Possible to get 90% eff. with current setup?

[ButterBar]

Good afternoon all!

I just collected the wort from my mash for an APA. I cooled the sample down to about 70 degrees and I measured a gravity reading on 1.06. My expected pre-boil gravity was supposed to be 1.046. Below is my equipment setup and mash bill, could anyone give me insight on why my apparent efficiency is this high?

Equipment:
10gal Rubbermaid MLT

Grain Bill:
8.5lbs 2-Row
.75lbs CaraPils
.75lbs Munich 10L
.5 Caramel/Crystal 60L

Mash: 152 degrees for 60 min
Mash-in: 3.5 gal at 163 degrees
1st runnings: 2 gal
Batch Sparge: 4gal @ 170 degrees, let it sit for 10min before collecting

Preboil volume: 5.7gal
Preboil Gravity: 1.060
Mash Efficiency: ~90%


Thanks all for your input. I just didn't think it would be possible for such high efficiency with batch sparging.

 

[cyanmonkey]

It's possible and been done, but I'm guessing someone made an error weighing out grain, or you made an error somehow. What's your typical efficiency run?

 

[ButterBar]

This is only my second AG batch. My previous efficiency was around 70% with over shooting my preboil volume and multiple stuck sparges.

 

[cyanmonkey]

I mean, it's certainly possible to hit 90%, but I doubt it. I have a friend with the same set up and he typically hits around 70%.

Either you have more grain than you realize, you're miscalculating, or you did actually hit 90%. Have you calibrated your hydrometer?

 

[doug293cz]

Your volume numbers don't add up. Two gal first runnings from 10.5 lb of grain and 3.5 gal strike water is reasonable. You can get this with 0.119 gal/lb grain absorption and 0.25 gal undrainable MLT volume (typical grain absorption is 0.11 - 0.125 gal/lb.) You should have recovered 4 gal of sparged wort from your 4 gal of sparge water, as no additional grain absorption takes place during sparging. Thus, you should have had a pre-boil volume of 6.0 gal, not 5.7 gal. So, there appear to be some volume measurement errors involved. If you want to get accurate efficiency calculations, you need to work on accurate volume measurements (including compensating for thermal expansion.)

If I plug your 10.5 grain bill, 3.5 gal strike, 2.0 gal first runnings, and 4 gal sparge into my batch sparge simulator, the maximum possible mash efficiency is 82% with a pre-boil SG of 1.051. If I drop your sparge vol to 3.7 gal and pre-boil to 5.7 gal, then the max possible mash efficiency is 81% with a pre-boil SG of 1.053.

There is no way you can get 5.7 gal pre-boil at 1.060 unless you had more grain than you thought you did. Just as for water/wort volumes, accurate efficiency calculations require accurate grain weight measurements.

Another possible source of error would be taking SG measurements at other than the calibration temperature of the hydrometer. You can calculate SG corrections for other measurement temps, but if you are more than 20˚F away from the hydro calibration temp, then the correction is likely to also contain errors.

Brew on

 

[chickypad]

I'll just also throw in a possible mixing error. If you took the gravity preboil maybe you got more first runnings in your sample prior to a thorough mix. Did you take a post boil reading and did those numbers match up?

 

[ButterBar]

I'll just also throw in a possible mixing error. If you took the gravity preboil maybe you got more first runnings in your sample prior to a thorough mix. Did you take a post boil reading and did those numbers match up?

WOW! I feel like the biggest dope now. I definitely forgot to mix the pre-boil wort; oops! That would explain it though. My post-boil OG turned out to be 1.060 as well, which I knew something was most likely wrong with my original pre-boil reading.

Thanks all for the help!