recipe numbers not matching up

just bought brewing classic styles and want to input the recipes into BS. but i can't get the numbers to match up consistently. according to JZ in the book: malt yield is 70% efficiency (i have also seen in his BS files that he uses 70% for his total efficiency so this is what i am using), batch size is 5.5 gallons into fermentor, evap rate is 15% per hour, boil time is 60 min, mash is 60 min (single temp infusion). so using those numbers someone put in this:

pilsner malt (wyermann) 8.5 lbs
munich 4 lbs
melanoidin malt 2 oz

this is the total grain bill. this is what he says you should get:
OG 1.055
FG 1.013
pre boil grav 1.047

BS gives:
1.060
1.013 est
1.049 est

why is the OG so far off?

so i found this and it seems to work from a few quick looks:

http://thebrewingnetwork.com/forum/viewtopic.php?f=2&t=17961

but i have no idea why you would put in 6 gallons when it is 5.5 gallons going into the fermentor? can anyone explain this?

It looks like you're seeing a higher OG than the recipe dictates. Could be a setting issue in your equipment profile - these things take a while to dial-in so don't sweat it too much. When I put those grains into BS2, I get 1.056 - close enough IMHO.

Concerning the 6 gallon thing - I do the same - my stated "Batch Size" in BS2 is 6 gallons, and I expect 5.5 in the fermenter. I know this throws BS2's calculated Brewhouse Efficiency for a loop on every batch (BS2 tells me I'm getting around 61%), but I don't care too much for that number because I know what the real number is, and it's that number that I put in my Equipment Profile (currently 73%) - this is just how BS2 works, so I go with it.

The reason for this discrepancy is the placement of the sugar calculators in the program. I used to use Trub Loss to compensate for discrepancies in my volumes, but learned quickly that my OG was coming up short because the total volume including Trub Loses, I thought, should contain the sugar calculations, but it doesn't.

BS2 ignores the Trub Loss volume in the initial gravity calcs but it also includes that volume in the total water needed. Even if it gets left behind in the kettle due to its infusion with hop-sludge, break material or whatever, it still should be included in the gravity calculations, no?

So I dropped Trub Loss to zero and upped the batch size from 5.5 to 6 gallons and Presto! Now I hit my gravity targets spot-on and seeing as I generally leave about half a gallon of gunk in the kettle, my volumes are pretty much spot-on as well.

Keep playing with the Equipment Profile and don't forget to plug it in under the Options menu so every time you go to create a new recipe, the updated profile will be there waiting for you. Again; it'll take a while to dial it in and get a good feel for it, but stick with it, you'll get there.

Ending up higher is often due to diff's in volume.  Less volume concentrates the sugars, boosting OG.

The two-point difference in Pre-Boil growing to five points in OG indicates a possible difference in boil-off. 

You don't mention whether you are setting JZ'S PBV of 7 gallons and if you cleared the Cal Boil Vol box.

The diastatic power of the grains is likely, along with some previous mentioned volume issue, part of the cause of the variations. JZ has been making great beers for many years. You don't know what brands or country of origin of the malt he used, but I would assume if Jamil was brewing a German beer, he would be using German malts, etc. The brew time is listed as 60 minutes, but if we have to boil 10 min or longer to concentrate the wort to hit the OG, that is what brewers do, if you are looking to brew consistent repeatable beer. Ingredients vary, we adjust!

Weyermann German pils will give you a higher SG than Castle Belgium pils. It is even listed in the software to reflect this. I edited my ingredients list to drop it even a couple of points lower after brewing a full sack. Use the freshest continental Munich you can find. Stale grain will deflate your #'s.

This software gives you an ESTIMATE, that you nudge in the direction of your resultant brew, after you have already dialed in the operation of the brewing system. 

###########################'S don't have to match!, Have fun tinkering with them!

P.S. You won't know what your numbers are until after you brew.

RiverBrewer said:

This software gives you an ESTIMATE, that you nudge in the direction of your resultant brew, after you have already dialed in the operation of the brewing system. 

Click to expand...

Amen.  Brewing software is an aid...we're still the brewer-in-charge.  The buck stops with the brewer.