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Scratching my head

B

Browny

Hi Gents,
I am having trouble understanding what I am doing wrong with Beersmith as I can never achieve Brewsmiths predictions for either post boil gravity or Litres into the fermenter. Here is my latest brew.

BeerSmith Recipe Printout - www.beersmith.com
Recipe: Glacier Pale Ale
Brewer: Tony Brown
Asst Brewer:
Style: American Pale Ale
TYPE: All Grain
Taste: (35.0)

Recipe Specifications
--------------------------
Batch Size: 21.00 L      
Boil Size: 28.59 L
Estimated OG: 1.058 SG
Estimated Color: 6.4 SRM
Estimated IBU: 34.8 IBU
Brewhouse Efficiency: 70.0 %
Boil Time: 60 Minutes

Ingredients:
------------
Amount        Item                                      Type         % or IBU      
5.50 kg       Pale Malt (2 Row) UK (3.0 SRM)            Grain        94.0 %        
0.25 kg       Wheat Malt, Bel (2.0 SRM)                 Grain        4.3 %        
0.10 kg       Caramel/Crystal Malt - 40L (40.0 SRM)     Grain        1.7 %        
20.00 gm      Glacier [5.60%]  (60 min) (First Wort Hop)Hops         14.4 IBU      
20.00 gm      Glacier [5.60%]  (30 min)                 Hops         10.0 IBU      
20.00 gm      Glacier [5.60%]  (15 min)                 Hops         6.5 IBU      
30.00 gm      Glacier [5.60%]  (5 min)                  Hops         3.9 IBU      
1.00 tsp      Irish Moss (Boil 15.0 min)                Misc                      
1.00 tsp      Sodium Chloride (Boil 60.0 min)           Misc                      
1 Pkgs        US-56 (Safale) [Starter 1000 ml]          Yeast-Ale                  


Mash Schedule: Single Infusion, Light Body, Batch Sparge
Total Grain Weight: 5.85 kg
----------------------------
Name               Description                         Step Temp     Step Time    
Mash In            Add 15.24 L of water at 75.9 C      65.6 C        75 min        

After sparging I ended up with 30.25L (1.66L more than predicted) in the kettle for an SG of 1.043 Exactly what Brewsmith predicted. However after boiling for 60 mins and getting exactly 21L in the fermenter, the OG was 1.049 instead of the predicted 1.058 ! I'm new to AG brewing (this was my 7th AG brew) and am stuffed if I know the answer here, the only thing I can think is that the graduations on my fermenter are miles out.

Any ideas Brad ?
 

bonjour

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1.043 with 30.25l should have given you (by rough calc) 1.061 at 21 liters.

Since (I assume) both measurements are "kettle" measurements (no losses) this means that one of the gravity readins is off.  Stratification, or uneven mixing, is a frequent cause.  I suspect the error is on the 21 liter reading because the 30.25 reading is close to BeerSmith's prediction.  

In accurate volume measurement is also a frequent problem,  some of these buckets are really off.  If you left trub in your kettle I'm sure you left wort too,  this "loss" could be at least part of the problem

Does this help some

Fred
 

BeerSmith

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 Most of the problems with volumes can be worked out by accurately measuring your setup during a brew and entering all of the data in the equipment profile.  You can also use the water needed tool to walk through the calculations by hand if you like.

 The lower SG could be related to volume, or perhaps you did not temperature-correct your reading when you made it in the boiler.  Try using the hydrometer adjust to make sure you did not take a reading at high temperature without correcting it.  

  As Fred points out you may need to look at the trub losses as well.  If you lost a lot of points in the boil you may have left a large quantity of trub behind.

Brad
 
B

Browny

I use a refractometer to take my readings and allow ample time for temp correction so I think the readings are probably pretty accurate. I have rechecked my dipstick (with cold water) so I don't know how this would affect things, I guess it would show there is more wort than there actually is (due to thermal expansion). Having said that, it wopuld mean there was really only 29.25L minus 4-5L boil off and 3L to trub would leave me with 21L. So does Beersmith predict cold amounts or hot amounts?

cheers

Browny
 

BeerSmith

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BeerSmith does include a 4% thermal expansion in the water calculations for hot water.

The only other thing I can think of (though you have probably done this) is that your refractometer calibration might be off a bit.  Did you use the calibration button under the refractometer tool to calibrate it?

Brad
 
B

Browny

No Brad, I have not done that yet, but something I'd be interested to know is that when I used the figures from the recipe above and put them into the boil off tool, it says that the SG should end up at 1.050 instead of the predicted 1.058 in the recipe sheet. I have my boil off set to 14% should it not give the same result ?

cheers

Browny
 

BeerSmith

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Browny,
 There is one big difference I forgot to mention.  The recipe calculator uses your gross brewing efficiency (say 70%) to determine final gravity and not the intermediate gravities.  The reason for this is the definition of brewhouse efficiency which is simply a number that accounts for all of the losses in your brewing system.

 The boil off tool does a straight concentration calculation without taking into account your brewhouse efficiency.  The recipe tool uses efficiency and your starting grains only to determine the original gravity, not the intermediate water losses (which are assumed to be part of the overall efficiency number).

 After substantial discussion here we have talked about an alternate system to allow people to enter mash efficiency instead and have BeerSmith do the calculations from there, but not many people know there mash efficiency.

 This could possibly account for the differences in final numbers you are seeing.  Perhaps your overall system efficiency is lower than you think it is.

Cheers!
Brad
 
B

Browny

OK Brad, taking that into account, would not the boil off tool show a higher OG (more efficient) than the recipe program ?

sorry about the questions, I am having a hard time getting my head around this. Really do love the program though Brad, best proggie I've ever bought.

cheers

Browny
 

BeerSmith

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Browny,
 It depends...the boil off tool does a straight calculation based on concentration of the wort.  Basically you are putting the same amount of sugar into a smaller volume when you boil it.  As you noted, using your figures the mash SG of 1.043 turns into a final gravity of 1.050 when you take into account only the boil off tool.

In contrast the estimated OG for the recipe is a straight calculation based on estimated final volume, amount of grains used and the overall brewhouse efficiency.  

 The problem in this case appears to be that you did not have a great efficiency in the mash.  The mere fact that the boil off tool results in 1.050 given your pre-boil gravity indicates that you were probably quite low on gravity going into the boil.  The low pre-boil gravity resulted in a final gravity of 1.048 - a number that is pretty close to what you would expect using the boil off tool.

 If you want to email the recipe to me I can do a more detailed analysis for you.  You might also want to compare the number on the "preview brewsheet" view which will show the estimated preboil gravity based only on the recipe.

Cheers!
Brad

 
 
B

Browny

But I got the correct SG 1.043 with 30.25L into the kettle which to me is more efficient than 1.043 with 28.59L as predicted by the brewsheet. I can't see that efficiency into the kettle was the problem as I was over and above what the brewsheet predicted.
Bugger, I'm doing another brew this weekend, I'll see what happens this time.

cheers

Browny
 

BeerSmith

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Browny,
 Email the recipe to me and I will do a more detailed analysis.

Brad
 
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