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Mash/Sparge water calculation

Merkur

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Feb 7, 2017
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Hi - I have just started using BeerSmith and am brewing the same recipe I did a couple of months ago with a few tweaks.  When I last brewed this batch, BeerSmith called for 13.7 quarts of strike water at 163F, followed by 4.99 gallons of sparge water at 168F.  The grain bill is 8.6Lbs.

The problem I have is that when I collected the wort prior to boiling, I collected the required 6.6 gallons and there was an 'Extra' 2.5 quarts in the mash tun.  This was at 1.015 so I still had sugars left that I would like to use to increase my efficiency.

The question I have is what parameter(s) do I change in BeerSmith to ensure I maximize the efficiency and get all the goodness I can out of the grains?  I do not want to 'brute force' it by just sparging with 2.5 quarts less because this may not be the right amount when I brew other beers.  The way I understand it, the runnings at the end of the sparge should be approaching 1.010 if the mash and sparge has been done correctly.  I have set up a Brewhouse profile with the following parameters if it helps:
Batch Size: 5.50 gal
  • Mash Volume: 10.00 gal
    Boil Volume: 6.64 gal
    Mash Tun Weight: 10 lbs
    Evaporation Rate: 9.0 % 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: 0.30 gal Cooling Loss (%): 4.00
    Top up water for Fermenter: 0.00 gal 


Thanks,

Paul
 
Paul,

Let's break this down by parts.  First, I assume -- perhaps wrongly -- that you are performing a fly sparge.(?)

If so, then you will always have some sugars left in the lauter tun, and there is nothing wrong with that.  Your comment about "the runnings at the end of the sparge should be approaching 1.010 if the mash and sparge has been done correctly." is perhaps taken out of context.  The warning of a final gravity of 1.010 in the final runnings is a minimum reading to prevent extraction of unwanted flavors and compounds from the grains (such as tannins).  Actually, I think a safer place is around 1.012-1.014, depending upon the OG of the recipe.

If you were to try to run the gravity of a large grain bill for a high gravity beer down to 1.010, you would end up with pails and pails of wort and a lot of boiling ahead of you to bring the gravity back up to where you wanted.

Next, I would suggest that your goal should be more to get a consistent efficiency and extraction from the grains instead of the maximum you can get.  The maximum efficiency could be achieved by doing a congress mash, wherein you grind all your grains into near flour.  I've done this before on a very small scale just to follow the procedure.  It works well to characterize the potential of the grain used, but makes for a very unappetizing wort. 

My goal in my process is to produce a consistent mash/lauter efficiency so that I can always accurately reproduce a recipe and predict what my outcome will be for a new recipe.  In effect, my "maximum" efficiency is the efficiency that maximizes my ability to achieve consistent results.

I've only done fly sparging a couple of times, but have seen it performed properly a good number of times.  Most people who fly sparge are draining their first runnings and then trying to create a slow "plug flow" of sparge water through the bed of grains, creating a gradient of sugar content from top to bottom with the sugars are extracted and concentrated as the plug of water flows down through the grain bed.  The sparge water is then shut off as the volume in the kettle nears the target pre-boil volume and the flow of wort shut off at the point where that volume is reached.  If they calculated correctly, there will be very little wort left in the mash tun, but some brewers will add additional water to ensure they reach the desired volumes.

Since you know you have excess wort left in your mash/lauter tun, you can be assured that the water balance in your process is off by at least that amount.  Bringing this into balance should not affect other recipes, as BeerSmith will use the grain absorption and boil off rates to adjust the amount of water in the mash and sparge based upon your grain bill and extraction efficiency.  Once you have your system in balance, the program will make the adjustments in water requirements to give you a consistent pre-boil volume.  I am guessing that your 0.75 gal of dead space is measured.  Using your water loss through your mash/lauter tun and this measured dead space, you should be able to calculate your grain absorption and update the program with that number.

Check your boil off rate and you can adjust the equipment profile to match your measured values.  This should bring your water requirements closer in line to your actual needs.

One of the things you left out of your equipment profile is your measured or intended brew house efficiency.  This should be adjusted based upon the results of a few brew sessions to reflect your actual values.  I keep a running spreadsheet of my important variables (grain absorption, boil off rate, process losses, fermenter volume, bottling volume, and efficiencies) to keep track of my process and variability.  It quickly lets me know if I am drifting or have suddenly changed in how I am using the process. 

Sorry for the long diatribe, but I hope this helps somewhat.
 
This is good news and validates what I have been thinking.

Namely:
- it is not that important that the end of sparge wort from the mash tun is close to 1.010.  This is a warning flag at which sparge should be stopped rather than a design value.  On my latest batch yesterday, the wort was at 1,018 out of the mash tun after I had collected 6.6 gallons.  The pre-boil SG was at 1.041 vs the Beersmith design value of 1.038 so I believe the mash/sparge process was efficient.
- I think I am leaning against fly sparging.  I have done 4-5 batches using fly sparging and the results are not consistent.  I either run out of sparge water too soon (30 mins) or it is still dribbling out after an hour.  I am going to try a brew using batch sparging.  Any tips there?
- I re-examined the Brewery profile I had created and realized that the 'loss due to trub' factor (the 'deadspace' at the bottom of the kettle) was about 0.5 gallons too low.  I have updated the profile and  predictably the amount of wort to be collected in the kettle prior to boil has gone up. 
- I now collect any remaining wort from the mash tun and put it aside for top-up (after boiling) later in the process should I need it.

This all seems so easy, but I am realizing that there is a lot of complexity to it and I cannot get too precise with the measurements.  The collected work volume out of he mash tun for example will expand 5% or so from the warm wort to boiling point.  I do not think that is taken into account.  I believe the intent is that the collected wort volume is the volume at the time it starts boiling.  This will be more than that collected at after sparging.  Inevitably there will be batches that I may have to top up with water in order to get the 5.5 gallons I need into the fermenter.  Is that a bad thing?  I don't think so.

Thanks for your well thought out and thought provoking response.  I like the idea of your process spreadsheet to track losses and process repeatability.  I may have to develop one of those.

Regards,

Paul
 
Merkur said:
This is good news and validates what I have been thinking.

Namely:
- it is not that important that the end of sparge wort from the mash tun is close to 1.010.  This is a warning flag at which sparge should be stopped rather than a design value.  On my latest batch yesterday, the wort was at 1,018 out of the mash tun after I had collected 6.6 gallons.  The pre-boil SG was at 1.041 vs the Beersmith design value of 1.038 so I believe the mash/sparge process was efficient.
- I think I am leaning against fly sparging.  I have done 4-5 batches using fly sparging and the results are not consistent.  I either run out of sparge water too soon (30 mins) or it is still dribbling out after an hour.  I am going to try a brew using batch sparging.  Any tips there?
- I re-examined the Brewery profile I had created and realized that the 'loss due to trub' factor (the 'deadspace' at the bottom of the kettle) was about 0.5 gallons too low.  I have updated the profile and  predictably the amount of wort to be collected in the kettle prior to boil has gone up. 
- I now collect any remaining wort from the mash tun and put it aside for top-up (after boiling) later in the process should I need it.

This all seems so easy, but I am realizing that there is a lot of complexity to it and I cannot get too precise with the measurements.  The collected work volume out of he mash tun for example will expand 5% or so from the warm wort to boiling point.  I do not think that is taken into account.  I believe the intent is that the collected wort volume is the volume at the time it starts boiling.  This will be more than that collected at after sparging.  Inevitably there will be batches that I may have to top up with water in order to get the 5.5 gallons I need into the fermenter.  Is that a bad thing?  I don't think so.

Thanks for your well thought out and thought provoking response.  I like the idea of your process spreadsheet to track losses and process repeatability.  I may have to develop one of those.

Regards,

Paul

When I am not doing a full volume BIAB, I do a batch sparge.  I find it a lot easier and quicker than fly sparging.  I drain the wort out of the mash tun then add the sparge water and stir vigorously to redistribute the grains.  I allow it to sit for about 20 minutes before vorlaufing and draining.  It is a lot easier to nail down your volumes with a batch sparge and to make corrections as I go.  I don't worry so much about the temperature of the sparge anymore as I have found it drains pretty much the same if the wort is at 165F or 145F.  I am usually bringing my initial runnings up towards a boil as I do the sparge anyway, so that stops further enzyme activity.

BeerSmith uses the thermal expansion coefficient on all hot volumes.  In my calculations, it does not scale this value based upon the temperature being less than boiling.  Since my critical measurements of volume are between 150F and 160F, I've set my thermal expansion to 2% and that seems to balance out the system accurately between strike water, sparge water and collected wort.  So while you are correct that the wort volume expands between the temperature of collection and boil, this is kind of ignored by the software.


 
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