efficiency calculator help

[grathan]

just punching numbers from my latest batch and am a little confused on how it works.

11 Lbs Canadian 2-row
.582 lb crystal 60L
1 LB crystal 40L

using the calculator here:
http://www.brewersfriend.com/brewhouse-efficiency/

If I measure pre-boil volume of 6.5 gallons at 11brix (1.045) it says %65

If I use post-boil 5.5 15brix(1.061) it says %75


I know that my measurements could be off, but does it seem odd boil-off would raise efficiency 10% with a gallon less wort?

Does kettle trub and hot breaks effect refractometer readings?

 

[ajf]

The most likely explanation is that you didn't stir your pre-boil sample sufficiently before taking the sample. If both samples were taken in the kettle, they should return the same number if the volume measurements are accurate.
Another thing to consider is that if you take a measurement at boiling temperature, the volume of wort will be about 4% higher than it would be when cooled to 60F

-a.

 

[TheHomebrewNerd]

The most likely explanation is that you didn't stir your pre-boil sample sufficiently before taking the sample. If both samples were taken in the kettle, they should return the same number if the volume measurements are accurate.

I agree with this. I think something went wrong with your gravity measurements or your volume measurements. According to your pre boil measurements you had 292.5 total 'gravity points' in your beer (6.5 gallons * 45 pts/gal). If you boil off 1 gallon, your post boil gravity should be 1.053 (292.5 points/5.5 gallons = 53 points).

Boiling won't change your extract efficiency.

 

[Buna_Bere]

11 lbs 2 row at 36 ppg 11x36= 396
0.582 lbs c60 at 34 ppg 0.582x34=20
1 lb c40 at 34 ppg 1x34=34

396+20+34= 450 potential gravity points

6.5 gallons x 45 = 292.5 gravity points extracted

292.5/450= 65% preboil efficiency(efficiency into the boiler)

292.5/5.5= 53 for a post boil gravity reading of 1.053


The guys above beat me to it.