Is it possible to have a 98% brewhouse efficiency?

Hi! Long time lurker, first time poster here. Im stumped. I'm pretty sure it must be wrong, but I can't figure out why.

We brewed an esb yesterday that's happily fermenting right now. Everything went swimmingly until we took the gravity reading. We got 1.074 post boil with 12.75lbs or grains!

here's the grain bill:

11.5lbs UK pale 2-row
.75lbs UK Brown malt
.5 UK Crystal 70L

Pre-boil Volume was 6.35 and post boil it was 5.2. I used 5 gallons in the calculator as the batch volume as we discarded about .2 gallons of trub.

We normally get around 75% efficiency with our setup so we were expecting a gravity of around 1.055 ish . What happened here??! Beersmith has our efficiency for this brew at 98.9% !!!!

here's a pic of the grav reading:

http://imgur.com/1QApU.jpg

I get 1.091 at 100% efficiency, and 82% at 1.074 for 5 gallons with that grain bill.

Where do you get 98%

What was the temperature of the wort when you measured the gravity?

what am I doing wrong here:

http://imgur.com/9PqcZ.png

temp was at 60 degrees . triple checked with 2 hydrometers. made sure the hydrometers were calibrated with water showing 1.000

bryan567 said:

what am I doing wrong here:

http://imgur.com/9PqcZ.png

temp was at 60 degrees . triple checked with 2 hydrometers. made sure the hydrometers were calibrated with water showing 1.000

Click to expand...

What are you using for the ppg of the grains? I used 1.036 for the UK pale malt.

ahhh.. that may be it there.. beersmith shows 1.029. never really thought those would be inaccurate..

but still, would it throw it off THAT much?

bryan567 said:

ahhh.. that may be it there.. beersmith shows 1.029. never really thought those would be inaccurate..

but still, would it throw it off THAT much?

Click to expand...

Sure. And each batch of malt is slightly different- that's why efficiency numbers are just a guess unless you have a malt analysis sheet in front of you with the actual numbers from your malt. I just used an average of my previous malts- yours may be quite a bit different.