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Batch sparge water quantities

Merkur

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I am honing my equipment profile and getting the Brewhouse efficiencies up.  After reading several articles on batch sparging, what I am trying to do is do a two stage batch sparge with equal quantities out of the mash tun, each equal to half the pre-boil volume.
  eg: My current recipe has 7.2 gallons into the kettle so I expect to get 3.6 gallons out after the mash and then put another 3.6 gallons into the mash tun to yield a total of 7.2.

I have the mash profile set in BeerSmith to Single infusion, No mash out and the three batch sparge options boxes ticked (Use equal batch sizes, Sparge using batches that fill 100% and Drain mash tun before sparging.)

Beersmith is telling me to mash in with 4.7 gallons which sounds correct given the grain bill size and assuming 0.1gallon/Lb of absorption that should yield exactly 3.6 gallons which is half the pre-boil volume.  The problem is that it then tells me to batch sparge with another 4.7 gallons.  Since here is little to no absorption after the mash, that will yield an extra 1.1 gallons of wort.  I was expecting that figure to be 3.6 gallons.

Am I missing something here?  I have tried un-checking the 'Batch sparge using equal volumes' checkbox but I get the same results.  It's not a big issue but in every other respect the Beersmith numbers are spot on.  I am just trying to gain confidence in the calculations and according to the experts (Denny Conn being one),  optimal efficiency is achieved with equal runnings out of the mash tun.

Thanks,

Paul
 
Hi Oginme.  Yes I have that all characterized in the Equipment profile.  I have 0.75 gallons of deadspace but that should all be figured into the quantities the way I understand it.

Here is the complete profile:
  Batch Size: 5.50 gal
  Mash Volume: 10.00 gal
  Boil Volume: 7.24 gal
  Mash Tun Weight: 10.00 lb
  Evaporation Rate: 8.3 %
  Mash Tun Specific Heat: 0.30 cal/g-deg C
  Boil Time: 60
  Mash Tun Deadspace: 0.75 gal
  Top-up for Boiler: 0.00 gal
  Equip Hop Utilization: 100.00 %
  Losses to Trub/Chiller: 0.87 gal
  Cooling Loss (%): 4.00
  Top up water for Fermenter: 0.00 gal 
 
So your initial infusion should be figured by the following equation:

Mash in Volume = (pre-boil volume/2) + Mash Tun Dead Space + grain absorption 

You don't state your total grain bill wt, but we can figure that out by the original volumes given your absorption of 0.1 gal/lb.  The program is telling you you need 4.7 + 4.7 gal for 9.4 gallons of total water for a recovery of 7.2 gallons of pre-boil water.  Your mash tun dead space is 0.75 gal, so that means that you have a grain absorption of 9.4 gal - 7.2 gal - 0.75 gal = 1.45 gal.  At 0.1 gal/lb, you grain bill is 14.5 lbs of grain.

So your initial infusion should be set for 3.6 gal + 0.75 gal +1.45 gal = 5.8 gallons initial infusion to drain out 3.6 gallons of wort.  This will leave 9.4 gallons - 5.8 gallons = 3.6 gallons of sparge water to add.

So you can edit your mash profile step for the initial infusion and set the infusion volume for 5.8 gallons and you should get approximately the same volume collected from the mash as the sparge.

Just to note, Denny has said that the volumes don't need to be exact to maximize the extraction efficiency but the idea is the avoid a gross imbalance between the first runnings and the second runnings.  As such, I have set up my profile to reflect an average grain bill and use that for all my recipes.  It makes life so much simpler instead of adjusting the infusion volumes for every single recipe. 

 
This is good.  It really got be thinking and I understand it much better now.  I still don't quite see why Beersmith chose to mash in with 4.7 gallons and then sparge with the same quantity, but I see what is happening. 

For the record the grain bill is 11.95Lb, so the absorption will be ~0.1 x 11.95=1.2 gallons.

The way I am thinking now, after reading your response is that in order to yield 3.6 gallons (half the boil volume) out of the mash, I need to mash in with 3.6 + 0.75 deadspace loss + 1.2 absorption loss = 5.6 gallons.

Then for the sparge I will need to add the other 3.6 gallons to yield a total of 7.2.  This is more or less what you stated. 

That is what I need to do, but in order for the Beersmith step by step instructions to be in line with this I need to change the Mash profile to reflect the different infusion volume.  I can do that but it seems to me I am going to be doing this math and changing the infusion values for every mash.  If my grain bill changes significantly then the values are going to change.  I would like to do this once (like the equipment profile settings) and forget about it.

Do you recalculate the losses for every mash and then go into the mash profile and change the volumes to be inlne with what you calculated?

Thanks for all the help & guidance,

Paul

 
As I had stated, I build the profile around an average batch for me (somewhere about 1.055 gravity) and let it ride from there.  While you can do the calculations for every single batch, it is much easier just to pick a mid-range recipe and keep the process consistent in terms of infusion water based upon grain amount and allow the sparge water to vary just a little bit.  It makes much more efficient for me to just keep with the one profile. In the end, the wort collected from first and second runnings will be close to equal.

As with all the profiles in BeerSmith, they are meant to be customized to your particular system and practices.
 
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