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First All-Grain Brew-Efficiency Questions


Well after many weeks of gathering a keg, converting it, and attaining other equipment and know how I finally brewed up the Surly Furious AG kit from NB using my stainless steel keg turned MLT. It has a jaybird false bottom with s.s. dip tube installed in the keg wall along with a miljoco thermometer that is also installed in the keg wall. I mashed with 4.12 gallons of water in the keg heated to 168 degrees and then wrapped in tons of reflectix insulation. Then the grains were mixed in and the mash tun covered with an insulated lid. I mashed at ~153ºF, although I do believe that I may have been a couple of degrees above that temperature. At the end of the mash I vorlaufed about 5 quarts total and then used a bucket of 168ºF sparge water to batch sparge and used a hose to allow it to flow into the mash tun. I conducted the recirculation and draining procedure just as with the mash water to collect ~7.3 gallons of wort in the boil kettle. Now, I took a hydrometer reading that read at 1.030, pre-boil where the wort was at about 160ºF. I used the following calculations to try to determine the efficiency of my system:

7.5 lbs. Canada Malting Pale Ale @ 34 ppg= ((34 ppg * 7.5 lbs.) / 7.3 gallons) = 34.9 ppg
3.25 lbs. British Golden Promise @ 36 ppg= ((36 ppg * 3.25 lbs.) / 7.3 gallons) = 16.03 ppg
0.88 lbs. English Medium Crystal @ 34 ppg= ((34 ppg * 0.88 lbs.) / 7.3 gallons) = 4.1 ppg
0.63 lbs. Belgian Aromatic Malt @ 34 ppg= ((34 ppg * 0.63 lbs.) / 7.3 gallons) = 2.93 ppg
0.125 lbs. English Roasted Barley @ 25 ppg= ((25 ppg * 0.125 lbs.) / 7.3 gallons) = 0.43 ppg
58.37 ppg.
After adding up all of these values to give 58.37 I determined the efficiency by dividing 30 by 58.37 to give an efficiency of 51% but after adjusting the hydrometer reading using the BeerSmith calculator I got a value of 1.053 at room temp. which seems too high to me, this gives an efficiency of 90% which also seems far too high. So, what does everyone think, am I doing this right or should I be determining my efficiency differently? Also, my post-boil, cooled OG was 1.057, missing the 1.064 value by a good bit…


First off I think you want to cool your preboil sample before taking the reading, there are correction factors but its not very accurate since the stuff is cooling off rapidly.

Second, I wonder how accurate your final volume is? Are you sure its exactly 5gal? Being off by a quart or two can make a big difference.

Your grain bill should generate 426pts total at 100%. You got 57x 5gal=285pts. 285/426=67% efficiency, not super but not abnormal by any means. If your volume is actually 5.25gal you’d have 70% efficiency. And thats brewhouse efficiency, so any trub you left behind or dead space in the MLT will be included in that. Pretty typical.

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