96% Efficiency into Boiler

6.8 gallons of wort collected with a pre-boil gravity of 1.037. Target pre-boil gravity was 1.031. BeerSmith tells me this is a 96% efficiency into the boiler. I'm not entirely sure what to make of this result, or if it even makes sense.

Had I done nothing I would have overshot my OG by a large margin, so I added 1.2 gallons of water to the boil to bring the gravity down to target. (The BeerSmith Dilution Tool helped me figure out how much to add.)

I ended up with 6.25 gallons of wort (target was 5.75 gallons) at an OG of 1.038, which was my target. This is an 88% efficiency into the fermenter based on actual volume.

My previous AG batch was similar, but I thought it was a fluke. I need to increase my efficiency assumption when I plan AG brews.

22 hours later it has 1" of krausen, the yeast is swirling like crazy, and theres 1-2 bubbs/sec from the blowoff tube.

Recipe/Proceedure details:

BeerSmith Recipe Printout - www.beersmith.com
Recipe: No Short Measure
Brewer: Beerthoven
Style: Standard/Ordinary Bitter
TYPE: All Grain

Recipe Specifications
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Batch Size: 5.50 gal
Boil Size: 6.74 gal
Estimated OG: 1.038 SG
Estimated Color: 10.2 SRM
Estimated IBU: 31.6 IBU
Brewhouse Efficiency: 80.00 %
Boil Time: 60 Minutes

Ingredients:
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Amount Item Type % or IBU
6 lbs 4.0 oz Pale Malt, Maris Otter (3.0 SRM) Grain 89.29 %
8.0 oz Caramel/Crystal Malt -120L (120.0 SRM) Grain 7.14 %
4.0 oz Special Roast (50.0 SRM) Grain 3.57 %
1.00 oz Challenger [6.90 %] (60 min) Hops 25.6 IBU
0.50 oz Goldings, East Kent [4.00 %] (30 min) Hops 5.7 IBU
0.50 oz Goldings, East Kent [4.00 %] (1 min) Hops 0.3 IBU
1.00 items Whirlfloc Tablet (Boil 10.0 min) Misc
1 Pkgs SafAle English Ale (DCL Yeast #S-04) Yeast-Ale

All grains crushed with a Barley Crusher at factory settings.

Mash Schedule: Single Infusion, Medium Body
Total Grain Weight: 7.00 lb
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Single Infusion, Medium Body
Step Time Name Description Step Temp
45 min Mash In Add 8.75 qt of water at 164.2 F 152.0 F
10 min Mash Out Add 4.90 qt of water at 200.7 F 168.0 F

Single batch sparge with 4.42 gallons of water at 175 F.

Aerate for 1 min with O2.

Pitch yeast at 65 F, ferment at 67 F.

Notes:
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Source: No Short Measure Ordinary Bitter, Jamil Z and John P, Brewing Classic Styles (1st Ed)

Similar thing happened to me on my last all grain batch, got about 94% efficiency into the boiler.

Haven't brewed since so I dunno if it was a fluke or a wrong measurement somewhere - although my OG was definately correct.

Try checking the potential extract in BS for your malts to see if they're the same as the malt suppliers analysis sheets. I've heard this can bugger up the results. I've changed mine now but haven't brewed since. Mine was out 2% on FGDB dunno how big of a difference it will make.

Actually 6.25 gallons of 1.038 is 94% brewhouse based on that bill.