and checked and re-checked the numbers I put into brew logs. It says, conversion efficiency is the total strike and sparge water I put into the mash tun measured with the pre-boil volume.

Today's brew example:

Grain bill: 9.62 lbs
Water/Grist ratio: 1.5 qts/lb

14.1 qts strike water plus 19.2 qts sparge water to reach a total of 33.3 qts water pre-boil. This minus losses should give me 28.6 qts pre-boil volume. My pre-boil gravity reading was 1.042

So, conversion efficiency would be 33.3 qts at 1.042 whereas my pre-boil efficiency is 28.6 qts at 1.042. Run the numbers I get 111% conversion eff and 85% pre-boil eff. What am I doing wrong???

 

[Ozarks Mountain Brewery]

100% is all you can get and good luck getting that, the highest efficiency Ive heard of is 90% so no its not even possible. don't pay attention to preboil gravity its just an estimate and many things can change that reading like not mixed up enough plus your readings are meant to be read at 60f not 168, just read the starting from the fermenter at 60 to 70 then when fermentation finishes

 

[jeffpn]

All I use to calculate efficiency is grain amount and kettle post boil volume. You've got other variables that makes my head spin. What was your kettle post boil volume and grain bill?

 

[UgliestLemming]

Conversion efficiency is first runnings (basically). It's total mash water not including sparge water, with gravity taken from that wort. Pre-Boil efficiency is total water (Mash + Sparge) and pre-boil gravity. Conversion efficiency should approach 100% (Typically 90%+ is good.) Everything after that should be lower, as your losses add up. That said, your pre-boil efficiency sounds correct, but your conversion efficiency is using the incorrect numbers.

You can not extract more fermentables from the grain than exists in the grain, so if your efficiency is over 100% either the measurements were incorrect or fermentables were added.

I find this chart helpful

 

[DoubleAbrew]

I normally fly sparge so I don't really look at first runnings anyway. In the FAQs, "Measurement Option B" states that the sample is taken from the blend of all runnings and uses total mash and sparge water. These are the numbers I'm putting in to get the 100%+ eff numbers. I know this isn't physically possible but I also know I'm putting the right numbers in. Granted, my measurements may be a little off, but if 90% is good, thats a 20% error to get to 110%!

 

[Head First]

I normally fly sparge so I don't really look at first runnings anyway. In the FAQs, "Measurement Option B" states that the sample is taken from the blend of all runnings and uses total mash and sparge water. These are the numbers I'm putting in to get the 100%+ eff numbers. I know this isn't physically possible but I also know I'm putting the right numbers in. Granted, my measurements may be a little off, but if 90% is good, thats a 20% error to get to 110%!

Play with your numbers a little bit as far as your volumes, hydrometer readings and actual grain weights and PPG's go. I Worked with Larry brewer quite a bit to fully understand the math of this software (still above me to completely get). It doesn't take much variation in volumes to give you off numbers as you are stating. In 2.5 gallons 1 quart is 10%. With a hydrometer reading there is some room for err also. Send that through some equations and it will change more. After a few more batches you will see a pattern and you will figure it out. Look on the bright side, its not 50%
And by the way you are looking and talking about Conversion Efficiency, so close to 100% with a good fly sparge is not out of the question. The Brewhouse Efficiency is the one where people usually claim higher than possible.

 

[Ozarks Mountain Brewery]

one thing to isn't really easily recorded is the first runnings, it all depends on how much water in the mash and how much the grain soaked up, it can be very misleading so I don't pay attention to it my self. most of this site isn't up to date with the latest modern setups like mine and could be yours too, its probably way down the list of things to change but it will be needed in the future

 

[wolfie7873]

This sounds like a terribly complicated way to calculate conversion efficiency.

I've been doing it this way:

Volume into the kettle * gravity pre-boil (temperature corrected) / ( pounds of grain * points per pound )

Technically not exact because of losses in the mash tun (or just runnings left behind after they got low), but isn't this the easiest way?