Calculating Efficiency - Double Check Plz

[Travel by the Pint]

I thought I would take a stab at calculating my system's efficiency. If I'm using the correct formula correctly, I come up with a pretty awesome result. So it begs the question, are my calculations accurate and/or are the baseline figures correct?

Brix reading at the beginning of the boil: 13
Volume at beginning of boil: 7 gallons

Grain bill:
9 lbs Bairds Two-Row (1.037 PPG*)
1 lb Belgian Aromatic (1.036 PPG*)
1 lb Crystal 90L (1.033 PPG*)

% efficiency = (boil kettle gravity point x volume)/sum (potential gravity points)

13 Brix = 1.053 SG, or 53 gravity points

53 * 7 = 371 (boil kettle gravity point x volume)

9 x 37 = 333
1 x 36 = 36
1 x 33 = 33
333 + 36 + 33 = 402 sum (potential gravity points)

Percent efficiency = 371/402 = 92%

*All PPG figures were drawn from a table posted on the Web and not from the maltster.

Thanks!

-Sally

[Jdl973]

Looks like you are on the money by the beer math

My guess is that your percent is a tad high. This is most likely due to the average PPG listing from the table you used. These numbers are averages from many batches of malt. I am betting if you used the Certificate of Analysis from the maltster, your numbers would come around the 86-89% range. Also the age of the grain will play a small part in the calculations.

I have done these calculations on my system with the general tables and the CA's, and got about he same numbers, 87% (CA) and 91% (tables). Well done.

Jason

[Travel by the Pint]

Looks like you are on the money by the beer math

Awesomeness!

I had my doubts about the outcome due to my sketchy track record. I tried this earlier in the year using a hydrometer and a non-cooled sample. Miraculously my efficiency on that batch was "over 100%." Ha!

Thanks for the confirm!

-Sally

[Jdl973]

Still can use a hydrometer as long as you take the temperature of the wort and adjust the reading for the temp..

Yea, the pros ain't getting 100%

[Travel by the Pint]

Still can use a hydrometer as long as you take the temperature of the wort and adjust the reading for the temp..

That had been my initial plan. But the adjustments only work within a narrow range, and I was measuring outside of that. If I had realized the adjustment was going to fall off (deliver bizarre results), I could have pulled a sample and cooled it in the refrigerator first. Then a hydrometer reading would have been a doable approach. Using the refractometer is much simpler and less wasteful, IMO.

Live and learn.

-Sally

[Jdl973]

Just remember your refractometer needs to have an ATM (aromatic temperature modifier) built into it in order to take a reading from hot samples. Some of the cheap ones do not have an ATM and the sample needs to be at 70F to be read.

Jason

[Travel by the Pint]

Just remember your refractometer needs to have an ATM (aromatic temperature modifier) built into it in order to take a reading from hot samples. Some of the cheap ones do not have an ATM and the sample needs to be at 70F to be read.

Jason

Right. But two drops cool a heck of a lot faster than enough to take a reading using a hydrometer.

-Sally